AIM To study the effects of
ginkgo leaf extract on the expression of cerebral cortex and hippocampal apolipoprotein E ApoE mRNA in brain of
diabetic rats with learning and memory dysfunction on the basis of open field test Morris water maze test and reverse transcription polymerase chain reaction RT-PCR. METHODS The experiment was completed in the Experimental Center of Guangxi Medical University from September 2003 to August in 2005. ① Totally 56 rats were divided randomly into normal control group n=12 diabetic
model group n=11 diabetic model + 10 μ/kg insulin group n =11 diabetic model + 100 mg/kg ginkgo leaf extract group n=11 and diabetic model + 50 mg/kg ginkgo leaf extract group n=11. ② Rats were injected intravenously with 55 mg/kg streptozotocin to establish diabetic models. Learning and memory abilities of rats were assayed with open field test and Morris water maze test and expressions of ApoE mRNA in cerebral cortex and hippocampus of diabetic rats with learning and memory dysfunctions were measured with RT-PCR. RESULTS Totally 56 rats entered the study but only 53 rats received open field test and Morris water maze test. Three rats died in diabetic model control group diabetic model + 10 μ/kg insulin group and diabetic model + 50 mg/kg ginkgo leaf extract group respectively during the experiment. Ten rats selected from normal control group and 8 from other groups respectively entered RT-PCR analysis. ① Open field test showed that staying time was prolonged and hole-probing times were decreased in diabetic group as compared with those in normal control group and staying time was shortened and hole-probing times were increased in ginkgo leaf extract groups as compared with those in diabetic group.② Morris water maze test showed that escape latency was long and platform-searching score was low in diabetic group as compared with those in normal control group and escape latency was short and platform-searching score was high in ginkgo leaf extract groups as compared with those in diabetic group. ③ RT-PCR showed that expressions of ApoE mRNA in hippocampus of rats in diabetic group were increased significantly as compared with that in normal control group but there were no obvious changes in cerebral cortex P > 0.05. The expressions of ApoE mRNA in hippocampus of 100 and 50 mg/kg ginkgo leaf extract groups were decreased significantly as compared with that in diabetic group but there were no obvious changes in cerebral cortex P >0.05. CONCLUSION Ginkgo leaf extract can inhibit the expression of ApoE mRNA in hippocampus of diabetic rats with learning and memory dysfunction this suggests that ginkgo leaf extract can protect the capacity of leaning and memory dysfunction of diabetic rats.
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