alpha-Melanotropin induced excessive grooming involves brain acetylcholine possible interaction in the ventral...

Alpha-melanotropin (alpha-MSH) injected into the ventral tegmental area (VTA) or intraventricularly (icv) elicits excessive grooming. The icv infusion of the peptide also induces the stretching-yawning syndrome (SYS). The present study demonstrates that intra-peritoneal, icv or VTA administration of atropine, suppresses alpha-MSH-induced behavior elicited by i cv or VTA injections of the peptide. Experimental evidence is presented suggesting that alpha-MSH may act specifically on a cholinergic afferent to the VTA. The results appear to indicate that a neural target distinct from the dopamine system may be formerly activated by the peptide to elicit behavioral changes such as excessive grooming.