Microinjection of NMDA Receptor Agents into the Central Nucleus of the Amygdale Alters Water Intake in Rats

Objective(s: The central nucleus of the amygdala (CeA) is a forebrain structure which is important in regulation of ingestive behavior and there is direct and circumstantial evidence to indicate that some circuits involved with feeding behavior include glutamatergic elements. The present study examined whether administration of NMA (N-Methyl-DL-aspartic acid) or MK801 into the CeA altered water intake under deprivation. Animals were deprived for 24 hr before tested for water intake. NMDA (N-methyl-D-aspartate) glutamatergic receptor agonist, NMA and its antagonist, MK801 were infused bilaterally, and water intake measured for 1 hr thereafter. The intra-CeA injection of NMDA glutamatergic agonist, NMA (0.25, 0.5 and 0.75 µg/rat) increased water intake (P<0.05). However, administration of NMDA glutamatergic antagonist, MK801 (0.25, 0.5 and 1 µg/rat) decreased water intake significantly (P<0.05). These data suggest that NMDA receptors in the CeA are responsible for the glutamatergic modulation of water intake in this nucleus.