Berberine Ameliorates Cold and Mechanical Allodynia in a Rat Model of Diabetic Neuropathy

This study evaluated the antiallodynic properties of berberine on cold and mechanical allodynia after streptozotocin (STZ)-induced diabetes using a rat model. Diabetic neuropathy was induced in rats by intraperitoneal injection of STZ. To measure cold and mechanical allodynia, a 4 degrees C plate and von Frey filament were used, respectively. Cold and mechanical allodynia induced by diabetes were significantly decreased by single and repeated intraperitoneal treatment of amitriptyline at 10 mg/kg, and berberine at 10 and 20 mg/kg. The hepatic malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase activities were significantly increased in diabetic rats as compared with those in intact rats; however, in amitriptyline-and berberine-treated rats, they were significantly decreased as compared to the STZ control. The overall effects of berberine 20 mg/kg on cold and mechanical allodynia were quite similar to those of amitriptyline 10 mg/kg, and berberine exhibited similar antioxidant effects as the same dosage of amitriptyline. In conclusion, berberine (10 and 20 mg/kg) was observed to have antiallodynic effects against diabetes, which are presumed to be associated with antioxidative effects. It can be considered that the anti-inflammatory or antidepressant capacity of berberine could contribute to the antiallonynic effects shown in this study.