右美托咪定对劳力性热射病大鼠相关性横纹肌溶解的缓解及其机制

Effect and mechanism of dexmedetomidine on alleviating heat stroke related rhabdomyolysis in rats

目的观察右美托咪定(DEX)可否通过激活肾上腺素能α_(2)受体(ADRA2A)缓解劳力性热射病(EHS)大鼠横纹肌溶解(RM),并基于活性氧(ROS)/含Pyrin结构域NOD样蛋白3(NLRP3)/白细胞介素(IL)-1β通路探索其潜在机制。方法将适应性训练7 d后的36只雄性SD大鼠随机分为6组:对照组(CN组)、EHS组、低DEX剂量组(EHS+低DEX组)、高DEX剂量组(EHS+高DEX组)、DEX联合育亨宾(YOH)组(EHS+高DEX+YOH组)、育亨宾组(EHS+YOH组);每组6只。造模前,EHS+高DEX+YOH组和EHS+YOH组腹腔注射YOH 1 mg/kg,其他4组腹腔注射等量生理盐水;造模时,除CN组外,其他5组大鼠均采用高温高湿舱内热运动法构建EHS大鼠模型,造模成功后,EHS+低DEX组大鼠腹腔注射DEX 10μg/kg,EHS+高DEX组和EHS+高DEX+YOH组大鼠腹腔注射DEX 30μg/kg,CN组、EHS组及DEX+YOH组大鼠腹腔注射等量生理盐水。6 h后麻醉,取腹主动脉血及腓肠肌组织。采用酶联免疫吸附试验(ELISA)法检测大鼠血清肿瘤坏死因子-α(TNF-α)、IL-6、IL-1β及肌红蛋白(MB)表达水平,生化试剂盒检测大鼠血清肌酸激酶(CK)水平,HE染色观察大鼠腓肠肌组织病理改变,透射电镜观察腓肠肌超显微结构改变,2′,7′-二氯荧光黄双乙酸盐(DCFH-DA)荧光探针检测活性氧(ROS)水平,Western blotting检测NLRP3、胱天蛋白酶-1(caspase-1)及肾上腺素能α_(2)受体(ADRA2A)表达水平。结果与CN组比较,EHS组大鼠血清IL-6、IL-1β、TNF-α、CK及MB均明显升高(P<0.01)。HE染色结果显示,EHS组大鼠腓肠肌组织出现纤维结构紊乱、出血、水肿、炎性细胞浸润等病理表现。透射电镜显示,EHS组腓肠肌超微结构出现肌纤维细胞肿胀、体积变大,胞质空泡化,线粒体明显肿胀、脱颗粒、双嵴消失等改变。与CN组比较,EHS组大鼠腓肠肌内ROS、NLRP3、caspase-1水平明显升高(P<0.01);与EHS组比较,EHS+低DEX组、EHS+高DEX组的TNF-α、IL-6、IL-1β、CK、MB及腓肠肌组织内ROS、NLRP3、caspase-1均呈剂量依赖性下降(P<0.05),且HE染色和透射电镜显示病理损伤有所减轻。与EHS+高DEX组比较,EHS+高DEX+YOH组大鼠血清TNF-α、IL-6、IL-1β、CK、MB及腓肠肌组织内ROS、NLRP3、caspase-1均升高(P<0.05),且HE染色和透射电镜显示病理损伤加重。与CN组比较,EHS组大鼠腓肠肌内ADRA2A表达明显下降(P<0.01),EHS+低DEX组和EHS+高DEX组大鼠肌肉中ADRA2A表达较EHS组明显升高(P<0.05)。结论DEX可通过激活ADRA2A减轻EHS诱导的RM,其机制可能与抑制ROS依赖性NLRP3/IL-1β炎性通路有关。

Objective To explore whether dexmedetomidine(DEX)can alleviate exertional heatstroke(EHS)-induced rhabdomyolysis(RM)in rats by activating adrenergicα_(2)receptors,and to explore its potential mechanism based on the reactive oxygen species(ROS)/NOD-like receptor protein 3(NLRP3)/interleukin-1β(IL-1β)pathway.Methods Thirty-six male Sprague-Dawley(SD)rats,after a 7-day acclimatization training,were randomly divided into six groups:control group(CN group),EHS group,low-dose DEX group(EHS+low DEX group),high-dose DEX group(EHS+high DEX group),DEX combined with yohimbine(YOH)group(EHS+high DEX+YOH group),and YOH group(EHS+YOH),with six rats in each group.Before modeling,EHS+high DEX+YOH group and EHS+YOH group were intraperitoneally injected with YOH at 1 mg/kg,while the other four groups were injected intraperitoneally with an equal dose of physiological saline(0.9%NS).During modeling,except for CN group,the other 5 groups of rats were subjected to heat exercise in a high-temperature and high-humidity chamber to construct an EHS rat model.After successful modeling,EHS+low DEX group was intraperitoneally injected with DEX at 10μg/kg,EHS+high DEX group and EHS+high DEX+YOH group were intraperitoneally injected with DEX at 30μg/kg,and CN group,EHS group and DEX+YOH group were intraperitoneally injected with equal doses of saline.After 6 h of observation,all rats were anesthetized,and their blood from the abdominal aorta and gastrocnemius muscle tissue were taken.Enzyme-linked immunosorbent assay(ELISA)was used to detect the expression levels of serum tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),IL-1βand myoglobin(MB)in rats;biochemical assay kit was used to measure the level of creatine kinase(CK)in rat serum;HE staining was used to observe pathological changes in rat gastrocnemius muscle tissues;transmission electron microscopy was used to observe ultrastructural changes in gastrocnemius muscle;2′,7′-dichlorofluorescent yellow diacetate(DCFH-DA)fluorescent probe was used to detect the level of reactive oxygen species(ROS);and Western blotting was performed to detect the expression levels of NOD-like receptors 3(NLRP3),aspartic protease-1(caspase-1)and adrenergicα_(2)A receptor(ADRA2A).Results Compared with CN group,the levels of serum IL-6,IL-1β,TNF-α,CK and MB in EHS group rats were significantly elevated(P<0.01).HE staining results revealed that the gastrocnemius muscle tissues of rats in EHS group had these pathological manifestations such as disarray of muscle fibrous structure,hemorrhage,edema,and infiltration of inflammatory cells.Transmission electron microscopy results showed that the ultrastructure of the gastrocnemius muscle in EHS group exhibited myofibroblasts with swelling and enlarging in size,cytoplasmic vacuolization,and mitochondria with obvious swelling,degranulation,and disappearance of double cristae.Compared with CN group,the expression levels of ROS,NLRP3,and caspase-1 in gastrocnemius of rats in EHS group significantly increased(P<0.01);Compared with EHS group,the levels of TNF-α,IL-6,IL-1β,CK,MB and the expression levels of ROS,NLRP3,caspase-1 in gastrocnemius tissue of rats in EHS+low DEX group and EHS+high DEX group decreased in a dose-dependent manner(P<0.05),and the pathological damage observed with HE staining and transmission electron microscopy was alleviated by DEX.After YOH pretreatment,compared with the EHS+high DEX group,the serum levels of TNF-α,IL-6,IL-1β,CK,MB and ROS,NLRP3 and caspase-1 in the gastrocnemius muscle tissue of rats in EHS+high DEX+YOH group relatively increased(P<0.05),and the pathological damage observed with HE staining and transmission electron microscopy was exacerbated.The expression of ADRA2A in gastrocnemius muscle of EHS group significantly decreased compared with CN group(P<0.01),and the expression of ADRA2A in muscle of rats in DES+low DEX group and EHS+high DEX group was higher than that in EHS group(P<0.05).Conclusions DEX can alleviate EHS-induced RM by activating ADRA2A,potentially through inhibiting the ROS-dependent NLRP3/IL-1βinflammatory pathway.