ELEVATED HYPOTHALAMIC NEUROPEPTIDE-Y LEVELS IN RATS WITH DORSOMEDIAL HINDBRAIN LESIONS

Lesions centered on the area postrema (AP) and adjacent nucleus of the solitary tract (AP/mNTS-lesions) are reported to result in increased consumption of highly palatable diets. Recent studies suggest that neu ropeptide Y (NPY) may cause a preference for carbohydrate-rich diets. Thus, it is possible that NPY may play a role in the enhanced intake o f highly palatable diets by AP/mNTS-lesioned rats. In the studies repo rted here, we found that lesions centered on the AP result in increase d levels of NPY-immunoreactivity in the paraventricular nucleus of the hypothalamus. Additionally, steady-state NPY mRNA in the basomedial h ypothalamus including the arcuate nucleus was elevated. Enhanced NPY w as not found throughout the hypothalamus however, as NPY-immunoreactiv ity was not elevated in the lateral hypothalamus or the tissue borderi ng the anteroventral third ventricle. These data suggest the possibili ty that elevated hypothalamic NPY, particularly in the arcuate and par aventricular nuclei, may contribute to the altered food intake and ene rgy balance observed in rats with lesions centered on the AP. (C) 1997 Elsevier Science B.V.