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Cerebrospinal fluid thyrotropin-releasing hormone concentrations in alcoholics and normal controls
BIOL PSYCHIATRY 1990;28:767-772
767
Cerebrospinal Fluid Thyrotropin-Releasing Hormone Concentrations in Alcoholics and Normal Controls Alec Roy, Garth Bissette, Charles B. Nemeroff, Judith DeJong, Bernard Ravitz, Bryon Adinoff, and Markku Linnoila
Alterations in hypothalamic-pituitary-thyroid axis function have been reported in alcoholism. Blunting of the thyroid-stimulating hormone (TSH) response to thyrotropinreleasing hormone (TRH) occurs in approximately 25% of alcoholic patients. Using a sensitive radioimmunoassay that aUows TRH itself to be measured in cerebrospinal fluid (CSF), CSF concentrations of TRH were measured in alcoholics and normal controls. There was no significant difference in TRH concentrations between the groups. However, among the controls there was a significant correlation between CSF concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and CSF concentrations of TRH. This correlation was lacking in the alcoholics. These findings are of interest because basic neurobiological studies have reported that TRH and serotonin are co-localized in certain neurons in the rat central nervous system.
The hypothalamic-pituitary-thyroid (HPT) axis ihas been previously shown to be altered in alcoholic patients. Blunting of the thyroid-stimulating hormone (TSH) response to intravenous infusion of the thyrotropin-releasing hormone (TRH) has been observed among alcoholics (Loosen et al 1979, 1983; Kallner 1981; Rojdmark et al 1984; Valimaki et al 1984; Willenbnng et al 1990), similar to deptessed and other psychiatric patients (reviewed in Roy et al 1984, 1988). The observation that blunted TSH responses were persistent in alcoholic patients over pre!onged periiods of abstinence led our group to examine whether this was a consequence of exposure to alcohol or whether it might be a trait "marker" of a genetic predisposition to alcoholism (Moss et al 1986). Recently, a sensitive and specific radioimmunoassay for TRH has been developed (Banki et al 1988). It allows measurement of the relatively low cerebrospinal fluid (CSF) concentrations of this peptide. Using this radioimmunoassay, Banki et al (19,58) reported that a population of depressed patients had markedly higher mean TRH concentrations in CSF than controls. They suggested that elevated TRH in CSF provides further evidence of HPT axis dysregulation in depression. Elevated CSF concentrations may be due to hypersecretion of TRH, and this in turn may downregulate pituitary TRH receptors on thyrotrophs, thus leading to a blunt TSH response upon stimulation with exogenous TRH. From the Laboratory of Clinical Studies, DICBR, National Institute on Alcohol Abuse and Alcoholism, Bethesda, ' taryland (AR, JDJ, BR, ML), Departments of Psychiatry and Pharmacology, Duke University Medical Center, Durham, North Carolina (GB, CBN), and Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina and VA Medical Center, Charleston, South Carolina ,n A Address reprint requests to Alec Roy, M.B., Hillside Hospital, P.O. Box 38, Glen Oaks, NY 11004. Received November 18, 1989; May 17, 1990. © 1990 Society of Biological Psychiatry
0006.3223/90/$03.50
768
BIOLPSYCHIATRY i990;28:767-772
A. Roy et al
We have previously performed lumbar punctures on a group of alcohol-dependent patients and normal controls and in dfis study we tested the hypothesis that alcoholics would have CSF TRH concentrations that are different from controls. As monoamines are known to be involved in the regulation of TRH release from the hypothalamus (Terry 1986; Gold et al 1977), and, moreover, serot~~iin and TRH ate co-localized in neurons within certain parts of the CNS (Johansson et al. 1981), we also sought correlations between CSF levels of TRH and CSF levels of monoamine metabolites. Subjects a n d M e t h o d s The sample consisted of 51 chronic alcoholics consecutively admitted to the 3B-North clinical research unit at the National Wnstitutesof Health (NIH) Clinical Center, Bethesda, Maryland. All patients were interviewed with the Schedule for Affective Disorders and Schizophrenia (SADS-L) (Endicott and Spitzer 1979) and met the Diagnostic and Statistical Manual (DSM-III-R) diagnostic criteria for alcohol dependence and the Research Diagnostic Criteria (RDC) for alcoholism (Spitzer et al 1978). None of the patients had major medical diso~ers, clinical evidence of alcoholic liver disease, history, of severe head trauma, or neurological disease. All subjects had been withdrawn from alcohol for at least 3 weeks at the time of the study. The alcoholics were compared with 15 normal controls also studied as inpatients o~ the same unit. Controls were interviewed by a research psychiatrist to exclude past or current psychiatric disorder. They had normal physical examination results, including ches~ ~e-~tgenogram, electrocardiogram, and routine blood tests including TSH and triiodothyronine (T3), and were medication free for at least 2 weeks before the study. All patients and controls followed a low-monoamine, alcohol-free, and caffeine-restricted diet during the study. In all alcoholics and controls a lumbar puncture was performed at 9 AM. Subjects fasted from after midnight and remained at bed rest in the morning for at least 2 hr following brief bathroom privileges. Subjects were then placed in the left lateral decubitus position and 32 ml of CSF was obtained. The first 12 ml of CSF was collected as a pool, mixed and placed on ice at the bedside, subsequently divided into aliquots, and then frozen at - 80°(2 until the time of assay. An aliquot of the pooled and mixed initial 12 ml of CSF was used in all alcoholics and controls. CSF concentrations of TRH were determined in duplicate by radioimmunoassay (Banki et al 1988). Assay sensitivity was 0.625 pg/tube and the ICso was 20 pg. All samples were assayed in the same run and interassay variation was 8%. CSF levels of monoamine metabolites were measured using high-pressure liquid chromatography with electrochemical detection (Scheinen et al 1983; Seppala et al 1984). Most of the CSF monoamine data have been previously reported (Limson et al 1990) and are used here only for correlations with CSF concentrations of TRH. Baseline plasma TSH and T3 concentrations were quantified in the NIH Clinical Center Clinical Pathology Laboratory with routine radioimmunoassays. Student's t-test was used to compare the groups. Pearson's method of correlation was employed to evaluate relationships between variables. Results The alcoholic group consisted of 48 men and 3 women and the control group of 13 men and 2 women. The mean (_+ SD) ages of the alcoholics (n = 51) and controls (n = 15)
Cerebmspinal Huid Thyrolropin-Releasing Hormone
A
O
0%
I--
toOL PSYCIELATRY 1990.~;28:767.-772
769
O
o
°°
8
o
8
Alcoholics
Contzols
(n=51)
(n=15)
Figure 1. CSF concentrations of TRH in ~coholics and healthy volunteers. There was no significant difference between the two groups (t = 0.41, df = 64, NS).
o
were 41.7 +_ 11.4 and 34.3 + 16.1 years, respectively (t - 2.01, df = 64, p < 0.05). There was no significant difference between alcoholic,~ (n = 37) and controls (n - 12) for plasma TSH ttU/ml (23. ! +_ 12.2 versus 28.6 _+ 17.2, t - 1.21, df - 47, NS) or '1"3 ng/dl (139.5 -+ 29.1 versus 122.0 _+ 23.2, t = 1.89, df = 47, NS). There was no significant correlation between age and CSF concentration of TRH among either the alcoholics or controls ( r - O. 17 and r = 0.36, respectively). There was no significant difference between the total groups for the mean CSF concentrations of TRH (mean alcoholics 1.9 4-_ 0.6 pg/ml versus controls 2.0 _+ 0.6 pg/ml, t - 0.41, df 64, NS) (Figure 1). There was also no significant difference between male alcoholics (n = 48) and male controls (n - 13) for CSF levels of T-till (mean aicottollcs 1.9 _+ 0.6 versus controls 1.9 _ 0.6 pg/ml, t = 0.11, df = 59, NS). As male controls were significantly younger than male alcoholics (29.1 - 9.1 versus 41.9 _+ 11.2, t - 3.81, df - 59, p < O.00!), analysis of covariance (ANCOVA) for age was also used to compare the two groups and was not significant. There were no significant correlations between CSF TRH and either plasma TSH or T3 concentrations. There was no significant difference between the alcoholic (n = 46) and control groups (n = 15) in CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA) (mean 89.4 _+ 27.0 versus 97.6 -- 39.9 pg/ml, t = 0.75, NS). However, there was a highly significant correlation between CSF concentrations of TRH and 5-HIAA among the controls (r = 0.68, p - 0.005, n = 15; Figure 2) but not among the alcoholics (r = 0.03, n = 46, NS). This correlation remained significant when only male controls were examined (r = 0.63, p = 0.02, n = 13). There were no other significant correlations between CSF TRH and CSF monoamine metabolite concentrations. Six of the alcoholics had a lifetime history of major depression. There was no significant different for CSF concentrations of TRH when depressed alcoholics (n - 6) were compared with nondepressed alcoholics (n = 39) (1.65 -+ 0.51 versus 1.93 +- 0.57 pg/ml, F = 1.31, df = 1,43, NS).
Discussion We compared CSF concentrations of TRH between a group of alcoholic patients and a group of healthy volunteers, There was no significant difference between ~he two groups.
770
A. Roy et al
BIOL PSYCHIATRY
1990;28:767-772
Controls 200
E
"6
o 150
0
o
E
Figure 2. CSF concemrations of TRH correlate significantly with CSF concentrations of 5-HIAA among healthy volunteers (p < 0.005). This correlation was also significant when the women were excluded (r = 0.63, p < 0.02, n = 13).
o
100
50
o o
o o
0
0
o o
r = .68 n=15 p = .005 4
CSF TRH (pg/ml)
Furthermore, there was no significant difference in CSF concentrations of TRH when the large group of male alcoholics was compared with only male controls. AP.,hough the alcoholics were selected for admission to a research ward, we have no reason to believe that they ~--e~ unusual smnp!e and that an unusual proportion of them would have shown TSH blunting to TRH infusion. However, it could be argued that if this proportion was unusually small it could result in no significant difference in CSF TRH concentrations between alcoholics and controls. The lack of significant difference could also be explained by CSF TRH concentrations being independent of the activity of the HPT axis. All subjects in the present study were studied as inpatients on the same clinical lresearch unit over a period of 2 years. No significant correlations were found between patient age and CSF concentrations of TRH. Also, the same fraction of CSF was used from all su0jects for the determination of TRH content. Thus, some of the potential confounding factors affecting CSF studies of peptide neurotransmitters were controlled in the present study. It is of note that the mean CSF TRH concentration of control subjects in the present study is lower than that in the report of Banki et al (1988) using the same radioimmunoassay (2.0 _ 0.6 versus 4.38 _ 1.8 pg/ml). This difference might be due to a different sex ratio between the control groups of the two reports; the controls in the present study censisted of 3 women and 13 men whereas in the study 3y Banki et al they consisted of 15 women and 1 man. The positive finding of the present study was that among the controls, but not the alcoholics, there was a highly significant correlation between CSF 5-HIAA and TRH. This is of particular interest because there are preclinical data suggesting that serotonin and TRH coexist in certain populations of central neurons. Using immunofluorescent histochemical techniques, Johansson et al (1981) studied the distribution of serotonin and TRH in the medulla oblongata and spinal cord of normal and colchicine-treated rats. They found that some cell bodies in the bralnstem raphe nuclei and adjacent areas contained both serotonin and TRH. This was found, for example, in both the nucleus raphe magnus and the nucleus raphe obscurus. The most homogenous distribution was found in the nucleus raphe pallidus, where almost all cells that contained serotonin contained TRH as well. The highest proportions (about 30%) of serotonin and TRH-containing cells were found at rostral levels of the medulla oblongata. Additional evidence for the coexistence of serotonin and TRH cam~ irom experiments with intracistemal or intraventricular treatment with the neurotoxins 5,6- or 5,7-dihydroxytryptamine, which destroy semtonin neurones with relative specificity. Such treat-
Cerebrospinal Fluid Thyrotropin-Releasing Hormone
BIOL PSYCHIATRY
1990;28:76"/-772
771
ment led to an ~most complete disappearance of both serotonin and TRH in neurons of the ventral horn of the spinal cord. Other studies have suggested the possibility that t~ere may also be a relationship between the serotonin system and HPT axis. For example, we noted that depressed patients with a blunted TSH response to intravenous infusion of TRH had a significantly reduced Vm~ of platelet serotonin uptake when compared to depressed patients without a blunted TSH response (Roy et al 1988). Conversely, Gold et al (1977) reported a significant negative correlation between TSH responses to TRH and the amount of 5-HIAA in CSF among depressed patients, although we were unable to replicate this finding (Roy et al 1988). In this regard it should be noted that, although CSF levels of 5-HIAA do not provide information concerning anatomic localization of central serotonin turnover, both Stanley et al (1985) and Knott et al (1989) have reported a strong positive correlation between CSF concentrations of 5-HIAA obtained at postmortem and the concentration of 5-HIAA in frontal cortex. In summary, in the present study we found no significant difference between alcoholics and normal controls in CSF concentrations of TRH. The positive finding of a significant correlation in the controls between CSF concentrations of TRH and 5-HIAA supports other data suggesting that there may be a relationship among CNS serotonin systems, central TRH, and HPT axis functioning. The lack of a correlation between CSF concentrations of TRH and 5-HIAA in alcoholics suggests the possibility of a subtle dysregulation of TRH-serotonin neuronal systems in this disorder. However, the present correlational data are preliminary and require replication. This study was supported in part by NIMH MH-40159and MH-42088.
References Banki C, Bissette G, Arato M, Nemeroff C (1988): Elevation of immunoreactive CSF TRH in depressed patients. Am J Psychiatry 145:1526-1531. Endicott J, Spitzer R (1979): A diagnostic interview: The scbedale for affective disorder and schizophrenia. Arch Gen Psychiatry 35:837-844. Gold P, Goodwin F, Wehr T, Rebar R (1977): Pituitary thyrotropin response to thyrotropin-releasing hormone in affective illness: Relationship to spinal fluid amine metabolites. Am l Psychiatry 134:1028-1031. Johansson O, Hokfelt T, Jeffcoate S, et a! (1981): Immunohistochemical support for three putative transmitters in one neuron: Coexistence of 5-hydroxytryptamine-substance P-, and thyrotropin releasing hormoneAike immunoreactivity medullary neurons projecting to the spinal cord. Neuroscience 6:1857-1881. Kallncc G (1981): Assessment of thyroid function in chronic alcoholics. Acta Med Scand 209:9396. Knott P, Haroutunian V, Lierer L, et al (1989): Correlations postmortem between ventricular CSF and cortical tissue concentrations of MHPG, 5-HIAA and HVA in Alzheimer's disease. Annual Meeting cf Snciety of Biological Psychiatry, San Francisco, 1989. Abstract 227. Limson R, Goldman D, Roy A, et al (1990): Personality and CSF monoamine metabolites in alcoholics and controls. Arch Gen Psychiatry (in press). Loosen PT, Prange AJ, Wilson IC (1979): TRH (protirelin) in depressed alcoholic men. Arch Gen Psychiatry 36:540-547. Loosen P, Wilson 1, Dew B, Tipermas A (1983): Thyrotropin-releasing hormone (TRH) in abstinent alcoholic men. Am J Psychiatry 140:1145-1149.
772
BIOLPSYCHIATRY 1990;28:767-772
A. Roy et al
Moss H, Guthrie S, Linnoila M (1986): Enhanced thymtropin response to thyrotmpin releasing hormone in boys at risk for development of alcoholism. Arch Gen Psychiatry 43:1137-1142. Rojdmark S, Adner N, Andersson D, Austere J, Lamminpaa S (1984): Prolactin and thyrotropin responses to thyrotropin-releasing hormone and metoclopramide in men with chronic alcoholism. J Clin Endocrinol Metab 59:595-600. Roy A, Pickar D, Paul S (1984): Biologic tests in depression. Psychosomatics 25:443-451. Roy A, Karoum F, Linnoila M, Pickax D (1988): TRH test in unipolar depressed patients and controls: Relationship to clinical and biological variables. Acta Psychiatr Scand 77:151-159. Scheinin M, Chang W, Kirk K, Linnoila M (1983): Simultaneous determination of 3-methoxy-4hydroxyphenylglycol, 5-hydroxyindoleacetic acid, and homovanillic acid in cerebrospinal fluid with high performance liquid chromatography using electrochemical detection. Ann Biochem 131:246-253. Seppala T, Scheinin M, Capone A, Linnoila M (1984): Liquid chromatographic assay for CSF catecholamines using electrochemical detection. Acta Pharmacol Toxicol 55:81-87. Spitzer R, Endicott J, Robins E 0978): Research diagnostic criteria: Rationale and reliability. Arch Gen Psychiatry 35:773-782. Stanley M, Traskman-Bendz L, Dorovin-Zis K (1985): Correlations between aminergic metabolites simultaneously obtained from human CSF and brain. Life Sci 37:1279-1288. Terry C (1986): Regulation of thyrotropin secretion by the central epinephrine system. Neuroendocrinology 42:102-108. Valimald M, Pelkonen R, Harkonen M, Ylikahri R (1984): Hormonal changes in noncirrhotic male alcoholics during ethanol withdrawal. Alcohol Alcohol 19:235-242. Wglenbring M, Anton R, Spring W, Shafer R, Donas W (1990): Thyrotropin and prolactin response to thyrotropin-releasing hormone in depressed and nondepressed alcoholic men. Biol Psychiatry 27:31-38.
767
Cerebrospinal Fluid Thyrotropin-Releasing Hormone Concentrations in Alcoholics and Normal Controls Alec Roy, Garth Bissette, Charles B. Nemeroff, Judith DeJong, Bernard Ravitz, Bryon Adinoff, and Markku Linnoila
Alterations in hypothalamic-pituitary-thyroid axis function have been reported in alcoholism. Blunting of the thyroid-stimulating hormone (TSH) response to thyrotropinreleasing hormone (TRH) occurs in approximately 25% of alcoholic patients. Using a sensitive radioimmunoassay that aUows TRH itself to be measured in cerebrospinal fluid (CSF), CSF concentrations of TRH were measured in alcoholics and normal controls. There was no significant difference in TRH concentrations between the groups. However, among the controls there was a significant correlation between CSF concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and CSF concentrations of TRH. This correlation was lacking in the alcoholics. These findings are of interest because basic neurobiological studies have reported that TRH and serotonin are co-localized in certain neurons in the rat central nervous system.
The hypothalamic-pituitary-thyroid (HPT) axis ihas been previously shown to be altered in alcoholic patients. Blunting of the thyroid-stimulating hormone (TSH) response to intravenous infusion of the thyrotropin-releasing hormone (TRH) has been observed among alcoholics (Loosen et al 1979, 1983; Kallner 1981; Rojdmark et al 1984; Valimaki et al 1984; Willenbnng et al 1990), similar to deptessed and other psychiatric patients (reviewed in Roy et al 1984, 1988). The observation that blunted TSH responses were persistent in alcoholic patients over pre!onged periiods of abstinence led our group to examine whether this was a consequence of exposure to alcohol or whether it might be a trait "marker" of a genetic predisposition to alcoholism (Moss et al 1986). Recently, a sensitive and specific radioimmunoassay for TRH has been developed (Banki et al 1988). It allows measurement of the relatively low cerebrospinal fluid (CSF) concentrations of this peptide. Using this radioimmunoassay, Banki et al (19,58) reported that a population of depressed patients had markedly higher mean TRH concentrations in CSF than controls. They suggested that elevated TRH in CSF provides further evidence of HPT axis dysregulation in depression. Elevated CSF concentrations may be due to hypersecretion of TRH, and this in turn may downregulate pituitary TRH receptors on thyrotrophs, thus leading to a blunt TSH response upon stimulation with exogenous TRH. From the Laboratory of Clinical Studies, DICBR, National Institute on Alcohol Abuse and Alcoholism, Bethesda, ' taryland (AR, JDJ, BR, ML), Departments of Psychiatry and Pharmacology, Duke University Medical Center, Durham, North Carolina (GB, CBN), and Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina and VA Medical Center, Charleston, South Carolina ,n A Address reprint requests to Alec Roy, M.B., Hillside Hospital, P.O. Box 38, Glen Oaks, NY 11004. Received November 18, 1989; May 17, 1990. © 1990 Society of Biological Psychiatry
0006.3223/90/$03.50
768
BIOLPSYCHIATRY i990;28:767-772
A. Roy et al
We have previously performed lumbar punctures on a group of alcohol-dependent patients and normal controls and in dfis study we tested the hypothesis that alcoholics would have CSF TRH concentrations that are different from controls. As monoamines are known to be involved in the regulation of TRH release from the hypothalamus (Terry 1986; Gold et al 1977), and, moreover, serot~~iin and TRH ate co-localized in neurons within certain parts of the CNS (Johansson et al. 1981), we also sought correlations between CSF levels of TRH and CSF levels of monoamine metabolites. Subjects a n d M e t h o d s The sample consisted of 51 chronic alcoholics consecutively admitted to the 3B-North clinical research unit at the National Wnstitutesof Health (NIH) Clinical Center, Bethesda, Maryland. All patients were interviewed with the Schedule for Affective Disorders and Schizophrenia (SADS-L) (Endicott and Spitzer 1979) and met the Diagnostic and Statistical Manual (DSM-III-R) diagnostic criteria for alcohol dependence and the Research Diagnostic Criteria (RDC) for alcoholism (Spitzer et al 1978). None of the patients had major medical diso~ers, clinical evidence of alcoholic liver disease, history, of severe head trauma, or neurological disease. All subjects had been withdrawn from alcohol for at least 3 weeks at the time of the study. The alcoholics were compared with 15 normal controls also studied as inpatients o~ the same unit. Controls were interviewed by a research psychiatrist to exclude past or current psychiatric disorder. They had normal physical examination results, including ches~ ~e-~tgenogram, electrocardiogram, and routine blood tests including TSH and triiodothyronine (T3), and were medication free for at least 2 weeks before the study. All patients and controls followed a low-monoamine, alcohol-free, and caffeine-restricted diet during the study. In all alcoholics and controls a lumbar puncture was performed at 9 AM. Subjects fasted from after midnight and remained at bed rest in the morning for at least 2 hr following brief bathroom privileges. Subjects were then placed in the left lateral decubitus position and 32 ml of CSF was obtained. The first 12 ml of CSF was collected as a pool, mixed and placed on ice at the bedside, subsequently divided into aliquots, and then frozen at - 80°(2 until the time of assay. An aliquot of the pooled and mixed initial 12 ml of CSF was used in all alcoholics and controls. CSF concentrations of TRH were determined in duplicate by radioimmunoassay (Banki et al 1988). Assay sensitivity was 0.625 pg/tube and the ICso was 20 pg. All samples were assayed in the same run and interassay variation was 8%. CSF levels of monoamine metabolites were measured using high-pressure liquid chromatography with electrochemical detection (Scheinen et al 1983; Seppala et al 1984). Most of the CSF monoamine data have been previously reported (Limson et al 1990) and are used here only for correlations with CSF concentrations of TRH. Baseline plasma TSH and T3 concentrations were quantified in the NIH Clinical Center Clinical Pathology Laboratory with routine radioimmunoassays. Student's t-test was used to compare the groups. Pearson's method of correlation was employed to evaluate relationships between variables. Results The alcoholic group consisted of 48 men and 3 women and the control group of 13 men and 2 women. The mean (_+ SD) ages of the alcoholics (n = 51) and controls (n = 15)
Cerebmspinal Huid Thyrolropin-Releasing Hormone
A
O
0%
I--
toOL PSYCIELATRY 1990.~;28:767.-772
769
O
o
°°
8
o
8
Alcoholics
Contzols
(n=51)
(n=15)
Figure 1. CSF concentrations of TRH in ~coholics and healthy volunteers. There was no significant difference between the two groups (t = 0.41, df = 64, NS).
o
were 41.7 +_ 11.4 and 34.3 + 16.1 years, respectively (t - 2.01, df = 64, p < 0.05). There was no significant difference between alcoholic,~ (n = 37) and controls (n - 12) for plasma TSH ttU/ml (23. ! +_ 12.2 versus 28.6 _+ 17.2, t - 1.21, df - 47, NS) or '1"3 ng/dl (139.5 -+ 29.1 versus 122.0 _+ 23.2, t = 1.89, df = 47, NS). There was no significant correlation between age and CSF concentration of TRH among either the alcoholics or controls ( r - O. 17 and r = 0.36, respectively). There was no significant difference between the total groups for the mean CSF concentrations of TRH (mean alcoholics 1.9 4-_ 0.6 pg/ml versus controls 2.0 _+ 0.6 pg/ml, t - 0.41, df 64, NS) (Figure 1). There was also no significant difference between male alcoholics (n = 48) and male controls (n - 13) for CSF levels of T-till (mean aicottollcs 1.9 _+ 0.6 versus controls 1.9 _ 0.6 pg/ml, t = 0.11, df = 59, NS). As male controls were significantly younger than male alcoholics (29.1 - 9.1 versus 41.9 _+ 11.2, t - 3.81, df - 59, p < O.00!), analysis of covariance (ANCOVA) for age was also used to compare the two groups and was not significant. There were no significant correlations between CSF TRH and either plasma TSH or T3 concentrations. There was no significant difference between the alcoholic (n = 46) and control groups (n = 15) in CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA) (mean 89.4 _+ 27.0 versus 97.6 -- 39.9 pg/ml, t = 0.75, NS). However, there was a highly significant correlation between CSF concentrations of TRH and 5-HIAA among the controls (r = 0.68, p - 0.005, n = 15; Figure 2) but not among the alcoholics (r = 0.03, n = 46, NS). This correlation remained significant when only male controls were examined (r = 0.63, p = 0.02, n = 13). There were no other significant correlations between CSF TRH and CSF monoamine metabolite concentrations. Six of the alcoholics had a lifetime history of major depression. There was no significant different for CSF concentrations of TRH when depressed alcoholics (n - 6) were compared with nondepressed alcoholics (n = 39) (1.65 -+ 0.51 versus 1.93 +- 0.57 pg/ml, F = 1.31, df = 1,43, NS).
Discussion We compared CSF concentrations of TRH between a group of alcoholic patients and a group of healthy volunteers, There was no significant difference between ~he two groups.
770
A. Roy et al
BIOL PSYCHIATRY
1990;28:767-772
Controls 200
E
"6
o 150
0
o
E
Figure 2. CSF concemrations of TRH correlate significantly with CSF concentrations of 5-HIAA among healthy volunteers (p < 0.005). This correlation was also significant when the women were excluded (r = 0.63, p < 0.02, n = 13).
o
100
50
o o
o o
0
0
o o
r = .68 n=15 p = .005 4
CSF TRH (pg/ml)
Furthermore, there was no significant difference in CSF concentrations of TRH when the large group of male alcoholics was compared with only male controls. AP.,hough the alcoholics were selected for admission to a research ward, we have no reason to believe that they ~--e~ unusual smnp!e and that an unusual proportion of them would have shown TSH blunting to TRH infusion. However, it could be argued that if this proportion was unusually small it could result in no significant difference in CSF TRH concentrations between alcoholics and controls. The lack of significant difference could also be explained by CSF TRH concentrations being independent of the activity of the HPT axis. All subjects in the present study were studied as inpatients on the same clinical lresearch unit over a period of 2 years. No significant correlations were found between patient age and CSF concentrations of TRH. Also, the same fraction of CSF was used from all su0jects for the determination of TRH content. Thus, some of the potential confounding factors affecting CSF studies of peptide neurotransmitters were controlled in the present study. It is of note that the mean CSF TRH concentration of control subjects in the present study is lower than that in the report of Banki et al (1988) using the same radioimmunoassay (2.0 _ 0.6 versus 4.38 _ 1.8 pg/ml). This difference might be due to a different sex ratio between the control groups of the two reports; the controls in the present study censisted of 3 women and 13 men whereas in the study 3y Banki et al they consisted of 15 women and 1 man. The positive finding of the present study was that among the controls, but not the alcoholics, there was a highly significant correlation between CSF 5-HIAA and TRH. This is of particular interest because there are preclinical data suggesting that serotonin and TRH coexist in certain populations of central neurons. Using immunofluorescent histochemical techniques, Johansson et al (1981) studied the distribution of serotonin and TRH in the medulla oblongata and spinal cord of normal and colchicine-treated rats. They found that some cell bodies in the bralnstem raphe nuclei and adjacent areas contained both serotonin and TRH. This was found, for example, in both the nucleus raphe magnus and the nucleus raphe obscurus. The most homogenous distribution was found in the nucleus raphe pallidus, where almost all cells that contained serotonin contained TRH as well. The highest proportions (about 30%) of serotonin and TRH-containing cells were found at rostral levels of the medulla oblongata. Additional evidence for the coexistence of serotonin and TRH cam~ irom experiments with intracistemal or intraventricular treatment with the neurotoxins 5,6- or 5,7-dihydroxytryptamine, which destroy semtonin neurones with relative specificity. Such treat-
Cerebrospinal Fluid Thyrotropin-Releasing Hormone
BIOL PSYCHIATRY
1990;28:76"/-772
771
ment led to an ~most complete disappearance of both serotonin and TRH in neurons of the ventral horn of the spinal cord. Other studies have suggested the possibility that t~ere may also be a relationship between the serotonin system and HPT axis. For example, we noted that depressed patients with a blunted TSH response to intravenous infusion of TRH had a significantly reduced Vm~ of platelet serotonin uptake when compared to depressed patients without a blunted TSH response (Roy et al 1988). Conversely, Gold et al (1977) reported a significant negative correlation between TSH responses to TRH and the amount of 5-HIAA in CSF among depressed patients, although we were unable to replicate this finding (Roy et al 1988). In this regard it should be noted that, although CSF levels of 5-HIAA do not provide information concerning anatomic localization of central serotonin turnover, both Stanley et al (1985) and Knott et al (1989) have reported a strong positive correlation between CSF concentrations of 5-HIAA obtained at postmortem and the concentration of 5-HIAA in frontal cortex. In summary, in the present study we found no significant difference between alcoholics and normal controls in CSF concentrations of TRH. The positive finding of a significant correlation in the controls between CSF concentrations of TRH and 5-HIAA supports other data suggesting that there may be a relationship among CNS serotonin systems, central TRH, and HPT axis functioning. The lack of a correlation between CSF concentrations of TRH and 5-HIAA in alcoholics suggests the possibility of a subtle dysregulation of TRH-serotonin neuronal systems in this disorder. However, the present correlational data are preliminary and require replication. This study was supported in part by NIMH MH-40159and MH-42088.
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