尼莫地平对惊厥持续状态幼鼠海马葡萄糖调节蛋白78、p38丝裂素激活蛋白激酶表达的影响

摘要

目的 探讨葡萄糖调节蛋白78(GRP78)、p38丝裂素激活蛋白激酶(p38MAPK)相关信号通路在惊厥性脑损伤中的作用及尼莫地平对其的影响.方法 雄性SD幼年大鼠分为惊厥持续状态组(SC组)、尼莫地平组(NM组)、正常对照组(NC组).采用免疫组织化学法、反转录(RT)-PCR技术检测海马CA1区GRP78/Bip、p38MAPK蛋白、mRNA表达动态变化;采用原位末端标记(TUNEL)检测神经细胞的凋亡.结果 1.免疫组织化学:GRP78/Bip蛋白惊厥后4h开始增加,24 h达高峰,之后下降.p38MAPK蛋白惊厥后4h表达开始增加,24 h达高峰,48 h稍有下降.2.RT-PCR:SC组海马GRP78/Bip mRNA表达于惊厥后4h开始少量增加,24 h达高峰,48 h回到基线水平.NM组4h,24 h和48 h表达情况较SC组和NC组均明显升高(P均＜0.05).SC组p38MAPK mRNA于惊厥后4h开始表达,24 h达高峰,48 h后有所下降,但均高于NC组;NM组24 h时间点明显高于NC组(P＜0.01).3.TUNEL:SC组海马CA1区TUNEL阳性细胞于惊厥后4h已有少量表达,48 h达高峰,之后有下降趋势;且24 h、48 h2个时间点均明显高于NC组(P均＜0.05).NM组24 h、48 h时间点TUNEL阳性细胞表达水平较SC组明显降低(P均＜0.05);但仍高于NC组(P＜0.01).结论 GRP78信号通路可能通过激活p38MAPK介导细胞凋亡,尼莫地平预处理可影响GRP78/Bip和p38MAPK的表达,缓解内质网应激,减轻惊厥后海马病理损伤程度.%Objective To explore the role of glucose-regulated protein 78 (GRP78),p38 mitogen-activated protein kinase(p38MAPK) signal pathway in seizure-reduced brain injures and the regulatory effect of Nimodipine on it.Methods Sprague-Dawley(SD) rats were randomly divided into status convulsion group (SC group),Nimodipine group(NM group),and a normal control group(NC group).The expressions of GRP78/Bip and p38MAPK mRNA and protein were detected by reverse transcription(RT)-PCR and immunohistochemistry.The expression of apoptosis cells was observed by TdT-mediated dUTP nick end labeling (TUNEL).Results (1) Immunohistochemistry:at 4 h after induction of status convulsion,the expression of GRP78 protein in the hippocampus CA1 domain began increasing slightly,and reached a maximum at 24 h,and then began decreasing slowly ; at 4 h after induction of status convulsion,the expression of p38MAPK protein in the hippocampus CA1 domain began increasing,and reached a maximum at 24 h,and decreased remarkably at 48 h.(2) RT-PCR:at 4 h after induction of status convulsion,the expression of GRP78 protein in the hippocampus CA1 domain began increasing slightly,and reached a maximum at 24 h,and then began decreasing slowly.The NM group was much higher than the SC group and the NC group(all P ＜ 0.05) ; at 4 h after induction of status convulsion,the expression of p38MAPK protein in the hippocampus CA1 domain began increasing,and reached a maximum at 24 h,and decreased remarkably at 48 h;the NM group was much lower than the SC group,and higher than the NC group (all P ＜ 0.05).(3) TUNEL:at 4 h after induction of status convulsion,the expression of the TUNEL positive cells in the hippocampus CA1 domain began increasing slightly,and reached a maximum at 48 h,and then began decreasing,and there was no difference between SC group and NC group;the NM group was much lower than the SC group(all P ＜ 0.05).Conclusions The correlation of the increased expression of p38MAPK and neuronal apoptosis indicates that GRP78 signal pathway may be mediated to cell apoptosis through p38MAPK.Nimodipine can affect the expression of GRP78/Bip and p38MAPK,and relieve endoplasmic reticulum stress,and lessen the pathologic damage to the hippocampus.