Abstract

Nickel sulfate stimulates inducible nitric oxide synthase (i-NOS) and increases serum nitric oxide concentration by overproduction of reactive nitrogen species due to nitrosative stress. The present study was undertaken to assess possible protective role of l-ascorbic acid as an antioxidant against nickel induced pulmonary nitrosative stress in male albino rats. We studied the effect of the simultaneous treatment with l-ascorbic acid (50 mg/100 g b. wt.; orally) and nickel sulfate (2.0 mg/100 g b. wt.; i.p.) on nitric oxide synthesis by quantitative evaluation of serum i-NOS activities, serum and lung nitric oxide, l-ascorbic acid and protein concentrations of Wister strain male albino rats. We have further studied histopathological changes in lung tissue after nickel sulfate treatment along with simultaneous exposure of l-ascorbic acid. Nickel sulfate treatment significantly increased the serum i-NOS activity, serum and pulmonary nitric oxide concentration and decreased body weight, pulmonary somatic index, serum and lung l-ascorbic acid and protein concentration as compared to their respective controls. Histopathological changes induced by nickel sulfate showed loss of normal alveolar architecture, inflammation of bronchioles, infiltration of inflammatory cells and patchy congestion of alveolar blood vessels. The simultaneous administration of l-ascorbic acid and nickel sulfate significantly improved all the above biochemical parameters along with histopathology of lung tissues of rats receiving nickel sulfate alone. The study clearly showed a protective role of l-ascorbic acid against nickel induced nitrosative stress in lung tissues.