Arcopallium, NMDA antagonists and ingestive behaviors in pigeons

This study investigated the effects of local injections of 6,7-dinitroquinoxaline-2,3(1H,4H)-dione (DNQX, AMPA–kainate receptor antagonist, 0.8 and 2.7 nmol) and MK-801 (NMDA receptor antagonist, 1.8 and 6.0 nmol) into the nucleus taeniae of the amygdala (TnA) and the arcopallium intermedium (AI) on ingestive and non-ingestive behaviors in free-feeding pigeons. Injections of DNQX into the TnA or into the AI failed to consistently affect feeding behavior; DNQX vehicle (DMSO) affected drinking when injected into the TnA. MK-801 injections into the AI produced a delayed increase in food and water intake. In the TnA, MK-801 increased water intake in the first two hours after the treatment. These data indicate that glutamatergic circuits in arcopallial structures in the pigeon, comparable to the mammalian medial amygdala, are involved in the inhibitory control of ingestive behaviors, suggesting that this can represent a conserved functional attribute in the amniote prosencephalon.