CENTRAL ADMINISTRATION OF THE EXCITOTOXIN N-METHYL-D-ASPARTATE INCREASES NERVE GROWTH-FACTOR MESSENGER-RNA IN-VIVO

N-methyl-D-aspartate (NMDA) receptor activation in the hippocampal for mation is thought to play an important role in learning and memory. Th is limbic structure contains one of the highest concentrations of NMDA binding sites in the brain. The hippocampal formation also contains h igh levels of nerve growth factor (NGF) mRNA and protein in the centra l nervous system. The expression of this neurotrophic factor may be re gulated by events involving glutamatergic neurotransmission. In the pr esent study, in situ hybridization histochemistry was used to determin e the effects of NMDA receptor activation on NGF mRNA expression in th e hippocampal formation. The gene encoding this neurotrophic factor wa s increased exclusively in the granule cells of the dentate gyrus, a h ippocampal structure that receives extensive glutamatergic innervation from the entorhinal cortex. It is suggested that one consequence of g lutamatergic neurotransmission in the dentate gyrus is the activation of NGF mRNA. The increased expression of this neurotrophic factor may ultimately influence the function of NGF-responsive cells innervating the hippocampal formation. (C) 1994 Intox Press, Inc.