ANORECTIC EFFECT OF PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE (PACAP) IN RATS - LACK OF EVIDENCE FOR INVOLVEMENT OF HYPOTHALAMIC NEUROPEPTIDE GENE-EXPRESSION

We investigated the effect of centrally administered pituitary adenyla te cyclase activating polypeptide (PACAP) on feeding in rats, and the involvement of hypothalamic neuropeptide gene expression using in situ hybridization. Intracerebroventricular injection of PACAP (1000 pmol/ rat) significantly decreased food intake in a dose-dependent manner. I n PACAP-treated rats, neuropeptide Y (NPY) mRNA levels in the arcuate nucleus and galanin mRNA levels in the paraventricular nucleus increas ed, and corticotropin-releasing hormone (CRH) mRNA levels in the parav entricular nucleus decreased. In rats fasted for 72 h, NPY mRNA levels increased, and CRH mRNA levels decreased, but galanin mRNA levels wer e unchanged. These results indicate that the anorectic function of PAC AP is not mediated by NPY or CRH, and that PACAP increases galanin syn thesis.