Effects of glucoprivation on gastric motility and pituitary oxytocin secretion in rats

Abstract

Pharmacological doses of insulin (3-25 U/kg sc) elicited feeding and increased gastric motility in rats. In contrast, the glucose analogue 2-deoxy-D-glucose (2-DG), given ip in doses known to increase food intake, had dose-dependent effects on gastric motility: 100 and 200 mg/kg 2-DG increased gastric motility, whereas 500 mg/kg 2-DG virtually eliminated gastric contractions. This latter result resembled the known effects on gastric motility of cholecystokinin (CCK) and LiCl. Moreover, like CCK and LiCl, 500 mg/kg 2-DG stimulated pituitary oxytocin (OT) secretion, and its effects on gastric motility and OT secretion were potentiated by pretreatment with the opioid antagonist naloxone. In contrast, OT secretion was not affected by insulin-induced hypoglycemia with or without naloxone pretreatment. These results suggest that there are two components to the effects of 2-DG on gastric motility: an insulin-like excitatory component and a CCK-LiCl-like inhibitory component. The latter inhibitory component may be mediated by the paraventricular nucleus of the hypothalamus, which has already been implicated in the inhibitory control of gastric motility.