Nitric oxide and peroxynitrite as factors to stimulate neurotransmitter release in the CNS

This review summarizes the stimulatory potentials of NO and peroxynitrite ( OONO-) on neurotransmitter release in the central nervous system. Exogenous and endogenous NO stimulates to release neurotransmitter. NO synthesized i ntracellularly diffuses out through neuronal membrane and acts on the outer side of membrane to depolarize neuronal membrane, which triggers neurotran smitter release. NO-induced release of neurotransmitters is mediated by Ca2 +-dependent and -independent processes. The latter process is operated by r everse process of the Na+-dependent carrier-mediated neurotransmitter uptak e system or by unknown mechanisms. Ca2+-dependent release of neurotransmitt er occurs in part subsequent to increase in Ca2+ influx via VDCCs, although N-type VDCCs may not involve in this action of NO because of suppression o f Ca2+ influx through N-type VDCCs by NO. Participation of cGMP formation b y NO on neurotransmitter release is controversial. A superoxide scavenger, Cu2+, Zn2+-superoxide dismutase, abolishes NO-induced neurotransmitter rele ase and synthesized OONO- induces neurotransmitter release, indicating that OONO- participates in NO-evoked neurotransmitter release. (C) 2001 Elsevie r Science Ltd. All rights reserved.