- Email: [email protected]
Profiles of spontaneous 24-hour and stimulated growth hormone secretion in male patients with endogenous depression
Psychiatry
215
Research, 471215-227
Elsevier
Profiles of Spontaneous 24-hour and Stimulated Growth Hormone Secretion in Male Patients With Endogenous Depression Ulrich Voderholzer, Gregor Laakmann, Reinhold Wittmann, Claudia Daffner-Bujia, Anita Hinz, Clemenz Haag, and Thomas Baghai Received
February
14.1992;
revised
version
received
January 25, 1993; accepted
February
18, 1993.
Abstract. Abnormalities of both the spontaneous and the stimulated release of growth hormone (GH) have been described in patients with endogenous depression. In this study, six unmedicated male patients with endogenous depression (ICD 296.1/3) were compared with six age-matched healthy men. Levels of GH were determined at 15minute intervals over 26 hours. A combined releasing hormone test was performed during the last 2 hours of blood sampling. The 24-hour profile of GH secretion was significantly lower in the depressed patients than in the healthy control subjects due to a significantly diminished sleep-related GH secretion. GH stimulation following releasing hormones was lower in the depressed patients than in healthy subjects. Hypersecretion of GH before the stimulation test might therefore not explain the blunted GH response to stimulation that has been observed in depressive patients. Key Words. Affective hormone, sleep, circadian
disorder, melancholia, growth rhythm, polysomnography.
hormone
releasing
Among the biological abnormalities found in patients with endogenous depression, disturbances of growth hormone (GH) secretion (Laakmann, 1980; Laakmann et al., 1990) and of polysomnographic sleep parameters (e.g., reduced latency and increased density of rapid eye movement sleep) have been described by many authors (Kupfer and Foster, 1972; Gillin et al., 1979; Reynolds and Kupfer, 1987; Benca et al., 1992). In most studies of GH secretion, various stimulation tests have been used because GH secretion is low during daytime (Takahashi et al., 1968) and single basal values do not indicate whether the somatotropic system is intact, Following stimulation by insulin hypoglycemia (Mueller et al., 1969), desimipramine (Laakmann, 1980), clonidine (Matussek et al., 1980; Checkley et al., 1981), and growth hormone releasing hormone (GHRH) (Laakmann et al., 1986a, 1990; Lesch et al., 1987), endogenous depressive patients show a diminished GH response compared with that of healthy age- and sex-matched control subjects. Studies examining the spontaneous secretion of GH are rare, however, because of the effort that is necessary to perform such investigations in unmedicated depressed patients. In 1975,
Ulrich Voderholzer, M.D., was Resident; Gregor Laakmann, M.D., is Professor and Chief; Reinhold Wittmann, M.D., is a graduate student; and Claudia Daffner, M.D., Anita Hinz, M.D., Clemenz Haag, M.D., and Thomas Baghai, M.D., are medical staff members, Inpatient Research Unit, Psychiatric Hospital, University of Munich. (Reprint requests to Dr. med. U. Voderholzer, Psychiatrische Klinik der Universitlt, Nussbaumstr. 7, 8000 Miinchen 2, Germany.) 01651781/93/SO6.00
@ 1993 Elsevier Scientific
Publishers
Ireland
Ltd.
216
Schilkrut et al. reported a diminished or even absent nighttime secretion of GH in a small group of endogenous depressive patients. Similar results have been obtained by Jarrett et al. (1985, 19906) and Steiger et al. (1989), who also reported a diminished GH release during the first hours of sleep in depressive patients compared with healthy control subjects. None of the authors cited above who found a diminished nocturnal GH release in depressives, however, measured the daytime GH secretion. in healthy subjects, GH concentrations are lower than 1 ng/ ml during most daytime hours, but occasional peaks may occur (Finkelstein et al., 1972). In 1985, Mendlewicz et al. reported that male patients with endogenous depression had a marked increase of daytime GH secretion during the acute state of the illness. Some of these patients were also studied after remission of their depressive symptomatology, and a normalization of their daytime GH values was found (Linkowski et al., 1987). In a study by Rubin et al. (1990), depressive patients showed relatively normal GH values with a trend, however, toward a lower nighttime secretion in the more severely depressed patients. It has not sufficiently been studied whether alterations of the GH response to various stimuli are associated with alterations of spontaneous GH release in endogenous depressed patients. Because the findings of the few previous reports that have described the spontaneous GH secretion in endogenous depression are not equivocal, the following three hypotheses were considered in the study reported below: (1) The spontaneous GH secretion is not altered and only the pituitary GH response to various stimuli is diminished in endogenous depression. (2) Both spontaneous GH secretion and stimulated GH secretion are inhibited by a still undefined mechanism. (3) The spontaneous GH secretion is elevated and leads to an inhibition of GH stimulation through feedback mechanisms. Methods Subjects. Six male patients with endogenous depression were included in this combined sleep and endocrine study. They were diagnosed according to ICD-9 (World Health Organization, 1978) Research Diagnostic Criteria (RDC; Spitzer et al., 1978; Endicott and Spitzer, 1979) and the Newcastle endogenous index (Carney and Sheffield, 1972; Roth et al., 1983). All patients met DSM-111 criteria for melancholia (American Psychiatric Association, 1980). Their mean age was 30.5 (SD = 8) years, and all were of normal height (mean = 180 cm, SD = 7 cm) and weight (mean = 77 kg, SD = 8 kg). Only severely depressed patients who came to the hospital in a drug-free state were chosen after provision of informed consent. The mean score on the Hamilton Rating Scale for Depression (Hamilton, 1960) was 31 (SD = 4) (Table I). All patients scored in the endogenous range (> 5) of the Newcastle index (mean = 8.7, SD = 1.5). The investigation was performed during the first days after admission. Two patients had never received any psychotropic medication; the other four patients had been previously treated with antidepressants but had been withdrawn from all medication at least 4 weeks before admission to the hospital. Six age-matched healthy male subjects between the ages of 22 and 40 years (mean = 30.2, SD = 7) consented in writing to serve as controls. All subjects were of normal height (mean = I83 cm, SD = 8 cm) and weight (mean = 76 kg, SD = 8 kg). Subjects with sleep difficulties, shift workers, or subjects with any personal or family history of psychiatric disorders were excluded. Intake of any drugs was prohibited during the preceding 4 weeks, and alcohol intake was not permitted 24 hours before the study began.
217
Table 1. Male patients with endogenous
depression:
data
Me
1
296.3
22
36
11
2
296.1
23
36
9
3
296.1
25
30
8
4 weeks
2 months
4
296.3
32
30
9
4 weeks
5 months
5
296.3
37
28
7
3 years
3 weeks
6
296.1
44
28
8
4 months
2 months
30
31
8.7
3.8 months
8
4
1.5
3.6
Mean SD
+= Never
Washout period
Duration of depression
Diagnosis
No.
Newcastle score
Demographic
HRSD score
l
II
2 weeks 10 months
treated with psychotropic medication. HRSD = Hamilton Rating Scale for Depression.
All control subjects and patients had a full hematology and neurological examinations, and electrocardiographic examinations.
and chemistry screen, physical and electroencephalographic
Procedure. Each investigation lasted 4 days and was performed in the sleep laboratory of the Psychiatric Hospital of the University of Munich. Polysomnographic assessments were obtained over 3 consecutive nights with electroencephalographic, horizontal electro-oculographic, and submental electromyographic lead placements. The polysomnograms were visually analyzed according to the criteria of Rechtschaffen and Kales (1968). Sleep onset was defined as the first half-minute epoch of stage 2 sleep followed by at least two epochs of any sleep stage. Rapid eye movement (REM) latency was defined as the time in minutes from sleep onset to the first half-minute epoch of stage REM. Stages 1,2, 3,4, and REM were calculated in minutes as well as percentages of the total sleep time. During the first 2 nights, polysomnographic data were obtained for adaptation to the laboratory conditions and to get baseline sleep parameters. Electrodes were fixed between 7 and 8 p.m. Subjects were not permitted to sleep before IO:30 p.m. On day 3, after the second night in the sleep laboratory, control subjects and patients received a standardized breakfast at 7:15 a.m. At 7.45 a.m., an indwelling catheter (Kowarski-Dakmed thromboresistant blood withdrawal needle and tubing set, 5 ft.) was placed in a forearm vein. Blood was continuously drawn from 8:30 a.m. (day 3) until IO:30 a.m. (day 4) with a constant speed of 15 ml/hour by using a pump (Dakmed ambulatory withdrawal pump, Model ML 6-SH). Blood was sampled at 15-minute intervals over the whole period, centrifuged every hour, and stored at -20” C until analysis. During the day, subjects received lunch and dinner at standardized times (noon and 5 p.m.). They were advised not to sleep before IO p.m. To document whether sleep stages occurred during daytime in spite of this order, daytime electroencephalographic activity was monitored continuously until the end of the study. The total number of GH measurements of each test was 104. During the night, the blood withdrawal catheter was placed through a soundproof lock in an adjacent room to avoid disturbances by the withdrawal procedure. The third polysomnographic examination took place on the same night that blood was drawn. At 8:30 a.m. on day 4, exactly 24 hours after the beginning of the blood sampling, a combined releasing hormone test was performed, as it was first described by Sheldon et al. (1985). Subjects and patients were not allowed to eat or drink within 10 hours preceding the releasing hormone injection. Throughout the test, they remained recumbent and were advised to remain awake. Electroencephalographic monitoring was continued until the end of the test at IO:30 a.m. Four releasing factors were given as slow intravenous bolus injections over 4 minutes in standardized order: CHRH, 100 ,ug. I minute; corticotropin releasing hormone (CRH), 100 pug, 30 seconds; gonadotropin releasing hormone (GnRH), 100 pg. 30 seconds; and thyrotropin releasing hormone, 200 pg, 2 minutes. Dose-response studies with GHRH have shown that intravenous administration of 100 pg or 1 I_rg/kg induces a maximal GH
218 response in healthy human subjects (Gelato et al., 1984). A recent study in healthy humans performed by Him et al. (1990) demonstrated that the simultaneous injection of all four releasing hormones has an equal stimulatory capacity to that of the injection of GHRH alone. In this article, we only refer to GH values and sleep electroencephalographic recordings. Levels of GH secretion were determined by the CIS Human Growth Hormone Radioimmunoassay (Gif-sur-Yvette, France). The sensitivity was 0.25 ng/ml, and intra-assay and interassay coefficients of variation were 7.6% and 1 1. I%, respectively. GH secretion was evaluated by descriptive analysis of the single hormone curves and by estimation of the integrated GH secretion by calculation of the area under the curve (AUC) as follows: AUC,t_t2 = Ztl_t2 X 15 (1 = Sum). AUCs were obtained for the total GH secretion over the 24 hours before the stimulation test (8:30 a.m. on day 3-8:30 a.m. on day 4) and within 2 hours following stimulation (8:30 a.m.-IO:30 a.m. on day 4). The integrated amounts of the diurnal and the sleep-related GH secretion were calculated according to the actual sleep-wake cycle, which was recorded by polysomnography. In addition, GH release during the first half of the sleep period was compared to that during the second half of the sleep period by calculating the AUCs of GH secretion during the first 180 minutes after actual sleep onset and of the GH secretion that occurred thereafter until the end of the sleep period. For statistical analysis, values were log-transformed to normalize the distribution. Student’s t test for independent samples was used to test for significant differences between depressed
patients and healthy subjects. Correlations moment correlations.
were evaluated by calculating
Pearson product-
Results Individual 24-hour GH Profiles. There was high interindividual variability of the 24-hour secretion of GH among both the endogenous depressive patients and the healthy control subjects (Fig. 1). An increase of GH concentrations above 5 ng/ml during the sleep period occurred in four of the six depressive patients and in all six control subjects. Half of the depressed patients and the control subjects additionally had GH peaks > 5 ng/ ml during the day. Two of the daytime peaks in the depressed patients occurred in the late evening hours within 3 hours before sleep onset. Mean Curves. Examination of the mean GH curves makes clear that the nocturnal increase was markedly lower in the depressed patients than that in the healthy control subjects (Fig. 2). Comparison of the mean GH profiles demonstrates a flattening of the curve in the depressed patients compared with the control subjects. Integrated Measures of 24-hour and Diurnal GH Secretion. The AUCs of the total 24-hour GH secretion were between 814 and 2158 ng/ml X 24 hours in the depressive patients and between 1439 and 7870 ng/ml X 24 hours in the control subjects. The 24-hour integrated amounts were markedly lower in the depressed (mean = 1490 ng/ml X 24 hours, SD = 550) as compared with the healthy subjects (mean = 3913 ng/ ml X 24 hours, SD = 2180). Fig. 3 shows the individual log-transformed AUCs of GH secretion. The depressive patients differed significantly (p = 0.02) from the healthy controls with regard to the 24-hour GH secretion. The integrated amounts of the diurnal GH release were comparable in the two groups of subjects (patients: mean = 629 ng/ ml X 12 hours, SD = 540; control subjects: mean = 964 ng/ml X 12 hours, SD = 860) (Fig. 3).
219
Fig. 1. Twenty-six-hour growth hormone profiles of 6 unmedicated male patients with endogenous depression (296.113, left panel) vs. 6 healthy age-matched male control subjects (right panel) conirols
depressives
_-
02
AId .-.
amom
am
0o.m
pm
Ih*
I.rn
pm
tl.%J-
‘-
ma pm
00.00
6.00 orn
Iha
Blood samplings began at 630 a.m. and finished at 1050 a.m. on the following day. The individual sleep period time is indicated as below the horizontal axis. Twenty-four hours after blood sampling began, acombined releasing hormone test (indicated as “PEP’) was performed. The combined test consisted of the simultaneous injection of growth hormone releasing hormone, 100 pg; corticotropin releasing hormone, 100 pg9;gonadotropin releasing hormone, 100 pg; and thyrotropin releasing hormone, 200 pg.
220 Fig. 2. Mean 24-hour GH curves (mean f SE) of 6 endogenous patients and 6 age-matched healthy male subjects
depressive PEP
GH @g/ml) 4035 -
sleep period 3025 zo15 -
l
l
controls
*
*
depressives
IO5: o--,......~.....,.....,.....,.....,....’,””’,””,“” a.30 o.m.
12.00
0.m.
6.00
pm”
00.00
6.00
a.m.
a.30 o.m
time Twenty-four hours after blood sampling began, a combined releasrng hormone test (indrcated as “PEP”) was performed. The combined test consisted of the simultaneous injection of growth hormone releasing hormone, 100 pg; corticotropin releasing hormone, 100 ,ug; gonadotropin releasing hormone, 1OOpg: and thyrotroprn releastng hormone, 200 /lg.
Fig. 3. Comparison of the log-transformed AUCs (ng/ml/time) of GH secretion during the whole 24-hour period (8:30 a.m.-8:30 a.m.), during the sleep period, and after a combined releasing hormone test (8:30 a.m.lo:30 p.m.) in 6 male endogenous depressive patients and 6 age- and sex-matched healthy male subjects 4 GH (AUC, ng/ml x time, log-transformed) 0 1
:
3.5 $
l
0 l l
i?k
depr.
2 0
controls
24-hours
AUC = area under the curve. GH = growth hormone.
depr.
0 0 0
controls
sleep-related
depr.
controls
GH stimulation
221 Sleep Parameters and Sleep-related GH Secretion. Sleep parameters differed between the depressive patients and the healthy control subjects during the night when blood samples were drawn. Mean sleep efficiency was 82% (SD = 13%) in the depressive patients compared with 91% (SD = 7%) in the control subjects (Table 2). This diminution was mostly due to a diminished time spent in stages 2 and 4, whereas the mean time spent in the other sleep stages did not differ between patients and control subjects. Sleep onset occurred between IO:30 p.m. and midnight in all depressive patients and control subjects (mean times of sleep onset did not differ between the two groups). The length of the first non-REM period was lower and the REM latencies were shorter in the depressive patients than in the healthy subjects. Two of the depressive patients, both of whom were older than 35 years of age, showed a sleep onset REM period. Early morning awakening was observed in three of the depressed patients and in none of the control subjects. Table 2. Sleep parameters during the night of continuous blood sampling in 6 male endogenous depressive patients vs. 6 age-matched healthy male subiects Depressive patients
Time of sleep onset
Control subjects
Mean
SD
Mean
SD
231 Oh
19 min
26 min
2303h
Sleep period time
491
47
454
22
Total sleep time
378
71
407
31
Sleep latency
24
11
19
21
REM latency
50
47
aa
27
68
24
a7
22
Stage W
Length of 1st non-REM
93
a2
42
34
Stage 1
39
14
38
26
Stage 2
195
53
224
41
Stage 3
40
24
33
22
Stage 4
a
12
23
25
93
17
a7
28
a2
13%
91
Stage REM Sleep efficiency
period
7%
Note. Values given are In minutes unless otherwise indicated. REM = rapid eye movement.
The depressed patients had diminished integrated GH amounts during the sleep period (Fig. 3). The mean AUC of the sleep-related release was markedly and statistically significantly (p < 0.01) lower in the depressive patients (mean = 659 ng/ml/time, SD = 380) than in the healthy subjects (mean = 2760 ng/ml/time, SD = 1550). The major part of the sleep-related GH secretion occurred during the first 180 minutes after sleep onset in both patients (mean = 508 ng/ml/ 3 hours, SD = 370) and control subjects (mean = 2045 ng/ ml/ 3 hours, SD = 930; p < 0.01). The timing of the sleep-related GH maximum was similar in the depressed and control subjects. The mean latency of the GH maximum after sleep onset was 100 (SD = 52) minutes in the depressive patients and 75 (SD = 21) minutes in the healthy control subjects. This difference was not statistically significant. The beginning of the sleep-related GH increase occurred during the first non-REM period in five of six
222 depressed patients and was temporally related to slow wave sleep (SWS) in three of them. The amount of GH secreted during the first non-REM period, however, did not correlate with the length of the first non-REM period or with percentage of SWS. The analysis of two cases with a sleep onset REM period revealed that GH concentrations did not increase during this sleep onset REM period but during the following non-REM period. In two depressed patients, a GH peak occurred within 3 hours before sleep onset. In five of six control subjects, the beginning of the sleeprelated GH increase occurred during the first non-REM period and coincided with SWS in all of them. In one control subject, GH markedly increased 1 hour before sleep onset and reached its maximum during the first non-REM period. Four of six control subjects had small GH increases (between 2 and 6 ng/ml) within 3 hours before sleep onset. Neither the depressive patients nor the healthy subjects showed significant correlations between sleep parameters and the AUCs of sleep-related GH secretion. During the second half of the sleep period after the first 3 hours of sleep, mean GH AUCs were 151 (SD = 76) and 716 (SD = 850) ng/ml/time in the depressive patients and the control subjects, respectively; this difference was not significant. GH Stimulation After Releasing Hormones. GH secretion was stimulated 24 hours after the beginning of the blood sampling period with a combined releasing hormone test. The maximum increase varied between 8.4 and 55 ng/ml in the depressive patients and between 79.7 and 19.4 ng/ml in the healthy subjects (Fig. 1). The AUCs of GH stimulation were lower in the depressed patients (mean = 1477 ng/ml X 120 minutes, SD = 1130) compared with those in the control subjects (mean = 2876 ng/ml X 120 minutes, SD = 1160). Statistical evaluation revealed a trend toward lower values in the depressive patients (p = 0.06). Fig. 3 shows the logtransformed AUCs of GH stimulation. Fig. 4 summarizes the results by demonstrating the mean integrated amounts of the total 24-hour GH secretion, the diurnal and the GH stimulation following releasing and sleep-related GH secretion, hormones in the depressed patients and the healthy subjects.
Discussion This study was undertaken to evaluate whether disturbances of GH secretion in response to stimulation are combined with alterations of the spontaneous 24-hour pattern of GH secretion in patients with endogenous depression. The main finding of this investigation was a reduction of the 24-hour integrated GH levels in six severely depressed male patients compared with those in healthy male control subjects. This reduction in turn reflected a marked reduction of the sleep-related GH release, a finding that is in agreement with earlier findings of Schilkrut et al. (1975), Jarrett et al. (1985, 19906), and Steiger et al. (1989). Even a long-lasting drug effect of previous treatment can be excluded since two of the patients were completely “drug-naive” and the others were studied after a long drug-free interval. An age effect also cannot explain this diminution of the spontaneous GH release since our comparatively young group of patients was compared with young healthy subjects of equal mean age. The spontaneous GH secretion of the depressed male patients was similar to
223
Fig. 4. Mean integrated amounts (AUCs, ng/ml/time, mean f SE) of the total 24-hour period, of the diurnal and the sleep-related GH secretion, and of the GH stimulation following a combined releasing hormone test in 6 male endogenous depressive patients and 6 age-matched healthy male subjects GH (AUCs, nglmb‘time) 5000
m
patients
controls
AUC = area under the curve. GH = growth hormone
that of older subjects (Carlson et al., 1972; Prinz et al., 1983). Our findings are in contrast to a study of Mendlewicz et al. (1985), who reported elevated 24-hour integrated GH levels in depressed patients compared with those in healthy control subjects due to a diurnal hypersecretion. The mean age of our patients, however, was much lower than that in the patients studied by Mendlewicz et al. (1985). In a study by Rubin et al. (1990), the 24-hour GH levels were not different in depressive patients than in control subjects, but there was a trend toward lower levels in the more severely depressed patients. Our findings are in agreement with the assumption of SouZtre et al. (1989) that a blunted amplitude is the main chronobiological abnormality in depression. The diminution of the sleep-related GH secretion was due to a reduction within the first 180 minutes after sleep onset, whereas during the second half of the night, no significant difference could be observed. This is in agreement with a study by Jarrett et al. (19906), who also reported a lowered GH secretion within the first 3 hours but not in the second half of sleep. In our study, the depressed patients did not differ from the healthy subjects with regard to the temporal relationship of GH secretion and sleep. The major part of GH secretion occurred during the first 180 minutes after sleep onset in both groups. The sleep-related GH increase began during the first non-REM period and the latency of the GH maximum relative to sleep onset was similar in both groups. When GH secretion began to increase, SWS was present in most (but not all) patients and control subjects; however, the amounts of sleeprelated GH release did not correlate with any of the sleep parameters in both groups. This agrees with several studies of GH and sleep that demonstrated a temporal
224 relationship between sleep-related GH secretion and the first non-REM period but no consistent relationship to SWS (Othmer et al., 1974; Weitzman et al., 1974; Born et al., 1988; Jarrett et al., 1990~). It was also shown that the sleep-related GH surge can be pharmacologically modulated without affecting SWS (Parker et al., 1974; Weitzman et al., 1982; Jarrett et al., 1988). In our group of comparatively young depressive patients, the total amount of SWS was similar to that of young subjects, whereas other parameters like REM latency, early morning awakening, and sleep efficiency differed between the depressed patients and the healthy control subjects. Our study indicates that the diminution of nocturnal GH secretion and the alterations of sleep parameters in depressive patients are not related to each other. GH response to releasing hormones was lower in the depressed patients compared with that in the healthy control subjects in this study. This confirms earlier findings with GHRH as the stimulus (Laakmann et al., 1986a, 1990; Lesch et al., 1987). The simultaneous application of four releasing hormones, as was done in this study, has an equal GH stimulatory capacity to the injection of GHRH alone (Sheldon et al., 1985; Schopohl et al., 1986; Ho11 et al., 1988; Hinz et al., 1990). A diminished GH stimulation in depressed patients is a well-known finding and was also observed with the use of other stimuli such as insulin hypoglycemia (Mueller et al., 1969) clonidine (Matussek et al., 1980) and desimipramine (Laakmann, 1980). This study in our small but homogeneous group of patients indicates that depression is associated with a decrease of total 24-hour GH secretion, sleep-related GH secretion, and stimulated GH release. A diminution of the GH response to stimulation with releasing hormones also seems to reflect a diminution of the spontaneous GH release. This underlines previous findings in a large sample of healthy subjects, showing a significant correlation between spontaneous 24-hour GH secretion and releasing hormone-induced GH stimulation (Voderholzer et al., in press). Therefore, neither a negative feedback effect nor an emptying of the quickly releasable pituitary GH storages secondary to an elevated spontaneous GH secretion would appear to account for the blunted GH response to stimulation in endogenous depression or to explain the diminution of the sleep-related GH release in this study. It is most likely that inhibitory factors lead to a reduction of both the spontaneous and stimulated secretion of GH. Such inhibiting factors could be an increased activity of central /3-adrenergic receptors, a hypothesis that is supported by the facts that P-adrenergic receptors are inhibitory to GH stimulation (Laakmann et al., 19866, 1991; Mauras et al., 1987) and that antidepressants lead to a downward regulation of /?-receptors in the brain (Sulser, 1981). Other inhibitory factors could be elevated central concentrations of CRH, which have been shown to induce a significant blunting of the sleep-related release of GH in men (Holsboer et al., 1988). This explanation would agree with the assumption of a CRH hypersecretion in depression (Banki et al., 1987; Nemeroff et al., 1988). In conclusion, this study demonstrates that male endogenous depressive patients, compared with healthy age-matched male control subjects, show a diminution of both spontaneous 24-hour GH secretion and GH secretion following stimulation with releasing hormones.
225 Acknowledgments. The authors thank Mrs. Birgit Beck for technical assistance and Mrs. Heike Gluba for performing all the growth hormone measurements. This study was supported by the Deutsche Forschungsgemeinschaft, Schwerpunktprogramm Neuropeptide (LA 418/5I, 5-2).
References Psychiatric Association. DSM-III: Diagnostic and Statistical Manual of Mental 3rd ed. Washington, DC: American Psychiatric Press, 1980. Banki, C.M.; Bissette, G.; Arato, M.; O’Connor, L.; and Nemeroff, C.B. CSF corticotropin-releasing factor-like immunoreactivity in depression and schizophrenia. American American
Disorders.
Journal
of Psychiatry,
144:873-877,
1987.
Benca, R.M.; Obermeyer, W.H.; Thisted, R.A.; and Gillin, J.C. Sleep and psychiatric disorders: A meta-analysis. Archives of General Psychiatry, 49:651-668, 1992. Born, J.; Muth, S.; and Fehm, H.L. The significance of sleep onset and slow wave sleep for nocturnal release of growth hormone (GH) and cortisol. Psychoneuroendocrinology, 13:233243, 1988.
Carlson, H.E.; Gillin, J.C.; Gorden, P.; and Snyder, F. Absence of sleep-related growth hormone peaks in aged normal subjects and in acromegaly. Journal of Clinical Endocrinology and Metabolism,
34:1102-l
105, 1972.
Carney, M.W.P., and Sheffield, B.F. Depression and the Newcastle scales: Their relationship to Hamilton’s scale. British Journal of Psychiatry, 12 1:35-40, 1972. Checkley, S.A.; Slade, A.P.; and Shur, E. Growth hormone and other responses to clonidine in patients with endogenous depression. British Journal of Psychiatry, 138:51-55, 1981.
Endicott, J., and Spitzer, R.L. Use of the Research Diagnostic Criteria and the Schedule for Affective Disorders and Schizophrenia to study affective disorders. American Journal of Psychiatry,
136:52-56,
1979.
Finkelstein, J.W.; Boyar, R.M.; Roffwarg, H.P.; Kream, J.; and Hellman, L. Age-related change in the twenty-four-hour spontaneous secretion of growth hormone. Journal of Clinical Endocrinology and Metabolism, 35:665-670, 1972. Gelato, M.C.; Pescovitz, O.H.; Cassorla, F.; Loriaux, D.L.; and Merriam, G.R. Doseresponse relationships for the effects of growth hormone-releasing factor-( l-44)-NH, in young adult men and women. Journal of Clinical Endocrinology and Metabolism, 59: 197-20 1, 1984. Gillin, J.C.; Duncan, W.; Pettigrew, K.D.; Frankel, B.L.; and Snyder, F. Successful separation of depressed, normal, and insomniac subjects by EEG sleep data. Archives of General
Psychiatry,
Hamilton, Psychiatry,
36:85-90,
M. A rating 23:56-62,
1979.
scale for depression.
Journal
of Neurology,
Neurosurgery,
and
1960.
Hinz, A.; Laakmann, G.; Daffner, C.: and Voderholzer, U. The simultaneous use of four releasing factors: Theoretical and practical issues. In: Bunney, W.E., Jr.; Hippius, H.; Laakmann, G.; and Schmauss, M., eds. Neuropsychopharmacology 1. Proceedings of the XVIth C. I. N. P. Congress, Munich, August 15-19. Berlin/ Heidelberg/New York: Springer, 1990. pp. 371-384. Holl, R.; Fehm, H.L.; Hetzel, W.D.; and Voigt, K.H. Globaler Hypophysenstimulationstest mit Releasinghormonen. Deutsche Medizinische Wochenschrtft, 110:953-955, 1988. Holsboer, F.; von Bardeleben, U.; and Steiger, A. Effect of intravenous corticotropinreleasing hormone upon sleep related growth hormone surge and sleep EEG in man. Neuroendocrinology,
48:32-38,
1988.
Jarrett, D.B.; Coble, P.; and Kupfer, D.J.; and Greenhouse, J.B. Sleep-related hormone secretion in depressed patients. Acta Psychiatrica Belgiae, 85:603-614, 1985. Jarrett, D.B.; Greenhouse, J.B.; Miewald, J.M.; Fedorka, LB.; and Kupfer, D.J. A reexamination of the relationship between growth hormone secretion and slow wave sleep using delta wave analysis. Biological Ps_vrhiatry, 27:497-509, 1990a.
226 Jarrett, D.B.; Miewald, J.M.; and Kupfer, D.J. Acute changes in sleep-related hormone secretion following oral imipramine. Biological Psychiatry, 24:541-554, 1988. Jarrett, D.B.; Miewald, J.M.; and Kupfer, D.J. Recurrent depression is associated with a persistent reduction in sleep-related growth hormone secretion. Archives of General Psychiatry,
47:
I 13-l 18, 1990b.
Kupfer, D.J., and Foster, F.G. Interval between onset of sleep and rapid eye movement sleep as an indicator of depression. Lancer, 1:684-686, 1972. Laakmann, G. Beeinflussung der Hypophysenvorderlappen-Hormonsekretion durch Antidepressiva bei gesunden Probanden, neurotisch und endogen depressiven Patienten. Nervenarzt,
5 11725-732,
1980.
Laakmann, G.; Hinz A.; Voderholzer, U.; Daffner, C.; Miiller, O.A.; Neuhauser, H.; Neulinger, E.; and Wittmann, M. The influence of psychotropic drugs and releasing hormones on anterior pituitary hormone secretion in healthy subjects and depressed patients. Pharmacopsychiatry,
23: 18-26,
1990.
Laakmann. G.; Munz, T.; Hinz, A.; and Voderholzer, U. Influence of clenbuterol, a fiadrenergic agonist, on desipramine induced growth hormone, prolactin and cortisol stimulation. Psychoneuroendocrinology, 15: l-9, 199 1. Laakmann, G.; Neuhauser, H.; Hinz, A.; Neulinger, E.; and Wittmann, M. Stimulation of growth hormone, prolactin and cortisol by GHRH and DMl in depressed patients. Pharmacopsychiatry,
19:235-236,
1986~.
Laakmann, G.; Zygan, K.; Schoen, H.W.; Weiss, A.; Wittmann, M.; Meissner, R.; and Blaschke, D. Effect of receptor blockers (methysergide, propranolol, phentolamine, yohimbine and prazosin) on desimipramine-induced pituitary hormone stimulation in humans: 1. Growth hormone. Psychoneuroendocrinology, 11:462-474, 1986b. Lesch, K.; Laux, G.; Pfiiller, H.; Erb, A.; and Beckmann, H. Growth hormone (GH) response to GH-releasing hormone in depression. Journal of Clinical Endocrinology and Metabolism,
65:1278-1281,
1987.
Linkowski, P.; Mendlewicz, J.; Kerkhofs, M.; Leclercq, R.; Golstein, J.; Brasseur, M.; Copinschi, G.; and van Cauter, E. Twenty-four-hour profiles of adrenocorticotropin, cortisol, and growth hormone in major depressive illness: Effect of antidepressant treatment. Journal of Clinical Endocrinology
and Metabolism,
65~141-152,
1987.
Matussek, N.; Ackenheil, M.; Hippius, H.; Miiller, F.; Schroder, H.T.; Schultes, H.; and Wasilewski, B. Effect of clonidine on growth hormone release in psychiatric patients and controls. Psychiatry Research, 2:25-36, 1980. Mauras, N.; Blizzard, R.M.; Thorner, M.O.; and Rogol, A.D. Selective P,-adrenergic receptor-blockade with atenolol enhances growth hormone releasing hormone and mediated growth hormone release in man. Metabolism, 36:369-372, 1987. Mendlewicz, J.; Linkowski, P.; Kerkhofs, M.; Desmedt, D.; Golstein, J.; Copinschi, G.; and van Cauter, E. Diurnal hypersecretion of growth hormone in depression. Journal of Clinical Endocrinology
Mueller, Archives
and Metabolism,
P.S.; Heninger, of General
60:505-512,
1985.
G.R.; and McDonald,
Psychiatry,
21:587-594,
R.K. Insulin tolerance
test in depression.
1969.
Nemeroff, C.B. The role of corticotropin-releasing factor in the pathogenesis of major depression. Pharmacopsychiatry, 21:76-82, 1988. Othmer, E.; Levine, W.R.; Marlakey, W.B.; Corvalan, J.C.; Hayden-Otto, M.P.; Fishman, P.M.; and Daughaday, W.H. Body build and sleep-related GH secretion. Hormone Research, 5:156-166,
1974.
Parker, D.C.; Rossman, L.G.; and Siler, T.M. Inhibition of the sleep-related physiologic human growth hormone release by somatostatin. Journal of Endocrinology
and Metabolism,
38:496-499,
peak in Clinical
1974.
Prinz, P.N.; Weitzman, E.D.; Cunningham, G.R.; and Karacan, I. Plasma GH during sleep in young and aged men. Journal of Gerontology, 38:5 19-524, 1983. Rechtschaffen, A., and Kales, A. A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Stages of Human Subjects. Los Angeles: UCLA Brain Information Service/Brain Research Institute, 1968. pp. I-60.
227 Reynolds, C.F. III, and Kupfer, D.J. Sleep research in affective illness: State of the art circa 1987. Sleep, 10:199-215, 1987. Roth, M.; Gurney, C.; and Mountjoy, C.Q. The Newcastle rating scales. Acta Psychiatrica Scandinavica, 310:42-54, 1983. Rubin, R.T.; Poland, R.E.; and Lesser, I.M. Neuroendocrine aspects of primary endogenous depression: X. Serum growth hormone measures in patients and matched control subjects. Biological Psychiatry, 27: 1065-1082, 1990. Schilkrut, R.; Chandra, 0.; Osswald, M.; Rtither, E.; Barfusser, B.; and Matussek, N. Growth hormone release during sleep and with thermal stimulation in depressed patients. Neuropsychobiology, 1:70-79, 1975. Schopohl, J.; Losa, M.; Konig, A.; Miiller, O.A.; Stalla, G.K.; and von Werder, K. Combined pituitary function-test with four hypothalamic releasing hormones. Klinische Wochenschrift, 64:3 14-3 18, 1986. Sheldon, W.R.; deBold, R.C.; Evans, W.S.; DeCharney, G.S.; Jackson, R.V.; Island, D.P.; Thorner, M.O.; and Orth, D.N. Rapid sequential intravenous administration of four hypothalamic releasing hormones as a combined anterior pituitary function test in normal subjects. Journal of Clinical Endocrinology and Metabolism, 60:623-630, 1985. Souetre, E.; Salvati, E.; Belugou, J.-L.; Pringuey, D.; Candito, M.; Krebs, B.; Ardisson, J.-L.; and Darcourt, G. Circadian rhythms in depression and recovery: Evidence for blunted amplitude as the main chronobiological abnormality. Psychiatry Research, 28:263-278, 1989. Spitzer, R.L.; Endicott, J.; and Robins, E. Research Diagnostic Criteria: Rationale and reliability. Archives of General Psychiatry, 35:773-782, 1978. Steiger, A.; von Bardeleben, U.; Herth, T.; and Holsboer, F. Sleep EEG and nocturnal secretion of cortisol and growth hormone in male patients with endogenous depression before treatment and after recovery. Journal of Affective Disorders, 16: 189-195, 1989. Sulser, F. New perspectives on the action of antidepressant drugs: Regulation of central adrenergic receptor function. In: Advances in Biological Psychiatry. Vol. 7. Basel: Karger, 198 1. pp. 90-99. Takahashi, Y.; Kipnis, D.M.; and Daughaday, W.H. Growth hormone secretion during sleep. Journal of Clinical Investigation, 47:2079-2090, 1968. Voderholzer, U.; Laakmann, G.; Hinz, A.; Daffner, C.; Haag, C.; Hofmann, H.-P.; and Boerschel, B. The dependency of the growth hormone (GH) stimulation following releasing hormones on the spontaneous 24-hour GH secretion in healthy male and female subjects. Psychoneuroendocrinology, in press. Weitzman, E.D.; Nogeire, C.; Perlow, M.; Fukushima, D.; Sassin, J.; McGregor, P.; Gallagher, T.F.; and Hellmann, T.L. Effects of a prolonged 3-hour sleep-wake cycle on sleep stages, plasma cortisol, growth hormone and body temperature in man. Journal of Clinical Endocrinology and Metabolism, 38: IO18- 1030, 1974. Weitzman, E.D., and Pollak, C.P. Effects of flurazepam on sleep and growth hormone release during sleep in healthy subjects. Sleep, 5:343-349, 1982. World Health Organization. International Clussification of Diseases. 9th ed. Geneva/ Berlin/ Heidelberg/New York: Springer, 1978.
215
Research, 471215-227
Elsevier
Profiles of Spontaneous 24-hour and Stimulated Growth Hormone Secretion in Male Patients With Endogenous Depression Ulrich Voderholzer, Gregor Laakmann, Reinhold Wittmann, Claudia Daffner-Bujia, Anita Hinz, Clemenz Haag, and Thomas Baghai Received
February
14.1992;
revised
version
received
January 25, 1993; accepted
February
18, 1993.
Abstract. Abnormalities of both the spontaneous and the stimulated release of growth hormone (GH) have been described in patients with endogenous depression. In this study, six unmedicated male patients with endogenous depression (ICD 296.1/3) were compared with six age-matched healthy men. Levels of GH were determined at 15minute intervals over 26 hours. A combined releasing hormone test was performed during the last 2 hours of blood sampling. The 24-hour profile of GH secretion was significantly lower in the depressed patients than in the healthy control subjects due to a significantly diminished sleep-related GH secretion. GH stimulation following releasing hormones was lower in the depressed patients than in healthy subjects. Hypersecretion of GH before the stimulation test might therefore not explain the blunted GH response to stimulation that has been observed in depressive patients. Key Words. Affective hormone, sleep, circadian
disorder, melancholia, growth rhythm, polysomnography.
hormone
releasing
Among the biological abnormalities found in patients with endogenous depression, disturbances of growth hormone (GH) secretion (Laakmann, 1980; Laakmann et al., 1990) and of polysomnographic sleep parameters (e.g., reduced latency and increased density of rapid eye movement sleep) have been described by many authors (Kupfer and Foster, 1972; Gillin et al., 1979; Reynolds and Kupfer, 1987; Benca et al., 1992). In most studies of GH secretion, various stimulation tests have been used because GH secretion is low during daytime (Takahashi et al., 1968) and single basal values do not indicate whether the somatotropic system is intact, Following stimulation by insulin hypoglycemia (Mueller et al., 1969), desimipramine (Laakmann, 1980), clonidine (Matussek et al., 1980; Checkley et al., 1981), and growth hormone releasing hormone (GHRH) (Laakmann et al., 1986a, 1990; Lesch et al., 1987), endogenous depressive patients show a diminished GH response compared with that of healthy age- and sex-matched control subjects. Studies examining the spontaneous secretion of GH are rare, however, because of the effort that is necessary to perform such investigations in unmedicated depressed patients. In 1975,
Ulrich Voderholzer, M.D., was Resident; Gregor Laakmann, M.D., is Professor and Chief; Reinhold Wittmann, M.D., is a graduate student; and Claudia Daffner, M.D., Anita Hinz, M.D., Clemenz Haag, M.D., and Thomas Baghai, M.D., are medical staff members, Inpatient Research Unit, Psychiatric Hospital, University of Munich. (Reprint requests to Dr. med. U. Voderholzer, Psychiatrische Klinik der Universitlt, Nussbaumstr. 7, 8000 Miinchen 2, Germany.) 01651781/93/SO6.00
@ 1993 Elsevier Scientific
Publishers
Ireland
Ltd.
216
Schilkrut et al. reported a diminished or even absent nighttime secretion of GH in a small group of endogenous depressive patients. Similar results have been obtained by Jarrett et al. (1985, 19906) and Steiger et al. (1989), who also reported a diminished GH release during the first hours of sleep in depressive patients compared with healthy control subjects. None of the authors cited above who found a diminished nocturnal GH release in depressives, however, measured the daytime GH secretion. in healthy subjects, GH concentrations are lower than 1 ng/ ml during most daytime hours, but occasional peaks may occur (Finkelstein et al., 1972). In 1985, Mendlewicz et al. reported that male patients with endogenous depression had a marked increase of daytime GH secretion during the acute state of the illness. Some of these patients were also studied after remission of their depressive symptomatology, and a normalization of their daytime GH values was found (Linkowski et al., 1987). In a study by Rubin et al. (1990), depressive patients showed relatively normal GH values with a trend, however, toward a lower nighttime secretion in the more severely depressed patients. It has not sufficiently been studied whether alterations of the GH response to various stimuli are associated with alterations of spontaneous GH release in endogenous depressed patients. Because the findings of the few previous reports that have described the spontaneous GH secretion in endogenous depression are not equivocal, the following three hypotheses were considered in the study reported below: (1) The spontaneous GH secretion is not altered and only the pituitary GH response to various stimuli is diminished in endogenous depression. (2) Both spontaneous GH secretion and stimulated GH secretion are inhibited by a still undefined mechanism. (3) The spontaneous GH secretion is elevated and leads to an inhibition of GH stimulation through feedback mechanisms. Methods Subjects. Six male patients with endogenous depression were included in this combined sleep and endocrine study. They were diagnosed according to ICD-9 (World Health Organization, 1978) Research Diagnostic Criteria (RDC; Spitzer et al., 1978; Endicott and Spitzer, 1979) and the Newcastle endogenous index (Carney and Sheffield, 1972; Roth et al., 1983). All patients met DSM-111 criteria for melancholia (American Psychiatric Association, 1980). Their mean age was 30.5 (SD = 8) years, and all were of normal height (mean = 180 cm, SD = 7 cm) and weight (mean = 77 kg, SD = 8 kg). Only severely depressed patients who came to the hospital in a drug-free state were chosen after provision of informed consent. The mean score on the Hamilton Rating Scale for Depression (Hamilton, 1960) was 31 (SD = 4) (Table I). All patients scored in the endogenous range (> 5) of the Newcastle index (mean = 8.7, SD = 1.5). The investigation was performed during the first days after admission. Two patients had never received any psychotropic medication; the other four patients had been previously treated with antidepressants but had been withdrawn from all medication at least 4 weeks before admission to the hospital. Six age-matched healthy male subjects between the ages of 22 and 40 years (mean = 30.2, SD = 7) consented in writing to serve as controls. All subjects were of normal height (mean = I83 cm, SD = 8 cm) and weight (mean = 76 kg, SD = 8 kg). Subjects with sleep difficulties, shift workers, or subjects with any personal or family history of psychiatric disorders were excluded. Intake of any drugs was prohibited during the preceding 4 weeks, and alcohol intake was not permitted 24 hours before the study began.
217
Table 1. Male patients with endogenous
depression:
data
Me
1
296.3
22
36
11
2
296.1
23
36
9
3
296.1
25
30
8
4 weeks
2 months
4
296.3
32
30
9
4 weeks
5 months
5
296.3
37
28
7
3 years
3 weeks
6
296.1
44
28
8
4 months
2 months
30
31
8.7
3.8 months
8
4
1.5
3.6
Mean SD
+= Never
Washout period
Duration of depression
Diagnosis
No.
Newcastle score
Demographic
HRSD score
l
II
2 weeks 10 months
treated with psychotropic medication. HRSD = Hamilton Rating Scale for Depression.
All control subjects and patients had a full hematology and neurological examinations, and electrocardiographic examinations.
and chemistry screen, physical and electroencephalographic
Procedure. Each investigation lasted 4 days and was performed in the sleep laboratory of the Psychiatric Hospital of the University of Munich. Polysomnographic assessments were obtained over 3 consecutive nights with electroencephalographic, horizontal electro-oculographic, and submental electromyographic lead placements. The polysomnograms were visually analyzed according to the criteria of Rechtschaffen and Kales (1968). Sleep onset was defined as the first half-minute epoch of stage 2 sleep followed by at least two epochs of any sleep stage. Rapid eye movement (REM) latency was defined as the time in minutes from sleep onset to the first half-minute epoch of stage REM. Stages 1,2, 3,4, and REM were calculated in minutes as well as percentages of the total sleep time. During the first 2 nights, polysomnographic data were obtained for adaptation to the laboratory conditions and to get baseline sleep parameters. Electrodes were fixed between 7 and 8 p.m. Subjects were not permitted to sleep before IO:30 p.m. On day 3, after the second night in the sleep laboratory, control subjects and patients received a standardized breakfast at 7:15 a.m. At 7.45 a.m., an indwelling catheter (Kowarski-Dakmed thromboresistant blood withdrawal needle and tubing set, 5 ft.) was placed in a forearm vein. Blood was continuously drawn from 8:30 a.m. (day 3) until IO:30 a.m. (day 4) with a constant speed of 15 ml/hour by using a pump (Dakmed ambulatory withdrawal pump, Model ML 6-SH). Blood was sampled at 15-minute intervals over the whole period, centrifuged every hour, and stored at -20” C until analysis. During the day, subjects received lunch and dinner at standardized times (noon and 5 p.m.). They were advised not to sleep before IO p.m. To document whether sleep stages occurred during daytime in spite of this order, daytime electroencephalographic activity was monitored continuously until the end of the study. The total number of GH measurements of each test was 104. During the night, the blood withdrawal catheter was placed through a soundproof lock in an adjacent room to avoid disturbances by the withdrawal procedure. The third polysomnographic examination took place on the same night that blood was drawn. At 8:30 a.m. on day 4, exactly 24 hours after the beginning of the blood sampling, a combined releasing hormone test was performed, as it was first described by Sheldon et al. (1985). Subjects and patients were not allowed to eat or drink within 10 hours preceding the releasing hormone injection. Throughout the test, they remained recumbent and were advised to remain awake. Electroencephalographic monitoring was continued until the end of the test at IO:30 a.m. Four releasing factors were given as slow intravenous bolus injections over 4 minutes in standardized order: CHRH, 100 ,ug. I minute; corticotropin releasing hormone (CRH), 100 pug, 30 seconds; gonadotropin releasing hormone (GnRH), 100 pg. 30 seconds; and thyrotropin releasing hormone, 200 pg, 2 minutes. Dose-response studies with GHRH have shown that intravenous administration of 100 pg or 1 I_rg/kg induces a maximal GH
218 response in healthy human subjects (Gelato et al., 1984). A recent study in healthy humans performed by Him et al. (1990) demonstrated that the simultaneous injection of all four releasing hormones has an equal stimulatory capacity to that of the injection of GHRH alone. In this article, we only refer to GH values and sleep electroencephalographic recordings. Levels of GH secretion were determined by the CIS Human Growth Hormone Radioimmunoassay (Gif-sur-Yvette, France). The sensitivity was 0.25 ng/ml, and intra-assay and interassay coefficients of variation were 7.6% and 1 1. I%, respectively. GH secretion was evaluated by descriptive analysis of the single hormone curves and by estimation of the integrated GH secretion by calculation of the area under the curve (AUC) as follows: AUC,t_t2 = Ztl_t2 X 15 (1 = Sum). AUCs were obtained for the total GH secretion over the 24 hours before the stimulation test (8:30 a.m. on day 3-8:30 a.m. on day 4) and within 2 hours following stimulation (8:30 a.m.-IO:30 a.m. on day 4). The integrated amounts of the diurnal and the sleep-related GH secretion were calculated according to the actual sleep-wake cycle, which was recorded by polysomnography. In addition, GH release during the first half of the sleep period was compared to that during the second half of the sleep period by calculating the AUCs of GH secretion during the first 180 minutes after actual sleep onset and of the GH secretion that occurred thereafter until the end of the sleep period. For statistical analysis, values were log-transformed to normalize the distribution. Student’s t test for independent samples was used to test for significant differences between depressed
patients and healthy subjects. Correlations moment correlations.
were evaluated by calculating
Pearson product-
Results Individual 24-hour GH Profiles. There was high interindividual variability of the 24-hour secretion of GH among both the endogenous depressive patients and the healthy control subjects (Fig. 1). An increase of GH concentrations above 5 ng/ml during the sleep period occurred in four of the six depressive patients and in all six control subjects. Half of the depressed patients and the control subjects additionally had GH peaks > 5 ng/ ml during the day. Two of the daytime peaks in the depressed patients occurred in the late evening hours within 3 hours before sleep onset. Mean Curves. Examination of the mean GH curves makes clear that the nocturnal increase was markedly lower in the depressed patients than that in the healthy control subjects (Fig. 2). Comparison of the mean GH profiles demonstrates a flattening of the curve in the depressed patients compared with the control subjects. Integrated Measures of 24-hour and Diurnal GH Secretion. The AUCs of the total 24-hour GH secretion were between 814 and 2158 ng/ml X 24 hours in the depressive patients and between 1439 and 7870 ng/ml X 24 hours in the control subjects. The 24-hour integrated amounts were markedly lower in the depressed (mean = 1490 ng/ml X 24 hours, SD = 550) as compared with the healthy subjects (mean = 3913 ng/ ml X 24 hours, SD = 2180). Fig. 3 shows the individual log-transformed AUCs of GH secretion. The depressive patients differed significantly (p = 0.02) from the healthy controls with regard to the 24-hour GH secretion. The integrated amounts of the diurnal GH release were comparable in the two groups of subjects (patients: mean = 629 ng/ ml X 12 hours, SD = 540; control subjects: mean = 964 ng/ml X 12 hours, SD = 860) (Fig. 3).
219
Fig. 1. Twenty-six-hour growth hormone profiles of 6 unmedicated male patients with endogenous depression (296.113, left panel) vs. 6 healthy age-matched male control subjects (right panel) conirols
depressives
_-
02
AId .-.
amom
am
0o.m
pm
Ih*
I.rn
pm
tl.%J-
‘-
ma pm
00.00
6.00 orn
Iha
Blood samplings began at 630 a.m. and finished at 1050 a.m. on the following day. The individual sleep period time is indicated as below the horizontal axis. Twenty-four hours after blood sampling began, acombined releasing hormone test (indicated as “PEP’) was performed. The combined test consisted of the simultaneous injection of growth hormone releasing hormone, 100 pg; corticotropin releasing hormone, 100 pg9;gonadotropin releasing hormone, 100 pg; and thyrotropin releasing hormone, 200 pg.
220 Fig. 2. Mean 24-hour GH curves (mean f SE) of 6 endogenous patients and 6 age-matched healthy male subjects
depressive PEP
GH @g/ml) 4035 -
sleep period 3025 zo15 -
l
l
controls
*
*
depressives
IO5: o--,......~.....,.....,.....,.....,....’,””’,””,“” a.30 o.m.
12.00
0.m.
6.00
pm”
00.00
6.00
a.m.
a.30 o.m
time Twenty-four hours after blood sampling began, a combined releasrng hormone test (indrcated as “PEP”) was performed. The combined test consisted of the simultaneous injection of growth hormone releasing hormone, 100 pg; corticotropin releasing hormone, 100 ,ug; gonadotropin releasing hormone, 1OOpg: and thyrotroprn releastng hormone, 200 /lg.
Fig. 3. Comparison of the log-transformed AUCs (ng/ml/time) of GH secretion during the whole 24-hour period (8:30 a.m.-8:30 a.m.), during the sleep period, and after a combined releasing hormone test (8:30 a.m.lo:30 p.m.) in 6 male endogenous depressive patients and 6 age- and sex-matched healthy male subjects 4 GH (AUC, ng/ml x time, log-transformed) 0 1
:
3.5 $
l
0 l l
i?k
depr.
2 0
controls
24-hours
AUC = area under the curve. GH = growth hormone.
depr.
0 0 0
controls
sleep-related
depr.
controls
GH stimulation
221 Sleep Parameters and Sleep-related GH Secretion. Sleep parameters differed between the depressive patients and the healthy control subjects during the night when blood samples were drawn. Mean sleep efficiency was 82% (SD = 13%) in the depressive patients compared with 91% (SD = 7%) in the control subjects (Table 2). This diminution was mostly due to a diminished time spent in stages 2 and 4, whereas the mean time spent in the other sleep stages did not differ between patients and control subjects. Sleep onset occurred between IO:30 p.m. and midnight in all depressive patients and control subjects (mean times of sleep onset did not differ between the two groups). The length of the first non-REM period was lower and the REM latencies were shorter in the depressive patients than in the healthy subjects. Two of the depressive patients, both of whom were older than 35 years of age, showed a sleep onset REM period. Early morning awakening was observed in three of the depressed patients and in none of the control subjects. Table 2. Sleep parameters during the night of continuous blood sampling in 6 male endogenous depressive patients vs. 6 age-matched healthy male subiects Depressive patients
Time of sleep onset
Control subjects
Mean
SD
Mean
SD
231 Oh
19 min
26 min
2303h
Sleep period time
491
47
454
22
Total sleep time
378
71
407
31
Sleep latency
24
11
19
21
REM latency
50
47
aa
27
68
24
a7
22
Stage W
Length of 1st non-REM
93
a2
42
34
Stage 1
39
14
38
26
Stage 2
195
53
224
41
Stage 3
40
24
33
22
Stage 4
a
12
23
25
93
17
a7
28
a2
13%
91
Stage REM Sleep efficiency
period
7%
Note. Values given are In minutes unless otherwise indicated. REM = rapid eye movement.
The depressed patients had diminished integrated GH amounts during the sleep period (Fig. 3). The mean AUC of the sleep-related release was markedly and statistically significantly (p < 0.01) lower in the depressive patients (mean = 659 ng/ml/time, SD = 380) than in the healthy subjects (mean = 2760 ng/ml/time, SD = 1550). The major part of the sleep-related GH secretion occurred during the first 180 minutes after sleep onset in both patients (mean = 508 ng/ml/ 3 hours, SD = 370) and control subjects (mean = 2045 ng/ ml/ 3 hours, SD = 930; p < 0.01). The timing of the sleep-related GH maximum was similar in the depressed and control subjects. The mean latency of the GH maximum after sleep onset was 100 (SD = 52) minutes in the depressive patients and 75 (SD = 21) minutes in the healthy control subjects. This difference was not statistically significant. The beginning of the sleep-related GH increase occurred during the first non-REM period in five of six
222 depressed patients and was temporally related to slow wave sleep (SWS) in three of them. The amount of GH secreted during the first non-REM period, however, did not correlate with the length of the first non-REM period or with percentage of SWS. The analysis of two cases with a sleep onset REM period revealed that GH concentrations did not increase during this sleep onset REM period but during the following non-REM period. In two depressed patients, a GH peak occurred within 3 hours before sleep onset. In five of six control subjects, the beginning of the sleeprelated GH increase occurred during the first non-REM period and coincided with SWS in all of them. In one control subject, GH markedly increased 1 hour before sleep onset and reached its maximum during the first non-REM period. Four of six control subjects had small GH increases (between 2 and 6 ng/ml) within 3 hours before sleep onset. Neither the depressive patients nor the healthy subjects showed significant correlations between sleep parameters and the AUCs of sleep-related GH secretion. During the second half of the sleep period after the first 3 hours of sleep, mean GH AUCs were 151 (SD = 76) and 716 (SD = 850) ng/ml/time in the depressive patients and the control subjects, respectively; this difference was not significant. GH Stimulation After Releasing Hormones. GH secretion was stimulated 24 hours after the beginning of the blood sampling period with a combined releasing hormone test. The maximum increase varied between 8.4 and 55 ng/ml in the depressive patients and between 79.7 and 19.4 ng/ml in the healthy subjects (Fig. 1). The AUCs of GH stimulation were lower in the depressed patients (mean = 1477 ng/ml X 120 minutes, SD = 1130) compared with those in the control subjects (mean = 2876 ng/ml X 120 minutes, SD = 1160). Statistical evaluation revealed a trend toward lower values in the depressive patients (p = 0.06). Fig. 3 shows the logtransformed AUCs of GH stimulation. Fig. 4 summarizes the results by demonstrating the mean integrated amounts of the total 24-hour GH secretion, the diurnal and the GH stimulation following releasing and sleep-related GH secretion, hormones in the depressed patients and the healthy subjects.
Discussion This study was undertaken to evaluate whether disturbances of GH secretion in response to stimulation are combined with alterations of the spontaneous 24-hour pattern of GH secretion in patients with endogenous depression. The main finding of this investigation was a reduction of the 24-hour integrated GH levels in six severely depressed male patients compared with those in healthy male control subjects. This reduction in turn reflected a marked reduction of the sleep-related GH release, a finding that is in agreement with earlier findings of Schilkrut et al. (1975), Jarrett et al. (1985, 19906), and Steiger et al. (1989). Even a long-lasting drug effect of previous treatment can be excluded since two of the patients were completely “drug-naive” and the others were studied after a long drug-free interval. An age effect also cannot explain this diminution of the spontaneous GH release since our comparatively young group of patients was compared with young healthy subjects of equal mean age. The spontaneous GH secretion of the depressed male patients was similar to
223
Fig. 4. Mean integrated amounts (AUCs, ng/ml/time, mean f SE) of the total 24-hour period, of the diurnal and the sleep-related GH secretion, and of the GH stimulation following a combined releasing hormone test in 6 male endogenous depressive patients and 6 age-matched healthy male subjects GH (AUCs, nglmb‘time) 5000
m
patients
controls
AUC = area under the curve. GH = growth hormone
that of older subjects (Carlson et al., 1972; Prinz et al., 1983). Our findings are in contrast to a study of Mendlewicz et al. (1985), who reported elevated 24-hour integrated GH levels in depressed patients compared with those in healthy control subjects due to a diurnal hypersecretion. The mean age of our patients, however, was much lower than that in the patients studied by Mendlewicz et al. (1985). In a study by Rubin et al. (1990), the 24-hour GH levels were not different in depressive patients than in control subjects, but there was a trend toward lower levels in the more severely depressed patients. Our findings are in agreement with the assumption of SouZtre et al. (1989) that a blunted amplitude is the main chronobiological abnormality in depression. The diminution of the sleep-related GH secretion was due to a reduction within the first 180 minutes after sleep onset, whereas during the second half of the night, no significant difference could be observed. This is in agreement with a study by Jarrett et al. (19906), who also reported a lowered GH secretion within the first 3 hours but not in the second half of sleep. In our study, the depressed patients did not differ from the healthy subjects with regard to the temporal relationship of GH secretion and sleep. The major part of GH secretion occurred during the first 180 minutes after sleep onset in both groups. The sleep-related GH increase began during the first non-REM period and the latency of the GH maximum relative to sleep onset was similar in both groups. When GH secretion began to increase, SWS was present in most (but not all) patients and control subjects; however, the amounts of sleeprelated GH release did not correlate with any of the sleep parameters in both groups. This agrees with several studies of GH and sleep that demonstrated a temporal
224 relationship between sleep-related GH secretion and the first non-REM period but no consistent relationship to SWS (Othmer et al., 1974; Weitzman et al., 1974; Born et al., 1988; Jarrett et al., 1990~). It was also shown that the sleep-related GH surge can be pharmacologically modulated without affecting SWS (Parker et al., 1974; Weitzman et al., 1982; Jarrett et al., 1988). In our group of comparatively young depressive patients, the total amount of SWS was similar to that of young subjects, whereas other parameters like REM latency, early morning awakening, and sleep efficiency differed between the depressed patients and the healthy control subjects. Our study indicates that the diminution of nocturnal GH secretion and the alterations of sleep parameters in depressive patients are not related to each other. GH response to releasing hormones was lower in the depressed patients compared with that in the healthy control subjects in this study. This confirms earlier findings with GHRH as the stimulus (Laakmann et al., 1986a, 1990; Lesch et al., 1987). The simultaneous application of four releasing hormones, as was done in this study, has an equal GH stimulatory capacity to the injection of GHRH alone (Sheldon et al., 1985; Schopohl et al., 1986; Ho11 et al., 1988; Hinz et al., 1990). A diminished GH stimulation in depressed patients is a well-known finding and was also observed with the use of other stimuli such as insulin hypoglycemia (Mueller et al., 1969) clonidine (Matussek et al., 1980) and desimipramine (Laakmann, 1980). This study in our small but homogeneous group of patients indicates that depression is associated with a decrease of total 24-hour GH secretion, sleep-related GH secretion, and stimulated GH release. A diminution of the GH response to stimulation with releasing hormones also seems to reflect a diminution of the spontaneous GH release. This underlines previous findings in a large sample of healthy subjects, showing a significant correlation between spontaneous 24-hour GH secretion and releasing hormone-induced GH stimulation (Voderholzer et al., in press). Therefore, neither a negative feedback effect nor an emptying of the quickly releasable pituitary GH storages secondary to an elevated spontaneous GH secretion would appear to account for the blunted GH response to stimulation in endogenous depression or to explain the diminution of the sleep-related GH release in this study. It is most likely that inhibitory factors lead to a reduction of both the spontaneous and stimulated secretion of GH. Such inhibiting factors could be an increased activity of central /3-adrenergic receptors, a hypothesis that is supported by the facts that P-adrenergic receptors are inhibitory to GH stimulation (Laakmann et al., 19866, 1991; Mauras et al., 1987) and that antidepressants lead to a downward regulation of /?-receptors in the brain (Sulser, 1981). Other inhibitory factors could be elevated central concentrations of CRH, which have been shown to induce a significant blunting of the sleep-related release of GH in men (Holsboer et al., 1988). This explanation would agree with the assumption of a CRH hypersecretion in depression (Banki et al., 1987; Nemeroff et al., 1988). In conclusion, this study demonstrates that male endogenous depressive patients, compared with healthy age-matched male control subjects, show a diminution of both spontaneous 24-hour GH secretion and GH secretion following stimulation with releasing hormones.
225 Acknowledgments. The authors thank Mrs. Birgit Beck for technical assistance and Mrs. Heike Gluba for performing all the growth hormone measurements. This study was supported by the Deutsche Forschungsgemeinschaft, Schwerpunktprogramm Neuropeptide (LA 418/5I, 5-2).
References Psychiatric Association. DSM-III: Diagnostic and Statistical Manual of Mental 3rd ed. Washington, DC: American Psychiatric Press, 1980. Banki, C.M.; Bissette, G.; Arato, M.; O’Connor, L.; and Nemeroff, C.B. CSF corticotropin-releasing factor-like immunoreactivity in depression and schizophrenia. American American
Disorders.
Journal
of Psychiatry,
144:873-877,
1987.
Benca, R.M.; Obermeyer, W.H.; Thisted, R.A.; and Gillin, J.C. Sleep and psychiatric disorders: A meta-analysis. Archives of General Psychiatry, 49:651-668, 1992. Born, J.; Muth, S.; and Fehm, H.L. The significance of sleep onset and slow wave sleep for nocturnal release of growth hormone (GH) and cortisol. Psychoneuroendocrinology, 13:233243, 1988.
Carlson, H.E.; Gillin, J.C.; Gorden, P.; and Snyder, F. Absence of sleep-related growth hormone peaks in aged normal subjects and in acromegaly. Journal of Clinical Endocrinology and Metabolism,
34:1102-l
105, 1972.
Carney, M.W.P., and Sheffield, B.F. Depression and the Newcastle scales: Their relationship to Hamilton’s scale. British Journal of Psychiatry, 12 1:35-40, 1972. Checkley, S.A.; Slade, A.P.; and Shur, E. Growth hormone and other responses to clonidine in patients with endogenous depression. British Journal of Psychiatry, 138:51-55, 1981.
Endicott, J., and Spitzer, R.L. Use of the Research Diagnostic Criteria and the Schedule for Affective Disorders and Schizophrenia to study affective disorders. American Journal of Psychiatry,
136:52-56,
1979.
Finkelstein, J.W.; Boyar, R.M.; Roffwarg, H.P.; Kream, J.; and Hellman, L. Age-related change in the twenty-four-hour spontaneous secretion of growth hormone. Journal of Clinical Endocrinology and Metabolism, 35:665-670, 1972. Gelato, M.C.; Pescovitz, O.H.; Cassorla, F.; Loriaux, D.L.; and Merriam, G.R. Doseresponse relationships for the effects of growth hormone-releasing factor-( l-44)-NH, in young adult men and women. Journal of Clinical Endocrinology and Metabolism, 59: 197-20 1, 1984. Gillin, J.C.; Duncan, W.; Pettigrew, K.D.; Frankel, B.L.; and Snyder, F. Successful separation of depressed, normal, and insomniac subjects by EEG sleep data. Archives of General
Psychiatry,
Hamilton, Psychiatry,
36:85-90,
M. A rating 23:56-62,
1979.
scale for depression.
Journal
of Neurology,
Neurosurgery,
and
1960.
Hinz, A.; Laakmann, G.; Daffner, C.: and Voderholzer, U. The simultaneous use of four releasing factors: Theoretical and practical issues. In: Bunney, W.E., Jr.; Hippius, H.; Laakmann, G.; and Schmauss, M., eds. Neuropsychopharmacology 1. Proceedings of the XVIth C. I. N. P. Congress, Munich, August 15-19. Berlin/ Heidelberg/New York: Springer, 1990. pp. 371-384. Holl, R.; Fehm, H.L.; Hetzel, W.D.; and Voigt, K.H. Globaler Hypophysenstimulationstest mit Releasinghormonen. Deutsche Medizinische Wochenschrtft, 110:953-955, 1988. Holsboer, F.; von Bardeleben, U.; and Steiger, A. Effect of intravenous corticotropinreleasing hormone upon sleep related growth hormone surge and sleep EEG in man. Neuroendocrinology,
48:32-38,
1988.
Jarrett, D.B.; Coble, P.; and Kupfer, D.J.; and Greenhouse, J.B. Sleep-related hormone secretion in depressed patients. Acta Psychiatrica Belgiae, 85:603-614, 1985. Jarrett, D.B.; Greenhouse, J.B.; Miewald, J.M.; Fedorka, LB.; and Kupfer, D.J. A reexamination of the relationship between growth hormone secretion and slow wave sleep using delta wave analysis. Biological Ps_vrhiatry, 27:497-509, 1990a.
226 Jarrett, D.B.; Miewald, J.M.; and Kupfer, D.J. Acute changes in sleep-related hormone secretion following oral imipramine. Biological Psychiatry, 24:541-554, 1988. Jarrett, D.B.; Miewald, J.M.; and Kupfer, D.J. Recurrent depression is associated with a persistent reduction in sleep-related growth hormone secretion. Archives of General Psychiatry,
47:
I 13-l 18, 1990b.
Kupfer, D.J., and Foster, F.G. Interval between onset of sleep and rapid eye movement sleep as an indicator of depression. Lancer, 1:684-686, 1972. Laakmann, G. Beeinflussung der Hypophysenvorderlappen-Hormonsekretion durch Antidepressiva bei gesunden Probanden, neurotisch und endogen depressiven Patienten. Nervenarzt,
5 11725-732,
1980.
Laakmann, G.; Hinz A.; Voderholzer, U.; Daffner, C.; Miiller, O.A.; Neuhauser, H.; Neulinger, E.; and Wittmann, M. The influence of psychotropic drugs and releasing hormones on anterior pituitary hormone secretion in healthy subjects and depressed patients. Pharmacopsychiatry,
23: 18-26,
1990.
Laakmann. G.; Munz, T.; Hinz, A.; and Voderholzer, U. Influence of clenbuterol, a fiadrenergic agonist, on desipramine induced growth hormone, prolactin and cortisol stimulation. Psychoneuroendocrinology, 15: l-9, 199 1. Laakmann, G.; Neuhauser, H.; Hinz, A.; Neulinger, E.; and Wittmann, M. Stimulation of growth hormone, prolactin and cortisol by GHRH and DMl in depressed patients. Pharmacopsychiatry,
19:235-236,
1986~.
Laakmann, G.; Zygan, K.; Schoen, H.W.; Weiss, A.; Wittmann, M.; Meissner, R.; and Blaschke, D. Effect of receptor blockers (methysergide, propranolol, phentolamine, yohimbine and prazosin) on desimipramine-induced pituitary hormone stimulation in humans: 1. Growth hormone. Psychoneuroendocrinology, 11:462-474, 1986b. Lesch, K.; Laux, G.; Pfiiller, H.; Erb, A.; and Beckmann, H. Growth hormone (GH) response to GH-releasing hormone in depression. Journal of Clinical Endocrinology and Metabolism,
65:1278-1281,
1987.
Linkowski, P.; Mendlewicz, J.; Kerkhofs, M.; Leclercq, R.; Golstein, J.; Brasseur, M.; Copinschi, G.; and van Cauter, E. Twenty-four-hour profiles of adrenocorticotropin, cortisol, and growth hormone in major depressive illness: Effect of antidepressant treatment. Journal of Clinical Endocrinology
and Metabolism,
65~141-152,
1987.
Matussek, N.; Ackenheil, M.; Hippius, H.; Miiller, F.; Schroder, H.T.; Schultes, H.; and Wasilewski, B. Effect of clonidine on growth hormone release in psychiatric patients and controls. Psychiatry Research, 2:25-36, 1980. Mauras, N.; Blizzard, R.M.; Thorner, M.O.; and Rogol, A.D. Selective P,-adrenergic receptor-blockade with atenolol enhances growth hormone releasing hormone and mediated growth hormone release in man. Metabolism, 36:369-372, 1987. Mendlewicz, J.; Linkowski, P.; Kerkhofs, M.; Desmedt, D.; Golstein, J.; Copinschi, G.; and van Cauter, E. Diurnal hypersecretion of growth hormone in depression. Journal of Clinical Endocrinology
Mueller, Archives
and Metabolism,
P.S.; Heninger, of General
60:505-512,
1985.
G.R.; and McDonald,
Psychiatry,
21:587-594,
R.K. Insulin tolerance
test in depression.
1969.
Nemeroff, C.B. The role of corticotropin-releasing factor in the pathogenesis of major depression. Pharmacopsychiatry, 21:76-82, 1988. Othmer, E.; Levine, W.R.; Marlakey, W.B.; Corvalan, J.C.; Hayden-Otto, M.P.; Fishman, P.M.; and Daughaday, W.H. Body build and sleep-related GH secretion. Hormone Research, 5:156-166,
1974.
Parker, D.C.; Rossman, L.G.; and Siler, T.M. Inhibition of the sleep-related physiologic human growth hormone release by somatostatin. Journal of Endocrinology
and Metabolism,
38:496-499,
peak in Clinical
1974.
Prinz, P.N.; Weitzman, E.D.; Cunningham, G.R.; and Karacan, I. Plasma GH during sleep in young and aged men. Journal of Gerontology, 38:5 19-524, 1983. Rechtschaffen, A., and Kales, A. A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Stages of Human Subjects. Los Angeles: UCLA Brain Information Service/Brain Research Institute, 1968. pp. I-60.
227 Reynolds, C.F. III, and Kupfer, D.J. Sleep research in affective illness: State of the art circa 1987. Sleep, 10:199-215, 1987. Roth, M.; Gurney, C.; and Mountjoy, C.Q. The Newcastle rating scales. Acta Psychiatrica Scandinavica, 310:42-54, 1983. Rubin, R.T.; Poland, R.E.; and Lesser, I.M. Neuroendocrine aspects of primary endogenous depression: X. Serum growth hormone measures in patients and matched control subjects. Biological Psychiatry, 27: 1065-1082, 1990. Schilkrut, R.; Chandra, 0.; Osswald, M.; Rtither, E.; Barfusser, B.; and Matussek, N. Growth hormone release during sleep and with thermal stimulation in depressed patients. Neuropsychobiology, 1:70-79, 1975. Schopohl, J.; Losa, M.; Konig, A.; Miiller, O.A.; Stalla, G.K.; and von Werder, K. Combined pituitary function-test with four hypothalamic releasing hormones. Klinische Wochenschrift, 64:3 14-3 18, 1986. Sheldon, W.R.; deBold, R.C.; Evans, W.S.; DeCharney, G.S.; Jackson, R.V.; Island, D.P.; Thorner, M.O.; and Orth, D.N. Rapid sequential intravenous administration of four hypothalamic releasing hormones as a combined anterior pituitary function test in normal subjects. Journal of Clinical Endocrinology and Metabolism, 60:623-630, 1985. Souetre, E.; Salvati, E.; Belugou, J.-L.; Pringuey, D.; Candito, M.; Krebs, B.; Ardisson, J.-L.; and Darcourt, G. Circadian rhythms in depression and recovery: Evidence for blunted amplitude as the main chronobiological abnormality. Psychiatry Research, 28:263-278, 1989. Spitzer, R.L.; Endicott, J.; and Robins, E. Research Diagnostic Criteria: Rationale and reliability. Archives of General Psychiatry, 35:773-782, 1978. Steiger, A.; von Bardeleben, U.; Herth, T.; and Holsboer, F. Sleep EEG and nocturnal secretion of cortisol and growth hormone in male patients with endogenous depression before treatment and after recovery. Journal of Affective Disorders, 16: 189-195, 1989. Sulser, F. New perspectives on the action of antidepressant drugs: Regulation of central adrenergic receptor function. In: Advances in Biological Psychiatry. Vol. 7. Basel: Karger, 198 1. pp. 90-99. Takahashi, Y.; Kipnis, D.M.; and Daughaday, W.H. Growth hormone secretion during sleep. Journal of Clinical Investigation, 47:2079-2090, 1968. Voderholzer, U.; Laakmann, G.; Hinz, A.; Daffner, C.; Haag, C.; Hofmann, H.-P.; and Boerschel, B. The dependency of the growth hormone (GH) stimulation following releasing hormones on the spontaneous 24-hour GH secretion in healthy male and female subjects. Psychoneuroendocrinology, in press. Weitzman, E.D.; Nogeire, C.; Perlow, M.; Fukushima, D.; Sassin, J.; McGregor, P.; Gallagher, T.F.; and Hellmann, T.L. Effects of a prolonged 3-hour sleep-wake cycle on sleep stages, plasma cortisol, growth hormone and body temperature in man. Journal of Clinical Endocrinology and Metabolism, 38: IO18- 1030, 1974. Weitzman, E.D., and Pollak, C.P. Effects of flurazepam on sleep and growth hormone release during sleep in healthy subjects. Sleep, 5:343-349, 1982. World Health Organization. International Clussification of Diseases. 9th ed. Geneva/ Berlin/ Heidelberg/New York: Springer, 1978.