绿茶提取物EGCG对乙醇诱导大鼠学习记忆功能障碍的作用

The effect of green tea compound epigallocatechin-3-gallate on alcohol-induced learning and memory damage in the rat

目的探讨绿茶提取物表没食子儿茶素没食子酸酯(epigallocatechin-3-gallate,EGCG)对乙醇诱导学习记忆功能障碍的作用及机制。方法以SD大鼠为实验对象建立乙醇性痴呆(ADD)大鼠模型,实验设对照组和EGCG组,每组15只,EGCG组在乙醇灌胃前1个月起给予EGCG(1 mg/mL)自由饮水至乙醇灌胃结束,对照组给予蒸馏水代替。观察两组大鼠Morris水迷宫行为,HE染色观察大鼠海马组织形态改变及Hoechst33342染色检测细胞凋亡,荧光实时定量PCR检测抗凋亡因子B淋巴细胞瘤-2蛋白(B-cell lymphoma-2, BCL2)、促凋亡因子BCL2-相关X蛋白(BCL2-associated X, BAX)表达及抗氧化酶和总超氧化物歧化酶(total superoxide dismutase,T-SOD)和谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性。结果与灌胃后对照组相比,灌胃后EGCG组大鼠逃避潜伏期时间缩短[(35.22±6.29)s vs.(19.55±3.45)s,t=2.183,P=0.049]、穿越平台次数增加(2.57±0.65 vs. 5.43±0.69,t=3.027,P=0.015)、第四象限路程/总路程(22.50±2.33 vs. 36.71±5.16,t=2.512,P=0.027)及第四象限时间/总时间百分比(24.55±1.79 vs. 37.39±5.57,t=2.194,P=0.049)增高,提示其学习记忆功能损害得到改善;EGCG组大鼠海马形态结构破坏明显减轻及凋亡细胞减少;EGCG组大鼠海马组织中BCL2表达(0.31±0.20 vs. 0.71±0.36,t=23.886,P=0.000)明显增高,BAX表达(4.92±0.35 vs. 2.01±0.10,t=19.643,P=0.000)明显降低;EGCG组大鼠海马组织中抗氧化酶T-SOD(7.03±0.35 vs. 17.41±0.19,t=64.911,P=0.000)和GSH-Px(2.27±0.03 vs. 6.11±0.27,t=34.579,P=0.000)的酶活性明显增高。结论 EGCG对乙醇诱导学习记忆功能障碍具有一定的改善作用,其机制可能与抑制海马神经细胞凋亡及抗氧化应激损伤有关。

Objective To observe the effect of green tea compound epigallocatechin-3-gallate (EGCG) on alcohol-induced learning and memory damage and discuss its mechanism. Methods To set up an alcohol-associated dementia (AAD) rat model, SD rats were selected randomly into two groups:EGCG group and control group ( n =15). Animals in EGCG group freely drank water containing EGCG (1 mg/mL) one month before giving ethanol lavage until that was finished, the control group was given distilled water instead of EGCG. The learning and memory function of rats was evaluated by observing Morris water maze behaviors and hippocampus morphology was detected with HE staining and cell apoptosis with Hoechst33342 staining. The expression of apoptosis factors including B-cell lymphoma-2 (BCL2) and BCL2-associated X (BAX) was detected by Real-time fluorescent quantitative PCR, the activity of antioxidant enzymes such as total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) in rat hippocampus was also studied. Results As compared to the control group, the escape latent (EL) time of rats in EGCG group was significantly shortened [(35.22±6.29)s vs .(19.55±3.45)s, t =2.183, P =0.049], the number of swimming through the platform was increased (2.57±0.65 vs . 5.43±0.69, t =3.027, P =0.015), the fourth quadrant distance/the total distance (22.50±2.33 vs . 36.71±5.16, t =2.512, P =0.027) and the fourth quadrant time/the total time was increased (24.55±1.79 vs . 37.39±5.57, t =2.194, P =0.049), suggesting alcohol-induced learning and memory impairment is improved. Also, as compared to the control group, alcohol-induced morphological damage in rat hippocampus was apparently improved and the number of apoptotic cell was decreased in EGCG group. Still, anti-apoptotic factor BCL2 was up-expressed (0.31±0.20 vs . 0.71±0.36, t =23.886, P =0.000) and pro-apoptotic factor BAX was down-expressed (4.92±0.35 vs . 2.01±0.10, t =19.643, P =0.000) in rat hippocampus of EGCG group. Moreover, the enzyme activity of T-SOD (7.03±0.35 vs . 17.41±0.19, t =64.911, P =0.000) and GSH-Px (2.27±0.03 vs . 6.11±0.27, t =34.579, P =0.000) in rat hippocampus of EGCG group was obviously increased. Conclusions The alcohol-induced damage of learning and memory function could be prevented with EGCG treatment, which is closely associated with its inhibition effect on alcohol-induced hippocampal neuron apoptosis and improvement of antioxidant enzyme activity.