Cortisol modulation of 5-HT-mediated growth hormone release in recovered depressed patients

Background: Recent formulations of the pathophysiology of major depression suggest that stress-induced cortisol secretion may lower brain serotonin (5-HT) function, thereby precipitating depressive symptomatology. This implies that people who develop depression after stressful life events may be particularly vulnerable to the effect of cortisol on brain 5-HT activity. We therefore assessed the effect of a single dose of hydrocortisone on 5-HT-mediated growth hormone (GH) release in healthy volunteers and euthymic subjects recovered from at least two episodes of major depression. Methods: Eleven recovered depressed patients and 20 healthy controls received intravenous tryptophan (TRP) 10.5 h after placebo and hydrocortisone (50 mg orally) in a double-blind, cross-over design. Plasma GH levels were sampled for 90 min after TRP infusion. Results: The GH response to TRP was significantly lower in the recovered depressed patients than controls after hydrocortisone. Limitations: The number of recovered depressed subjects studied was small and the effect of hydrocortisone on TRP-induced GH release was different to that observed in a previous study. Conclusions: These findings are consistent with other evidence suggesting abnormal regulation of 5-HT neurotransmission in people vulnerable to recurrent depression.