Hormone response to repeated electroconvulsive therapy: effects of naloxone

Plasma prolactin (PRL), cortisol, and growth hormone (GH) were measured before, and at 15-min intervals for 1 hr after, electroconvulsive therapy (ECT). This was repeated over a series of 6 consecutive treatments for each of 12 depressed drug-free inpatients. Patients received naloxone, 2 mg or 20 mg, by intravenous infusion before the third and fifth treatment. ECT was consistently followed by a release of PRL and cortisol, although two patterns of PRL response could be distinguished. In eight patients, the PRL response did not change significantly with repeated ECT, whereas in four patients, the plasma PRL increased tenfold after the first treatment and decreased after each successive treatment. The GH level varied widely, with no evidence of a reliable response to ECT. Opiate receptor blockade with low- or high-dose naloxone did not alter the release of PRL or cortisol after ECT. These findings demonstrate a reliable PRL and cortisol response to ECT, but do not support a role for endogenous opiates in these hormonal changes.