Amygdaloid lesions impair ingestive responses to 2-deoxy-D-glucose but not insulin.

Bilateral lesions of the amygdala in male rats impaired the feeding response to 2-deoxy-D-glucose (2-DG; 100, 200, and 400 mg/kg). During the first 3 h postinjection, control rats displayed a dose-related increase in both food and water consumption. Rats with amygdaloid lesions did not respond to 2-DG until the 3rd h postinjection, when only the two largest doses significantly increased food consumption. Their water intake remained unaffected throughout the 3-h postinjection period. During the 4th-24th h post-2-DG administration, both groups displayed a dose-related suppression of food and water intake. Following insulin (10 U/kg), amygdaloid and control animals were indistinguishable: both groups showed a significant short-term increase in food and water intake followed by a reduction in intakes during the 4th-24th h. Central visceral pathways that are important for the ingestive responses to 2-DG may be interrupted by amygdaloid lesions. However, pathways responsible for the ingestive behavior induced by insulin appear unaffected by damage to the amygdala.