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

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.

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.

The GH response to TRP was significantly lower in the recovered depressed patients than controls after hydrocortisone.

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.

These findings are consistent with other evidence suggesting abnormal regulation of 5-HT neurotransmission in people vulnerable to recurrent depression.