脂多糖诱导大鼠肝脏中两类磷脂酶A_2激活及基因表达

The expression of two main subtypes of phospholipase A _2 in rat liver induced by lipopolysaccharide

目的 :观察脂多糖 (L PS)在大鼠肝脏中诱导磷脂酶 A2 (PL A2 )亚型的激活和基因表达情况。方法 :大鼠腹腔注射脂多糖 (L PS,2 mg/ kg)后不同时间取血 ,分别测定分泌型 PL A2 (s PL A2 )活性和前列腺素 E2(PGE2 )含量 ,用 Western blot检测肝脏中胞浆型 PL A2 (c PL A2 )蛋白的表达和时间进程 ;采用免疫组化法检测s PL A2 和 c PL A2 蛋白在肝脏中的表达 ;用 m RNA斑点杂交法检测 s PL A2 、c PL A2 m RNA在脏器中的转录水平。结果 :L PS可以时间依赖方式升高大鼠血清 s PL A2 活性、PGE2 含量以及肝脏中 c PL A2 蛋白表达 ;免疫组化显示肝细胞可表达两类 PL A2 ,且 L PS可加强其表达 ;肝脏及其它脏器中均有两类 PL A2 m RNA转录 ,受 L PS刺激后反应各不相同 ,而在肝脏中均有加强。结论 :L PS可明显增强大鼠肝脏中两类 PL A2 的基因转录和蛋白表达 ,同时可引起血中 PL A2 活性增高和花生四烯酸代谢产物明显增高 ;肝脏可能是炎性反应中外周血 PL A2活性及脂类介质的主要来源 ,L PS对肝脏中两类 PL A2

Objective:To investigate the effects of lipopolysaccharide (LPS) on the induction of two main subtypes of phospholipase A 2(PLA 2) in the liver.Methods:After rats were treated by LPS (2 mg/kg,i.p),sample were collected at different intervals to determine sPLA 2 activity and prostaglandin E 2(PGE 2) concentration.The protein expression of sPLA 2,cPLA 2 in liver was examined by immunohistochemistry.The timephase alteration of cPLA 2 protein synthesis was determined by Western blot.In addition,mRNA levels of sPLA 2 in liver and other organs were assayed using dothybridization.Results: The activity of sPLA 2 and concentration of PGE 2 in serum increased time dependently,elevation of cPLA 2 protein synthesis in liver also showed timedependent response during 24 hours seconary LPS challenge.sPLA 2 and cPLA 2 proteins were expressed in rat liver and were enhanced after LPS treatment.Although mRNA levels of sPLA 2,cPLA 2 in various organs showed different alterations after LPS administration,both of them were enhanced in the liver.Conclusions:LPS treatment can result in gene transcription and protein expression of two main subtypes of PLA 2 in rat liver,in turn leading to the elevation of sPLA 2 activity and lipid mediator production in serum.The synthesis and release of two main subtypes of PLA 2 in the liver induced by LPS challenge might play an important role in the development of systemic inflammatory response syndrome.