右美托咪定预先给药对肝缺血再灌注致大鼠心肌损伤时JAK/STAT信号通路的影响

Effect of dexmedetomidine pretreatment on JAK/STAT signaling pathway during myocardial injury induced by liver ischemia-reperfusion in rats

目的探讨右美托咪定预先给药对大鼠肝缺血再灌注致大鼠心肌损伤时Janus激酶/信号转导和转录激活子(JAK/STAT)信号通路的影响。方法成年雄性SD大鼠24只,周龄8~10周,体重220~250 g,采用随机数字表法分为3组(n=8):采用随机数字表法分为3组(n=8):假手术组(S组)、肝缺血再灌注组(I/R组)和右美托咪定预先给药组(D组)。采用夹毕门静脉、肝上下腔静脉、肝下下腔静脉和肝固有动脉,经门静脉向肝脏灌注4 ℃乳酸钠林格液60 min的方法制备肝脏冷缺血再灌注损伤模型。D组于缺血前30 min腹腔注射右美托咪定100 μg/kg。再灌注8 h时,下腔静脉取血样,应用全自动生化分析仪检测血清cTnI和心型脂肪酸结合蛋白(H-FABP)的浓度,采用ELISA法测定血清TNF-α和高迁移率族蛋白B1(HMGB1)的浓度;然后处死大鼠,取心肌组织,采用硫代巴比妥酸法测定MDA含量,采用黄嘌呤氧化酶法测定SOD活性,采用Western blot法测定磷酸化STAT1(p-STAT1)、磷酸化STAT3(p-STAT3)和磷酸化JAK2(p-JAK2)的表达水平。光镜下观察心肌病理学变化。结果与S组比较,I/R组和D组血清cTnI、H-FABP、TNF-α和HMGB1的浓度升高,心肌组织MDA含量升高,SOD活性下降,p-JAK2、p-STAT1和p-STAT3表达上调(P<0.05);与I/R组比较,D组血清cTnI、H-FABP、TNF-α和HMGB1的浓度降低,心肌组织MDA含量下降,SOD活性升高,心肌病理学损伤减轻,p-JAK2、p-STAT1和p-STAT3表达下调(P<0.05)。结论右美托咪定预先给药减轻肝缺血灌注致大鼠心肌损伤的机制可能与抑制JAK/STAT信号通路的激活有关。

Objective To investigate the effect of dexmedetomidine pretreatment on Janus kinase/signal transducer and activator of transcription(JAK/STAT)signaling pathway during myocardial injury induced by liver ischemia-reperfusion(I/R)in rats. Methods Twenty-four healthy adult male Sprague-Dawley rats, aged 8-10 weeks, weighing 220-250 g, were divided into 3 groups(n=8 each)using a random number table method: sham operation group(group S), liver I/R group(group I/R), and dexmedetomidine pretreatment group(group D). The portal vein, superior and inferior vena cava, subhepatic inferior vena cava and hepatic artery were clamped, and the liver was perfused with 4 ℃ lactated Ringer′s solution for 60 min through the portal vein to establish the model of liver cold I/R in anesthetized rats.Dexmedetomidine 100 μg/kg was intraperitoneally injected at 30 min before ischemia in group D. Blood samples were collected at 8 h of reperfusion from the inferior vena cava for determination of serum cardiac troponin Ⅰ(cTnI) and heart-type fatty acid binding protein(H-FABP)concentrations(using the automatic biochemistry analyzer), tumor necrosis factor-alpha(TNF-α)and high-mobility group box 1 protein(HMGB1)concentrations(by enzyme-linked immunosorbent assay). The rats were then sacrificed, and hearts were harvested for examination of histopathological changes(with a light microscope)and for determination of the malondialdehyde(MDA)content(using thiobarbituric acid method)and superoxide dismutase(SOD)activity(by xanthine oxidase method), and expression of phosphorylated STAT1 and STAT3(p-STAT1, p-STAT3)and phosphorylated JAK2(p-JAK2)in myocardial tissues(by Western blot). Results Compared with group S, the serum concentrations of cTnI, H-FABP, TNF-α and HMGB1 were significantly increased, the MDA content was increased, the SOD activity was decreased, and the expression of p-JAK2, p-STAT1 and p-STAT3 was up-regulated in I/R and D groups(P<0.05). Compared with group I/R, the serum concentrations of cTnI, H-FABP, TNF-α and HMGB1 were significantly decreased, the MDA content was decreased, the SOD activity was increased, the expression of p-JAK2, p-STAT1 and p-STAT3 was down-regulated(P<0.05), and pathological changes of myocardium were significantly attenuated in group D. Conclusion The mechanism by which dexmedetomidine pretreatment mitigates myocardial injury induced by liver cold I/R may be related to inhibiting activation of JAK/STAT signaling pathway in rats.