EFFECTS OF METHYSERGIDE AND RITANSERIN ON THE PROLACTIN AND THYROTROPIN RESPONSES TO TRH IN DEPRESSED-PATIENTS

Despite extensive study of the effects of various pharmacological agen ts on the thyrotropin (TSH) and prolactin (PRL) responses to TRH chall enge, the effect of serotoninergic agents remains inconclusive. We stu died the effect of the serotonin antagonists methysergide (non-selecti ve 5-HT1/5-HT2 blocker with dopaminergic properties) and ritanserin (s elective 5-HT2 blocker) on the TSH and PRL responses to TRH stimulatio n in two groups of medication-free female depressed patients in a doub le-blind, within-subject design. Methysergide was found to decrease si gnificantly the PRL response to TRH, while ritanserin had no effect. N either compound influenced the TSH response. Results suggest that 5-HT 2 mechanisms do not mediate the PRL and TSH responses to TRH challenge in depression. The reduction in PRL observed after methysergide is pr obably due to either 5-HT1 or dopaminergic mechanisms.