Role of glutamate in the amygdala and lateral hypothalamus in conditioned taste aversion

The role of glutamate in conditioned taste aversion was investigated. Both, in the amygdala (AMYG) and in the lateral hypothalamus (LH) extracellular levels of glutamate were assessed by microdialysis and capillary electropho resis with laser induced fluorescence detection. Rats were conditioned by p airing a novel flavor (strawberry flavor) with an intraperitoneal injection of lithium chloride. When the conditioned stimulus (strawberry flavored so lution) was injected into the mouth of conditioned rats, then was an increa se of glutamate release in the AMYG, and a decrease in glutamate release in the LH. These results predicted that glutamate release in the AMYG and the LH was involved in CTA. This possibility was tested by MK-801 (glutamate a ntagonist) and glutamate microinjections. MK-801 injections in AMYG attenua ted the rejection of the novel flavor, and in the LH did not cause any effe ct on CTA. Glutamate microinjections in the AMYG caused CTA. These results suggest that glutamatergic activity in the AMYG might be a relevant neuroch emical correlate and cause of conditioned taste aversion. (C) 1998 Elsevier Science B.V. All rights reserved.