The dentate gyrus continues to incorporate granule neurons during adulthood. Among the factors that we know modulate adult neurogenesis in the dentate gyrus, one of the first studied was the influence of excitatory amino-acids. These neurotransmitters, acting through NMDA receptors, are able to modulate both the proliferation of progenitor cells as well as the rate of neurogenesis in the adult dentate gyrus. However, the mechanisms by which these processes are influenced are not clearly known. Although there is no anatomical evidence of NMDA receptor expression in adult hippocampal progenitor cells or differentiating granule neurons, electrophysiological data and in vitro studies suggest that NMDA receptors may be expressed by certain precursor cells and immature granule neurons. This review summarizes findings on the influence of pharmacological manipulation of NMDA receptors on adult neurogenesis. We also analyze previous studies that have suggested the expression of NMDA receptors in progenitors and immature granule cells and discuss the putative role of these receptors in the regulation of developmental processes such as proliferation, migration, or neurite outgrowth.
(c) 2006 Wiley-Liss, Inc.