Nitric oxide mediates glutamate-linked enhancement of cGMP levels in the cerebellum.

TLDR

Nitric oxide is produced in the brain from arginine, generating citrulline, and mediates the effects of many neurotransmitters on vascular smooth muscle and leukocytes. Glutamate and related amino acids markedly stimulate arginine–citrulline conversion and raise cGMP levels in cerebellar slices, an effect blocked by N‑omega‑monomethyl‑L‑arginine, reversed by arginine, inhibited by hemoglobin, enhanced by superoxide dismutase, and shown to be mediated by nitric oxide.

Abstract

Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. We show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine--citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. N omega-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of N omega-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.