RAT HYPOTHALAMIC NPY MESSENGER-RNA AND BROWN FAT UNCOUPLING PROTEIN MESSENGER-RNA AFTER HIGH-CARBOHYDRATE OR HIGH-FAT DIETS

We measured the influence of diet composition on hypothalamic neuropep tide Y (NPY) message and brown fat uncoupling protein (UCP) mRNA using different diets. Sprague-Dawley rats ate ad libitum either chow, a hi gh-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 w k, we killed the animals and extracted total RNA from arcuate nucleus, cortex, and brown adipose tissue (BAT). Arcuate NPY mRNA in the HF gr oup 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 wer e significantly higher (P = 0.001) in the HF group. Thus HF compared w ith HC and chow diet reduces expression of NPY mRNA in hypothalamic nu clei and increases expression of BAT UCP message.