silymarin: a novel natural agent to restore defective pancreatic beta cells in streptozotocin (stz)-induced diabetic rats

this study aimed to investigate the potency of silymarin (smn) and melatonin (mel) on restoring the pancreatic  cells in streptozotocin (stz)-induced diabetic rats. male wistar rats were divided into five groups, including: control (c), untreated diabetic (d), smn-treated diabetic (50 mg/kg, orally), mel-treated diabetic (10 mg/kg, i.p.), and smn plus mel-treated diabetic rats. diabetes was induced by injection of stz (50 mg/kg, i.p.). the blood glucose and insulin levels were measured. after the 28 days treatment period, antioxidant status was analyzed by determination of total antioxidant capacity (tac) in the liver and serum. the histopathological changes in the pancreatic islets were examined by histochemical staining and enumeration of  cells. although none of the test compounds reduced the blood glucose level to normal concentration, however smn alone and in combination with mel was able to decline it significantly (p<0.05) after 28 days administration. both smn and mel could recover the diabetes-reduced tac values. moreover, the diabetes-induced cellular vacuolation and  cells depletion were improved by smn treatment. our data suggest that the smn and mel treatment was able to normalize the antioxidant status, while only smn administration could restore the cells of langerhans islets in diabetic rats.