V. Paul et Ar. Jayakumar, A role of nitric oxide as an inhibitor of gamma-aminobutyric acid transaminase in rat brain, BRAIN RES B, 51(1), 2000, pp. 43-46
The present study has been aimed to investigate the effect of nitric oxide
(NO) on the concentration of gamma-aminobutyric acid (GABA) in rat brain. T
he concentrations of GABA and glutamate and the activities of glutamic acid
decarboxylase (GAD) and gamma-aminobutyric acid transaminase (GABA-T) were
determined in groups of animals 5 and 30 min after intraperitoneal injecti
on of a NO-increasing dose (1000 mg/kg) of its precursor, L-arginine and a
dose (50 mg/kg) of N-nitro-L-arginine methyl ester (L-NAME) that inhibits N
O synthesis from L-arginine. L-arginine-induced elevation of NO concentrati
on was accompanied by an increased concentration of GABA in the brain, GABA
-T activity was inhibited in these animals. NO-decreasing action of L-NAME
coincided with a reduction in the concentration of GABA and an enhancement
of GABA-T activity. Both L-arginine and L-NAME did not alter the activity o
f GAD and the concentration of glutamate, An interpretation of these data s
uggests that NO has a GABA-T-inhibiting role in the brain. (C) 2000 Elsevie
r Science Inc.