title: Social isolation stress-induced oxidative damage in mouse brain and its modulation by majonoside-R2, a Vietnamese ginseng saponin.
abstract: Stressors with a physical factor such as immobilization, electric foot shock, cold swim, etc., have been shown to produce oxidative damage to membrane lipids in the brain. In this study, we investigated the effect of protracted social isolation stress on lipid peroxidation activity in the mouse brain and elucidated the protective effect of majonoside-R2, a major saponin component of Vietnamese ginseng, in mice exposed to social isolation stress. Thiobarbituric acid reactive substance levels, one of the end products of lipid peroxidation reaction, were increased in the brains of mice subjected to 6-8 weeks of social isolation stress. Measurements of nitric oxide (NO) metabolites (NO(x)(-)) also revealed a significant increase of NO production in the brains of socially isolated mice. Moreover, the depletion of brain glutathione content, an endogenous antioxidant, in socially isolated animals occurred in association with the rise in lipid peroxidation. The intraperitoneal administration of majonoside-R2 (10-50 mg/kg) had no effect on thiobarbituric acid reactive substances (TBARS), NO, or glutathione levels in the brains of group-housed control mice but it significantly suppressed the increase in TBARS and NO levels and the decrease in glutathione levels caused by social isolation stress. These results suggest that mice subjected to 6-8 weeks of social isolation stress produces oxidative damage in the brain partly via enhancement of NO production, and that majonoside-R2 exerts a protective effect by modulating NO and glutathione systems in the brain.
authors.affiliation: Division of Medicinal Pharmacology, Institute of Natural Medicines, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Nguyen Thi Thu
authors.initials: NT
authors.lastname: Huong
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Murakami
authors.forename: Michihisa
authors.initials: M
authors.lastname: Tohda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Kinzo
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D036145:Ginsenosides / Q000302:isolation & purification / Q000494:pharmacology*; D015227:Lipid Peroxidation; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018384:Oxidative Stress; D005894:Panax / Q000737:chemistry*; D012934:Social Isolation; D013315:Stress, Psychological / Q000517:prevention & control*
chemical_list: D036145:Ginsenosides; C098043:majonoside R2