Effect of extract of Ginkgo bilob on learning and memory, neuron apoptosis and neurogenesis of juvenile rats with kindled seizure

Objective To study the effect of extract of Ginkgo bilob (EGb) on learning and memory,nerve cell apoptosis and neurogenesis of juvenile rats with kindled seizure.Methods Two hundred and forty 21-d old SD rats were equally randomized into normal saline group (NS),kindled control for 7 d group (P-A7),kindled control for 14 d group (P-A14),EGb treatment for 7 d group (P-E7),EGb treatment for 14 d group (P-E14).All the rats,except rats of the NS group,were induced chronic kindling seizure by pentylenetetrazol.Morris maze test was used to detect the learning and memory abilities.Immunohistochemical staining was used to observe the nerve cell apoptosis and neural stem cell proliferation and differentiation in the hippocampus.BrdU/NeuN or BrdU/GFAP double-labeled staining was employed to observe the nerve cell differentiation.Results (1) The escape latency in Morris maze test in rats of every group was gradually shorted during 4 days of pre-treatment; the escape latency was (31.72±8.37) in P-E7 group and (31.29±4.35) in P-E14 group,which was significantly shorten than that in NS group (18.93±6.40),P-A7 group (47.86±9.14) and P-A14 group (44.79±7.72) (P＜0.05); the time in target quadrant in maze test showed gradual increase in rats of the NS,P-A7 and P-A14 groups and was significantly increased in rats of the P-E7 and P-E14 groups after EGb treatment (P＜0.05); the cross-platform times of rats in the P-A7 and P-A14 groups (4.38±1.06,4.50±0.93) in maze test were significantly shorter than those of NS rats (11.13±0.99),P-E7 rats (10.00±2.00) and P-E14 rats (10.63±0.92,P＜0.05).(2) TUNEL-positive cells in CA3 area ofhippocampus in rats of the NS group were obviously fewer than those in the other 4 groups (P＜0.05).The number of apoptotic cells in P-E7 and P-E 14 groups was (28.25±4.65) and (28.13±6.08),which was significantly reduced as compared with that in the P-A7 and P-A14 groups (P＜0.05).(3) Nestin-positive cells in the hippocampal CA1,CA3 and DG regions of rats from the NS group were fewer than those in the other 4 groups (P＜0.05); those in the P-E7 and P-E14 groups enjoyed the highest levels.(4) The number of BrdU/NeuN cells after EGb treatment was significantly larger than that before EGb treatment,and BrdU/NeuN-positive cells percentage in P-E14 group was higher than that in P-E7 group (P＜0.05),meanwhile,the co-expression ofBrdU/GFAP was about 4％-5％ after EGb treatment.Conclusion EGb can significantly improve the learning and memory abilities in young rats with kindled seizure; anti-apoptosis and promoted neural stem cell proliferation and differentiation effect of EGb might be the mechanism. Key words: Extract of Ginkgo bilob; Epilepsy; Learning and memory; Neurogenesis