Neuropeptide Y (NPY) levels in alcoholic and food restricted male rats: implications for site selective function

Neuropeptide Y (NPY) has been implicated in the control of ingestive, cardiovascular, and reproductive function. Blood pressure and sexual function were examined in Long-Evans rats receiving 6% ethanol-containing or calorically matched liquid diets, or rat chow ad lib. After 12 weeks of exposure, rats were sacrificed and plasma hormone levels and NPY content of microdissected brain regions were determined. Neither long-term alcohol ingestion nor caloric restriction were associated with major decrements in copulatory behavior. Long-term alcohol ingestion was associated with decrements in erectile function ex copula. Long-term alcohol ingestion was also associated with: (i) a moderate degree of hypertension; (ii) a failure to gain weight; (iii) decrements in circulating levels of LH, testosterone, and ACTH (but not progesterone); and (iv) increased corticosterone levels. Long-term alcohol ingesting and calorically-restricted rats exhibited alterations in daily feeding patterns. These physiological changes in response to long-term alcohol ingestion or caloric restriction were associated with neural site-selective differences in NPY content. Elevated NPY in the paraventricular nucleus was associated with voluntary (as in alcohol ingestion) or involuntary (as in caloric restriction) reductions in food intake. Differences in NPY in the suprachiasmatic and ventromedial nuclei were associated with the differences in feeding patterns. The decrements in hormone levels were associated with higher levels of NPY in the median eminence and in the arcuate nucleus.