Paraventricular hypothalamic alpha-melanocyte-stimulating hormone and MTIIreduce feeding without causing aversive effects

alpha -Meanocyte-stimulating; hormone (alpha -MSH) appears to play a tonic inhibitory role in feeding and energy storage. MTII, a specific synthetic M C3-R/MC4-R agonist, has similar. effects on feeding in rats. The current st udies demonstrate that PVN administration of alpha -MSH or MTII decreases n octurnal and NPY-stimulated food in take without causing aversive effects. Co-administration with NPY of 600 pmol (alpha -MSH or 1 pmol MTII into the PVN caused a significant decrease in NPY-induced feeding. PVN administratio n of MTII or alpha -MSH at doses effective to suppress feeding did not caus e conditioned taste aversion (CTA). ICV administration of ru-MSH, however, did cause weak CTA. These results indicate that the potent effects on feedi ng of MC3-R and MC4-R agonists when injected into the PVN are not due to av ersive effects. (C) 2001 Elsevier Science Inc. All rights reserved.