Role of noradrenaline and serotonin in the basolateral region of the amygdala in food preferences and learned taste aversions in the rat

Abstract

First, it was confirmed that bilateral lesions in the basolateral region of the amygdala (ABL) of the rat increased the time spent eating novel as compared to familiar food in a food preference test, and that the lesions impaired learned taste aversion to a sucrose solution which had been paired with lithium chloride. Then the roles of noradrenaline and serotonin in the amygdala in these aspects of food intake were investigated. In Experiment 2, it was shown that injections of 10 and 20 nmoles of noradrenaline (NA) into the ABL increased the time spent eating familiar food in the food preference test. Higher doses of NA (50 and 100 nmoles) increased the total time spent eating without changing the preference of the rats for familiar or novel food, and produced behavioral side effects. Serotonin (5HT) injected into the ABL in doses of 10, 50 and 100 nmoles did not modify the pattern of choice of the foods. In Experiment 3, it was shown that depletion of NA in the ABL with 10 μg 6-hydroxydopamine did not alter the level of feeding of novel and familiar foods, but did impair taste aversion Depletion of 5HT in the ABL with 10 μg 5,7 dihydroxytryptamine did not alter food preferences or impair the taste aversion learning. The depletions of NA and 5HT were confirmed biochemically. These results provide further evidence for a role of the amygdala in preferences for novel as compared to familiar foods and in learning that the ingestion of a food is associated with sickness, and suggest that noradrenaline but not serotonin in the amygdala is involved in these types of control of food intake.