Induction of wet-dog shakes by intracerebral 'acid' TRH in rats.

Less than Glu-His-Pro-OH or 'acid' TRH, until now considered to be an inactive metabolite of TRH, induces in rats when administered intracerebroventricularly (i.c.v.), stereotyped behavior and, from 12.5 micrograms, wet-dog shakes (WDS). WDS induced by 200 micrograms less than Glu-His-Pro-OH are antagonized by apomorphine, haloperidol and cyproheptadine while phentolamine and naloxone are without effect. For this action 'acid' TRH appears as effective as TRH itself and might have the same mechanism.