The protective effects of silymarin, a free radical scavenger on normal and alloxan-induced diabetic rats were studied for four weeks. Some endocrine pancreatic function and hematological parameters were measured. Histological structure of pancreas, Pancreatic activities of superoxide dismutase (SOD) and catalase, levels of lipid peroxidation product malondialdehyde (MDA) and reduced glutathione (GSH) were also estimated. A single s/c injection of alloxan (150mg/kg BW) elicited a significant decrease in serum insulin, activities of SOD and catalase, content of GSH and a significant increase in pancreatic MDA, blood glucose level, and glycated hemoglobin%. In addition to adverse effects on beta cell function indices, hematological parameters and marked necrotic changes in the pancreatic ultrastructure compared to control rats. The repeated oral intake of silymarin (100 mg/kg BW) for 4 weeks interrupted by a single s.c. injection of alloxan improved significantly the previously mentioned parameters compared to their values in alloxan treated group. This improvement indicates a partial restoration of beta cell function relieving the alloxan induced damage. In conclusion, silymarin administration caused an improvement in normal rats pancreatic function and was able to reduce the pancreatic damage induced by alloxan which might be contributed to its direct cytoprotective effect on beta cells or simply related to restoration of some of the antioxidant capacity in pancreatic tissue.

Key words: Alloxan, Antioxidant, Beta cells, Pancreas, Silymarin