Oleoyl-estrone does not alter hypothalamic neuropeptide Y in Zucker lean and obese rats

Female Zucker lean and obese rats were treated for 14 days with 3.5 mu mol/ kg oleoyl-estrone (OE) in liposomes (Merlin-2). After 0, 3, 6, 10, and 14 d ays of treatment, the rats were killed and hypothalamic nuclei (lateral pre optic, median preoptic, paraventricular, ventromedial and arcuate) were use d for neuropeptide Y (NPY) radioimmunoassay. In 14 days, OE decreased food intake by 26% in lean and 38% in obese rats and energy expenditure by 6% in lean and 47% in obese rats; the body weight gap between controls and treat ed rats becoming -17.8% of initial b.wt. in the lean and -13.6% in the obes e rats. Obese rats showed higher NPY levels in all the nuclei than the lean rats. Despite a negative energy balance and decreased food intake, there w ere practically no changes in NPY with OE treatment. The results indicate t hat oleoyl-estrone does not act through NPY in its control of either food i ntake or thermogenesis in lean and genetically obese rats. (C) 1998 Elsevie r Science Inc.