Silymarin: A novel natural agent to restore defective pancreatic β cells in streptozotocin (STZ)-induced diabetic rats

This study aimed to investigate the potency of silymarin (SMN) and melatonin (MEL)
on restoring the pancreatic β 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 MELtreated
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 β 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 β cells
depletion were improved by the 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 β cells of Langerhans islets in diabetic rats.