INHIBITION OF STRESS-INDUCED PLASMA-CORTICOSTERONE LEVELS BY GINSENOSIDES IN MICE - INVOLVEMENT OF NITRIC-OXIDE

GINSENG total saponins (GTS) injected intracerebroventricularly (i.c.v .) at doses of 0.1-1 mu g inhibited the i.c.v. injection stress-induce d plasma corticosterone levels in mice. The inhibitory action of GTS w as blocked by co-administered N-G-nitro-L-arginine methyl ester (L-NAM E; 1.5 mu g, i.c.v.), an inhibitor of nitric oxide synthase (NOS). Of the ginsenosides Rbl, Rb,, Re, Rd, Re, Rf, Rg(1), 20(S)-Rg(3) and 20(R )-Rg(3) injected i.c.v. at doses of 0.01-1 mu g, 20(S)-Rg(3) and Rc si gnificantly inhibited the i.c.v. injection stress-induced plasma corti costerone levels. The inhibitory actions of ZO(S)-Rg(3) and Rc were bl ocked by co-administered L-NAME (1.5 mu g, i.c.v.). These results sugg est that GTS, 20(S)-Rg, and Re may inhibit the i.c.v. injection stress -induced hypothalamo-pituitary-adrenal response by inducing NO product ion in the brain. Neuro Report 9: 2261-2264 (C) 1998 Rapid Science Ltd .