Changes in feeding behavior after intracerebral injections in the rat

Abstract

Changes in basal liquid food intake in sated or fasted rats were measured after localized intracerebral injections (5 µl) of 17 chemical solutions. Lidocaine, pentobarbital, and epinephrine produced feeding in sated or fasted rats with ventromedial hypothalamic (VMH) cannulas; neostigmine, norepinephrine, pentylenetetrazol, and 1.5% NaCl reduced food intake in fasted rats; acetylcholine, histamine, and dextrose had no effect in either state. In sated rats with lateral hypothalamic (LHA) implants, epinephrine, norepinephrine, and 1.5% NaCl produced feeding; lidocaine and neostigmine reduced, whereas norepinephrine augmented food intake in fasted LHA animals. No effect on consumatory behavior was observed after injections into the lateral amygdala. Lidocaine reduced food intake in fasted rats with globus pallidus implants; epinephrine and norepinephrine initiated feeding. Eight other chemicals had no effect on feeding in limited tests. Neostigmine and acetylcholine produced drinking in sated VMH and LHA animals, respectively. These results suggest that closely adjacent neuronal aggregates (VMH-LHA) may have different metabolic requirements for single compounds, and that the VMH functions in satiety mechanisms for food as well as water intake.