Suppressive effects of Vietnamese ginseng saponin and its major component majonoside-R2 on psychological stress-induced enhancement of lipid peroxidation in the mouse brain

We investigated the in vivo effects of Vietnamese ginseng saponin (VG sapon in) and its major component majonoside-R2 (MR2) on psychological stress-ind uced enhancement of lipid peroxidation in the mouse brain. Psychological st ress exposure using a communication box system for 4 h significantly increa sed the content of thiobarbituric acid reactive substance (TBARS), an index of lipid peroxidation activity, in the brain. Pretreatment with VG saponin (15-25 mg/kg, PO) and MR2 (1-10 mg/kg, IP) significantly attenuated the ps ychological stress-induced increase in TEARS content in the brain. The agly cone of MR2 (MR2-aglycone: 1.2 mg/kg, IP), at the equivalent dose of MR2 (i .e,, 3 mg/kg, IP), also produced the suppressive effect on the increase in the TBARS content. The in vivo suppressive effect of MR2 was dose dependent ly attenuated by flumazenil (3 and 10 mg/kg, IP), a benzodiazepine receptor antagonist. and pregnenolone sulfate (10 mg/kg, IP), a neurosteroidal nega tive allosteric modulator of GABA(A) receptors. These findings suggest that VG saponin and its major component MR2 have preventive effects on the psyc hological stress-induced brain cell membrane damage, and that the effect of MR2 is partly due to enhancement of GABA(A)-ergic systems in the brain. (C ) 2000 Elsevier Science Inc.