Lesions of the amygdala central nucleus abolish lipoprivic-enhanced responding during oil-predicting conditioned stimuli

T. L. Davidson, A. M. Altizer, S. C. Benoit, E. K. Walls, and T. L. Powley (1997) reported that rats show facilitated responding to conditioned stimul i (CSs) that predict oil, after administration of the lipoprivic agent, Na- 2-mercaptoacetate (MA). This facilitation was blocked by vagal deafferentat ion. The present article extends that investigation to another structure, t he amygdala central nucleus (CN). The CN receives inputs from dorsal vagal nuclei, and neurotoxic lesions of this nucleus are reported to abolish feed ing in response to lipoprivic challenges. In Experiment 1, rats with iboten ic acid (IBO) lesions of the CN failed to show enhanced appetitive respondi ng during oil-predicting CSs after administration of MA. Experiment 2 used a conditioned taste-aversion procedure to establish that rats with IBO lesi ons of the CN were able to discriminate the tastes of sucrose and peanut oi l and had intact CS-US representations. It is concluded that the amygdala C N is a necessary structure for the detection of lipoprivic challenges.