Infusion of the serotonin1B (5-HT1B) agonist CP-93,129 into the parabrachial nucleus potently and selectively reduces food intake in rats

Unilateral infusion of the selective 5-HT1B agonist, CP-93,129 (3-(1, 2, 5, 6,-tetrahydropyrid-4-yl) pyrrolo[3,2-b]pyrid-5-one) into the parabrachial nucleus (PBN) of the pens reduced food consumption by rats. The hypophagia was dose-related (ED50 approximate to 1 nmol) and associated with fewer observations of feeding and more periods of inactivity. Water intake, grooming and exploratory activity were unaffected. CP-93.129 also decreased food intake when injected into the hypothalamic paraventricular nucleus, but this action was 50-fold less potent than administration into the PBN. Autoradiography demonstrated 5-HT1B sites in the PBN: this binding was displaced by CP-93,129. The results implicate parabrachial 5-HT1B receptors in mediating serotonergic enhancement of satiation.