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The serum cortisol concentration following administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, a precursor of serotonin (5-HT), was significantly greater in unmedicated depressed and manic patients than in normal controls. Increases in serum cortisol levels greater than 5 micrograms/dL were significantly more frequent in both unmedicated depressed and manic patients than in the normal controls. There was significant test-retest reliability. Baseline serum cortisol concentration correlated negatively with the cortisol response to 5-HTP in normal controls. These results suggest increased 5-HT receptor sensitivity may be present, possibly in the hypothalamus or pituitary, in some patients with affective disorders. These results are consistent with the hypothesis that decreased serotonergic activity, which would be expected to produce increased 5-HT receptor sensitivity, may be present in both depression and mania.

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Serum cortisol levels were significantly higher after administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, in unmedicated patients with affective disorders than in controls. The magnitude of the serum cortisol increase correlated positively with the Schedule for Affective Disorders and Schizophrenia-Change (SADS-C) depression syndrome ratings and correlated negatively with psychotic symptoms in 26 patients with major depression. The serum cortisol response was greater in four depressed and three manic patients who made suicide attempts than in 33 patients who were not suicidal or only had suicidal thoughts. The cortisol response was also greater in patients with bipolar depression than in those with unipolar depression and those with a first-degree relative with an affective disorder. Absence of psychotic symptoms and commission of suicidal acts were associated with an increased cortisol response to 5-HTP in the depressed patients. The cortisol response to 5-HTP in the manic patients also tended to correlate with the SADS-C manic syndrome score.

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The serum cortisol responses to D,L-5-hydroxytryptophan (5-HTP), 200 mg per oral, in unmedicated depressed and manic patients, were both significantly greater than that of normal controls. The cortisol response to 5-HTP in depressed patients was significantly correlated with ratings of specific symptoms of depression. It was also greater in non-psychotic than in psychotic depressed patients as well as in those manic or depressed patients who attempted suicide compared to those who had not. In view of evidence for decreased brain serotonergic activity in depression and perhaps mania, the results suggest at least some serotonin receptors may be supersensitive in some patients with affective disorders.

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Two putative biological markers of some forms of depressive illness, the dexamethasone suppression test (DST) and the Vmax of serotonin (5-hydroxytryptamine, 5-HT) uptake in blood platelets, were studied in 40 unipolar, bipolar, and schizoaffective depressed patients. The Vmax levels in those whose cortisol levels suppressed normally after dexamethasone (n = 25) were not significantly different from those of the nonsuppressors (n = 15). When a criterion of Vmax greater than or equal to 8.5 pmoles/10(7) platelets/minute of 14C-5-HT uptake was used as the lower limit of normal, 18 patients had Vmax values lower than normal, only four of whom were nonsuppressors. There was a tendency for the incidence of lower than normal Vmax levels in nonsuppressors (4/15, 26.7%) to be less than that of the suppressors (14/25, 56.0%). These results suggest that the two abnormalities are independent of each other but tend to support the hypothesis that decreased Vmax may be an adaptive response which restores serotonergic function to normal. Twenty-nine of the 40 patients (72.5%) had one or both abnormalities, a finding which suggests that determination of both parameters would significantly increase the proportion of depressed patients who could be diagnosed by these biological tests.

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Bromocriptine (0.5-6.0 mg/day) was administered to seven unmedicated chronic schizophrenic and two schizoaffective patients. Transient slight improvement was noted in four patients and marked improvement in one other. Clinical improvement was associated with nausea and drowsiness. These doses of bromocriptine stimulated serum growth hormone and inhibited serum prolactin levels in some subjects. These results suggest that bromocriptine may stimulate dopamine autoreceptors and, through this mechanism, attenuate symptoms in a small proportion of psychiatric patients.

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The authors determined the platelet MAO activity of 57 psychotic patients after a placebo period and after 3-65 days of neuroleptic treatment. Platelet MAO activity significantly decreased in both men and women after neuroleptic treatment. The platelet MAO activity of neuroleptic-treated schizophrenic women was significantly less than that of drug-free schizophrenic women, who did not differ from normal women. There were trends in the same direction for the schizophrenic men. Previous studies that reported lower platelet MAO activity in neuroleptic-treated schizophrenic patients than in normal controls may have been influenced by this neuroleptic effect.

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In addition to its ability to decrease plasma cortisol levels, dexamethasone can also significantly decrease plasma prolactin levels. In 52 psychiatric patients, including 26 patients with primary major depression or schizoaffective depression, primarily affective type, there was a significant association between nonsuppression of plasma cortisol and prolactin after administration of dexamethasone. These results suggest that the abnormal cortisol response to dexamethasone in some psychiatric patients may be due to a pituitary gland abnormality rather than to a limbic system abnormality. The sensitivity and specificity of the dexamethasone suppression test for endogenous depression were less than previously reported.

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Des-tyrosine-gamma-endorphin (DT gamma E), a derivative of gamma-endorphin, which has been reported to have some neuroleptic-like properties in man, was administered to eight hospitalized schizophrenic patients (six chronic, one subacute, one acute) in an open study. Following an initial drug-free period, patients were given DT gamma E for 12 days in doses ranging from 1 to 10 mg/day. Two of the patients were markedly improved after receiving DT gamma E. The improvement was sustained for 2 months in one subjects, while the other deteriorated to pretreatment status within 48 hours of the discontinuation of DT gamma E. Of the other six patients, one showed moderate improvement, three showed minimal improvement, and two showed no change. Improvement was mainly in the area of social functioning; change in positive psychotic symptoms was less noticeable. The positive results obtained in this study in some subjects could have been nonspecific effects, rather than pharmacological action, since social functioning, the main area of improvement, may be especially sensitive to expectancy effects in open trials. Nevertheless, further study of DT gamma E in acute schizophrenics for longer periods appears indicated.

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Unlike neuroleptic drugs, the effect of antidepressant drugs on the neuroendocrine axis in man is highly variable and may or may not be intimately related to their antidepressant action. However, the limited neuroendocrine data available does shed some light on the mechanism of action of these agents and raises some important questions, particularly about the regulation of PRL secretion and the interaction between various neurotransmitter systems. At one end of the spectrum, the ability of nomifensine and buproprion to lower serum PRL levels, presumably due to their ability to block the reuptake of DA by tuberoinfundibular DA neurons, suggests that it may be necessary to reconsider the conclusion that these neurons lack a DA reuptake mechanism or that these two agents are antidepressant by virtue of their ability to block DA uptake. Similarly, the inability of amphetamine or methylphenidate to decrease serum PRL levels in man suggests important differences between the tuberoinfundibular DA neurons in man and the rat. These findings also call into question the ability of these agents to block DA uptake or increase DA release in the tuberoinfundibular DA neurons. The finding that fluoxetine raises serum PRL levels, even in one subject, whereas zimelidine has not yet been shown to do so, and that fluoxetine does not potentiate the ability of 5-HTP to stimulate PRL secretion, has raised important questions about the role of 5-HT in PRL and GH regulation in man and the relationship between 5-HT and DA neurons in man. The occasional increase in serum PRL levels found in patients treated with lithium or the MAO inhibitor phenelzine are suggestive of important interindividual differences which may be revealed by neuroendocrine studies, differences which could be valuable in understanding the mechanism of action of these agents - e.g., does lithium decrease DA receptor sensitivity? - and fundamental aspects of neuroendocrine regulation - e.g., do the MAO inhibitors stimulate the production of a PRF? Further studies of the neuroendocrine effects of antidepressant treatments are clearly indicated. It is likely that such studies will enrich our understanding of how these agents work, of the difference between agents which have been classed together on the basis of preclinical studies (e.g., DMI, which appears to increase PRL and GH, and NT which appears not to) and provided additional evidence to test current hypotheses about the biological basis of their antidepressant action.

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Platelet serotonin (5-HT) uptake was determined in 72 newly admitted, unmedicated psychiatric patients. Decreased maximum velocity (Vmax) of 5-HT uptake was present in unipolar and bipolar depressed patients as well as schizoaffective depressed patients. The apparent Michaelis constant (km) of 5-HT uptake was normal in these groups, as was Vmax and Km in manic-depressive and chronic schizophrenic patients. Treatment of depressed patients with notriptyline hydrochloride or imipramine hydrochloride increased Km significantly. There was a trend for the increase in Km in the nortriptyline-treated patients to correlate with clinical improvement. Decreased 5-HT uptake in platelets provides additional evidence for the role of 5-HT in the pathophysiologic process of some forms of depression.

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