GASTRIC-MOTILITY AND FOOD-INTAKE IN RATS AFTER LESIONS OF HYPOTHALAMIC PARAVENTRICULAR NUCLEUS

Systemic administration of cholecystokinin (CCK) or LiCl inhibits gastric motility and food intake in rats. Brain stem-projecting oxytocin (OT) neurons in the hypothalamic paraventricular nucleus (PVN) have been proposed to mediate the inhibitory effects of CCK and LiCl on gastric motility and food intake. In the present studies, we found that basal gastric motility was elevated in rats 12-20 h after knife-cut lesions of the PVN; however, this effect disappeared 3 days later. Furthermore, CCK and LiCl inhibited gastric motility at 12-20 h, 3 days, and 3 wk after PVN lesions, although their effects were blunted. Injection of the local anesthetic lidocaine into the PVN had effects similar to acute PVN lesions. In rats with PVN lesions, the inhibitory effects of CCK and LiCl on food intake were indistinguishable from those in sham-lesioned rats. We conclude that the PVN tonically inhibits gastric motility and that it participates in, but is not essential for, the inhibitory effects of CCK and LiCl on gastric motility and food intake in rats.