ECT treatment does not enhance neuroendocrine responses to serotonergic challenge

We prospectively investigated the effects of a course of electroconvulsive therapy (ECT) on neuroendocrine responses to serotonergic challenge in five depressed patients. Low dose intravenous chlorimipramine (CMI) challenge produced a modest release of prolactin and significant increases in plasma adrenocorticotrophic hormone (ACTH) and cortisol. Interestingly, ECT did not alter the neuroendocrine responses to serotonergic challenge despite clinical response in four of the five patients. If anything, the modest prolactin (PRL) response to CMI, rather than being enhanced, appeared to be abolished following ECT. Using confidence intervals, we estimate that there is less than a 5% probability of a 78% increase in prolactin response to CMI after ECT. To detect this, a sample size of greater than 35 would be needed. These findings suggest that neither ECT nor the clinical response in severely depressed patients is likely to produce consistent changes in neuroendocrine response to the acute serotonergic effects of CMI infusion. The lack of effect of ECT on prolactin response to serotonergic challenge might be explained by simultaneous enhancement of both serotonergic and dopaminergic neurotransmission.