Protective Effects of Red Onion (Allium cepa) Ethanolic Extract on Learning and Memory Impairments in Animal Models of Diabetes

Abstract

Background: Onion (Allium cepa) is a plant with antidiabetic and antioxidant properties. The aim of this study was to evaluate the protective effects of red onion ethanolic extract on learning and memory impairments in animal models of diabetes. Material and Methods: For induction of diabetes, streptozotocin (55 mg/kg) was injected intraperitoneally in male Wistar rats. Thirty-two male Wistar rats were randomly divided into 4 groups (n = 8). Diabetic rats were placed in 3 groups, including 2 groups treated with onion ethanolic extract (125 and 250 mg/kg/day) for 4 weeks and one diabetic control group. In addition, a fifth group was considered a health control group. Finally, learning and memory changes were evaluated through the Morris water maze and passive avoidance tests. Results: Our findings showed that escape latency and traveled distance were significantly increased in the diabetic control compared with the health control. The administration of onion extracts at 125 and 250 mg/kg significantly decreased the escape latency and traveled distance. In addition, the induction of diabetes caused a significant impairment in memory consolidation compared with healthy rats. However, animals that received extract at 125 mg/kg spent a longer time and traveled a greater distance in the target quarter compared with the diabetic control. Our data in the passive avoidance test also showed that diabetes reduced step-through latency in the animals. However, administration of onion ethanolic extract led to increased step-through latency in diabetic rats. Conclusions: Our findings show that oral administration of red onion ethanolic extract improves learning and memory performances impaired by streptozotocin in diabetic rats. [GMJ.2017;6(3):249-257] DOI:10.22086/gmj.v0i0.909