5-HT2A/2C receptor antagonists in the paraventricular nucleus attenuate the action of DOI on NPY-stimulated eating

HYPOTHALAMIC neuropeptide Y (NPY) and serotonin (5-HT)-containing neurons are believed to exert an interactive effect on ingestive behavior. The present study-examined the ability of two serotonergic antagonists, spiperone (SPIP), a 5-HT2A antagonist, and mianserin (MIAN), a 5-HT2A/2C antagonist, to block the inhibitory action of the 5-HT2A/2C receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) on NPY-stimulated eating. Drugs were injected directly into the;paraventricular nucleus (PVN), the perifornical (PFH) or the ventromedial hypothalamus (VMH) at the onset-of the dark cycle. PVN, PFH and VMH injections of NPY potentiated food intake although only PVN pretreatment with DOI (5-20nmol) suppressed NPY-induced eating. SPIP or MIAN, injected immediately prior to PVN DOI, reversed the suppressive effect of DOI on NPY feeding. These findings are consistent with other-recent data showing that 5-HT2A receptors within. the PVN modulate NPY's effect on food intake at the start of the nocturnal period. (C) 1999 Lippincott Williams & Wilkins.