ROLE OF NO PRODUCTION IN NMDA RECEPTOR-MEDIATED NEUROTRANSMITTER RELEASE IN CEREBRAL-CORTEX

L-Glutamate and norepinephrine are examples of a major excitatory neur otransmitter and a neuromodulator in the cerebral cortex, respectively . Little is known of how chemical signaling between the anatomically d istinct chemical pathways occurs. Specific activation of the N-methyl- D-aspartate (NMDA) class of glutamate receptor in synaptosomal prepara tions from guinea pig cerebral cortex caused release of both of these chemicals, and this release was blocked by agents that inhibit nitric oxide (NO) production or remove NO from the extracellular space. Furth ermore, neurotransmitter release correlated with cortical NO productio n after NMDA receptor stimulation. These results suggest that NO produ ction and its extracellular movement may be links in the pathway from NMDA receptor activation to changes in chemical signaling in surroundi ng synaptic terminals in the cerebral cortex.