EATING-ASSOCIATED VMN-DOPAMINE LEVELS OF RATS - COMPARISON OF ORAL AND INTRAGASTRIC FEEDING

EATING is associated with persistently low dopamine (DA) concentration in the ventromedial hypothalamic nucleus (VMN), postulated to influen ce postprandial satiety. Whether pregastric factors contribute to eati ng-associated low VMN-DA was examined. VMN-DA levels were continuously measured in awake rats, food-deprived for 24 h, and either subsequent ly allowed to eat solid chow freely available for 20 min, an oral liqu id diet, or an isovolemic isocaloric liquid diet infused intragastrica lly to bypass the oropharynx. Eating either solid chow or a liquid die t was associated with an immediate decrease in VMN-DA concentration. T he lower VMN-DA concentration lasted longer after solid chow was consu med than following consumption of the liquid diet. When the oropharynx was bypassed no significant change in VMN-DA concentration was observ ed either during or after the liquid diet was infused. Results suggest that pregastric oropharyngeal factors contribute to eating-associated low VMN-DA concentration.