possible protective role of some antioxidants on nephrotoxicity of chronic aluminium exposure in adult albino rats: histochemical and ultrastructural study

ABSTRACT

Aluminium [Al] is one of the most abundant and ubiquitous element in the nature, and its long-term administration causes accumulation of it in the tissues of vital organs including the kidneys. This study detected the effect of chronic Al administration on the kidney function and on the proximal convoluted tubules of adult albino rats, by histochemical and electron microscopical examinations. Forty rats were divided into 4 equal groups, and the period of the study was 3 months. The 1 st group was a control and the 2 nd received aqueous solution of Al chloride [AlCl 3] in a daily oral dose of 330 mg/ kg b.w., which is equal to 1/10 th of its LD50. The possible protective effect of vitamins C and E, which act as antioxidants, was examined in the 3 rd and 4 th groups, respectively. The 3 rd group of rats received the same dose of AlCl 3 as in the 2 nd group concomitant with vit C in a dose of 100 mg/ kg, while the 4 th group received the same dose of AlCl 3 + vit E in a dose of 30 mg/ 100 gm. At the end of the 3 months, the kidney function tests of A1Cl 3- treated rats were significantly elevated in comparison with the control group, as blood urea nitrogen [BUN] and serum creatinine [Cr] were 65.44 and 2.45 mg/ dl, respectively. Also, the enzymatic activities of succinic dehydrogenase [SD] and alkaline phosphatase [Alk. Ph.] were markedly decreased and acid phosphatase was markedly increased, compared to their activities in the control group. The lesions detected in the proximal convoluted tubules confirmed these results. These lesions, of A1Cl 3- treated group, were marked thickening of the cellular basement membranes with widely separated basal infoldings. The cytoplasm contained multiple lysosomes and vacuoles, whereas the mitochondria were irregular in shape and variable in the size and number. The microvilli showed focal loss and the nuclei were irregular. Co-administration of vit C with AlCl 3 showed a significant decrease in kidney function tests [BUN=30.69 and serum Cr=1.12 mg/ dl], improvement of the enzymatic activities which were more or less similar to the normal activities, and the lesions in the renal tubules were disappeared as the ultrastructural findings were similar to those in the control group. On the other hand, vit E ameliorated the Alcl3 toxicity but to a lesser extent than vit C, as the kidney function tests and activities of the enzymes were improved but not reached to the normal levels, and most of the tubular damage was disappeared, but minimal lesions could be detected. So, chronic Al exposure induced nephrotoxicity that was counteracted by vit C, and only ameliorated by vit E administration