SUBNORMAL GROWTH-HORMONE RESPONSES TO ACUTELY ADMINISTERED DEXAMETHASONE IN DEPRESSION

OBJECTIVE Acute oral administration of dexamethasone (DEX) stimulates growth hormone (GH) release at 3 hours in normal controls and provides us with a novel probe with which to study the somatotrophic axis. In affective illness GH release is subnormal in response to a number of s timuli. We decided to investigate the acute effects of DEX-induced GH release in depression. DESIGN a between subjects parallel group design was employed. METHODS Baseline levels of GH and cortisol were taken a fter which 4 mg of oral DEX was administered. Plasma samples for GH es timation were taken at +60, +180, +240 and +300 minutes. PATIENTS Sixt een normal subjects and 16 unipolar, nonpsychotic, melancholic DSM-111 R major depressives were studied. Depressed subjects had to score over 17 on the Hamilton Depression Rating Scale; the mean +/-SEM scores we re 27.4 +/- 1.0. MEASUREMENTS Plasma GH and cortisol levels were measu red by radioimmunoassay. RESULTS Baseline mean +/-SEM GH levels (depre ssives 2.4 +/- 0.6 mU/l; controls 2.6 +/- 0.4 mU/l) did not differ sig nificantly between the two groups (P < 0.28). DEX-induced GH secretion was subnormal in depressives as opposed to controls (2.1 +/- 0.7 vs 1 9.4 +/- 2.2 mU/l, P < 0.001). There were significant differences betwe en the two groups at 60, 180 and 240 minutes (P < 0.05). Baseline cort isol values were significantly different between the two groups (depre ssives 303.3 +/- 31.5 nmol/l; controls 138 +/- 4.7 nmol/l). An analysi s of covariance, with cortisol as a covariate, still found the depress ives to have significantly subnormal GH responses as compared to the c ontrol group (P < 0.05). CONCLUSION Dexamethasone-induced GH release i s subnormal in depression.