溶血磷脂酸对背根神经髓鞘相关糖蛋白表达的影响及机制的研究

摘要

Objectives:To investigate the effects and mechanism of lysophosphatidic acid (LPA) on expression of myeline-associated glycoprotein (MAG) in dorsal root (DR).Methods:Experiment 1: Male C56 mice were randomly divided into artificial cerebralspinal fluid (aCSF) group and LPA group. Western blot was used to observe the MAG expression in the DR at different time points (on post-injection 24 hours, day 3, day 7). Experiment 2: Male C56 mice were randomly divided into aCSF group, LPA group, calpain inhibitor X (CaIX) + LPA group and aCSF + CalX group. We tested mechanical hyperalgesia and thermal hyperalgesia at different time points (post-injection day 1, day 3, day 7, day 14) by using Von Frey filament test and thermal test. Experiment 3: Male C56 mice were randomly divided into aCSF group,aCSF+LPA group and CalX+LPA group. Immunofluorescence technique and western blot were used to test the effect of CalXafter post-injection 24 hours.Results:①Compared with aCSF group, we found that intrathecal injection of LPA down-regulates MAG in the DR. The most obvious reduction in MAG levels occurred at 24 hour post-injection and it also decreased on day 3, but it was not significant on day 7;②Compared with aCSF group and aCSF+CalX group, it showed that LPA induced thermal hyperalgesia and mechanical allodynia during post-injection day 1 to day 7. Compared with LPA group, it showed a significant inhibition of LPA-induced thermal hyperalgesia and mechanical allodynia in CalX+LPA group during post-injection day 1 to day 7.③Compared with aCSF group and aCSF + LPA group, it could completely blocked MAG decreased and similar results were obtained with immunofluorescence in CalX + LPA group.Conclusion:The expression of MAG in DR was decreased after the treatment of LPA , and it was mediated by the activation of calpain.%目的:探讨单次鞘内注射溶血磷脂酸(lysophosphatidic acid,LPA)对背根神经髓鞘相关糖蛋白(myeline-associated glycoprotein,MAG)表达的影响以及其作用机制;方法:实验1:C56雄性小鼠随机分为人造脑脊液(artificial cerebralspinal fluid,aCSF)组和LPA组,在注射后24小时、3天和7天处死小鼠取其背根神经(dorsal root,DR),采用原位杂交(western blot,WB)方法测定DR中MAG的表达.实验2:C56雄性小鼠随机分为aCSF组,LPA组,钙蛋白酶抑制剂X(calpain inhibitor X,CalX)+LPA组和aCSF+CalX组,在注射后0天、24小时、3天、7天和14天测定小鼠机械性阈值及热阈值.实验3:C56雄性小鼠随机分为aCSF组,aCSF+LPA组和CalX+LPA组,在注射后24小时处死小鼠取其背根神经,采用WB和免疫荧光的方法观察CalX对MAG的影响.结果:①与aCSF组对比,LPA注射后24小时MAG显著降低,持续到第3天,第7天降低不明显;②与aCSF组和aCSF+CalX组对比,LPA组在术后1~7天有明显的热痛敏和机械痛敏;与LPA组对比,CalX+LPA组热痛敏和机械痛敏明显减轻;③与aCSF组和aCSF+LPA组对比,CalX+LPA组WB结果显示CalX能完全阻止LPA诱导DR中MAG的下调,免疫荧光和WB结果是一致的.结论:单次鞘内注射LPA可以诱导背根神经MAG的下调,且是通过钙蛋白酶激活介导的.