Differential effects of the 5-HT1A agonist gepirone on food intake in rats may depend on their motivation to eat.

Abstract

It has previously been suggested that the differential effects of 5-hydroxytryptamine1A (5-HT1A) receptor agonists on food intake in non-deprived and food-deprived animals may be related to their motivation to feed. The present study was therefore conducted to investigate a possible relationship between the effects of the 5HT1A agonist gepirone on food intake in rats and their motivation to eat. In the first experiment, motivation to feed was varied by depriving the rats of food for different periods of time. In the second experiment, motivation to feed was varied by presenting them with highly palatable food. The results obtained from the first experiment showed that gepirone (1-4 mg/kg) increased food intake in non-deprived rats but decreased intake in 5-h and 22-h fasted animals. The extent of the hypophagia was related to the time the animals were fasted. The results from the second experiment showed that gepirone (0.5-5 mg/kg) reduced food intake in non-deprived rats presented with a highly palatable diet. The results obtained in this study suggest that the effects of gepirone on food intake may be related to the motivation of the animals to eat.