人参皂苷Rg1对发育期癫痫模型大鼠认知功能的影响

Effects of ginsenoside Rg1 on cognitive functions in a rat model of developmental epilepsy

目的探讨人参皂苷Rg1对发育期癫痫模型大鼠认知功能的影响。方法50只14d龄SD大鼠按随机数字表法分为对照组、模型组和人参皂苷Rg1低、中、高剂量组(人参皂苷Rg110、30、60mg/kg),每组10只;模型组和人参皂苷Rg1低、中、高剂量组大鼠称重后,给予红藻氨酸10mg/kg剂量腹腔注射制备慢性癫痫模型;对照组大鼠腹腔注射相同体积的生理盐水。Morris水迷宫测定大鼠的学习记忆功能;Western blot法检测大鼠海马神经限制性沉默因子(NRSF)蛋白表达;RT-qPCR法检测大鼠海马组织NRSF mRNA和miR-124表达;尼氏染色(Nissl染色)检测大鼠海马结构的病理改变。结果与对照组比较,模型组大鼠定位巡航实验第3~6天逃避潜伏期显著延长[(54.80±7.34)s比(28.60±5.16)s,(52.10±9.89)s比(18.63±6.87)s,(47.11±9.67)s比(15.57±6.26)s,(39.05±8.74)s比(9.02±6.34)s,P均<0.01];空间探索实验目的象限游泳时间百分比明显减少[(13.23±5.43)%比(44.23±8.12)%,P<0.01];海马NRSF蛋白表达量明显增加[(0.71±0.11)比(0.31±0.04),P<0.01];海马NRSF mRNA及miR-124表达量明显增加[NRSF mRNA:(0.84±0.09)比(0.46±0.06);miR-124:(0.60±0.08)比(0.41±0.07),P均<0.05]。与模型组比较,人参皂苷Rg1高剂量组大鼠定位巡航实验第3~6天逃避潜伏期显著缩短[(40.10±9.14)s比(54.80±7.34)s,(30.10±7.76)s比(52.10±9.89)s,(24.90±6.32)s比(47.11±9.67)s,(17.09±7.56)s比(39.05±8.74)s,P均<0.01],空间探索实验目的象限游泳时间百分比明显增加[(35.27±5.49)%比(13.23±5.43)%,P<0.01];海马NRSF蛋白及NRSF mRNA表达量明显减少[NRSF蛋白:(0.50±0.06)比(0.71±0.11),P<0.01;NRSF mRNA:(0.59±0.07)比(0.84±0.09),P均<0.05];海马miR-124表达量明显增加[(0.84±0.07)比(0.60±0.08),P<0.05]。Nissl染色结果显示,对照组大鼠海马CA3区锥体细胞排列整齐、紧密,细胞结构完整,神经元内布满深蓝色颗粒状的尼氏小体;模型组大鼠海马CA3区锥体细胞排列疏松,部分神经元胞体皱缩、碎裂,核固缩,胞质内尼氏小体大量脱失;人参皂苷Rg1各剂量组大鼠海马CA3区神经元皱缩、碎裂、尼氏小体减少、脱失较模型组减轻,以高剂量组减轻明显。结论人参皂苷Rg1能改善发育期癫痫模型大鼠认知功能,这可能与减少海马NRSF表达量及增加miR-124表达量有关。

Objective To investigate the effects of ginsenoside Rg1 on cognitive functions in a rat model of developmental epilepsy.Methods Fifty Sprague-Dawley rats of 14 day-old were divided into five groups of control,model,and model plus low-,medium-and high-doses ginsenoside Rg1(10,30,and 60 mg/kg,respectively)according to a random number table(n=10 rats per group).To establish the model,rats were weighed and intraperitoneally injected with 10 mg/kg of red algine,while the control rats were intraperitoneally injected with the same volume of normal saline.After that,the treatment groups of rats were treated with ginsenoside Rg1(10,30,and 60 mg/kg,respectively).Morris water maze was used to determine the learning and memory functions of each rat.Expression of hippocampal restrictive silencing factor(NRSF)protein was assayed using Western blot,while levels of NRSF mRNA and mir-124 in rat hippocampus were analyzed using quantitative RT-PCR.Histology changes in the rat hippocampal structures were detected using the Nissl staining.Results The data showed that the escape incubation time in model rats was significantly longer than that of the control rats at Day 3 to 6 using the location cruise experiment(54.80±7.34 vs.28.60±5.16 s,52.10±9.89 vs.18.63±6.87 s,47.11±9.67 vs.15.57±6.26 s,39.05±8.74 vs.9.02±6.34 s,respectively;P<0.01).Compared with the control rats,the percentage of swimming time in the space exploration quadrant of model rats was significantly decreased(13.23±5.43 vs.44.23±8.12%;P<0.01),whereas expression of NRSF protein in the hippocampus was significantly increased(0.71±0.11 vs.0.31±0.04;P<0.01)and NRSF mRNA and mir-124 levels in the hippocampus were also significantly increased(NRSF mRNA,0.84±0.09 vs.0.46±0.06;mir-124,0.60±0.08 vs.0.41±0.07;both P<0.05).However,compared with the model rats,the escape latency in high-dose ginsenoside Rg1-treated rats was significantly shortened from Day 3 to Day 6 using the positioning cruise experiment(40.10±9.14 vs.54.80±7.34 s,30.10±7.76 vs.52.10±9.89 s,24.90±6.32 vs.47.11±9.67 s,17.09±7.56 vs.39.05±8.74 s,respectively;P<0.01).The percentage of swimming time in the quadrant of space exploration experiment was significantly increased(35.27±5.49 vs.13.23±5.43%;P<0.01).Levels of hippocampal NRSF protein and mRNA were significantly decreased(protein,0.50±0.06 vs.0.71±0.11;P<0.01;mRNA,0.59±0.07 vs.0.84±0.09;P<0.05);however,miR-124 level in the rat hippocampus was significantly increased(0.84±0.07 vs.0.60±0.08;P<0.05).In addition,the Nissl staining results showed that the pyramidal cells in the hippocampal CA3 area of the control rats were neatly arranged and compact with intact cell structures and the neurons were covered with dark blue granular Nissl bodies.In contrast,pyramidal cells in the hippocampal CA3 area of model rats were loosely arranged;some neuronal cell bodies were shrunken and fragmented,and showed nuclear pyknosis and lost a large number of Nissl bodies in the cytoplasm.Compared with those of model rats,the shrinkage,fragmentation,reduction and loss of Nissl corpuscles in the region were much reduced,especially in the high dose group of rats.Conclusion Ginsenoside Rg1 was able to improve the cognitive functions in a rat model of developmental epilepsy.At the gene level,Ginsenoside Rg1 could reduce NRSF expression but induce miR-124 expression in the hippocampus.