Growth hormone responses to L-dopa in depressed patients.

Plasma human growth hormone responses to oral administration of 500 milligrams of L-dopa were analyzed in three groups of subjects: normals, age 20 to 32; normals, age 48 to 68; and unipolar depressed patients, age 45 to 68. While only 7 percent of the young normals had deficient human growth hormone responses to this stimulus, 36 percent of the older normals and 77 percent of the depressed patients failed to have adequate responses, suggesting an effect of age and a further effect of depressive illness. Because the release of human growth hormone appears to be closely related to brain catecholamine metabolism, the deficient responses in the depressed patients may provide further support to the concept of a neurochemical defect in depressive illness.

Growth hormone responses to hypoglycemia in postmenopausal depressed women.

Human growth hormone (HGH) responses to insulin-induced hypoglycemia were measured in ten postmenopausal women suffering from primary unipolar depressive illness, and in ten age-matched normal postmenopausal women. The mean maximal HGH response in the depressed patients was 4.6 plus or minus 4.4 ng/ml, and in the normals 13.3 plus or minus 9.8 ng/ml (P less than .05). All of the normal subjects had clinically adequate HGH responses, in contrast to only four of the depressed patients (P less than .01). The blood glucose responses were virtually the same in the two groups. Since brain catecholamines play a major role in mediating HGH responses to hypoglycemia, the findings are consistent with the hypothesis of diminished functional catecholaminergic activity in the depressed patients.

Prolactin responses to neuroleptics in normal and schizophrenic subjects.

The prolactin response to neuroleptics can serve as an index of dopamine blockade in humans. Plasma prolactin increments to single doses of chlorpromazine, and prolactin decrements to single doses of levodopa, were similar in normal and schizophrenic subjects. Antischizophrenic drugs of all chemical classes stimulated prolactin release,while chemically related drugs and other psychotropic agents ineffective in schizophrenia did not. The prolactin response to neuroleptic therapy occurred in all patients, and tolerance did not develop. Within subjects, prolactin responses were graded according to neuroleptic dose, but the upper limit of sensitivity of the response curve was achieved at doses below the therapeutic range. Relative prolactin-stimulating potency in humans of chlorpromazine, thioridazine, trifluoperazine, butaperazine, and haloperidol correlated well with their relative clinical potencies.

Relation of plasma prolactin to clinical response in schizophrenic patients.

It has been suggested that, if dopamine antagonism is a necessary condition for the antischizophrenic action of neuroleptics, the prolactin response, as an index of dopamine blockade, would correlate with clinical response. Morning prolactin and clinical symptomatology were measured in 15 schizophrenic patients before neuroleptic therapy, and after three and six weeks of high-dose butaperazine or loxapine treatment. Prolactin levels were transiently elevated during the unmedicated admission period, probably reflecting a normal stress response. Prolactin increased in all patients during neuroleptic therapy. There was, however, no correlation between magnitude of prolactin changes and clinical response, probably because the prolactin response achieved a maximum at relatively low doses of neuroleptics.

Thioridazine stimulates prolactin secretion in man.

Thioridazine, unlike most other effective antipsychotic drugs, appears to be only a weak dopamine antagonist in various regions of the brain. We decided to test, indirectly, thioridazine's effects on another brain dopaminergic system, the tuberoinfundibular tract, which regulates prolactin secretion by stimulating hypothalamic secretion of prolactin-inhibiting factor. Chlorpromazine and several other phenothiazines have been shown to stimulate prolactin secretion. Five healthy men ingested 50 mg of chlorpromazine concentrate on one occasion, and 50 mg of thioridazine concentrate on another. Both drugs noticeably stimulated prolactin secretion within two hours. It is concluded that thioridazine is a potent dopamine antagonist in the tuberoinfundibular system, and it is suggested that this system's regulation of prolactin secretion may provide a useful method for studying antipsychotic drug effects in man.

Human growth hormone response to levodopa. Relation to menopause, depression, and plasma dopa concentration.

After ingestion of 500 mg of levodopa, postmenopausal women had significantly diminished human growth hormone (HGH) responses (mean, 4.6 ng/ml), as compared with those of age-matched men (mean, 9.1 ng/ml; P smaller than .05). The differences between the groups were not related to plasma dopa concentrations. The HGH responses to levodopa of age-matched unipolar and bipolar depressed men, and of unipolar depressed postmenopausal women, did not differ significantly from their respective normal control groups. Depressive illness of these types does not appear to affect the HGH response to levodopa, once the effect of the menopause is taken into account.

Paradoxical cortisol responses to dextroamphetamine in endogenous depression.

Dextroamphetamine hydrochloride was administered intravenously (IV) in the morning and evening to 22 unmedicated patients with severe endogenous depressions and 18 normal control subjects. While the normal subjects generally had a sharp increase in plasma cortisol level by 30 minutes after drug administration, two thirds of the depressed patients showed instead a paradoxical suppression of cortisol levels by 60 minutes. Discrimination between normal subjects and depressives was greatest in the evening. These results are consistent with other reports of abnormal cortisol responses in depressed patients to smaller IV doses of dextroamphetamine and larger doses of methamphetamine hydrochloride. A defect in activation or noradrenergic alpha receptors may account, in part, for the abnormal cortisol responses. The dextroamphetamine cortisol test in other patient populations requires study before its diagnostic use in endogenous depression can be established.

Dextroamphetamine and cortisol in depression. Morning plasma cortisol levels suppressed.

Dextroamphetamine sulfate administered intravenously in the morning to 11 unmedicated depressed patients suppressed previously elevated plasma cortisol levels to normal in 90 minutes, a fall of 33% from baseline. Ten other depressed patients, without amphetamine, maintained high cortisol levels during the same time period. In each of five normal young men, amphetamine identically administered stimulated a rise in cortisol between 15 and 30 minutes after infusion, an acute response absent in ten of the 11 depressed patients; by 90 minutes after amphetamine administration, plasma cortisol had fallen to normal and identical levels in both groups. Since noradrenalin normally inhibits hypothalamic corticotropin releasing factor (and adrenocorticotropic hormone) secretion, a noradrenergic deficit may account for cortisol hypersecretion in depression; amphetamine may transiently "correct" this deficit in depressed patients, thereby reducing their cortisol secretion.

Growth hormone secretion in prepubertal children with major depression. II. Sleep-related plasma concentrations during a depressive episode.

Plasma growth hormone (GH) concentrations were determined every 20 minutes during sleep in 71 prepubertal children: 22 had endogenous major depressive disorder, 20 had nonendogenous major depressive disorder, 21 had nondepressed neurotic disorders, and eight were normal. Both depressive groups secreted significantly more GH during sleep than did controls. Measures included maximal GH plasma peak and area under the curve (AUC) during the total sleep period, during the first three hours after sleep onset, and during the first five hours after sleep onset. An AUC cutoff of 2,000 ng X min/mL identified positively half the prepubertal children with major depression; with a specificity of 78% (v neurotics) and 100% (v normal children). Increased GH secretion during sleep may be a marker of illness, a past episode, or trait for prepubertal major depression regardless of endogenicity.

Growth hormone secretion in prepubertal children with major depression. IV. Sleep-related plasma concentrations in a drug-free, fully recovered clinical state.

Prepubertal children with major depressive disorder have shown increased growth hormone (GH) secretion during sleep while in a depressive episode. When restudied in a fully recovered state (for at least three months) and drug free (for at least one month), their increased GH secretory pattern during sleep had not changed. Illness-recovery correlations using area under the curve for GH secretion during sleep were highly significant, whereas paired comparisons showed no significant differences. In addition, children who had recovered from major depressive episodes secreted significantly more GH during sleep than did nondepressed neurotic and normal children. No significant differences in delta-sleep were found in the depressed group between ill and recovered states nor among those who had recovered from major depressive episodes or controls. It is concluded that increased GH secretion during sleep is independent of depressive episodes, remains unaltered after full recovery, and may be a true marker of trait for major depressive disorder in prepuberty.

Growth hormone secretion in prepubertal children with major depression. I. Final report on response to insulin-induced hypoglycemia during a depressive episode.

Insulin tolerance tests (ITTs) were carried out on 46 drug-free prepubertal children with severe emotional disorders. Thirteen met unmodified Research Diagnostic Criteria for major depressive disorder, definite endogenous subtype, 17 met the criteria for nonendogenous major depressive disorder, and 16 fit DSM-III criteria for nondepressed neurotic disorders. The group with endogenous depression had significant hyposecretion of growth hormone (GH) in this test when compared with the other groups. Since GH hyposecretion in response to ITT has been found in most studies to be associated with endogenous major depression in adults, the data support the validity of the diagnosis of prepubertal endogenous major depressive disorder and the hypothesis of similarity or identity of prepubertal and adult major depressive disorders.

Growth hormone secretion in prepubertal children with major depression. III. Response to insulin-induced hypoglycemia after recovery from a depressive episode and in a drug-free state.

Insulin tolerance tests (ITTs) were performed after at least four months of sustained recovery from an episode of a major depressive disorder in 18 drug-free prepubertal children. Eleven had a definite endogenous subtype; seven did not. Sixteen children with nondepressed neurotic disorders made up a control group. The children with past endogenous depression continued to have significant hyposecretion of growth hormone (GH) in this test when compared with the other groups. Illness-recovery correlations were highly significant for the major depressive group as a whole. Paired comparisons of both depressive groups were not significantly different from illness to recovery. We conclude that prepubertal children with endogenous major depression continue to have hyposecretion of GH in response to ITTs in a recovered state and that this neuroendocrine marker is state independent. A GH hyporesponse to ITT may be a true marker of a past episode or of trait for endogenous major depressive disorder in prepuberty.

Growth hormone response to dextroamphetamine in depressed patients and normal subjects.

The human growth hormone (HGH) response to dextroamphetamine sulfate (doses, 0.1 and 0.15 mg/kg) was determined in both the morning and evening in patients with endogenous and atypical depression and in normal young men and normal postmenopausal women. Although the HGH response was found to be reduced in endogenously depressed postmenopausal women, it was equally reduced in normal postmenopausal women and in patients with atypical depression. Depressed and normal men had larger HGH responses, but there were no differences between depressed and normal men. These results do not confirm an earlier report that the reduced HGH response to dextroamphetamine is specific to endogenous depression. The results do suggest the importance to control for other variables in studies of HGH responses in psychiatric patients.

Thiethylperazine; clinical antipsychotic efficacy and correlation with potency in predictive systems.

A one-to-one relationship between clinical antipsychotic potency and pharmacologic dopaminergic antagonism is implicit in the dopamine hypothesis of neuroleptic action. Thiethylperazine maleate, a classical antiemetic phenothiazine, displays dopaminergic antagonism in behavioral, neurochemical, and neuroendocrine systems, but is paradoxical insofar as it is thought not to possess clinical neuroleptic activity. In three tests of dopaminergic antagonism--elevation of levels of CSF homovanillic acid in monkeys, striatal dihydroxyphenylacetic acid in rats, and prolactin in man--as well as in a clinical trial of neuroleptic efficacy in schizophrenics, thiethylperazine was fully active and approximately three times as potent as chlorpromazine. Differences in efficacy between this and earlier clinical studies can be accounted for on the basis of dosage.

Cortisol and GH responses to D- and L-amphetamine in monkeys.

Equimolar doses of D-amphetamine and L-amphetamine, and a water placebo were injected intravenously on different days into rhesus monkeys, and their plasma cortisol and GH responses were determined over a 3-hour period. D- and L-amphetamine (but not the placebo) equally suppressed plasma cortisol concentration and equally increased plasma GH concentration. Pretreatment of the monkeys with large doses of pimozide, a specific dopamine receptor blocker, did not appear to block the hormonal responses to either isomer of amphetamine. The results suggest that the hormonal responses to both D- and L-amphetamine were mediated by noradrenergic neurones stimulatory to GH and inhibitory to ACTH, and that D- and L-amphetamine exert equipotent noradrenergic effects in the neuroendocrine system.

Failure of dopaminergic blockade to affect prolactin, growth hormone, and cortisol responses to insulin-induced hypoglycemia in schizophrenics.

The PRL, GH, and cortisol responses to insulin tolerance tests (ITTs) were evaluated in 12 medically healthy schizophrenic patients during a drug-free period and after 1 and 6 weeks of treatment with penfluridol, a potent, long acting, dopamine-blocking neuroleptic. Hypoglycemic responses were the same before and during penfluridol therapy. Although resting PRL levels were evaluated during initial penfluridol therapy (week 1), hypoglycemia provoked a further substantial PRL increment, not significantly different in magnitude from that induced by hypoglycemia during the drug-free period. However, there was a 54% reduction (P less than 0.05) in the increase in the area under the PRL curve during week 6 compared to the drug-free period. Regarding GH and cortisol, resting levels, areas under the curve, and maximal increments after ITT were essentially the same during weeks 1 and 6 of penfluridol treatment as in the drug-free period. The failure of 1 week of dopaminergic blockade to significantly alter the hormonal (PRL, GH, and cortisol) responses to ITT in the group as a whole suggests that dopamine-blocking mechanisms play little role in mediating these responses, at least in schizophrenic patients.

Effect of cyproheptadine and atropine on the diurnal prolactin responses to insulin-induced hypoglycemia in normal men.

There is a diurnal variation in the PRL response to insulin-induced hypoglycemia in normal men, with a substantially larger response in the evening. This study investigated the possible serotonergic and cholinergic influences on these diurnal PRL responses. Morning and evening PRL responses to hypoglycemia were compared in the same five normal young men without drug pretreatment, after cyprohepatadine, and after atropine sulfate. Cyproheptadine had no effect on the basal PRL concentration or the PRL response to hypoglycemia in either the morning or evening. Atropine had no effect on basal PRL concentrations in the morning or evening or on the morning PRL response to hypoglycemia. However, the evening PRL response was significantly inhibited by atropine (P less than 0.02), with an abolition of the normal diurnal difference in response (P less than 0.001) to insulin-induced hypoglycemia. These data suggest the involvement of a cholinergic mechanism in regulation of diurnal PRL responses to hypoglycemia.

Diurnal variation in the response of plasma prolactin, cortisol, and growth hormone to insulin-induced hypoglycemia in normal men.

Plasma PRL, cortisol, and GH responses to a standard iv dose of regular insulin were studied during the morning and evening in seven normal young men. Hypoglycemia achieved during morning and evening in the same aubjects was equal. There was a substantially greater maximal increment in PRL in the evening compared to the morning (P less than 0.01). The peak levels of cortisol achieved in the morning and evening were equal, but the evening maximal increase was greater (P less than 0.05) because of the significantly lower evening basal cortisol level. Evening increases in GH were greater than in the morning in five subjects and were essentially the same in two subjects; for the group, the evening maximal increment in GH was significantly greater (p less than 0.05 after log transformation). Since serotonergic mechanisms appear to be involved in the PRL, GH, and cortisol responses to hypoglycemia, we suggest the possibility of a diurnal variation in hypothalamic serotonin activity which may partly mediate these differential diurnal hormonal responses to hypoglycemia (although other neurotransmitters may also be involved). The data on cortisol are discussed with regard to the reset hypothesis of feedback inhibition.

Dopamine antagonism by thioridazine in schizophrenia.

One of the leading current theories of the etiology of schizophrenia is excessive activity of some brain dopaminergic tracts. One of the major objections to the theory is that thioridazine is clinically as effective a treatment of schizophrenia as other neuroleptic drugs but appears to have much less dopamine-blocking properties than these agents in man and laboratory animals. Serum prolactin levels are increased by dopamine receptor-blocking drugs. We have found that thioridazine is as effective as chlorpromazine, trifluperazine, and prolixin enanthate in increasing serum prolactin levels in unmediated schizophrenic patients, indicating it is an effective dopamine-blocking agent.

Prepubertal endogenous major depressives hyposecrete growth hormone in response to insulin-induced hypoglycemia.

Insulin tolerance tests (ITT) were carried out during illness in 27 drug-free prepubertal children with emotional disorders: 10 fit unmodified Research Diagnostic Criteria (RDC) for major depressive disorder endogenous subtype, 10 fit RDC for nonendogenous major depressive disorder, and 7 fit DSM-III criteria for nondepressed neurotic disorders. The endogenous depressed group hyposecreted growth hormone (GH) in this test as compared to the other groups. Since GH hyposecretion in response to ITT is a characteristic of adult endogenous depressives, the data support the validity of the diagnosis of prepubertal endogenous major depressive disorder and the hypothesis of similarity of prepubertal and adult major depressions.