Microinjection of NMDA Receptor Agents into the CentralNucleus of the Amygdale Alters Food Intake in Rats

Abstract:Food intake is the primary factor for body weight regulation in animals. Eating behavior is known to be modulated by various neurotransmitters and receptors. The central nucleus of the amygdala (CeA) is the forebrain structures which are important in regulation of ingestive behavior. 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 or MK801 in the CeA alters food intake under deprivation. Animals were deprived for 24 h before tested for food intake. NMDA glutamatergic receptor agonist, NMA (N-Methyl-DL-aspartic acid) and its antagonist, MK801 (Dizocilpine hydrogen maleate) were infused bilaterally, and food intakes were measured for 12 h post-injection.The intra-CeA injection of NMDA glutamatergic agonist NMA (0.25, 0.5 and 0.75μg/ rat) showed no effect on cumulative food intake. However, administration of NMDA glutamatergic antagonist, MK801 (0.25, 0.5 and 1 μg/rat) increased food intake in the deprived rats. The finding suggest that NMDA receptors in the CeA are responsible for the glutamatergic modulation of feeding in this nucleus.