We examined whether water-immersion restraint stress (WIRS) disrupts nonenzymatic antioxidant defense systems through ascorbic acid depletion in the adrenal gland of rats. Rats were exposed to WIRS for 0.5, 1.5, 3 or 6h. WIRS increased serum adrenocorticotropic hormone, corticosterone and glucose concentrations and adrenal corticosterone content at each time point. WIRS increased adrenal lipid peroxide content at 3 and 6h, and the increase was twofold higher than the unstressed level at 6h. WIRS decreased adrenal ascorbic acid content at each time point, and the decrease reached one-third of the unstressed level at 6h. WIRS increased adrenal reduced glutathione content at 0.5 and 6h but reduced that content to half of the unstressed level at 6h. WIRS increased adrenal α-tocopherol content at 1.5h but returned that content to the unstressed level thereafter. When rats with 6h of WIRS was orally preadministered with l-ascorbic acid (250mg/kg), WIRS-induced changes in adrenal lipid peroxide, ascorbic acid and reduced glutathione contents were attenuated without any change in stress response. These results indicate that WIRS disrupts nonenzymatic antioxidant defense systems through rapid and continuous ascorbic acid depletion in the adrenal gland of rats.
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