Administration of satiety factors and gustatory responsiveness in the nucleus tractus solitarius of the rat.

The administration of certain factors associated with postprandial satiety decreases gustatory responsiveness. We compared the effects of intravenous injections of glucose, insulin, pancreatic glucagon (PG), and cholecystokinin (CCK) on multiunit activity evoked from taste responsive neurons in the nucleus tractus solitarius of rats. Glucose, insulin, and PG reliably suppressed evoked responses to lingual application of 1.0M glucose, whereas responses that followed CCK remained unchanged. A common physiological consequence of glucose, insulin, and glucagon is increased glucose availability which may impact directly on gustatory neurons or indirectly through modifications in ventral forebrain or vagal afferent activity.