Effects of Gingko leaf extractive on learning and memory in the diabetic rats

Objective To explore the effect of extract of Gingko biloba leaves(EGb) on the streptozotocin(STZ)-induced diabetic rats with learning and memory impairment.Methods The diabetic rats model were established by injection of STZ (48 mg·kg~(-1)).Then the rats were randomly divided into model group,insulin treatment group(insulin 10 U·kg~(-1),hypodermic injection),high dose EGb group(EGb 100 mg·kg~(-1),intragastric administration) and low dose EGb group(EGb 50 mg·kg~(-1),intragastric administration),fifteen rats in each group.Fifteen rats in control group were treated with citrate buffer solution by intraperitoneal injection.After 3 months of administration,the ethological changes of learning and memory were observed through Morris water maze test.Results Compared with control group,the results of Morris water maze test showed that, for the diabetic rats,the times to firstly cross the target area from the first to the sixth day and the seventh day after training both prolonged,the frequencies to cross the target area also decreased significantly(P0.01),the time and distance in the first quadrant also decreased significantly(P0.01).Compared with the rats in diabetic model group,for the rats in the insulin and the EGb treatment groups(high and low dose),the time to firstly cross the target area was shortened significantly,the frequencies to cross target area increased significantly and the scores of time and distance in the first quadrant also increased significantly (P0.01);The times to firstly cross the target area at the seventh day in the EGb treatment group(high and low dose) were longer than that in the insulin treatment group(P0.05);And there was no statistical significance among the other groups(P0.05).Conclusion EGb can significantly ameliorate the deficiency of learning and memory induced by diabetes.