Thyrotropin-releasing hormone and its analog MK-771 increase the cerebroventricular perfusate content of dihydroxyphenylacetic acid.

The effects of thyrotropin-releasing hormone (TRH) and its synthetic analog, pyro-2-aminoadipyl-histidyl-thiazolidine-4-carboxamide (MK-771), were determined on the efflux of dihydroxyphenylacetic acid (DOPAC) collected from push-pull cannulae chronically implanted into the lateral cerebral ventricles of rats. Intracerebroventricular and intraperitoneal injections of both peptides increased the efflux of DOPAC. These results suggest that TRH and MK-771 increase the activity of dopaminergic neurons that terminate in periventricular regions.