OBJECTIVETo examine the protective effect of Ginkgo biloba leaf extract (GbE) on learning and memory deficit induced by aluminum chloride (AlCl(3)), and explore its mechanisms.

METHODSThe rat models with learning and memory deficit were induced by administering via gastrogavage and drinking of AlCl(3) solution. And the model rats were treated with GbE at the dose of 50, 100, 200 mg/kg every day for 2 months accompanied with drinking of AlCl(3) solution, respectively. Their abilities of spatial learning and memory were tested by Morris water maze, and the acetylcholinesterase (AChE) activity in serum was assayed with chemical method, the AChE expression in hippocampus was observed by immunohistochemistry assay, and then quantitative analysis was done by BI 2000 image analysis system.

RESULTSLearning and memory deficit of rats could be induced by AlCl(3) solution (P < 0.01), and AChE expressions in rats hippocampus were increased (P < 0.01); GbE ameliorated learning and memory deficit and reduced AChE expression in rats hippocampus in a dose-dependent manner, while GbE significantly increased serum AChE activity at the dose of 200 mg/kg each day (P < 0.05).

CONCLUSIONGbE can ameliorate learning and memory deficit induced by AlCl(3), which may be due to its inhibition of the AChE expression in hippocampus.