Rat hypothalamic NPY mRNA and brown fat uncoupling protein mRNA after high-carbohydrate or high-fat diets.

We measured the influence of diet composition on hypothalamic neuropeptide Y (NPY) message and brown fat uncoupling protein (UCP) mRNA using different diets. Sprague-Dawley rats ate ad libitum either chow, a high-carbohydrate (HC), an intermediate-carbohydrate (IHC), a high-fat (HF), or an intermediate-fat (IHF) diet, all with equal protein content (g/kcal). The HF and IHF groups ate less food mass and, except for HC, all groups consumed similar kilocalories during the study. After 1 wk, we killed the animals and extracted total RNA from arcuate nucleus, cortex, and brown adipose tissue (BAT). Arcuate NPY mRNA in the HF group was significantly (P < 0.001) lower than in the HC and chow group. There were no differences between groups in NPY message in cortex or NPY protein in the paraventricular nucleus. BAT UCP message levels were significantly higher (P = 0.001) in the HF group. Thus HF compared with HC and chow diet reduces expression of NPY mRNA in hypothalamic nuclei and increases expression of BAT UCP message.