Increase of the aversive value of taste stimuli following ibotenic acid lesion of the central amygdaloid nucleus in the rat

Abstract

Male Sprague-Dawley rats received bilateral ibotenic acid lesions of the central amygdaloid nucleus (CeA) and were compared to sham-lesioned rats in their response to different concentrations of saccharin and quinine solutions. In two-bottle choice test situation, the lesioned rats exhibited a lower saccharin preference at concentrations of 2.5; 7.5 and 25 mM, while their aversion towards quinine and the highest concentration of saccharin (50 mM) was increased. In a one-bottle test, the lesioned rats showed consistent decreases in their consumption of 2.5 and 7.5 mM saccharin solutions whereas their intake of 0.9 mM solution of saccharin was equal to that of the sham-lesioned rats. The lesion of the CeA had no significant effects on the acquisition of conditioned taste aversion. There was less postoperative weight gain in lesioned rats as compared to sham-lesioned animals but the lesion had no significant effect on daily water intake. These findings suggest that the CeA plays an important role in the normal response to exteroceptive food stimuli via modulation of the aversive value of taste stimuli. The results are discussed in the context of an interaction between the CeA and the lateral hypothalamus (LH) in the modulation of palatability and feeding behavior.