DOWN-REGULATED NPY RECEPTOR SUBTYPE-5 MESSENGER-RNA EXPRESSION IN GENETICALLY-OBESE MOUSE-BRAIN

BRAIN neuropeptide Y (NPY) subtype-5 (Y5 receptor) mRNA expression in lean (+/+) and obese (ob/ob) C57Bl/6 mice was examined using a non-rad ioactive in situ hybridization detection method. Significant decreases in Y5 receptor mRNA expression were found in the ventromedial, dorsom edial and arcuate hypothalamic nuclei, midline thalamic nuclei, pirifo rm, cingulate and retrosplenial granular cortices of the obese mouse b rain. There were minor changes in the amount of Y5 receptor mRNA expre ssion in the hippocampal formation and medial habenular nucleus. Resul ts indicated that Y5 receptor mRNA expression is downregulated in here ditary obese (ob/ob) mice. This is possibly due to over-expression of hypothalamic NPY which occurs in this phenotype.