异甘草酸镁对大鼠肢体缺血再灌注肝损伤时磷脂酶A2的影响

Effect of magnesium isoglycyrrhizinate on PLA： during liver tissue injury following limb ischemia/reperfusion in rats

目的探讨异甘草酸镁（MI）对大鼠肢体缺血再灌注肝损伤时磷脂酶如（PLA2）的影响。方法选取健康、雄性、清洁级SD大鼠24只，体质量（230±30）g，随机分成3组（每组8只）：对照组（C组）、缺血再灌注组（I／R组）、异甘草酸镁治疗组（MI组）。C组仅麻醉，肢体没有缺血操作；I／R组于再灌注前颈外静脉注入生理盐水1ml；MI组于再灌注前同法给异甘草酸镁30mg／kg，计1ml。以橡皮带环绕结扎大鼠左后肢根部至趾掌无血流信号达4h后放开橡皮带，再灌注6h建立大鼠后肢缺血再灌注肝损伤模型。再灌注6h后各组处死动物采集标本，分别取大鼠的血清测定ALT、AST、乳酸脱氢酶（LDH）、肌酸激酶（CK），取肝组织做10％的匀浆，采用硫代巴比妥酸法测匀浆及血清的丙二醛（MDA）、髓过氧化物酶（MPO）值，采用酶联免疫法测匀浆及血清PLA2、肿瘤坏死因子α（TNFα），电镜观察肝组织的超微结构改变。结果（1）C组肝匀浆PLA2、TNFα、MDA、MPO分别为（74．1±3．1）Hg／g、（152．4±7．9）ng／g、（2．02±0．16）nmol／g、（0．20±0．03）活力单位／g；血清PLA2、TNFα、MDA、MPO分别为（80．3±3．9）μg／L、（121．7±6．6）ng／L、（4．89±0．64）nmol／ml、（65．62±8．33）活力单位／ml；I／R组肝匀浆PLA2、TNFα、MDA、MPO分别为（94．83±21．99）μg／g、（361．3±46．6）ng／g、（3．038±0．391）nmol／g、（0．422±0．062）活力单位／g；血清PLA2、TNFα、MDA、MPO分别为（118．4±9．3）μg／L、（152．7±15．7）ng／L、（7．30±0．73）nmol／ml、（94．83±21．99）活力单位／ml；MI组肝匀浆PLA2、TNFα、MDA、MPO分别为（84．3±5．8）μg／g、（314．4±13．9）ng／g、（2．49±0．07）nmol／g、（0．31±0．05）活力单位／g；血清PLA2、TNFα、MDA、MPO分别为（96．0±4．4）μg／L、（137．0±5．5）ng／L、（5．61±0．36）nmol／ml、（74．26±5．81）活力单位／ml，与C组比较，I／R组肝匀浆及血清PLA2、TNFα、MDA、MPO均升高，t值分别为10．743、12．504、5．458、8．939和12．303、5．154、7．019、3．513，P值均〈0．01，差异有统计学意义。与I／R组比较，MI组肝匀浆及血清PLA2、TNFα、MDA、MPO均降低，t值分别为6．170、2．726、3．409、3．946和6．543、2．676、5．926、2．558，P值均〈0．05，差异有统计学意义。（2）C组血清中ALT、AST、CK、LDH分别为（64．0±8．9）U／L、（113．4±18．2）U／L、（286．5±26．5）U／L、（190．8±39．0）U／L；I／R组分别为（381．0±133．8）U／L、（1227．0±383．8）U／L、（3944．9±552．0）U／L、（3050．0±833．3）U／L；MI组分别为（205．6±68．7）U／L、（851．8±126．7）U／L、（1252．5±196．3）U／L、（1177．5±244．0）U／L，与C组比较，I／R组血清中ALT、AST、CK、LDH均明显升高，t值分别为6．687、8．197、19．188、9．376，P值均〈0．01，差异有统计学意义。与I／R组比较，MI组血清中ALT、AST、CK、LDH均明显降低，r值分别为3．298、2．626、12．998、6．100，P值均〈0．05，差异有统计学意义。（3）电镜下组织超微结构I／R组中肝组织损伤明显，而用MI组肝组织的损伤明显减轻。结论异甘草酸镁能够通过降低PLA，和TNFα生成而减少炎症介质的释放、抑制氧自由基代谢产物MDA的产生和减少MPO的活性，对肢体缺血再灌注过程中的肝损伤有一定的保护作用。

Objective To investigate the effects of magnesium isoglycyrrhizinate （MI） on the changes of phospholipase A2 （PLA2） induced during liver tissue injury following limb ischemia/reperfusion （I/R） in rats. Method Twenty-four healthy male Sprague-Dawley rats weighing （230±30）g were randomly divided into three groups 07=8 each） as follows： control （Group C： anesthetization without any ischemia）; FR injury （Group I/R： 4 h ischemia induced by rubber band ligation of the left hind limb around the roots of the hind limb, followed by 6 h of reperfusion, with 1 mL normal saline given via tail vein prior to reperfusion）; MI- treated group （Group MI： underwent ischemia and reperfusion, with 1 mL MI （30 mg/kg） infused prior to reperfusion）. Levels of TNFα and PLA2 in plasma and liver tissue were measured by enzyme-linked immumosorbent assay （ELISA）. Levels of plasma alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, lactate dehydrogenase （LDH）, creatine kinase （CK）, myeloperoxidase （MPO）, and malondialdehyde （MDA）, and activities of MPO and MDA in liver tissue were measured by colorimetry. Ultrastructural changes of liver tissue were observed by electron microscopy. Results The MI group had significantly lower PLA2 and TNFα in liver homogenates and serum than the I/R group （bothP〈0.05）. Serum ALT, AST, LDH, and CK were significantly lower in the MI group than in the I/R group （all P〈0.05）, as were the levels of MPO and MDA in liver homogenates and serum （allP〈0.05）. The I/R group showed significantly more liver tissue damage, which appeared to be attenuated in the MI group. Conclusion MI treatment can inhibit the I/R-induced TNFα, PLA2, and MDA in plasma and liver tissue, as well as decrease the I/R-induced MPO activity in rats. Thus, MI may have protective effects against liver tissue injury following limb ischemia/reperfusion.