Prolactin and thyrotropin in serum during electroconvulsive therapy in patients with major depressive illness

Thirty-three patients with major depressive illness received electroconvulsive therapy (ECT), and serum prolactin (PRL) and thyrotropin (TSH) levels were measured 30 min before and 1, 5, 15, 30, and 60 min after the treatment. There was a threefold increase in PRL levels with a maximum after 15 min. The TSH plasma levels rose significantly with a maximum at 30 min after ECT. No change in PRL and TSH concentrations was seen in control experiments when the patients received anaesthesia only. In 15 patients the hormone levels were studied both during the first and sixth (last) ECT. The PRL and TSH levels were significantly higher following the first as compared to the sixth ECT. Patients on phenothiazines had higher PRL and lower TSH levels than those on other drugs or without medication, but there was no significant difference in the mean increment by ECT. Dopamine depresses PRL and TSH secretion. The diminished hormone release after a series of ECT may be explained by ECT-induced increase of postsynaptic dopamine receptor function leading to inhibition of PRL and TSH release from the pituitary gland.