RÉSUMÉ
Free oxygen radicals, easily formed in the diabetic patients, were thought to play an important role in the development of diabetic complications. This study investigated the effects of the diabetic milieu on the weight and renal glomeruli of the fetuses of the pregnant diabetic albino rats. It also evaluated the protective role of melatonin, as an antioxidant, and the insulin on the fetal developing glomeruli. Diabetes was induced in the virgin adult female rats by a single dose of alloxan [160 mg / Kg BW] intraperitoneally. The study was done on five groups of pregnant albino rats: 1] control group, 2] diabetic untreated group, 3] diabetic group treated with insulin [crystalline insulin, 2 - 6 IU / day, subcutaneously, from the start of pregnancy to GD 20], 4] diabetic group treated with melatonin [9 mg / Kg BW / day, intragastrically, from the start of pregnancy to GD 20] and 5] diabetic group treated with both melatonin and insulin. Thirty-eight fetuses were collected randomly form each group on GD 20; their weights were recorded then their renal glomeruli were evaluated histologically, immunohistochemically and morphometrically. The results revealed that in group 2 there was a significant increase in fetal weight accompanied by an increase in the glomerular number and surface area. Also the incidence of thickening of glomerular basement membrane, expansion of mesangial matrix and deposition of collagen IV in the fetal kidney were the highest in this group. In group 3, all the above mentioned parameters were shifted towards the control side. In group 4, only the number of glomeruli and the incidence of glomerular basement membrane thickening were improved. In group 5, the addition of melatonin to insulin did not improve, as expected, the evaluated parameters when compared to insulin alone in group 2. These results indicate that a mechanism rather than free radical pathway leads to the pathogenesis of fetal nephropathy and that melatonin antagonizes the beneficial effects of insulin