Effects of the Hydroalcoholic Extract of Zingiber officinale on Arginase I Activity and Expression in the Retina of Streptozotocin-Induced Diabetic Rats

BACKGROUND Emerging evidence suggests that an increased arginase activity is involved in vascular dysfunction in experimental animals. Zingiber officinale Roscoe, commonly known as ginger, has been widely used in the traditional medicine for treatment of diabetes. OBJECTIVES This study aimed at investigating the effects of the hydroalcoholic extract of Z. officinale on arginase I activity and expression in the retina of streptozotocin (STZ)-induced diabetic rats. METHODS In this experimental study, 16 male Wistar rats weighing 200 - 250 g were assessed. Diabetes was induced via a single intraperitoneal injection of STZ (60 mg/kg body weight). The rats were randomly allocated into four experimental groups. Untreated healthy and diabetic controls received 1.5 mL/kg distilled water. Treated diabetic rats received 200, and 400 mg/kg of the Z. officinale extract dissolved in distilled water (1.5 mL/kg). Body weight, blood glucose and insulin concentration were measured by standard methods. The arginase I activity and expression were determined by spectrophotometric and western blot analysis, respectively. RESULTS Our results showed that blood glucose concentration was significantly decreased in diabetic rats treated with the extract compared to untreated diabetic controls (P < 0.01). Treatment with 400 mg/kg of the extract reduced arginase I activity and expression (P < 0.05). A significant elevation in body weight was observed in diabetic rats treated with the extract. Serum insulin was significantly increased in diabetic rats treated with 400 mg/kg of the extract compared to diabetic controls (P < 0.05). CONCLUSIONS Our results suggest that the Z. officinale hydroalcoholic extract may potentially be a promising therapeutic option for treating diabetes-induced vascular disorders, possibly through reducing arginase I activity and expression in the retina.