Subnormal growth hormone responses to acutely administered dexamethasone in depression

Association of depressiveness with blunted growth hormone response to maximal physical exercise in young healthy men

Blunted response of growth hormone secretion to several pharmacological challenges is present in depression, but much less is known about the relationship of depression and secretion of growth hormone elicited by physiological stimuli. Furthermore, it is not known whether blunted growth hormone response occurs in depressiveness as measured with psychometric scales. A total of 82 healthy male volunteers (age 18-26 years) exercised on a bicycle ergometer with incremental load to achieve their maximal performance. Before exercise, subjects filled in approbated versions of Beck Depression Inventory (BDI), Spielberger's State-Trait Anxiety Scale, Cohens Perceived Stress Scale, and Schwartzers Self-Efficacy Scale. Blood samples were collected before and after exercise, and growth hormone, cortisol, and testosterone were measured by chemiluminescence immunoassay. Median perceived stress score of the subjects was identical to our population-based database median value, but the subjects had higher self-efficacy and lower depressiveness as shown by median values. In the majority of subjects, physical exercise induced remarkable increases in blood levels of the hormones. Cortisol and testosterone levels were not associated with the scores of psychometric scales. However, growth hormone response was virtually absent in high scorers (above median population score, n = 24) in BDI total score and the negative attitude subcomponent. Hence, this study demonstrates that growth hormone response to physiological stimuli is reduced in psychometrically measured depressiveness.

Psychoneuroendocrinology of depression. Growth hormone

The release of growth hormone (GH) from the anterior pituitary is regulated by hypothalamic peptides especially GH-releasing hormone (GHRH) and somatostatin, which in turn are controlled by classic neurotransmitters such as noradrenaline, dopamine, and acetylcholine, as well as negative feedback from GH and insulin-like growth factor-1. There has been extensive investigation of this axis in patients with depression. The most consistently reported abnormality is in noradrenergic-mediated GH release, which probably occurs via GHRH containing neurones. ACh-induced GH release through the somatostatin system, GABA, and also GHRH-stimulated release are reported as abnormal by some researchers.

Marked differences in functioning of the hypothalamic-pituitary-adrenal axis between groups of men

To compare profiles of hypothalamic-pituitary-adrenal (HPA) responsiveness, healthy, moderately trained men (n = 15) were classified as high (n = 7) or low responders (n = 8) on the basis of plasma adrenocorticotropic hormone (ACTH) responses to strenuous treadmill exercise 4 h after 4 mg of dexamethasone (Dex). These groups were then evaluated to compare 1) HPA and growth hormone responses to exercise at 90% maximal oxygen uptake 4 h after placebo, Dex (4 mg), and hydrocortisone (100 mg); 2) pituitary-adrenal responses to infusion of arginine vasopressin (AVP); 3) plasma cortisol after a Dex suppression test (1 mg); and 4) behavioral characteristics. In comparison to low responders, high responders exhibited significantly 1) higher plasma ACTH responses to exercise after placebo and Dex; 2) higher plasma AVP secretion with exercise after placebo and marked Dex- and hydrocortisone-induced enhancement of exercise-induced AVP secretion; 3) lower Dex-induced increases in basal and stimulated growth hormone secretion; 4) higher plasma ACTH responses to infusion of AVP; and 5) a trend (P = 0.09) for higher trait anxiety ratings. Similar suppression of plasma cortisol was noted after 1 mg Dex. We conclude that subgroups of healthy male volunteers exhibit unique profiles of HPA responsiveness. We also believe that glucocorticoid pretreatment combined with strenuous exercise allows functional HPA responsiveness to be distinguished between subgroups of healthy controls and may be useful in the determination of susceptibility to disorders characterized by hyper- and hypo-HPA activation.

Blunted dexamethasone-induced growth hormone responses in acute mania

Dynamic endocrine testing using a variety of probes has revealed abnormalities of the somatotropic axis in bipolar mania. In health, acute administration of dexamethasone (DEX) results in the secretion of growth hormone (GH) by possibly inhibiting somatostatin tone. We elected to determine DEX/GH responses in acute mania. Eight male bipolar manics were compared with eight age-matched healthy volunteers. Four milligrams of oral DEX was administered at 0900 h (time 0 min) and plasma samples for GH were taken at +60, +180, +240 and +300 min. Baseline samples for GH and cortisol were taken at -15 min and 0 min. Patients had higher basal cortisol levels (391.6 +/- 89.4 nmol/l) as opposed to controls (138.0 +/- 13.2 nmol/l) (paired t-test, t = 4.68, df = 6, p < .0004). The mean (+/- SD) delta GH (calculated as the maximum GH level relative to baseline) in the manic patients was 0.7 +/- 0.8 ng/ml and in the healthy controls was 9.2 +/- 4.3 ng/ml (paired t-test, t = -0.589, df = 6, p < .0001). In conclusion, patients with bipolar mania had lower DEX-induced GH responses in comparison to controls.

Are blunted dexamethasone-induced growth hormone responses unique to depression?

In health, acute administration of glucocorticoids, such as dexamethasone (DEX), leads to growth hormone (GH) secretion. Depression is characterized by blunted DEX/GH responses. In order to determine the specificity of this test for depression we administered 4 mg of oral DEX, to patients with a DSM-III-R diagnosis of depression, schizophrenia, mania and alcohol dependency syndrome. Samples for GH estimation were taken at -15 min, 0 min, +60 min, +180 min, +240 min and +300 min. GH responses were attenuated to a similar degree in depression and mania. Less marked attenuation was seen in schizophrenia while those with alcohol dependency syndrome had GH responses indistinguishable from normal volunteers. Overall, we conclude that subnormal DEX/GH secretion is not specific to depression.