REGULATION OF LEPTIN RECEPTOR AND NPY GENE-EXPRESSION IN HYPOTHALAMUSOF LEPTIN-TREATED OBESE (OB OB) AND COLD-EXPOSED LEAN MICE/

Leptin receptor gene expression has been measured in arcuate and ventr omedial hypothalamic nuclei. Receptor mRNA in both hypothalamic areas was higher in obese mice than in lean littermates. Twice daily leptin administration for 7 days profoundly affected food intake, reduced lep tin receptor mRNA in the arcuate nucleus, and had a similar effect on neuropeptide Y gene expression. A single leptin injection was ineffect ive. Exposure of lean mice to cold for 24 h caused an induction of lep tin receptor and NPY mRNA which was normalized when animals were retur ned to the warm. Regulation of receptor gene expression may be an impo rtant component in the reading of the leptin signal.