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Increased CSF levels of endorphines in chronic psychosis
Neuroscience Letters, 3 (1976) 157--162 © Elsevier/North-Holland Biomedical Press
157
INCREASED CSF LEVELS OF E N D O R P H I N E S IN CHRONIC PSYCHOSIS
L~ TERENIUS, A. WAHLSTROM, L. LINDSTROM and E. WIDERLOV
Department of Medical Pharmacology and (L.L. and E. W.) Psychiatric Research Center University of Uppsala, Uppsala (Sweden) (Received July 14th, 1976) (Accepted July 22nd, 1976)
SUMMARY
The levels of t w o endorphines, endogenously occurring morphinomimetic peptides, were measured in serial samples of CSF from seven psychiatric patients. Four cases with chronic schizophrenia were studied before and after treatment with the antipsychotic agent clozapine (Leponex). Supernormal fraction II levels were found on at least one sampling occasion in each patient. Two patients, who responded well to clozapine treatment, showed a clear-cut drop in fraction II levels, whereas two patients showed increased levels which paralleled a deterioration of the schizophrenic symptoms. Three manic-depressive cases showed abnormally high levels of endorphine fraction I in the manic phase which declined during normal or depressed phases. Levels of fraction II varied in a less consistent manner and appeared to be at maximum during the apparently normal phases. Although preliminary, the data indicate that endorphines may reach supernormal levels in patients with chronic psychoses.
Morphine is a psychopharmacological agent affecting the CNS in a variety of ways. Although its clinical use is mainly for the relief of severe pain, its effects on m o o d and behaviour are of a much more general character. The distribution of opioid receptors in the CNS is also widespread and not only confined to earlier known pain pathways [ 5,11]. The detection of endogenously occurring morphinomimetic peptides, endorphines [6,7,14] suggested to us that such peptides may play a role in mental disorders. Since it was k n o w n that endorphines are present in cerebrospinal fluid (CSF) of humans [15], a study was conducted for analysis of endorphine levels in CSF samples of psychotic patients. Four schizophrenic and three manic-depressive patients were studied. The disease duration of the schizophrenics w~ts more than ten years. They all showed productive s y m p t o m s b u t one patient (C) had a fluctuating course with periods of negligible symptoms. Before the first CSF sample was taken,
158 the patients had been off antipsychotic medication for more than one month. Then, 50 mg clozapine (Leponex, Sandoz) was given twice a day for three days and thereafter the dosage was increased with 50 mg every third day until a dose of 300 or 350 mg twice a day was reached. The second and the third sample of CSF was taken 2 and 4 weeks after the onset of clozapine treatment. The manic-depressive patients had suffered from recurrent episodes of mania and depression between 5 (subject G) and 37 (subject F) years. They received lithium treatment (except subject E in samples 3 and 4), which, however, was not sufficient to prevent the mood fluctuations. CSF samples were taken in different phases of the disease. CSF samples (5--10 ml) of the schizophrenics were taken at 8 a.m. and of the manic-depressives at 1 p.m. by lumbar puncture with the patient in a supine position. The samples were frozen and kept at --20°C until analyzed. Aliquots were taken for the analysis of endorphines and in a few cases also of monoamine metabolites. The CSF sample was filtered through an Amicon PM10 filter (nominal cut-off 10,000 M.W.). Five millilitres of the filtrate was run through a Sephadex G10 column (45 X 2 cm) previously equilibrated with 0.2 M acetic acid. The column was eluted at 1 ml/min and 5 ml samples were collected. The eluate was continuously monitored for UV absorption. Each sample was analyzed for content of primary amines with fluorescamine. Two major fractions with endorphine activity were collected: fraction I in sample 14--16 and fraction II in sample 22--25. Minor peaks of activity were occasionally observed before the peak I and before the peak II. These additional peaks never contributed more than 25% to the combined fractions I and II. Fraction II co-chromatographs with Met-enkephalin, an endorphine isolated by Hughes et al. [7] on the Sephadex column and in several high-pressure liquid chromatograph~ systems [16]. The chemical nature of fraction I is presently u~known. When authentic samples of Metenkephalin were run through the column, no receptor activity was recovered in the fraction I. The fractions were lyophilized and the residues were tested in a radioreceptor assay. In this assay [13] the fractions are incubated with a receptorcontaining preparation of synaptic plasma membranes from rat brain and 0.4 X 10 .9 M [3H]dihydromorphine (sp. act. 75 Ci/mmole from the Radiochemical Centre, Amersham, Bucks, England) in a total volume of 0.4 ml HEPES buffer, pH 7.4. Incubation is terminated by centrifugation. The receptor-containing membranes are collected as a pellet at the b o t t o m of the tubes. The pellets are digested with Soluene (Packard) and their content of radioactivity is measured. Every run included samples w i t h o u t any chromatographic fraction (controls) and samples with an excess (10 -6 M) of unlabelled dihydromorphine (blanks). Blank values were subtracted from all experimental values and the inhibitory effect on receptor binding was expressed as a percentage of the
159
controls. Using a displacement curve with Met-enkephalin as the competitor, inhibition values were read and expressed as if they were due to Met-enkephalin. In the text and the tables, the unit pM.E. means picomoles of Metenkephalin. To test the reproducibility of the method, aliquots of a pool of CSF from patients with neurological disorders were run at intervals. In four runs the standard error of the mean was + 15% for fraction I and + 13% for fraction II. Five millilitre samples of synthetic CSF were run to give the method blank. The fraction I-blank was 2.3 + 0.09 pM.E./ml (mean + S.E.M.; n = 5) while the fraction II-blank was negligible. All values for fraction I in the tables were corrected for this blank value. Serial CSF samples from four schizophrenic cases were obtained before treatment and after standardized periods of treatment with clozapine. The endorphine levels (Table I) should be compared with those observed in patients with no psychiatric background (undergoing neurological or X-ray examination). In such patients, the level of fraction I is 1.4 -+ 1.2 pM.E./ml and of fraction II 5.2 +- 6.2 pM.E./ml (mean + S.D.; n = 9 and n = 12 respectively). It is obvious that the four schizophrenic patients had elevated fraction II levels on at least one sample occasion. Patients C and D also showed high fraction I levels. In patients A and B, the marked clinical improvement after clozapine treatment was parallelled by a marked drop in fraction II levels. Patient C showed a deterioration of the schizophrenic symptoms in spite of
TABLEI E ~ D O R P H I N E L E V E L S IN S E R I A L S A M P L E S O F CSF F R O M S C H I Z O P H R E N I C PATIENTS UNDERGOING CLOZAPINE TREATMENT 1 = n o active m e d i c a t i o n for 1 m o n t h ; 2 = a f t e r 14 days o f t r e a t m e n t w i t h c l o z a p i n e ; a n d 3 = m a x i m u m individual dose o f clozapine. Case
Sample
E n d o r p h i n e level ( p M . E . / m l CSF) a I
A
Clinical r e s p o n s e
II
1 2 3
<0.1 < 0.1 < 0.1
7.2 4.8 1.1
improvement further improvement
B
1 3
0.1 0.5
18 3.4
marked improvement
C
1 2 3
5.6 6.4 1.8
1.7 2.8 14
no improvement no improvement
1 2 3
3.9 5.2 < 0.1
23 12 47
no improvement, sedated improvement, more out-acting
D
apicomoles of Met-enkephalin.
160 increased dosage o f clozapine, t h e e f f e c t being paralleled b y increased f r a c t i o n II levels. This p a t i e n t had higher f r a c t i o n I t h a n f r a c t i o n II levels in s a m p l e s 1 a n d 2. I n p a t i e n t D t h e e f f e c t o f c l o z a p i n e o n t h e clinical r e s p o n s e and e n d o r p h i n e levels was less clear-cut. A biphasic f r a c t i o n II r e s p o n s e was seen w i t h a v e r y high value in s a m p l e 3, w h i c h was t a k e n at a t i m e w h e n t h e p a t i e n t was m o r e o u t - a c t i n g a n d less a f f e c t i v e t h a n previously. T h e m o n o a m i n e m e t a b o l i t e s H V A , 5 - H I A A and M O P E G w e r e a n a l y z e d in p a t i e n t s C and D. T h e levels s h o w e d negligible changes during the c l o z a p i n e t r e a t m e n t . CSF s a m p l e s o f t h r e e p a t i e n t s w i t h m a n i c - d e p r e s s i v e disorders w e r e a n a l y z e d in d i f f e r e n t phases o f t h e disease (Table II). T h e m o s t significant o b s e r v a t i o n was t h a t o f high f r a c t i o n I levels w h i c h w e r e p a r t i c u l a r l y elevated in t h e m a n i c phase. Each p a t i e n t also s h o w e d a high f r a c t i o n II level o n o n e or m o r e s a m p l i n g occasions. TABLE II
ENDORPHINE LEVELS IN SERIAL SAMPLES OF CSF FROM MANIC-DEPRESSIVE PATIENTS Case
E
F
G
Sample
Date
Endorphine level (pM.E./ml CSF) a I
II
Clinical phase
1 2 3 4 1 2 3 4 5
75-09-12 75-10-06 75-01-20 76-02-03 75-09-30 75-10-10 75-10-16 76-02-05 76-02-19
7.2 1.6 4.4 0.4 2.5 4.0 6.3 2.8 2.0
6.7 4.4 14 25 2.4 3.1 3.2 8.0 5.2
mania depression depression normal depression normal mania normal depression
1 2
76-01-20 76-02-05
7.2 6.3
13.4 11.2
mania normal
apicomoles of Met-enkephalin
T h e d e t e c t i o n o f t h e e n d o r p h i n e s y s t e m leads t o several i m p o r t a n t q u e s t i o n s including, f o r instance, w h a t is its p h y s i o l o g i c i m p o r t a n c e ? It m i g h t be d e d u c e d i n d i r e c t l y t h a t , since w h e n given a l o n e n a r c o t i c a n t a g o n i s t s like n a l o x o n e ( w h i c h b l o c k e n d o r p h i n e a c t i o n ) p r o d u c e negligible e f f e c t s in e x p e r i m e n t a l a n i m a l s [3,12] a n d in h u m a n s [ 2 , 1 0 ] , t h e p h y s i o l o g i c a l i m p o r t a n c e m a y n o t be v e r y significant. H o w e v e r , all t h e s e studies w e r e d o n e in n o r m a l animals and h u m a n v o l u n t e e r s . In view of t h e v e r y e x t e n s i v e e f f e c t s o f o p i o i d s o n m o o d a n d b e h a v i o u r , it seems plausible t h a t p a t h o l o g i c a l e n d o r p h i n e levels m i g h t cause e x t e n s i v e p s y c h i c effects, clinically m a n i f e s t e d in
161
psychotic disorders. We are presently engaged in a large exploratory investigation aimed at the elucidation of such possible relationships. The present series of patients are of interest since they could be followed longitudinally and under comparatively standardized conditions. Analysis of CSF samples is probably the most direct approach to a study of the endorphine system in man. Since we use a receptor-binding assay we measure biologically relevant material. However, this approach is not devoid of interpretative difficulties since the relation between active concentration in brain and concentration in CSF is not known and may be different for different endorphines. The schizophrenic patients showed a considerable variation in fraction II in the drug-free stage. It is interesting that of the three patients with high initial levels, two responded to clozapine both with a clinical improvement and a drop in endorphine levels. In fact, in three of the four patients studied, the levels of fraction II seemed to be correlated with the severity of the schizophrenic symptoms. In manic-depressive patients, high levels were observed particularly in fraction I and, in several instances, the fraction I quantitatively surpassed the fraction II level. Whether there are qualitative differences between fractions I and II is not known, in receptor binding tests they behave similarly [16]. It is a clinical observation that various symptoms of pain are much more frequent in manic-depressives compared to controls [1]. There also exist 'masked depressions' with pain as the only s y m p t o m [8]. Fluctuating levels of endorphines in different phases of the disease might be a biochemical correlate of the clinical findings. Although the present clinical material is small, there is an indication that endorphines may reach abnormal levels in psychiatric disorders. This suggests therapeutic measures against endogenous or drug-induced abnormalities in endorphine levels. Preliminary trials with the narcotic antagonist naloxone in chronic schizophrenia show that at least some of the symptoms can be relieved temporarily [4]. ACKNOWLEDGEMENTS
We thank Mrs. L. Bennich-Bjorkman and Mrs. I. Eriksson for expert technical assistance. We are grateful to Prof. G. Sedvall for monoamine analysis. The work was supported by the Swedish Medical Research Council (Project No. B76-03766-05}. REFERENCES Cassidy, W.L., Flanagan, N.B., Spellman, M. and Cohen, M.E., Clinical observations in manic-depressive disease: a qualitative study of one hundred manic-depressive patients and fifty medically sick controls, J. Amer. Med. Ass., 164 (1957) 1535.
162
2 Foldes, F.F., Duncalf, D. and Kuwabara, S., The respiratory, circulatory and narcotic antagonistic effects of nalorphine, levallorphan ana naloxone in anesthetized subject, Canad. Anaesth. Soc. J., 16 (1969) 151--161. 3 Goldstein, A. and Lowery, P.J., Effect of the opiate antagonist naloxone on body temperature in rats, Life Sci., 17 (1975) 927--932. 4 Gunne, L.-M., LindstrOm, L.H. and Terenius, L., Naloxone-induced reversal of schizophrenic hallucinations, submitted for publication. 5 Hiller, J.M., Pearson, J. and Simon, E.J., Distribution of stereospecific binding of the potent narcotic analgesic etorphine in the human brain: predominance in the limbic system. Res. Commun. Chem. Path. Pharmacol., 6 (1973) 1052--1062. 6 Hughes, J., Isolation of an endogenous compound from the brain with pharmacological properties similar to morphine, Brain Res., 88 (1975) 295--308. 7 Hughes, J., Smith, T.W., Kosterlitz, H.W., Fothergill, L.A., Morgan, B.A. and Morris, H.R., Identification of two related pentapeptides from the brain with potent opiate agonist activity, Nature (Lond.), 258 (1975) 577--579. 8 Ibor, J.J.L., Masked depression, Brit. J. Psychiat., 120 (1972) 245--258. 9 Jacob, J.J., Tremblay, E.C. et Colombel, M.-C., Facilitation de reactions nociceptives par la naloxone chez la souris et chez le rat, Psychopharmacologia (Berl.), 37 (1974) 217--223. 10 Jasinski, D.R., Martin, W.R. and Haertzen, C.A., The human pharmacology and abuse potential of N-allylnoroxymorphone (naloxone), J. Pharmacol. exp. Ther., 157 (1967) 420--426. 11 Kuhar, M.J., Pert, C.B. and Snyder, S.H., Regional distribution of opiate receptor binding in monkey and human brain, Nature (Lond.), 245 (1973) 447--450. 12 McClane, T.K. and Martin, W.R., Effects of morphine, nalorphine, cyclazocine and naloxone on the flexor reflex, Int. J. Neuropharmacol., 6 (1967) 89--98. 13 Terenius, L., A rapid assay for the narcotic receptor in rat brain: application to methadone analogues, Acta pharmacol (Kbh.), 34 (1974) 88--91. 14 Terenius, L. and WahlstrOm, A., Search for an endogenous ligand for the opiate receptor, Acta physiol, scand., 94 (1975) 74--81. 15 Terenius, L. and Wahlstr~m, A., Morphine-like ligand for opiate receptors in human CSF, Life Sci., 16 (1975) 1759--1764. 16 Wahlstr~m, A., Johansson, L. and Terenius, L., Characterization of endorphines (endogenous morphine-like factors) in human CSF and brain extracts. In H.W. Kosterlitz (Ed.), Cellular effects of opiates, in press.
157
INCREASED CSF LEVELS OF E N D O R P H I N E S IN CHRONIC PSYCHOSIS
L~ TERENIUS, A. WAHLSTROM, L. LINDSTROM and E. WIDERLOV
Department of Medical Pharmacology and (L.L. and E. W.) Psychiatric Research Center University of Uppsala, Uppsala (Sweden) (Received July 14th, 1976) (Accepted July 22nd, 1976)
SUMMARY
The levels of t w o endorphines, endogenously occurring morphinomimetic peptides, were measured in serial samples of CSF from seven psychiatric patients. Four cases with chronic schizophrenia were studied before and after treatment with the antipsychotic agent clozapine (Leponex). Supernormal fraction II levels were found on at least one sampling occasion in each patient. Two patients, who responded well to clozapine treatment, showed a clear-cut drop in fraction II levels, whereas two patients showed increased levels which paralleled a deterioration of the schizophrenic symptoms. Three manic-depressive cases showed abnormally high levels of endorphine fraction I in the manic phase which declined during normal or depressed phases. Levels of fraction II varied in a less consistent manner and appeared to be at maximum during the apparently normal phases. Although preliminary, the data indicate that endorphines may reach supernormal levels in patients with chronic psychoses.
Morphine is a psychopharmacological agent affecting the CNS in a variety of ways. Although its clinical use is mainly for the relief of severe pain, its effects on m o o d and behaviour are of a much more general character. The distribution of opioid receptors in the CNS is also widespread and not only confined to earlier known pain pathways [ 5,11]. The detection of endogenously occurring morphinomimetic peptides, endorphines [6,7,14] suggested to us that such peptides may play a role in mental disorders. Since it was k n o w n that endorphines are present in cerebrospinal fluid (CSF) of humans [15], a study was conducted for analysis of endorphine levels in CSF samples of psychotic patients. Four schizophrenic and three manic-depressive patients were studied. The disease duration of the schizophrenics w~ts more than ten years. They all showed productive s y m p t o m s b u t one patient (C) had a fluctuating course with periods of negligible symptoms. Before the first CSF sample was taken,
158 the patients had been off antipsychotic medication for more than one month. Then, 50 mg clozapine (Leponex, Sandoz) was given twice a day for three days and thereafter the dosage was increased with 50 mg every third day until a dose of 300 or 350 mg twice a day was reached. The second and the third sample of CSF was taken 2 and 4 weeks after the onset of clozapine treatment. The manic-depressive patients had suffered from recurrent episodes of mania and depression between 5 (subject G) and 37 (subject F) years. They received lithium treatment (except subject E in samples 3 and 4), which, however, was not sufficient to prevent the mood fluctuations. CSF samples were taken in different phases of the disease. CSF samples (5--10 ml) of the schizophrenics were taken at 8 a.m. and of the manic-depressives at 1 p.m. by lumbar puncture with the patient in a supine position. The samples were frozen and kept at --20°C until analyzed. Aliquots were taken for the analysis of endorphines and in a few cases also of monoamine metabolites. The CSF sample was filtered through an Amicon PM10 filter (nominal cut-off 10,000 M.W.). Five millilitres of the filtrate was run through a Sephadex G10 column (45 X 2 cm) previously equilibrated with 0.2 M acetic acid. The column was eluted at 1 ml/min and 5 ml samples were collected. The eluate was continuously monitored for UV absorption. Each sample was analyzed for content of primary amines with fluorescamine. Two major fractions with endorphine activity were collected: fraction I in sample 14--16 and fraction II in sample 22--25. Minor peaks of activity were occasionally observed before the peak I and before the peak II. These additional peaks never contributed more than 25% to the combined fractions I and II. Fraction II co-chromatographs with Met-enkephalin, an endorphine isolated by Hughes et al. [7] on the Sephadex column and in several high-pressure liquid chromatograph~ systems [16]. The chemical nature of fraction I is presently u~known. When authentic samples of Metenkephalin were run through the column, no receptor activity was recovered in the fraction I. The fractions were lyophilized and the residues were tested in a radioreceptor assay. In this assay [13] the fractions are incubated with a receptorcontaining preparation of synaptic plasma membranes from rat brain and 0.4 X 10 .9 M [3H]dihydromorphine (sp. act. 75 Ci/mmole from the Radiochemical Centre, Amersham, Bucks, England) in a total volume of 0.4 ml HEPES buffer, pH 7.4. Incubation is terminated by centrifugation. The receptor-containing membranes are collected as a pellet at the b o t t o m of the tubes. The pellets are digested with Soluene (Packard) and their content of radioactivity is measured. Every run included samples w i t h o u t any chromatographic fraction (controls) and samples with an excess (10 -6 M) of unlabelled dihydromorphine (blanks). Blank values were subtracted from all experimental values and the inhibitory effect on receptor binding was expressed as a percentage of the
159
controls. Using a displacement curve with Met-enkephalin as the competitor, inhibition values were read and expressed as if they were due to Met-enkephalin. In the text and the tables, the unit pM.E. means picomoles of Metenkephalin. To test the reproducibility of the method, aliquots of a pool of CSF from patients with neurological disorders were run at intervals. In four runs the standard error of the mean was + 15% for fraction I and + 13% for fraction II. Five millilitre samples of synthetic CSF were run to give the method blank. The fraction I-blank was 2.3 + 0.09 pM.E./ml (mean + S.E.M.; n = 5) while the fraction II-blank was negligible. All values for fraction I in the tables were corrected for this blank value. Serial CSF samples from four schizophrenic cases were obtained before treatment and after standardized periods of treatment with clozapine. The endorphine levels (Table I) should be compared with those observed in patients with no psychiatric background (undergoing neurological or X-ray examination). In such patients, the level of fraction I is 1.4 -+ 1.2 pM.E./ml and of fraction II 5.2 +- 6.2 pM.E./ml (mean + S.D.; n = 9 and n = 12 respectively). It is obvious that the four schizophrenic patients had elevated fraction II levels on at least one sample occasion. Patients C and D also showed high fraction I levels. In patients A and B, the marked clinical improvement after clozapine treatment was parallelled by a marked drop in fraction II levels. Patient C showed a deterioration of the schizophrenic symptoms in spite of
TABLEI E ~ D O R P H I N E L E V E L S IN S E R I A L S A M P L E S O F CSF F R O M S C H I Z O P H R E N I C PATIENTS UNDERGOING CLOZAPINE TREATMENT 1 = n o active m e d i c a t i o n for 1 m o n t h ; 2 = a f t e r 14 days o f t r e a t m e n t w i t h c l o z a p i n e ; a n d 3 = m a x i m u m individual dose o f clozapine. Case
Sample
E n d o r p h i n e level ( p M . E . / m l CSF) a I
A
Clinical r e s p o n s e
II
1 2 3
<0.1 < 0.1 < 0.1
7.2 4.8 1.1
improvement further improvement
B
1 3
0.1 0.5
18 3.4
marked improvement
C
1 2 3
5.6 6.4 1.8
1.7 2.8 14
no improvement no improvement
1 2 3
3.9 5.2 < 0.1
23 12 47
no improvement, sedated improvement, more out-acting
D
apicomoles of Met-enkephalin.
160 increased dosage o f clozapine, t h e e f f e c t being paralleled b y increased f r a c t i o n II levels. This p a t i e n t had higher f r a c t i o n I t h a n f r a c t i o n II levels in s a m p l e s 1 a n d 2. I n p a t i e n t D t h e e f f e c t o f c l o z a p i n e o n t h e clinical r e s p o n s e and e n d o r p h i n e levels was less clear-cut. A biphasic f r a c t i o n II r e s p o n s e was seen w i t h a v e r y high value in s a m p l e 3, w h i c h was t a k e n at a t i m e w h e n t h e p a t i e n t was m o r e o u t - a c t i n g a n d less a f f e c t i v e t h a n previously. T h e m o n o a m i n e m e t a b o l i t e s H V A , 5 - H I A A and M O P E G w e r e a n a l y z e d in p a t i e n t s C and D. T h e levels s h o w e d negligible changes during the c l o z a p i n e t r e a t m e n t . CSF s a m p l e s o f t h r e e p a t i e n t s w i t h m a n i c - d e p r e s s i v e disorders w e r e a n a l y z e d in d i f f e r e n t phases o f t h e disease (Table II). T h e m o s t significant o b s e r v a t i o n was t h a t o f high f r a c t i o n I levels w h i c h w e r e p a r t i c u l a r l y elevated in t h e m a n i c phase. Each p a t i e n t also s h o w e d a high f r a c t i o n II level o n o n e or m o r e s a m p l i n g occasions. TABLE II
ENDORPHINE LEVELS IN SERIAL SAMPLES OF CSF FROM MANIC-DEPRESSIVE PATIENTS Case
E
F
G
Sample
Date
Endorphine level (pM.E./ml CSF) a I
II
Clinical phase
1 2 3 4 1 2 3 4 5
75-09-12 75-10-06 75-01-20 76-02-03 75-09-30 75-10-10 75-10-16 76-02-05 76-02-19
7.2 1.6 4.4 0.4 2.5 4.0 6.3 2.8 2.0
6.7 4.4 14 25 2.4 3.1 3.2 8.0 5.2
mania depression depression normal depression normal mania normal depression
1 2
76-01-20 76-02-05
7.2 6.3
13.4 11.2
mania normal
apicomoles of Met-enkephalin
T h e d e t e c t i o n o f t h e e n d o r p h i n e s y s t e m leads t o several i m p o r t a n t q u e s t i o n s including, f o r instance, w h a t is its p h y s i o l o g i c i m p o r t a n c e ? It m i g h t be d e d u c e d i n d i r e c t l y t h a t , since w h e n given a l o n e n a r c o t i c a n t a g o n i s t s like n a l o x o n e ( w h i c h b l o c k e n d o r p h i n e a c t i o n ) p r o d u c e negligible e f f e c t s in e x p e r i m e n t a l a n i m a l s [3,12] a n d in h u m a n s [ 2 , 1 0 ] , t h e p h y s i o l o g i c a l i m p o r t a n c e m a y n o t be v e r y significant. H o w e v e r , all t h e s e studies w e r e d o n e in n o r m a l animals and h u m a n v o l u n t e e r s . In view of t h e v e r y e x t e n s i v e e f f e c t s o f o p i o i d s o n m o o d a n d b e h a v i o u r , it seems plausible t h a t p a t h o l o g i c a l e n d o r p h i n e levels m i g h t cause e x t e n s i v e p s y c h i c effects, clinically m a n i f e s t e d in
161
psychotic disorders. We are presently engaged in a large exploratory investigation aimed at the elucidation of such possible relationships. The present series of patients are of interest since they could be followed longitudinally and under comparatively standardized conditions. Analysis of CSF samples is probably the most direct approach to a study of the endorphine system in man. Since we use a receptor-binding assay we measure biologically relevant material. However, this approach is not devoid of interpretative difficulties since the relation between active concentration in brain and concentration in CSF is not known and may be different for different endorphines. The schizophrenic patients showed a considerable variation in fraction II in the drug-free stage. It is interesting that of the three patients with high initial levels, two responded to clozapine both with a clinical improvement and a drop in endorphine levels. In fact, in three of the four patients studied, the levels of fraction II seemed to be correlated with the severity of the schizophrenic symptoms. In manic-depressive patients, high levels were observed particularly in fraction I and, in several instances, the fraction I quantitatively surpassed the fraction II level. Whether there are qualitative differences between fractions I and II is not known, in receptor binding tests they behave similarly [16]. It is a clinical observation that various symptoms of pain are much more frequent in manic-depressives compared to controls [1]. There also exist 'masked depressions' with pain as the only s y m p t o m [8]. Fluctuating levels of endorphines in different phases of the disease might be a biochemical correlate of the clinical findings. Although the present clinical material is small, there is an indication that endorphines may reach abnormal levels in psychiatric disorders. This suggests therapeutic measures against endogenous or drug-induced abnormalities in endorphine levels. Preliminary trials with the narcotic antagonist naloxone in chronic schizophrenia show that at least some of the symptoms can be relieved temporarily [4]. ACKNOWLEDGEMENTS
We thank Mrs. L. Bennich-Bjorkman and Mrs. I. Eriksson for expert technical assistance. We are grateful to Prof. G. Sedvall for monoamine analysis. The work was supported by the Swedish Medical Research Council (Project No. B76-03766-05}. REFERENCES Cassidy, W.L., Flanagan, N.B., Spellman, M. and Cohen, M.E., Clinical observations in manic-depressive disease: a qualitative study of one hundred manic-depressive patients and fifty medically sick controls, J. Amer. Med. Ass., 164 (1957) 1535.
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