Studies on thyrotropin-releasing hormone-induced micturition in cats

In unanaesthetized cats micturition produced by thyrotropin-releasing hormone (TRH) was investigated after its injection into the cerebral ventricles through chronically implanted cannulae. TRH in doses from 0.1 to 1.0 mg evoked dose-dependent micturition. In cats treated with intracerebroventricular (i.c.v.) reserpine and 6-hydroxydopamine, but not with i.c.v. 5,6-dihydroxytryptamine and hemicholinium, the micturition caused by i.c.v. TRH was abolished. Chlorpromazine and antazoline injected into the cerebral ventricles prevented the micturition induced by i.c.v. TRH. On the other hand, mecamylamine, yohimbine, propranolol, atropine and methysergide injected i.c.v. had virtually no effect or partially antagonized the micturition evoked by TRH similarly injected. It is apparent therefore that centrally induced TRH micturition could be related to central catecholaminergic mechanisms.