The present work has studied the influence of two doses of melatonin (low and high doses: 100 & 200mg / kg, respectively) for 30 days, on experimentally alloxan - diabetic adult rats (weighing 80±5g). Melatonin was administered intraperitoneally at night. The histochemical results demonstrated that the polysaccharides (using PAS technique) and total proteins (using bromophenol blue stain) displayed almost normal distribution in pancreatic tissue in both acinar and islet cells of diabetic rats. In contrary, the activities of acid and alkaline phosphatases (using azo dye precipitation technique) were decreased in the pancreatic tissue of diabetic rats. Both applied doses of melatonin to diabetic rats showed no change in a picture of pancreatic polysaccharides and protein contents, which appeared, more or less, similar to the control ones. However, treatment of diabetic rats with low dose of melatonin restored the activity of both acid and alkaline phosphatases, while no improvement in these enzymes activity could be detected in the pancreatic tissue of diabetic rats treated with high dose of melatonin.
Key words: Pancreas, Histochemistry, Enzymes, Melatonin, Diabetes, Rats
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