Investigation of the effect of Ginkgo biloba leaf extract on spatial memory impairment and hippocampal neuronal loss caused by diabetes induced by streptozotocin in rats

Abstract

ABSTRACT Background and Aim: Learning and memory defect occurs following chronic diabetes with uncontrolled blood glucose. Ginkgo leaf extract improves brain blood flow. Also it contains antioxidant components and has shown beneficial effects in neurological diseases. In this study we investigated the effects of Ginkgo leaf extract on spatial memory impairment and hippocampal neuronal loss caused by diabetes. Material and Methods: This experimental study included 28 adult male Sparague-Dawley rats. The rats were made diabetic by injection of streptozotocin (STZ: 60 mg/kg). Ginkgo leaf extract (40 mg/kg) was administrated orally every day for two weeks and its effects on memory impairment and hippocampal tissue damage were investigated. Spatial memory was assessed in Morris water maze for four days. Then, the brains of the animals were extracted and after tissue staining hippocampal tissue damage were evaluated by neuronal count. Results: Latency to find the platform in water maze were significantly increased in STZ group compared to that in the control group (p<0.05). While, administration of the Ginkgo extract in STZ injected animals significantly reduced the latency to find the platform (p<0.05). In addition, STZ reduced hippocampal neuronal count (p<0.001) and administration of the Ginkgo extract in STZ injected animals significantly improved hippocampal neuronal loss (p<0.01). Conclusion: Ginkgo leaf extract significantly improved spatial memory impairment and hippocampal neuronal loss, induced by diabetes.