内源性Leptin对大鼠肝再灌注损伤的保护作用

Endogenous leptin protects the liver from reperfusion injury in rats

目的探讨缺血预处理（IP）对大鼠肝再灌注后血清Leptin及肝细胞Leptin受体（Leptin-R）变化的影响,从而阐明IP保护作用可能存在的机制。方法 120只健康雄性Wistar大鼠（质量190~210 g,6~7周龄）,随机分为缺血预处理组（IP）、再灌注组（IR）和假手术组（SO）。前两组分别建立左半肝缺血再灌注损伤模型,缺血时间均为60 min,IP组于半肝阻断前缺血5 min,再灌注5 min;SO组只进行麻醉下的开腹、关腹,不阻断肝门,余处理同前两组;3组腹腔暴露时间相同。之后每组分别按肝缺血再灌注后0.5、1、3、6 h采集标本。酶联免疫吸附实验竞争法集中测定血清Leptin的浓度;酶联免疫吸附法（Elisa）测定血清中TNF-α的水平;比色法测定肝细胞线粒体中丙二醛（MDA）的浓度;并通过免疫组织化学的方法对肝细胞Leptin-R进行染色及浓度测定。结果 IP组在再灌注后的各时点Leptin的浓度均显著高于IR组及SO组（P〈0.05）;IR组与SO组相比再灌注后0.5 h呈显著性的降低（P〈0.05）;之后的各时点Leptin的浓度均呈显著性的升高（P〈0.05）。IP及IR组再灌注后的各时点血清中TNF-α浓度缓慢增加,IP组在再灌注后各时点的血清TNF-α及线粒体MDA浓度显著低于IR组（P〈0.05）,同时显著的高于SO组（P〈0.05）。IP组及IR组在再灌注后各时点的Leptin-R阳性细胞率显著高于SO组（P〈0.05）;同时IP组与IR组相比再灌注后3、6 h的时点Leptin-R阳性细胞率均显著性增高（P〈0.05）。结论 IR可以增加血清中Leptin的浓度及Leptin-R在肝细胞内的蛋白表达,IP可以使这种作用加大及提前,此种变化可能是IP保护作用的机制之一。

【Objective】 To investigate the effect of ischemia preconditioning（IP） on the change of serum Leptin and hepatic Leptin-R and further the protect mechanism of IP in liver ischemia reperfusion（I/R） injury in rats.【Methods】 120 male Wistar rats（weight of 190～210 grams,age of 6～7 weeks） were divided into three groups at random： Ischemia preconditioning group（IP）,operation control group（IR） and sham operation group（SO）.IP and IR were separately used to establish ischemia reperfusion injury model of levo-liver,the ischemia time was 60 minutes;IP ischemia for 5 minutes and then reperfused for 5 minutes before blocking up the portal heptis;the abdomen was opened and closed under anesthesia for SO without blocking up the portal heptis,other steps were the same as the IP and IR;Three groups have the same exposure time.Then samples were collected at 0.5 h,1 h,3 h and 6 h after reperfusion respectively in each group.The concentration of serum Leptin and MDA in hepatic mitochondria were determined;Immunohistochemical strained Leptin-R in liver tissue.【Results】 The level of Leptin determined at each time after reperfusion in IP group was totally significantly higher than that in IR and SO（P 0.05）;Compared with that in SO,that significantly decreased at 0.5 h in IR,however,it gradually increased after 0.5 h（P 0.05）.The level of TNF-α and MDA determined at each time after reperfusion in IP group was significantly lower than that in IR groups,but higher than that in SO correspondingly（P 0.05）.The expressing level of Leptin-R（%） determined at each time after reperfusion in IP and IR group was totally significantly higher than that in SO groups correspondingly（P 0.05）;the expressing level of Leptin-R（%） measured at 3,6 h after reperfusion in IP group was totally significantly higher than that in IR groups corresponding（P 0.05）.【Conclusion】 IR increases the concentration of Leptin and the expression of Leptin-R in liver,the effect above is advanced and enhanced by IP,which is one of the possible protective mechanisms of IP.