Modulation of ACTH-induced grooming by [Des-Tyr1]-gamma-endorphin and haloperidol

Intraventricular administration of ACTH1-24 into the rat induced excessive grooming behavior. This response could be blocked by local administration of of neuroleptics into either the nucleus accumbens or the neostriatum. Local administration of [Des-Tyr1]-gamma-endorphine (LPH62-77) but not alpha-endorphin (LPH61-76) in either the nucleus accumbens or the neostriatum mimicked the effect of the neuroleptics. A second intraventricular injection of ACTH1-24 4 h after the first did not cause excessive grooming suggesting the development of acute tolerance. Both haloperidol and DT-gamma-E reduced the development of acute tolerance to ACTH-induced grooming. It is suggested the DT-gamma-E modulates the dopaminergic activity underlying the display of ACTH-induced excessive grooming.