The cortisol responses to 5-hydroxytryptophan, orally, in depressive inpatients

Estrogen-dependent effects of 5-hydroxytryptophan on cortical spreading depression in rat: Modelling the serotonin-ovarian hormone interaction in migraine aura

Background Cortical spreading depression (CSD) is the likely culprit of the migraine aura. Migraine is sexually dimorphic and thought to be a "low 5-HT" condition. We sought to decipher the interrelation between serotonin, ovarian hormones and cortical excitability in a model of migraine aura. Methods Occipital KCl-induced CSDs were recorded for one hour at parieto-occipital and frontal levels in adult male (n = 16) and female rats (n = 64) one hour after intraperitoneal (i.p.) injection of 5-hydroxytryptophan (5-HTP) or NaCl. Sixty-five oophorectomized females were treated with estradiol- (E2) or cholesterol- (Chol) filled capsules. Two weeks later we recorded CSDs after 5-HTP/NaCl injections before or 20 hours after capsule removal. Results 5-HTP had no effect in males, but decreased CSD frequency in cycling females, significantly so during estrus, at parieto-occipital (-3.5CSD/h, p < 0.001) and frontal levels (-2.5CSD/h, p = 0.014). In oophorectomized rats, CSD susceptibility increased during E2 treatment at both recording sites (+5CSD/h, p = 0.001 and +3CSD/h, p < 0.01), but decreased promptly after E2 withdrawal (-4.7CSD/h, p < 0.001 and -1.7CSD/h, p = 0.094). The CSD inhibitory effect of 5-HTP was significant only in E2-treated rats (-3.4CSD/h, p = 0.006 and -1.8CSD/h, p = 0.029). Neither the estrous cycle phase, nor E2 or 5-HTP treatments significantly modified CSD propagation velocity. Conclusion 5-HTP decreases CSD occurrence in the presence of ovarian hormones, suggesting its potential efficacy in migraine with aura prophylaxis in females. Elevated E2 levels increase CSD susceptibility, while estrogen withdrawal decreases CSD. In a translational perspective, these findings may explain why migraine auras can appear during pregnancy and why menstrual-related migraine attacks are rarely associated with an aura.

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

The inflammatory & neurodegenerative (I&ND) hypothesis of depression: leads for future research and new drug developments in depression

Despite extensive research, the current theories on serotonergic dysfunctions and cortisol hypersecretion do not provide sufficient explanations for the nature of depression. Rational treatments aimed at causal factors of depression are not available yet. With the currently available antidepressant drugs, which mainly target serotonin, less than two thirds of depressed patients achieve remission. There is now evidence that inflammatory and neurodegenerative (I&ND) processes play an important role in depression and that enhanced neurodegeneration in depression may-at least partly-be caused by inflammatory processes. Multiple inflammatory-cytokines, oxygen radical damage, tryptophan catabolites-and neurodegenerative biomarkers have been established in patients with depression and these findings are corroborated by animal models of depression. A number of vulnerability factors may predispose towards depression by enhancing inflammatory reactions, e.g. lower peptidase activities (dipeptidyl-peptidase IV, DPP IV), lower omega-3 polyunsaturated levels and an increased gut permeability (leaky gut). The cytokine hypothesis considers that external, e.g. psychosocial stressors, and internal stressors, e.g. organic inflammatory disorders or conditions, such as the postpartum period, may trigger depression via inflammatory processes. Most if not all antidepressants have specific anti-inflammatory effects, while restoration of decreased neurogenesis, which may be induced by inflammatory processes, may be related to the therapeutic efficacy of antidepressant treatments. Future research to disentangle the complex etiology of depression calls for a powerful paradigm shift, i.e. by means of a high throughput-high quality screening, including functional genetics and genotyping microarrays; established and novel animal and ex vivo-in vitro models for depression, such as new transgenic mouse models and endophenotype-based animal models, specific cell lines, in vivo and ex vivo electroporation, and organotypic brain slice culture models. This screening will allow to: 1) discover new I&ND biomarkers, both at the level of gene expression and the phenotype; and elucidate the underlying molecular I&ND pathways causing depression; and 2) identify new therapeutic targets in the I&ND pathways; develop new anti-I&ND drugs for these targets; select existing anti-I&ND drugs or substances that could augment the efficacy of antidepressants; and predict therapeutic response by genetic I&ND profiles.

Serotonergic disturbances in autistic disorder: L-5-hydroxytryptophan administration to autistic youngsters increases the blood concentrations of serotonin in patients but not in controls

Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) may play a role in the pathophysiology of autistic disorder. This study examines the whole blood concentrations of 5-HT and 5-hydroxy-indoleacetic acid (5-HIAA) in baseline conditions and during a challenge with L-5-OH-tryptophane (5-HTP; 4 mg/kg in non enteric-coated tablets), the precursor of 5-HT, in a study group of 18 male, post-pubertal, Caucasian autistic patients (age 13-19 y.; I.Q.>55) and 20 matched healthy volunteers. In baseline conditions, no significant differences in 5-HT or 5-HIAA levels could be found between autistic youngsters and normal controls. 5-HTP administration significantly increased the levels of 5-HT in autistic youngsters but not in normal controls. Following 5-HTP challenge the 5-HT levels were significantly higher in autistic patients than in healthy volunteers. After challenge with 5-HTP, no significant differences were found in the concentrations of 5-HIAA or the test substance between autistic youngsters and normal controls. Differences in the peripheral metabolism of 5-HT which may not be observed in baseline conditions but which became clear after loading with 5-HTP, suggest that an increased synthesis of 5-HT from its precursor 5-HTP might be a one factor responsible for differences in the serotonergic system between autistic post-pubertal youngsters and normal controls.

Serotonin and the neuroendocrine regulation of the hypothalamic--pituitary-adrenal axis in health and disease

Serotonin (5-hydroxytryptamine, 5-HT)-containing neurons in the midbrain directly innervate corticotropin-releasing hormone (CRH)-containing cells located in paraventricular nucleus of the hypothalamus. Serotonergic inputs into the paraventricular nucleus mediate the release of CRH, leading to the release of adrenocorticotropin, which triggers glucocorticoid secretion from the adrenal cortex. 5-HT1A and 5-HT2A receptors are the main receptors mediating the serotonergic stimulation of the hypothalamic-pituitary-adrenal axis. In turn, both CRH and glucocorticoids have multiple and complex effects on the serotonergic neurons. Therefore, these two systems are interwoven and communicate closely. The intimate relationship between serotonin and the hypothalamic-pituitary-adrenal axis is of great importance in normal physiology such as circadian rhythm and stress, as well as pathophysiological disorders such as depression, anxiety, eating disorders, and chronic fatigue.

Effects of subchronic treatment with valproate on L-5-HTP-induced cortisol responses in mania: evidence for increased central serotonergic neurotransmission

The mechanisms underlying the acute and prophylactic antimanic properties of valproate have remained elusive. There are some reports that treatment with valproic acid may increase brain serotonergic neurotransmission in the rodent. This study was carried out in order to investigate the effects of subchronic therapy with valproate on central serotonin metabolism in manic patients. Toward this end, the authors examined plasma cortisol responses to 200 mg (orally) L-5-hydroxy-tryptophan (L-5-HTP) in 10 manic patients both before and after subchronic treatment with valproate. Administration of L-5-HTP resulted in significantly increased cortisol responses both before and after treatment with valproate. The L-5-HTP-induced cortisol responses were significantly higher after treatment with valproate than before treatment. It is suggested that valproate may increase central serotonergic neurotransmission and that this stimulation may play a role in the antimanic effects of valproate.

Prolactin and cortisol responses to fenfluramine in Parkinson's disease

Dysfunction of the central serotonergic system has been associated with depression in Parkinson's disease. To evaluate central serotonergic function in Parkinson's disease in relation to depression, we examined prolactin and cortisol responses to a single-dose challenge with fenfluramine (60 mg orally), a serotonin releasing/uptake-inhibiting agent, in the course of 5 hours in 11 patients with Parkinson's disease associated with major depression (SADS-RDC), 22 nondepressed parkinsonians, and 20 age- and gender-matched healthy controls. No difference in cortisol responses were observed between the groups; however, prolactin responses to fenfluramine were significantly impaired in patients with Parkinson's disease compared to controls, and the response was significantly more blunted in parkinsonian patients with major depression in comparison with the nondepressed ones. These findings indicate that there is a diminished serotonergic responsivity in depression associated with Parkinson's disease.

Effects of ipsapirone on plasma cortisol and body temperature in major depression

Major depressed patients have been reported to exhibit significantly attenuated hypothermic responses to ipsapirone, a serotonin (5-HT)-1A partial agonist, compared to normal controls. This study further investigated the cortisol and temperature responses to ipsapirone (0.5 mg/kg orally) and placebo in 20 normal volunteers and 12 major depressed patients. Both plasma cortisol and temperature were measured every 30 min before ipsapirone or placebo administration until 180 min post administration. Ipsapirone administration produced a significant increase in plasma cortisol levels as well as hypothermia. Major depressed patients showed significantly blunted ipsapirone-induced cortisol responses compared to normal controls. No significant differences in ipsapirone-induced hypothermic responses were found between major depressed patients and normal controls.

Effect of pindolol pretreatment on MK-212-induced plasma cortisol and prolactin responses in normal men

Previous reports based on studies with serotonin (5-HT) precursors or direct acting agonists have suggested that postsynaptic 5-HT1A and 5-HT2A/5-HT2C receptors may stimulate cortisol and prolactin (PRL) secretion in man. To further clarify the role of these receptors in the regulation of cortisol and PRL secretion in man, the effects of 6-chloro-2-(1-piperazinyl) pirazine (MK-212), a centrally acting direct 5-HT2A/5-HT2C agonist, on the above hormones were studied in 11 normal men with and without pretreatment with pindolol, a 5-HT1A partial agonist. MK-212 induced a significant increase in plasma concentrations of cortisol and PRL. The MK-212-induced response in plasma cortisol was not diminished by pindolol pretreatment, whereas the MK-212-induced PRL response was significantly inhibited by pindolol pretreatment. These data suggest that the MK-212-induced cortisol response may be mediated by 5-HT2A or 5-HT2C receptor activation, or both, despite 5-HT1A inhibition; however, PRL secretion by MK-212 requires 5-HT1A receptor availability as well as 5-HT2A/5-HT2C receptor activation, since blockade of the former appears to blunt the PRL responses to MK-212. These findings may be explained by postulating a cooperativity between 5-HT1A and 5-HT2A/5-HT2C receptors with regard to the 5-HT-dependent stimulation of PRL secretion.

Effects of serotonin precursors on the negative feedback effects of glucocorticoids on hypothalamic-pituitary-adrenal axis function in depression

In order to investigate the relationships between brain serotonergic turnover and hypothalamic-pituitary-adrenal (HPA) axis function in unipolar depression, the authors measured intact adrenocorticotropic hormone (ACTH) and cortisol levels in baseline conditions and after combined dexamethasone (1 mg PO) and L-5-hydroxytryptophan (L-5-HTP, 200 mg PO) administration in 13 minor, 17 simple major, and 17 melancholic subjects. L-5-HTP significantly enhanced post-DST ACTH and cortisol secretion in major--but not in minor--depressed subjects. Major depressed subjects with or without melancholia exhibited significantly higher post-DST ACTH and cortisol responses to L-5-HTP than minor depressed subjects. L-5-HTP administration converted some major depressed ACTH or cortisol suppressors into nonsuppressors. L-5-HTP stimulated ACTH or cortisol secretion to the same extent in major depressed HPA-axis suppressors and nonsuppressors. It is concluded that L-5-HTP loading may augment ACTH and, consequently, cortisol escape from suppression by dexamethasone in major but not in minor depressed subjects. The findings show that serotonergic mechanisms modulate the negative feedback of glucocorticoids on central HPA-axis regulation. It is hypothesized that the higher L-5-HTP-induced post-DST HPA-axis hormone responses in major depression reflect upregulated 5-HT2 receptor-driven breakthrough secretion of pituitary ACTH from suppression by dexamethasone.

5-Hydroxytryptamine2 and beta-adrenergic receptor regulation in rat brain following chronic treatment with desipramine and fluoxetine alone and in combination

A chronic (14-day) study was initiated to investigate the effects of combined fluoxetine (FLU) and desipramine (DMI) treatment on the densities and affinities of beta-adrenergic and 5-hydroxytryptamine2 (5-HT2) receptors. Male Sprague-Dawley rats were administered the following doses using osmotic minipumps: FLU, 10 mg/kg/day; DMI, 5, 10, or 15 mg/kg/day; FLU, 10 mg/kg/day, plus DMI, 5 mg/kg/day; or vehicle (distilled water). After 14 days the cortex was dissected out and used for [3H]-ketanserin (5-HT2) binding, [3H]CGP-12177 (beta-adrenergic) binding, and drug level analysis. All animals receiving DMI showed significant down-regulation of 5-HT2 receptors except those receiving FLU in combination. DMI down-regulated beta-adrenergic receptors in a dose-dependent manner, with significantly greater down-regulation seen with the combination than with DMI (5 mg/kg/day) alone. This latter effect was apparently the result of greater levels of DMI in cortex with the combination than with DMI (5 mg/kg/day) alone. FLU had no effect on 5-HT2 or beta-adrenergic receptors on its own. Coadministration of FLU and DMI resulted in a doubling of levels of FLU and its demethylated metabolite, norfluoxetine (NFLU), and a tripling of DMI levels compared with values observed when FLU (10 mg/kg/day) or DMI (5 mg/kg/day) was administered alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the placebo control condition in neuroendocrine challenge studies

Neuroendocrine challenge studies are frequently used to make inferences about the pathophysiology of psychiatric illness or about the effects of chronic psychotropic drug treatment on brain monoamine function. The outcome of these exploratory neuroendocrine tests, however, may be influenced by the effects of confounding variables, such as specific stress effects and variations in basal hormone levels. The inclusion of a placebo control condition minimizes the variability due to these variables. A number of recent neuroendocrine studies have omitted the placebo control condition. Based on experimental data, it can be shown that failure to include a placebo control condition may result in both Type I and Type II errors of inference. These results suggest a placebo control condition should be included in exploratory neuroendocrine challenge studies.

Effect of pindolol on the L-5-HTP-induced increase in plasma prolactin and cortisol concentrations in man

Previous studies with direct-acting serotonin (5-HT) agonists and antagonists have demonstrated that stimulation of 5-HT1A, 5-HT1C and 5-HT2 receptors may promote cortisol and prolactin (PRL) secretion in man. There is also evidence that 5-HT1C/2 receptor stimulation contributes to the cortisol and PRL responses following administration of the 5-HT precursor, L-5-hydroxytryptophan (L-5-HTP), in man. To clarify the possible contribution of 5-HT1A receptor stimulation to the ability of L-5-HTP to stimulate cortisol and PRL secretion in man, the effect of pindolol, a beta adrenoceptor antagonist that is also a 5-HT1A partial agonist, on the L-5-HTP-induced increases in cortisol and PRL secretion, was examined in 12 normal male volunteers. Pretreatment with pindolol, 30 mg orally, significantly inhibited the PRL but not the cortisol response to L-5-HTP, 200 mg PO. Pindolol alone decreased basal plasma PRL levels and increased basal plasma cortisol levels, possibly due to 5-HT1A antagonist and agonists effects, respectively. These data, coupled with observations from other studies, suggest that the L-5-HTP-induced increase in PRL but not cortisol secretion requires 5-HT1A receptor activation. PRL secretion due to 5-HT formed from exogenous L-5-HTP may require the availability of both intact 5-HT1A and 5-HT2/5-HT1C receptors, since blockade of either receptor type inhibited the PRL response to L-5-HTP. The implication of this synergistic effect for interpretation of neuroendocrine studies involving the serotonergic system in man is discussed.

Pharmacologic treatment of schizoaffective disorder

In contrast to the considerable systematic study of the pharmacologic treatment of schizophrenia and mood disorders, the pharmacologic treatment of schizoaffective disorder has been relatively ignored. The authors reviewed the available literature regarding the pharmacologic treatment of schizoaffective disorder. The total number of controlled studies of the acute and prophylactic treatment of schizoaffective disorder was small and few used modern criteria to define the disorder. In studies of schizoaffective disorder, bipolar type (manic), lithium and antipsychotics produced comparable albeit incomplete responses, except in highly agitated patients when antipsychotics exerted superior efficacy. The combination of lithium and antipsychotics appeared to be superior to antipsychotics alone for schizoaffective, bipolar type patients. In the only controlled study of schizoaffective disorder, depressed type, the presumed superiority of combined antidepressant and antipsychotic treatment to antipsychotic alone was not found. Although combined antipsychotic and thymoleptic treatment represents common prophylactic management of schizoaffective disorder in clinical practice, the efficacy of this strategy has not been studied in controlled trials. Advances in the nosology of schizoaffective disorder, emerging epidemiologic data demonstrating large numbers of patients with this disorder in clinical populations, and preliminary evidence that clozapine may have combined antipsychotic and thymoleptic properties as well as efficacy in both the psychotic and affective components of schizoaffective disorder, suggest that renewed interest in the diagnosis and treatment of this disorder may lead to improved delivery of care for this understudied but seriously ill group of patients.

Effects of buspirone on plasma prolactin and cortisol levels in major depressed and normal subjects

The cortisol response to ipsapirone (a 5-HT1A-partial agonist that produces a dose-dependent increase in plasma cortisol secretion in man) is blunted in major depression. Buspirone is another 5-HT1A agonist that increases cortisol secretion in man. This study investigated cortisol and prolactin (PRL) responses to buspirone (30 mg orally) in 45 major depressed subjects and 28 normal controls. Buspirone administration yielded a significant increase in cortisol and PRL levels in both normal controls and depressed subjects. No differences in buspirone-induced hormone responses were found either between major depressives and normal controls or between melancholic and nonmelancholic depressives. There were no significant relationships between severity of depression and any of the hormonal responses to buspirone. PRL responses to buspirone were significantly higher in women than in men.

Biological studies of dysthymia

Dysthymic disorder (DD) is a chronic subsyndromal depressive condition that has generated increasing interest since its formal introduction into the psychiatric nomenclature in 1980. Although DD was included among the affective disorders in DSM-III, this classification was controversial. Some clinical and family studies support an association between DD and major depression disorder (MDD), but there has been little additional research firmly establishing the diagnostic validity of DD or clarifying its relation to MDD and to personality disorders. In this article, the literature on the biology of DD is reviewed. Studies of rapid eye movement (REM) latency, electrodermal activity, and the thyroid axis show similarities between DD and MDD, but the findings are mixed. Other investigations, including the Dexamethasone Suppression Test (DST), catecholamines, and several other electroencephalogram (EEG) sleep variables, show more consistent differences between DD and MDD. These findings suggest that DD manifests primarily trait characteristics of depression, thus differentiating it from the state characteristics of MDD. The methodological problems and implications of these studies, and suggestions for future research, are discussed.

Abnormal pituitary function during melancholia: reduced alpha-melanocyte-stimulating hormone secretion and increased intact ACTH non-suppression

In order to investigate pituitary alpha-melanocyte-stimulating hormone (alpha-MSH), intact (1-39 structure) adrenocorticotropic hormone (ACTH), and adrenal cortisol secretion, we measured 8 a.m. plasma levels of those hormones before and after administration of 1 mg dexamethasone in 39 depressed inpatients and 10 healthy controls. We found a significantly lower baseline alpha-MSH secretion in melancholic patients as opposed to healthy controls. There were no significant relations between alpha-MSH secretion on the one hand and ACTH or cortisol secretion on the other. Dexamethasone did not affect the 8 a.m. alpha-MSH circulating levels. The post-dexamethasone intact ACTH and cortisol values were significantly higher in melancholics as compared with healthy, minor and simple major depressed subjects. ACTH non-suppression was defined as post-dexamethasone intact ACTH greater than or equal to 12 pg/ml. ACTH non-suppression was found to be more sensitive (70%) and specific (100%) for melancholia than cortisol non-suppression. By means of pathway analysis we have established that cortisol non-suppression during a severe depression is completely determined by an augmented ACTH escape from suppression by dexamethasone. It is concluded that the assay of post-dexamethasone intact ACTH could, in the future, replace post-dexamethasone cortisol determination.

A multivariate study of simultaneous escape from suppression by dexamethasone of urinary free cortisol, plasma cortisol, adrenocorticotropic hormone and beta-endorphin in melancholic patients

To investigate the relationships between pre- and postdexamethasone hypothalamic-pituitary-adrenal (HPA) axis functioning in depression, we measured the levels of baseline and postdexamethasone urinary free cortisol (UFC), plasma cortisol, adrenocorticotropic hormone (ACTH) and beta-endorphin. We found that dexamethasone significantly suppressed all hormone levels. All 4 postdexamethasone hormones--but not their baseline levels--were significantly higher in melancholic subjects than in minor and simple major depressives. We have accumulated evidence that the melancholic and minor depression groups form discrete classes in postdexamethasone HPA axis hormone levels; this supports the biological heterogeneity hypothesis of melancholia. We found that a combination of the postdexamethasone UFC and beta-endorphin values yielded the most significant diagnostic tool for melancholia. Our results suggest that the measurements of both hormones may constitute the most accurate index reflecting the HPA axis escape from suppression by dexamethasone in melancholia. By means of pathway analysis, we determined the causal relationships between age, dexamethasone circulating levels, diagnostic depression classification and the various baseline and postdexamethasone hormone values.

L-5-hydroxytryptophan stimulated cortisol escape from dexamethasone suppression in melancholic patients

The dexamethasone suppression test (DST) was carried out in 62 depressed patients. At 0800 the postdexamethasone cortisol values were determined and 125 mg L-5-hydroxytryptophan (L-5-HTP) was administered. The second cortisol sample at 0930 revealed a significant enhancing effect for L-5-HTP on the postdexamethasone cortisol values in melancholic patients, whereas no effects were detected in minor depressives. Our results show that L-5-HTP converts some DST suppressors into nonsuppressors, whereas the escape from dexamethasone in some nonsuppressors is markedly stimulated. The L-5-HTP-stimulated 0930 postdexamethasone cortisol values performed markedly better than the 0800 DST results: at a cut-off value of greater than or equal to 5 micrograms/dl the sensitivity for melancholia increased from 46% to 68%, and the specificity remained unchanged (96%).

Inhibitory effect of ritanserin on the 5-hydroxytryptophan-mediated cortisol, ACTH and prolactin secretion in humans

Oral administration of the serotonin (5-HT) precursor L-5-hydroxytryptophan (5-HTP), 200 mg, significantly increased plasma cortisol levels in man. L-5-HTP had no significant effect on the plasma prolactin levels. A borderline effect of 5-HTP on plasma ACTH levels was found. Pretreatment with the 5-HT2/5-HT1c antagonist ritanserin (5 mg, PO, b.i.d. for 2 days) significantly inhibited 5-HTP-induced cortisol secretion. Ritanserin had no effect on the basal plasma cortisol or prolactin levels. These data are suggestive that 5-HTP stimulates cortisol secretion in man via 5-HT2/5-HT1c receptor mechanisms.

A revised interpretation of postdexamethasone ACTH and cortisol findings in unipolar depressed females

Baseline 8 a.m. adrenocorticotropic hormone (ACTH) and cortisol levels and the postdexamethasone ACTH/cortisol values at 8 a.m. and 4 p.m. were determined in 86 depressed females diagnosed using DSM-III criteria. Postdexamethasone ACTH and cortisol values were significantly correlated with their baseline levels. We have shown that regression analysis should be used to assess dexamethasone-induced changes as the residual ACTH and cortisol responses, with the relative effects of the baseline data on the hormone responses being partialed out. The residual ACTH and cortisol values were significantly increased in the most severely depressed females as compared to minor depressives. The residual ACTH responses were markedly correlated with the residual cortisol responses. Cortisol nonsuppression during a depressive episode appeared to be determined by an augmented ACTH escape from dexamethasone suppression. The residual ACTH and cortisol responses could prove to be the most sensitive reflection of the disorder in the negative feedback by dexamethasone on the pituitary. In clinical practice, the ratio ln (postdexamethasone ACTH): ln (basal ACTH) can be used, since this ratio is linearly correlated with the residual ACTH responses.

Hormonal responses to fenfluramine in depressive subtypes

In order to study putative differences in central neurotransmitter function in depressive subtypes, serum cortisol and prolactin responses to the putative serotonin agonist fenfluramine were examined in 30 subjects with major depression. Patients with endogenous depression (melancholia) as defined by each of ICD-9, DSM-III, RDC and Newcastle scale demonstrated a reduced prolactin response to 60 mg oral fenfluramine when compared with non-endogenous subjects. This was independent of either prolactin or cortisol baseline levels, and indicates that there are differences in brain neurotransmitter function in the endogenous and non-endogenous subtypes of depression. Basal prolactin levels were reduced in bipolar compared with unipolar subjects, and delusional compared with non-delusional patients, although there were no differences in the prolactin responses to fenfluramine between these subgroups. Basal cortisol levels and cortisol response to fenfluramine did not distinguish between any of the subtypes.

The relationships between the cortisol responses to dexamethasone and to L-5-HTP, and the availability of L-tryptophan in depressed females

In order to investigate the relationships between the hypothalamic-pituitary-adrenal (HPA)-axis activity, the central serotonergic neurotransmission, and the peripheral metabolism of l-tryptophan (L-TRP), the authors measured the following: the postdexamethasone cortisol values, the cortisol responses to 125 mg 5-hydroxy-L-tryptophan (L-5-HTP) orally, and the total L-TRP/competing amino acids (CAA) ratio in 64 depressed females. Severely depressed females showed significantly lower values for L-TRP/CAA, significantly higher postdexamethasone cortisol values, and cortisol responses to L-5-HTP as compared with minor depressives. Dexamethasone nonsuppressors showed significantly lower L-TRP/CAA values as compared with suppressors. The cortisol responses to dexamethasone were significantly and negatively correlated with the availability of L-TRP. The cortisol responses to L-5-HTP were not related to either the availability of L-TRP or to the postdexamethasone cortisol values.

Sex-linked differences in cortisol, ACTH and prolactin responses to 5-hydroxy-tryptophan in healthy controls and minor and major depressed patients

Some researchers have found that the administration of 5-hydroxytryptophan (5-HTP) results in increased cortisol secretion in major depressives but not in healthy controls. Other authors observed gender-related differences in cortisol responses to 5-HTP in major depressives. In order to investigate the pituitary/adrenal responsivity to 5-HTP, the authors measured cortisol, adrenocorticotropic hormone (ACTH) and prolactin (PRL) in 30 healthy controls and in 90 depressed patients; the hormone levels were determined in baseline conditions and 60, 90 and 120 min after 125 mg L-5-HTP (orally, non-enteric coated). We found that healthy men had significantly higher cortisol responses to L-5-HTP than healthy women. In the major depressives with melancholia and/or psychotic features these differences were reversed: women exhibited significantly higher cortisol and PRL responses than men. In the female group the most severely depressed patients had increased cortisol and PRL responses to L-5-HTP. The amplitudes of the cortisol, ACTH and PRL responses to L-5-HTP were significantly and positively correlated. It was concluded that the central serotonergic regulation of ACTH and PRL is significantly different between the sexes and between healthy controls, minor depressives and severely depressed patients.

Influences on cortisol and noradrenergic turnover of healthy controls and depressed patients during L-tryptophan loading

To investigate the interrelationships between the noradrenergic and serotonergic systems and the hypothalamic-pituitary-adrenal (HPA) axis, we measured the excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) and free cortisol (UFC) in 24-h urine both before and after loading with 2 g L-tryptophan (L-TRP) orally in 24 healthy controls and 33 depressed patients categorized according to DSM-III. Loading with L-TRP reduced MHPG excretion significantly by 56% in major depressives, whereas in healthy controls and in minor depressives no significant effects were observed. Although basal MHPG did not differ among these study groups, loading with L-TRP resulted in MHPG excretion in major depressives being significantly lower than in healthy controls and minor depressives. Loading with L-TRP increased UFC significantly by 49% only in major depressives with associated features. After L-TRP those patients exhibited significantly increased UFC as compared with all other depressives and controls, whereas basal UFC values did not differ among the study groups. In baseline conditions there were no significant correlations between MHPG and UFC excretion.

Increased serotonin2 (5-HT2) receptor binding as measured by 3H-lysergic acid diethylamide (3H-LSD) in the blood platelets of depressed patients

3H-Lysergic acid diethylamide (3H-LSD) binding, a putative measure of 5-HT2 receptor binding, was studied in the blood platelets of 29 depressed patients and 24 normal controls. The Bmax (maximum number of 3H-LSD binding sites) in the blood platelets of depressed patients was significantly greater than that of normal volunteers. This increase in Bmax was due to an increase in female depressed patients only. Bmax was significantly lower in female compared to male normal controls but there was no difference between male and female depressed patients. There was also no difference in Kd (an inverse measure of affinity of 3H-LSD binding to its sites) between normal controls and depressed patients. The correlations between Bmax of 3H-LSD binding and the Bmax of the 3H-imipramine binding site or the Vmax of 5-HT uptake sites were not significant. The role of serotonergic processes in the psychobiology of depression is discussed.

Sex-related differences in the relationships between self-rated depression and biological markers

Gender-related differences in self-reported depression, in biological factors putatively related to depression and in the associations between severity of illness and biological factors were investigated. To this end the Zung Self-Rating Depression Scale (SDS), the ratio L-tryptophan/valine + leucine (L-TRP/CAA) and basal cortisol in serum at 8 a.m. were determined in 51 depressed inpatients undergoing a dexamethasone suppression test (DST). In the total study group no significant relationships were established between severity of illness and either of the biological markers. In women, SDS correlated significantly (P less than 0.01) negatively with the ratio L-TRP/CAA and positively with post-dexamethasone cortisol (P less than 0.01). In men these relationships tended to be inverted. The differences in the two sexes between these correlation coefficients were significant (P less than 0.01). These gender-related differences in the relationships between self-reported depression and the biological variables could be explained by differential psychoneuroendocrine and psychobiochemical responses. Future work on the severity of illnesses in terms of biological factors must take into account these differential responses between depressed males and females.