Vascular effects of red wine polyphenols in chronic stress-exposed Wistar-Kyoto rats.

Present study investigated the effect of red wine polyphenolic compounds (Provinols) on blood pressure (BP), nitric oxide synthase (NOS) activity and vascular function in Wistar-Kyoto (WKY) rats exposed to chronic social stress produced by crowding. Adult male rats were divided into four groups: control (480 cm(2)/rat), Provinols-treated (20 mg/kg/day, 480 cm(2)/rat), crowded (200 cm(2)/rat) and crowded treated with Provinols (20 mg/kg/day, 200 cm(2)/rat) for 8 weeks. No differences in BP were observed among the groups at the end of experiment, however, reduced BP was observed in Provinols-treated rats after 3 weeks of treatment. NOS activity in the aorta was significantly elevated in crowded rats, while Provinols alone had no effect on nitric oxide (NO) production. Acetylcholine-induced relaxation of the femoral artery was significantly improved in stressed and Provinols-treated rats vs. control, without significant changes in their noradrenaline-induced vasoconstriction. Interestingly, Provinols blunted the elevation of NO production and vasorelaxation during crowding. Increased endothelium-dependent vasorelaxation and NO synthesis in crowded rats may represent the adaptation mechanisms, resulting in unaltered blood pressure in stress-exposed normotensive rats. This study further demonstrated that elevated release of NO during chronic stress may be prevented by Provinols. Thus, Provinols might maintain equilibrium between endothelium-derived vasoconstrictor and vasodilator factors in stress.