Effect of Berberine Hydrochloride on memory and learning in Streptozotocin-induced diabetic rats

  Background: Chronic diabetes mellitus affects the hippocampus via various pathways including augmented oxidative stress , and leads to learning and memory impairment. It is indicated that berberine has anti-diabetic, antioxidant and neuroprotective effects.   Objective: The aim of this study was to determine the effects of berberine hydrochloride on short-term spatial memory and passive avoidance learning and memory in streptozotocin-induced diabetic rats.   Methods: In this experimental study, 40 male wistar rats were randomly divided into five groups: control, berberine-treated control (100 mg/kg), diabetic and berberine-treated diabetic (50, 100 mg/kg). Diabetes was induced by intraperitoneal injection of 60 mg/kg streptozotocin . One week after streptozotocin injection, rats were treated with 50 and 100 mg/kg/day berberine orally, for 7 weeks. 1,3,5,7 weeks after streptozotocin injection, blood samples were taken from the tail vein to measure blood glucose levels. In order to investigate the effects of berberine on passive avoidance learning and memory , Initial Latency (IL) and Step-Through Latency ( STL) were measured by shuttle box . Short-term spatial memory was assessed by percentage of alternation behavior in the Y maze. Data were analyzed by ANOVA, Kruskal-Wallis test and Mann Whitney U test.   Findings: Alternation percentage in the diabetic group was significantly lower than the control group, and was increased significantly in the berberine-treated (100 mg/kg) diabetic group compared to the diabetic group. STL was significantly decreased in the diabetic group compared to the control group and was significantly increased in the berberine-treated (100 mg/kg) diabetic group compared to the diabetic group. The STL difference between the control group and the berberine-treated control group was not statistically significant.   Conclusion: With regards to the results, 7 weeks treatment with berberine improves short-term spatial memory and passive avoidance learning and memory in streptozotocin-induced diabetic rats.