Protective effects of grape seed proanthocyanidins against iron overload-induced renal oxidative damage in rats

Excessive exposure to iron can cause kidney damage, and chelating drugs such as deferoxamine and deferiprone have limited usefulness in treating iron poisoning. This study was designed to investigate the protective effects of grape seed proanthocyanidins (GSPAs) against iron overload induced nephrotoxicity in rats. The roles of GSPAs in chelating iron, antioxidant activity, renal function, pathological section, and apoptosis-related gene expression were assessed.

Newly weaned male Sprague-Dawley rats aged 21 days (weight, 65 ± 5 g) were randomly divided into four groups containing 10 rats each: normal control (negative) group, iron overload (positive) group, GSPAs group, and GSPAs + iron overload (test) group. Iron dextran injections (2.5 mg⋅ kg^-1) and GSPAs (25 mg⋅ kg^-1) were intraperitoneally and intragastrically administered to rats daily for 7 weeks, respectively. Measurements included red blood cell (RBC) count and hemoglobin (Hb) level, serum total iron-binding capacity (TIBC), renal iron content, glutathione peroxidase (GSH-Px) activity, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, total antioxidant activity (T-AOC), creatinine (CR) and blood urea nitrogen (BUN) levels, pathological changes, and apoptotic Fas, Bax expressions in the kidney tissue. Differences among the dietary groups were determined using one-way analysis of variance with post-hoc Tukey's test. P < 0.05 was considered statistically significant.

RBC count, Hb level, renal iron content, MDA content, CR and BUN levels, and Fas, Bax expressions significantly increased in the positive group than in the negative group; contrarily, TIBC, GSH-Px activity, and T-AOC significantly decreased in the positive group than in the negative group (P < 0.05). Although not statistically significant, SOD activity was slightly reduced in the positive group than in the negative group. Inflammatory cell infiltration and fibrous tissue proliferation were observed in the kidney tissue of the rats in the positive group; in contrast, the rats exhibited better recovery when GSPAs were used instead of iron alone. Compared with the positive group, RBC counts, Hb levels, renal iron contents, the MDA content, CR and BUN levels, and Fas, Bax expressions significantly decreased, whereas the TIBC, the GSH-Px and SOD activities as well as T-AOC significantly increased in the test group rats (P < 0.05). There were no significant differences in the RBC counts, Hb levels, TIBC, renal iron contents, the SOD activity and MDA content, CR and BUN levels, and Fas expression between the GSPAs and negative groups. The GSH-Px activity and T-AOC were significantly increased whereas Bax expression was significantly decreased in the GSPAs group rats than in the negative group rats (P < 0.05). The rats in the GSPAs, test, and negative groups displayed glomeruli and tubules with a clear structure; further, the epithelial cells in the renal tubules were neatly arranged.

GSPAs have protective effects on nephrotoxicity in rats with iron overload. Thus, further investigation of GSPAs as a new and natural phytochemo-preventive agent against iron overload is warranted.