Thyrotropin releasing hormone (TRH): a useful tool for psychoneuroendocrine investigation

The thyrotropin-releasing hormone test in depressed and non-depressed psychiatric patients

The thyrotropin-releasing hormone (TRH) test was carried out in 231 depressed patients undergoing a dexamethasone suppression test (DST), and in 63 psychiatric control patients. The patients were classified according to DSM-III. Thyrotropin-secreting hormone (TSH) was determined in basal conditions, 20 and 60 min after the administration of 200 μg TRH. The Δ max TSH values (peak TSH response minus basal TSH) showed no significant difference between psychiatrie Controls and patients with major depression (296.00X2, 296.00X3, 296.00X4) or with depression (major and minor depression; 300,40, 296,82, 309.00). Consequently, the TRH test is not specifie either for depression or for major depression. Within the selected group of depressive patients, major depressives showed significantly (P<0.005) lower Δ max TSH responses than minor depressives. The TRH test could barely be used as a clinical diagnostic aid for major depression, since the predictive value for a positive test resuit was too low (maximal 70.2%). To separate major from minor depression, a single DST was more suitable than the TRH test or the combination of both tests. Age showed a negative correlation (P<0.005) with the Δ max TSH responses and could be considered as a predisposing factor for a blunted TSH response to TRH in depressive patients.

Hormonal differences between psychotic and non-psychotic melancholic depression

BACKGROUND

The dexamethasone suppression test (DST) is the main hormonal disturbance in psychotic depression compared to non-psychotic depression. However, although there have been many studies of individual hormonal axes in depression, few multi-axial studies have been reported. This study aims to examine hormonal differences between these groups of patients through three functional hormonal tests: DST, thyroid stimulating hormone response to thyroid releasing hormone (TSH-TRF) and growth hormone response to growth hormone releasing factor (GH-GRF).

METHODS

Forty inpatients meeting DSM-III-R criteria for major depressive episode with melancholia (21 non-psychotic and 19 psychotic) were studied. Dexamethasone suppression test, TSH-TRF and GH-GRF tests were undertaken for all patients.

RESULTS

In the whole melancholic sample, 80.0% showed disturbances in at least one hormonal axis, 40.0% in two axes and 5.0% in all three axes. Basal and post-dexamethasone cortisol levels were significantly higher in psychotic than in non-psychotic patients. An association between post-dexamethasone cortisol and blunted GH-GRF response was demonstrated in those with psychotic depression. In the whole sample, GH blunting was found in 62.5% of patients, DST non-suppression in 37.5% and TSH blunting in 25.0% (no differences were found between psychotic and non-psychotic patients).

LIMITATIONS

Sample was restricted to melancholia and unknown factors may influence hormonal responses to stress.

CONCLUSIONS

Hormonal disturbances in depression are more evident when studying several axes, being the HPA and the GH axes the most prominents. Psychotic depression showed more HPA disturbance than non-psychotic depression. Influence of the HPA on the GH axis is discussed.

The combined T3/TRH test in depressed patients and healthy controls

It is well established that depressed patients show a blunted TSH response in the TRH-stimulation test. However, it has not been investigated so far whether pre-treatment with 3,5,3'-triiodothyronine (T3) is able to further suppress the TRH-induced TSH response in depressed patients or whether it may cause an escape-phenomenon with paradoxically enhanced TSH stimulation in a subsequent TRH test. In 20 drug-free depressed patients (eight men, 12 women) suffering from a major depressive episode according to DSM-IV criteria and in 20 age- and sex-matched healthy controls, the single TRH-stimulation test (administration of 200 microg TRH at 09:00 h) was carried out followed by a combined T3/TRH test (pre-treatment with 40 microg T3 at 23:00 h the night before; administration of 200 microg TRH at 09:00 h the next day). Compared to the controls, the depressed patients showed a significantly blunted TSH response in the single TRH test. However, the percentage suppression of TRH-induced TSH stimulation after pre-treatment with 40 microg T3 was comparable in the depressive patients (61.07%) and the healthy volunteers (64.20%). Prolactin secretion did not differ between patients and controls either in the single TRH test or in the combined T3/TRH test. Apparently, in contrast to the hypothalamo-pituitary-adrenocortical (HPA) system, no disturbance of feedback control in regulation of the hypothalamo-pituitary-thyroid (HPT) axis secretion can be demonstrated in depressed patients when using the combined T3/TRH test.

Low-dose thyrotropin-releasing hormone effects in cognitively impaired alcoholics

The cognitive effects of a low dose of thyrotropin-releasing hormone (TRH) (2.0 mg, IV) were evaluated in 18 chronic alcoholic patients who exhibited memory dysfunction secondary to chronic alcohol abuse. The study used a double-blind crossover design that compared cognitive functions in patients with 2.0 mg of TRH IV as compared with a placebo. TRH was chosen because of its ability to enhance cholinergic transmission. Only minimal effects were seen with TRH. Patients with a shorter duration of alcohol use (mean of 16 years) performed significantly better with TRH as compared with placebo on a test involving verbal learning and memory. Those with a more chronic history of alcohol abuse (mean of 27 years) did not show such a response. All of the subjects showed cardiovascular response to TRH. Factors that may have contributed to the results of our study are discussed. It is our impression that future studies evaluating the cognitive effects of TRH in chronic alcoholics need to include an evaluation of the functional activity of TRH in the brain.

The TRH-test in depression: a review

The TRH-test in depression: a review This paper reviews the literature on the thyrotropin releasing hormone (TRH)-test in depressive patients. The TRH-test appears to exhibit some use as an external validating criterion for the clinical diagnosis of major depression and, in particular melancholia versus minor depression once the clinical diagnosis depression is made. However, the clinical use of this test is hampered by the low sensitivity (±50%) and by the fact that abnormal tests occur in non-depressive states such as borderline personality disorder, schizophrenia, and anxiety disorders. The TRH-test may be used as a predictor for a positive response to biological therapies. In addition, the test has some value for the outcome of a depressive episode. The pathophysiology underpinning an abnormal TRH-test may be determined by noradrenergic (central and peripheric) or serotonergic (central) dysfunctions, thyroid hormone and cortisol hypersecretion, phenomena that are pertinent to severe depression. Recently, it has been established that an abnormal depression-linked TRH-test reflects lower basal thyroid secreting hormone (TSH) secretion. The determination of basal TSH may, in the future, replace TRH-testing.

Disappearance of hypothalamic TRH asymmetry in suicide patients

The aim of the present study was to investigate the functional and/or pathological significance of the hemispherical lateralization of TRH using radioimmunoassay to determine the TRH concentration of nuclei and areas within the hypothalamus of suicide patients, with matching measurement being carried out on control subjects. In suicide patients, we found no significant difference in TRH concentration between the left and right intrahypothalamic structures, while the group used as control subjects (see Borson-Chazot, 1986) showed a significant left side predominance in the ventromedial nucleus, paraventricular nucleus and area dorsalis. As regards the TRH concentration in the right intrahypothalamic structures, no significant difference was found between the suicide patients and the control subjects. The absence of the left TRH predominance for the three intra-hypothalamic structures in question may be of pathological significance.

Neuropeptide concentrations in the cerebrospinal fluid of depressed patients treated with electroconvulsive therapy. Corticotrophin-releasing factor, beta-endorphin and somatostatin

The CSF concentrations of CRF, somatostatin and beta-endorphin were determined in nine patients who fulfilled DSM-III criteria for major depression with psychotic features. CSF samples were obtained at baseline in the depressed state, and again after a course of ECT. Concentrations of both CRF and beta-endorphin decreased after ECT, while the concentration of somatostatin increased, although the latter difference did not attain statistical significance. The increase in CSF concentrations of CRF and beta-endorphin in depressed patients is therefore seen to be state-dependent.

Suppressive effects of dexamethasone on hypothalamic-pituitary-thyroid axis function in depressed patients

This study investigated the effects of dexamethasone (1 mg orally) on the function of the hypothalamic-pituitary-thyroid (HPT) axis. We determined pre- and post-dexamethasone thyroid-secreting hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), reverse T3 and cortisol levels in 61 depressed inpatients. Dexamethasone had a pronounced suppressive effect on basal TSH and FT3 levels. It had a significant stimulating effect on rT3 levels. No differences were found between melancholic and minor depressives in the effects of dexamethasone on basal TSH, FT3 and rT3. Cortisol non-suppressors were characterized by less suppression of basal TSH values.

Neuroendocrine aspects of primary endogenous depression. X: Serum growth hormone measures in patients and matched control subjects

To determine the extent of dysregulation of growth hormone (GH) secretion in endogenous depression, we measured nocturnal serum GH concentrations and GH responses to thyrotropin-releasing hormone (TRH, gonadotropin-releasing hormone (LHRH), and dexamethasone administration in 40 Research Diagnostic Criteria primary, definite endogenous depressives and 40 individually matched normal control subjects. Compared with their controls, the patients showed no difference in basal nocturnal GH concentrations or in GH responses to TRH or LHRH. The GH measures were not significantly related to the other endocrine measures reported previously, including dexamethasone suppression test status. None of the diagnostic schemes for endogenous/melancholic depression which we studied was significantly related to the GH measures in the patients. Of the other subject and symptom variables, the mood depression factor of the Hamilton depression scale and the performance difficulty factor of the Beck depression inventory were moderately negatively correlated with the nocturnal GH measures. These findings suggest that, in contrast to the previously reported hypothalamopituitary-adrenal cortical and thyroid axis abnormalities in our patients, GH secretion was relatively normal. Patients with more severe depressed mood and greater difficulty accomplishing tasks did have moderately lower nocturnal GH values.

The decreased availability of L-tryptophan in depressed females: clinical and biological correlates

1. The plasma levels of L-tryptophan (L-TRP) and the sum of five competing amino acids (CAA) namely tyrosine, phenylalanine, valine, leucine, isoleucine, were determined in 79 depressed females categorized according to the DSM-III. 2. In these patients the authors measured several parameters known to affect the availability of the above amino acids, i.e. triidothyronine (FT3) and thyroxine (FT4), vanilylmandelic acid (VMA), noradrenaline and adrenaline in 24 hr urine, the sex hormonal and nutritional state. 3. The 1 mg dexamethasone suppression test was performed and the pre and postdexamethasone cortisol and adrenocorticotropic hormone (ACTH) levels were determined at 8 a.m. 4. L-TRP and the ratio L-TRP/CAA were significantly lower in severely depressed females (296.X3, 296.X4) as compared with minor (300.40, 309.00) and simple major depressives (296.X2). The ratio L-TRP/CAA performed well as a clinical tool separating melancholic from minor depression. 5. FT3, FT4, VMA and noradrenaline were significantly increased in the severely depressed females, but these data did not correlate with the availability of L-TRP. Neither baseline cortisol nor the sex hormonal, nor the nutritional state related to the L-TRP data. The ratio L-TRP/CAA was significantly and negatively correlated with the postdexamethasone cortisol and ACTH values.

A revised interpretation of the TRH test results in female depressed patients. Part I: TSH responses. Effects of severity of illness, thyroid hormones, monoamines, age, sex hormonal, corticosteroid and nutritional state

Thyrotropin secreting hormone (TSH) levels were recorded in baseline conditions and 20 and 60 min after thyrotropin releasing hormone (TRH) administration (200 micrograms i.v.) in 60 depressed females categorized according to DSM-III. Basal TSH (TSHB) and peak TSH responses (TSHP) were measured using ultrasensitive RIA assays. The use of delta max TSH (TSHP minus TSHB) had no advantage over the use of TSHP since both factors were almost linearly (r = 0.98) correlated. TSHP was largely (72% of the variance) predicted by TSHB. It was suggested that TSHP consisted of two components. The first part was a relative deduction from TSHB. The second part was the newly proposed concept of the residual TSH (TRHR). This part was computed by partialling out the relative effects of TSHB on TSHP by means of regression analysis. In clinical practice two relevant factors should be used to evaluate the hypothalamic-pituitary-thyroid (HPT) axis: (1) TSHB reflecting the setpoint of the HPT axis and (2) TSHR reflecting the latent capacity of the HPT axis to respond to overwhelming amounts of exogenous TRH. TSHB was significantly reduced in severely depressed patients (296.X3, 296.X4) as compared with minor depressives (300.40, 309.00). These differences could be attributed to significantly increased free thyroxine levels and to noradrenergic hyperactivity in the severely depressed females. TSHR correlated significantly and negatively with follicle stimulating hormone levels, age, body mass index and the post-dexamethasone cortisol values. TSHR was significantly reduced in the post-menopausal state.

The DST and TRH test in bulimia nervosa

Abnormal neuroendocrine responses have been found in depression and eating disorders. It remains unclear whether these reflect an underlying shared biology or epiphenomena. To evaluate this further, we conducted the 1 mg DST and the TSH response to 500 micrograms i.v. TRH in normal-weight bulimics and controls. Bulimics (n = 18) demonstrated significantly more DST non-suppression (45%) than controls (18%; n = 20). In the bulimic group, non-suppressors were significantly thinner than suppressors, but did not differ from them on any measure of depression. Bulimics (n = 19) and controls (n = 12) responded similarly without blunting on the TSH response to TRH. These data suggest that DST non-suppression may be related to non-specific variables such as weight. Bulimics do not demonstrate TSH blunting as found in some depressed patients. These tests do not support evidence for a biological link between these disorders.

Thyroid function and therapeutic efficacy of thyroxine in depression

The authors administered 50-100 micrograms of thyroxine (T4) alone for 2 weeks to 20 patients with primary major depressive disorders, evaluated clinical changes, and compared the thyroid functions before and after the trial. The results showed a significant decrease in the Hamilton Rating Scale scores, and the efficacy of thyroid hormone alone was demonstrated against depression. It was also shown that this antidepressive effect varied widely from marked improvement to mild aggravation. The degree of clinical improvement had no significant relationship with sex, age, subtype of depression, and severity of symptoms before treatment. But it had significant positive correlations with the pre-trial T3, T4, T3 uptake, free T4 index and BMR. That is, patients with a higher pre-trial thyroid function showed a greater improvement. Thus, it was suggested that the antidepressive effects is closely associated with the mechanism which suppresses endogenous thyroid hormones.

TRH test and DST in schizoaffective mania, mania, and schizophrenia

The thyrotropin-releasing hormone (TRH) test and the Dexamethasone Suppression Test (DST) were given to 10 patients who met Research Diagnostic Criteria (RDC) for schizoaffective disorder, manic type, 9 who met the criteria for mania, and 27 who met the criteria for schizophrenia. A blunted thyrotropin (TSH) response to TRH was observed in 3 of the 10 schizoaffective manics, 4 of the 9 manics, and 3 of the 27 schizophrenics. Nonsuppression on the DST was observed in 5 of the 10 schizoaffective manics, 2 of the 9 manics, and 2 of 22 schizophrenics. The schizoaffective manic and the manic patients had similar rates of TSH blunting and DST nonsuppression, and these were significantly higher than the rates in the schizophrenic patients. This difference was not attributable to baseline TSH and cortisol levels or to neuroleptic treatment. It is suggested that patients with RDC schizoaffective mania and mania have more disturbance in the hypothalamic-pituitary adrenal and thyroid axes than patients with schizophrenia.

TSH response to TRH and haloperidol response latency in psychoses

Thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) was measured in 19 acutely psychotic (DSM-III schizophrenia, 7; schizophreniform, 2; schizoaffective, 3; affective, mood-incongruent psychosis, 5; manic, mood-congruent psychosis, 2) drug-free patients prior to systematic trials of lithium and/or haloperidol. TSH response was not associated with sex, age, baseline T4, or baseline TSH. A reduced TSH response was associated with affective diagnosis and was a significant predictor of a positive, rapid response to neuroleptic treatment.

TRH: behavioral and endocrine effects in man

1. The tripeptide TRH exerts a spectrum of biological activities in both animals and man. Some of these activities have been extensively studied, particularly in psychiatric patients. 2. Behaviorally, TRH appears to increase the sense of well-being, motivation, relaxation, and coping capacity in both normal subjects and patients with psychiatric and neurologic disease. These effects are not disease-specific; attempts to use TRH as a treatment tool have thus been disappointing. 3. Endocrinologically, administration of TRH stimulates the response of TSH; this response has been reported to be blunted in approximately 30% of patients with major depression. However, TSH blunting is not specific for depression, it has also been observed in a variety of other psychiatric conditions. 4. The relevance of these effects for psychiatry in general, and for psychoneuroendocrinology especially, is discussed in this review.

The prolonged increase in thyrotropin-releasing hormone in rat limbic forebrain regions following electroconvulsive shock

We have previously demonstrated substantial increases in thyrotropin-releasing hormone (TRH) in specific regions of rat forebrain two days after single or repeated alternate-day electroconvulsive shock (ECS). To determine longer term effects of ECS-induced seizures on forebrain TRH content, we extended the time of the post-ECS observations to 6 and 12 days following 1 (ECS x 1) or 3 (ECS x 3) alternate-day ECS. Previous observations at 2 days post-ECS were confirmed except that hippocampal content of TRH was higher after ECS x 1. In pyriform cortex TRH remained elevated for 6 days after ECS x 1 and 3, and for 12 days after ECS x 3. In hippocampus TRH was elevated for 6 days after ECS x 1 and tended to remain elevated beyond 2 days after ECS x 3. In anterior cortex the increase persisted 6 days after ECS x 1 and 12 days after ECS x 3. These data show that convulsive seizures can induce sustained elevations of TRH beyond 48 h. This finding may be especially important in pyriform cortex and hippocampus where TRH may function as an endogenous anti-epileptic. Our data are also consistent with a possible role for TRH in affective regulation in the hippocampus, amygdala, pyriform and other cortical regions. Moreover, the present results further advance the analogy of the time-course of the TRH changes in rat to the course of the antidepressant response to electroconvulsive treatment in humans.

[Correlation of "latent hyperthyroidism" with psychological and somatic changes]

The study reported here was undertaken to establish the degree to which a person in a preclinical state of hyperthyroidism, with (by definition) euthyroid T3 and T4 levels but suppressed TRH on testing, already exhibits psychological changes and clinical symptoms. Two groups of 20 patients each, with clear clinical and preclinical hyperthyroidism (as defined by laboratory parameters), were studied, as well as a group of 20 controls. The subjects' psychological state of mind was investigated using self-rating scales, including the state-trait-anxiety inventory (STAI), "Befindlichkeits"-Skala (Bf-S'), depression scale (D-S'), and a list of adjectives (EWL-K) with 14 different aspects of affective moods. Cognitive achievements were evaluated using the d2 test. Subjects were examined for somatic symptoms in accordance with Crooks' index of hyperthyroidism. The results clearly showed that typical psychological and somatic changes are already present in preclinical hyperthyroidism, these changes being partly identical with those of definite hyperthyroidism. In both patient groups, a significant increase in anxiety, a sense of not feeling well, and emotional irritability were found, as well as a tendency towards depressiveness, and an increased lack of vitality and activity. Attentiveness and concentration in both patient groups were lower than in the control group. Both patient groups showed the same prevalence of symptoms, such as palpitations, preference of cold over heat, excessive sweating, nervousness, fine digital tremor, and increased heart rate. With regard to the results, the diagnosis "preclinical hyperthyroidism" thus gains importance. Further prospective studies are required to answer the question whether antithyroidal treatment will influence the described psychological and somatic state of patients with preclinical hyperthyroidism.

Effects of ECT on the TRH stimulation test

The prognostic value of the TRH stimulation test was evaluated in 23 inpatients with major depressive disorder before and after a trial of ECT. In contrast to previous reports, the peak TSH response to TRH was significantly decreased after treatment compared with before treatment. This effect was consistent across individuals and subgroups (responders/nonresponders; unilateral/bilateral ECT). The particular ECT technique used in the study may account for the discrepancies between these findings and those previously reported by other authors.

Neuroendocrine aspects of primary endogenous depression--IV. Pituitary-thyroid axis activity in patients and matched control subjects

In order to ascertain the extent of hypothalamo--pituitary--thyroid (HPT) axis dysfunction in endogenous depression, we determined nocturnal serum thyrotropin (TSH) concentrations, TSH responses to thyrotropin releasing hormone (TRH) administration, and serum triiodothyronine (T3) and thyroxine (T4) concentrations in 40 Research Diagnostic Criteria primary, definite endogenous depressives and 40 individually matched normal control subjects. We also examined the relationships of the HPT measures to pre- and post-dexamethasone (DEX) serum and urine cortisol measures and, in the patients, to subject characteristics, the diagnosis of endogenous/melancholic depression by different systems, and the overall severity and specific dimensions of depressive symptomatology. Compared to their matched controls, the patients showed significant reductions in nocturnal serum TSH and serum T3 concentrations. Neither the TSH responses to TRH nor serum T4 concentrations were significantly different between the two groups of subjects. In the patients, none of the subject characteristics, diagnostic schemes for endogenous/melancholic depression or specific aspects of depressive symptomatology were significantly related to HPT activity. The measures of HPT activity were unrelated to measures of hypothalamo--pituitary--adrenal cortical (HPA) axis activity in both groups of subjects.

Is there paradoxical growth hormone response to thyrotropin-releasing hormone in depression?

Several investigators have reported a paradoxical growth hormone (GH) response to thyrotropin-releasing hormone (TRH) in depressed patients, but other studies have failed to confirm this. In the present study, the GH response to TRH was studied in depressed patients and normal subjects. The rate of paradoxical GH response to TRH in depression was no different than that observed in control subjects. This was the case whether the data was examined using mean values or using frequency of abnormal responses. Patients with blunted thyrotropin (TSH) responses did not differ in GH release from patients with normal TSH response. A variety of factors may have contributed to the earlier reports of a positive GH response to TRH, including the definition of paradoxical GH release and the fact that depressed patients exhibit more frequent spontaneous diurnal GH release than do normal subjects.

Effect of hypoglycaemia, TRH and levodopa on plasma growth hormone, prolactin, thyrotropin and cortisol in Parkinson's disease before and during therapy

Thirteen drug-free and not severely affected patients with idiopathic Parkinson's disease underwent an insulin-hypoglycaemia test, a TRH test and a levodopa test. The responses of growth hormone, prolactin, cortisol and thyrotropin were measured, and retested under stable therapy with levodopa and benserazide. Mean basal and stimulated hormonal concentrations were in the normal range before and during therapy. Minor abnormalities were observed in individual cases, but did not indicate a hypothalamic dopamine deficit.

Weight loss causes neuroendocrine disturbances: experimental study in healthy starving subjects

A variety of endocrine dysfunctions have been reported for anorexia nervosa, protein caloric malnutrition, and depression. The effect of reduced caloric intake and weight loss on endocrine functions was assessed in an experiment with five healthy female subjects during an initial baseline phase, a 3-week phase of complete food abstinence, weight gain to the original level, and a final baseline phase. During fasting, disturbances in hypothalamic-pituitary-adrenal function were observed, with elevated plasma cortisol levels, increase in the number of secretory episodes, increase in cortisol plasma half-life, and insufficient suppression following 1.5 mg dexamethasone. While all dexamethasone suppression tests (DSTs) were normal at baseline, 7 of 14 DSTs showed insufficient suppression in the fasting phase. During fasting, basal thyroid-stimulating hormone (TSH) values were lowered and the TSH response to thyrotropin-releasing hormone (TRH) was blunted. The plasma level of growth hormone (GH) over 24 hours was elevated during fasting and administration of the alpha 2-adrenergic receptor agonist clonidine resulted in a subnormal GH response after restoration of original body weight. One of the five subjects showed increased irritability, distress, anxiety, and depression as measured by various psychological scales. The results show that reduced caloric intake, weight loss, or catabolic state have powerful effects on several endocrine systems. The specificity of measures of endocrine disturbances (DST, TRH tests, and clonidine tests) as biological markers for certain types of depression must be questioned, and the metabolic state should be given more consideration in future studies.

Clinical neuroendocrinology and neuropharmacology of alcohol withdrawal

A number of alcohol research groups have measured anterior and posterior pituitary hormones, the endogenous opiates, CNS peptides, and putative neurotransmitters during alcohol withdrawal. The data are often complex and contradictory, though a number of themes have emerged. Activity of the hypothalamic-pituitary-adrenal axis (HPA) is increased during chronic alcohol exposure and appears to remain altered for at least 2 to 4 weeks after cessation of drinking. There is increased turnover of norepinephrine and enhanced binding of CNS adrenergic receptors. By contrast, there are decreases in CNS activity of select endogenous opiates and GABA. Other CNS compounds that may play a role in alcohol withdrawal are prolactin, thyrotropin-releasing hormone (TRH), vasopressin, cyclic 3'5'-adenosine monophophate (cAMP), Delta-sleep-inducing peptide (DSIP), and iron. Despite many studies in humans and animals, the roles of CNS dopamine and serotonin in withdrawal remain unclear. A number of peptides, including cholecystokinin (CCK), neurotensin, and bombesin, have been shown to interact with the CNS actions of alcohol and may play a role in alcohol withdrawal. Inadequate work has been performed on acetylcholine (ACh), human growth hormone (HGH) and luteinizing hormone (LH). Studies of the recently identified GABA-benzodiazepine-barbituate receptor complex indicate that this system is likely to be involved in the pathophysiology of alcohol withdrawal. Perturbation studies with corticotropin-releasing factor (CRF) and TRH (with measures of ACTH and cortisol and TSH and prolactin, respectively), may identify patients with withdrawal-related autonomic dysfunction.

Effect of experimental and pathological weight loss upon the hypothalamo-pituitary-adrenal axis

Five healthy female subjects participated in a starvation experiment. After an initial baseline phase (A) they lost about 8 kg in a 3-week phase of complete food abstinence (B); thereafter they recovered to their original body weight (C) and kept this weight stable over more than 4 weeks (D). While all dexamethasone suppression tests (DST's) during the initial baseline were normal, half of the DST's (7/14) in the fasting phase showed insufficient suppression. In the following weight gain phase, all DST's were sufficiently suppressed. Twenty-four hour plasma cortisol patterns during fasting (B) showed a significant increase, as well as increased cortisol half-life, increased time in secretory activity, and increased number of secretory episodes. Administration of the alpha 2-adrenergic receptor agonist clonidine during fasting did not induce a further decrease in plasma cortisol level, whereas it did during baseline. The results demonstrate that weight loss, reduced caloric intake, and catabolic state have a very powerful influence on the hypothalamo-pituitary-adrenal (HPA) axis and other endocrine systems. The results shed new light on endocrine dysfunctions in mental disorders associated with reduced caloric intake, such as anorexia nervosa and depression, and question the specificity of certain endocrine dysfunctions for depression.

The TRH test during dopamine receptor blockade in depressed patients

In an evaluation of the possible role of dopamine on TRH test results, 21 depressed patients were given TRH before and after one week of treatment with a low dose of haloperidol. Haloperidol significantly increased serum prolactin (both basal and after TRH) and cortisol levels, decreased body temperature, and had no effect on serum TSH, growth hormone, or thyroid hormone levels. Five of six patients with initial TSH blunting were retested with TRH; in four patients the TSH response remained blunted. These data render it unlikely that dopamine exerts a major inhibitory input on TSH secretion in depression.

The TRH stimulation test and reverse T3 in depression

Blunted TSH response to TRH and elevation of reverse T3 (rT3) have been reported in depression, though the relationship between these two abnormalities has not been clear. The authors measured basal levels of T4, T3, rT3 and the TSH response to TRH in a group of 28 depressed men and women, unipolar and bipolar subtypes. No significant difference was found between these two subtypes of depression with respect to mean basal hormonal levels or magnitude of the TSH response to TRH. Two males had slight, but significant elevations of rT3 though only one of them had a blunted TSH response to TRH levels and the TSH response to TRH. Finally no significant correlation was found between rT3 levels and the TSH response to TRH.

[Causal analytic studies on demonstration of neuroendocrine parameters in combined hypoglycemia test in depressive subgroups]

With the help of an analytical path structure model (causal analysis) the aim of the study was to elucidate further, in female patients with various depressive disorders, some correlations of causal interdependencies between changes both in basal secretion of anterior pituitary hormones and in their responses to the (combined) insulin tolerance test (ITT) with extraneous factors--such as age, deviation from ideal body weight (in percentage), severity of depression and score in the Newcastle Scale (NCS)--that may influence these abnormalities. In various depressive subgroups the strength of influence and the different importance of deviation from ideal body weight and basal growth hormone (GH) concentration (as exclusion criteria) for their neuroendocrine reactivity in the combined ITT was shown. The hypothesis that cortisol hypersecretion may be the primary disturbance and the other possible neuroendocrine changes such as blunted GH, cortisol and TSH responses to stimuli in some depressive patients all may be secondary to the (elevated) cortisol level could not be corroborated. The endogenous mono- and bipolar subtypes of major depressive disorders showed intimate connections between the various neuroendocrine functional systems and the above mentioned extraneous factors resulting in a narrowed variability and a stronger coupling in the reactivity of these hormonal functional systems, a condition which can be seen as analogous to experimental results at the psychophysiological level in these nuclear groups of depressed patients, whose psychopathological state is also characterized by similar limitations in their "degree of freedom" (Heimann).

Central administration of thyrotropin-releasing hormone and histidyl-proline-diketopiperazine disrupts the acquisition of a food rewarded task by a non-aversive action

The effects of thyrotropin-releasing hormone (TRH) and its metabolites on operant behaviour have rarely been explored. In this study, the effects of intracerebroventricular (icv) administration of TRH and histidyl-proline-diketopiperazine (DKP), a metabolite of TRH, on the acquisition of a food-rewarded lever-press task were compared with saline-treated controls. TRH and DKP severely retarded the acquisition of lever pressing. The effects of systemically administered D-amphetamine were also examined in order to test whether this result was due to any stimulant properties of these peptides. These results suggest that stimulatory effects do not adequately account for impaired acquisition. The possibility that the disruption of learning was due to an aversive effect of icv administration of these peptides was tested by means of a conditioned place paradigm. Neither peptide induced an avoidance of the environment with which it had previously been paired. Several possible reasons for the peptides' adverse effect on learning are discussed, including the possibility that TRH and DKP act on attentional mechanisms.

Neuroendocrine alterations in systemic disease

Systemic disorders clearly may exert a significant influence on neuroendocrine function. Disorders that cause significant stress to the body, either physical or psychological, may cause a resetting upward of the HPA axis to provide sufficient cortisol to counteract the stress and to help sustain energy substrate levels. GH levels also increase in many of these situations, again promoting sufficient energy substrate levels. In some circumstances the concomitantly low somatomedin activity may be speculated to be adaptative to prevent the insulin-like agonist activity of these substances as well as to prevent energy expenditure in body growth. However, in other situations such as chronic renal failure and cirrhosis, the decreased somatomedin activity may be primary, causing decreased feedback at the hypothalamic-pituitary level and increased GH levels. The stress-induced rise in PRL may also play a minor role in preserving energy substrate since high levels may promote insulin resistance. In most illnesses the 'euthyroid sick syndrome' develops. Whether such patients are 'euthyroid' or mildly hypothyroid is a matter of controversy. The fact that protein losses are increased during fasting when the lowered T3 levels are returned to normal with exogenous T3 supplementation suggests that these patients are indeed hypothyroid and this hypothyroidism serves to conserve energy substrate by decreasing the metabolic rate. The reproductive axis is often impaired with systemic illness. Again, teleologically this may be viewed as an inactivation of non-essential functions in times of stress. It would appear that the changes that occur with systemic illness, in general, are favourable to the organism in that they promote survival. The detailed neurotransmitter and hypophyseotrophic hormone changes resulting in the alteration in pituitary function remain to be elucidated for the most part.

The TRH test and urinary MHPG in unipolar depression

Twenty-five men and 26 women with major unipolar depression were evaluated by the TRH test and urinary MHPG excretion. A significant positive correlation between TSH response to TRH and urinary MHPG was found in the men, though not in the women. These findings suggest that at least for depressed men, central norepinephrine deficiency may be the neurobiological substrate of blunted TSH responses to TRH.

Methodological issues in the measurement of serum TSH--implications for psychiatry

The TSH response to TRH has been reported to be blunted in endogenous depression. We compared two radioimmunoassay (RIA) techniques of TSH in 21 subjects (7 psychiatric inpatients, 14 normal controls) to determine whether differences in assay could account for discrepancies in the reported prevalence rates of blunted TSH responses in depression. A highly significant correlation (p less than 0.001) was found between the delta MAX TASH values of the two assays. The mean delta MAX TSH of one assay was significantly greater than the mean of the second assay. One assay yielded 6 blunted TSH responses to TRH, while the other yielded 9 such responses. Different TSH assay methods might account for discrepancies of the prevalence rates of blunted TSH response in depression.

Dysregulation of hypothalamic-pituitary-adrenal axis function in depressed alcoholic patients

Hypothalamic-pituitary-adrenal (HPA) axis function was examined in 28 hospitalized, withdrawing alcoholic patients. Fourteen patients met DSM-III criteria for Major Depressive Disorder. Elevated 8 a.m. basal cortisols were noted in 7 depressed alcoholic patients (50%) and no non-depressed alcoholics (P less than 0.01). Escape from dexamethasone suppression was noted in 9 depressed alcoholics (64%) and no non-depressed alcoholics (P less than 0.005). The measurement of HPA axis function may be a useful marker for endogenous depression in an alcoholic population.

Hyperthyroxinemia in patients with acute psychiatric disorders

Thyroid function tests were measured in 645 patients admitted to an acute psychiatric disorders unit. Thirty-three percent had elevated serum thyroxine (T4), and 18 percent had an elevated free T4 index (FTI). Serum triiodothyronine (T3) was low, normal, or minimally elevated in 77 patients, with a high initial free T4 index. Twenty-two patients with an initial elevation of their free T4 index were serially followed (study group). Serum T4, free T4 index, and free T4 fell in every patient: serum T4 from 13.95 +/- 1.93 micrograms/dl (mean +/- standard deviation: SD) to 9.33 +/- 2.4 micrograms/dl (p less than 0.001); free T4 index, from 6.15 +/- 0.83 to 3.79 +/- 1.1 (p less than 0.001); free T4, from 2.43 +/- 0.65 mg/dl to 1.38 +/- 0.35 ng/dl (p less than 0.001). Serum T3 was initially normal or low, and then fell in 17 patients, and rose in five. Serial testing of thyrotropin-releasing hormone (TRH) demonstrated both flat and normal responses in patients with a variety of psychiatric diagnoses and at varying stages of thyroid disease activity.

The TRH stimulation test in subtypes of unipolar depression

The thyrotropin releasing hormone (TRH) stimulation test was administered to 54 primary unipolar endogenously depressed and 19 non-depressed hospitalized inpatients. Blunted TSH responses to TRH infusion (delta max TSH less than 7 microunits/ml) were revealed in 18 depressed and no non-depressed patients (P less than 0.01). Augmented TSH responses (delta max TSH greater than 23 microunits/ml) were noted in 8 depressed and no non-depressed patients (P = n.s.). The TRH stimulation test did not distinguish between subtypes of unipolar depression using the familial subtyping criteria of Winokur. These findings are discussed in light of previously reported dexamethasone suppression test subtype distinctions.

Compensatory pituitary-thyroid mechanisms in major depressive disorder

The thyrotropin-releasing hormone (TRH) stimulation test was administered to 47 patients meeting DSM-III criteria for major depressive disorder (with melancholia) and to 19 nondepressed patients. The wide variability of pituitary responses to TRH stimulation noted in the depressed patients provides evidence for the dysregulation of compensatory hypothalamic-pituitary-thyroid function in acute depression. Blunted thyroid-stimulating hormone (TSH) responses to TRH injection were found in 16 depressed (34%) and no nondepressed patients (p less than 0.01). Depressed patients who revealed blunted TSH responses also had blunted prolactin responses to TRH relative to other depressed and nondepressed patient groups (p less than 0.01). These patients (with blunted TSH and prolactin responses) may represent a psychobiologically distinct subgroup of endogenously depressed patients. Augmented (high normal) TSH responses to TRH stimulation were found in eight depressed patients (all women), in contrast to no nondepressed patients. These patients may have a subtle thyroidal dysfunction affecting the underlying endogenous depressive diathesis.

Improvement in ratings of tension after TRH administration in healthy women

Administration of thyrotropin releasing hormone (TRH), 400 micrograms i.v., to healthy premenopausal women resulted in improvement in ratings of tension on the 100 mm line test. The max. mean improvement in tension ratings was significantly greater after TRH than after saline (t = 2.27, df = 9, p less than 0.05); after TRH administration, eight of 10 subjects showed greater than 30% improvement in tension ratings, while only three of 10 subjects receiving saline reported a comparable degree of improvement. No significant improvement in ratings of mood state were noted after administration of either TRH or saline. These findings extend previous reports of behavioral effects of TRH in normal subjects. The possibility that the behavioral effects of TRH may be influenced by the state of activity of the CNS is discussed.

Blunted aldosterone response to dexamethasone in female patients with endogenous depression

(1) The dexamethasone suppression test (DST) was utilized to study the aldosterone (Aldo) response in patients with endogenous depression (ED). This adrenal steroid is believed to be regulated by CNS factors different from ACTH. (2) Six female patients (two pre- and four post-menopausal) and six female healthy controls (three pre-and three post-menopausal) were studied under equivalent conditions. Venous blood samples were taken at 0900 and 2300 hr before and at 0900, 1600 and 2300 hr after dexamethasone (2 mg p.o.) given at 2300 hr. In healthy controls, the median of plasma Aldo at 0900 hr before dexamethasone was lower than at 0900 hr after drug administration (p less than 0.01), while the opposite change occurred in the patients. The median of the controls at 0900 hr post-dexamethasone was 101 pg/ml, and that of the patients was 23 pg/ml (p less than 0.025). (3) According to these observations dexamethasone appears to have a stimulatory effect on 0900 hr plasma Aldo-levels, which are blunted in patients with ED. This finding possibly signifies disinhibited central dopaminergic function in ED. Whether dopamine acts directly on the adrenal gland or modulates Aldo secretion via Aldo-releasing factors different from ACTH remains unresolved. The neurotransmitter process which underlies Aldo regulation appears to be substantially altered in ED.

Is thyrotropin releasing hormone an endogenous ergotropic substance in the brain?

The neuropharmacological profile for thyrotropin releasing hormone (TRH) has been compared with various other types of central nervous system stimulants, and the results of the comparison, considered together with the results obtained by other workers, suggest that TRH may function as an endogenous ergotropic substance. Its ergotropic properties suggest that TRH analogues with better biological stability than the parent compound may be useful agents for treating some psychiatric disorders; for hastening the recovery of consciousness and respiration after anaesthesia; for treating narcotic overdosage or dependence, narcolepsy, minimal brain damage, and various neuromuscular disorders; and for aiding the diagnosis of "brain death".

Neuroendocrine measures in psychiatric patients: course and outcome with ECT

Measures of neuroendocrine function--plasma cortisol and its response to dexamethasone, and plasma thyroid-stimulating hormone (TSH) and its response to thyrotropin-releasing hormone (TRH)--were employed in 50 hospitalized male veteran psychiatric patients with diagnoses of unipolar or bipolar melancholia, secondary depression, or schizophrenia. Of 20 cases of unipolar melancholia, 17 (85%) exhibited hypercortisolism; 14 (70%) failed to suppress plasma cortisol after dexamethasone; and 4 (31%) of 13 tested had an abnormal TSH response to intravenous TRH. Two patients with secondary depression also exhibited hypercortisolism; no other patients evinced abnormal neuroendocrine test results. These measures were repeated in 14 unipolar depressed patients after a course of electroconvulsive therapy (ECT). Improvement in psychopathology was directly related to normalization of measures of hypothalamic-pituitary-adrenal (HPA) function. The TSH response to TRH was not systematically altered. After a followup period of 1 to 9 months, there was a good correlation between the measures of HPA function and the clinical outcome. These findings encourage further study of HPA function measures as outcome criteria for depressed patients receiving ECT.

Endocrine and behavioral changes in depression after thyrotropin-releasing hormone (TRH). Alteration by pretreatment with thyroid hormones

The effects of pretreatment with a single dose of thyroid hormones (TH) on the subsequent endocrine and behavioral response to TRH was evaluated in unipolar depressed women. TH pretreatment altered neither serum levels of thyroid hormones nor the TRH-induced TSH response. It antagonized, however, the behavioral response to TRH. This was apparent in 2 self-assessment scales but not in an objective rating scale. Taken together the data suggest that (a) there is an impaired pituitary response to TH feedback in depressed patients; (b) TH pretreatment may affect self-assessment of behavioral effects of TRH in depression.