STIMULATION OF 5-HT2A RECEPTORS IN THE PARAVENTRICULAR HYPOTHALAMUS ATTENUATES NEUROPEPTIDE Y-INDUCED HYPERPHAGIA THROUGH ACTIVATION OF CORTICOTROPIN-RELEASING FACTOR

The effect of 5-HT1 and 5-HT2 receptor agonists administered into the paraventricular hypothalamus was studied on the hyperphagia caused by neuropeptide Y (NPY) injected into the same area. The 5-HT2A/2C recept or agonist DOI (10-20 nmol/0.5 mu l) significantly reduced NPY overeat ing while the 5-HT1A/1B receptor agonist RU 24969 (3.5-14 nmol/0.5 mu l) and the 5-HT1B/2C receptor agonist mCPP (5-20 nmol/0.5 mu l) had no such effect. The 5-HT2A receptor antagonist spiperone (5 mu g/0.5 mu l) and the corticotropin releasing factor antagonist alpha-helical-CRF (9.41) (0.5-1 mu g/0.5 mu l) completely antagonized the effect of 10 n mol DOI.