REGULATION OF ADULT NEUROGENESIS BY EXCITATORY INPUT AND NMDA RECEPTOR ACTIVATION IN THE DENTATE GYRUS

The effects of afferent input and N-methyl-D-aspartate (NMDA) receptor activation on neurogenesis were examined in an intact system, the rat dentate gyrus, where neurons are naturally born in the adult, In the adult dentate gyrus, activation of NMDA receptors rapidly decreased th e number of cells synthesizing DNA, whereas blockade of NMDA receptors rapidly increased the number of cells in the S phase identified with H-3-thymidine, Acute treatment with NMDA receptor antagonists increase d the birth of neurons and increased the overall density of neurons in the granule cell layer, Lesion of the entorhinal cortex, the main exc itatory afferent population to the granule neurons, also increased the birth of cells in the dentate gyrus, These results suggest that adult neurogenesis in the dentate gyrus of the rat is altered by afferent i nput, via NMDA receptors, and may be regulated naturally by endogenous excitatory amino acids.