Nitric oxide synthase mediates the antioxidant effect of L-Arginine in the brain of mice subjected to chronic restrain stress

Competing Abstract Chronic restraint stress (CRS) immobilize animal and induces the production of oxidative radicals as a preliminary cause of various health complications. CRS-induced oxidative stress led to pathological changes in brain tissue and consequently the general body condition. Thus, we elucidated the potential protective impact of L-Arginine (L-Arg), conditional amino acid and essential source of nitric oxide, on oxidative stress and brain tissue. BALB/c mice were randomly divided into five groups (n = 6) that received either 1) daily intraperitoneal (I.P) injection of phosphate-buffered saline (PBS) (Control group) (0.5ml), 2) I.P injection of PBS in combination with CRS (2h/day for 10 consecutive days) (CRS group), 3) I.P injection of L-Arg (500 mg/kg b.wt) with CRS (L-Arg + CRS group), 4) L-Arg alone (L-Arg group), or 5) pretreatment with I.P injection of L-N G –nitro-L-arginine methyl ester (l-NAME) (30 mg/kg b.wt), a potent common inhibitor of nitric oxide synthase (NOS), 30 minutes before L-Arg injection and CRS application (L-Arg + L-NAME + CRS group). Total antioxidant capacity (T-AOC), catalase, and histopathological status of brain tissue were evaluated. CRS significantly suppressed the T-AOC compared to the control. Furthermore, L-Arg elevated the T-AOC whereas L-NAME significantly reversed the action of L-Arg on CRS-induced T-AOC. L-Arg could not rescue CRS-decreased catalase. It is concluded that NOS is an essential mediator of the L-Arg ameliorative effect on CRS-induced oxidative stress in serum and brain tissue. Moreover, L-Arg antioxidant action is not mediated by catalase.