冷却治疗对劳力性热射病大鼠下丘脑AVPmRNA表达及蛋白表达的影响

Effects of Cooling Therapy on AVPmRNA Expression and AVP Protein Expression in Hypothalamus of Rats with Exertional Heat Stroke

目的:研究冷却治疗对劳力性热射病(Exertional heat stroke,EHS)大鼠抗利尿激素合成与释放的影响,探讨下丘脑AVPmRNA表达及蛋白表达在改善机体水代谢中的中枢激活作用。方法:雄性SD大鼠,随机分为常温对照组(NC)和高温运动组。高温运动组又分为高温运动即刻组(HE)、高温运动休息1组(HER1)、高温运动冷浸1组(HEC1)、高温运动休息2组(HER2)和高温运动冷浸2组(HEC2)。高温运动组大鼠在36℃高温环境中运动至力竭,并使直肠温度上升到约42℃,建立EHS大鼠模型。采用19℃冷水浸泡5min作为EHS大鼠冷却治疗方法。麻醉取血、取下丘脑,采用全自动血细胞分析仪测试Hct和Hb,ELISA法测定血清AVP,qRT-PCR法检测下丘脑AVPmRNA表达,Western Blot法检测下丘脑AVP蛋白表达。结果:热射病发作时,核心温度显著性上升;Hct显著性升高,而Hb无显著性变化;调节水代谢的AVP、AVPmRNA表达以及AVP蛋白表达非常显著性上调。冷浸后即刻及60min时,核心温度显著性下降;Hct、Hb及AVP无显著性变化。冷浸后即刻,HEC1组的AVPmRNA表达较HE组非常显著性下调,且与HER1组相比有非常显著性差异;HEC1组的AVP蛋白表达较HE组非常显著性下调。冷浸后60min时,HEC2组的AVPmRNA表达及蛋白表达较HE组均显著性下调。结论:冷浸可以快速降低热射病大鼠机体核心温度;使AVPmRNA表达及蛋白表达显著性下调,改善AVP在下丘脑的合成;但是冷浸对血清AVP和Hct没有显著性影响,不能明显改善AVP在下丘脑的释放以及改善机体脱水状况。

Objectives:Through investigating the effect of cooling therapy on the synthesis and release of arginine vasopressin in rats with exertional heat stroke, explore the central activation of AVP mRNA expression and AVP protein expression in hypothalamus in improving water metabolism.Methods:Male Sprague Dawley rats were randomly divided into normal temperature control group(NC)and high temperature exercise group.The high temperature exercise group was divided into instant group(HE),rest group 1(HER1),cold water immersion group 1(HEC1),rest group 2(HER2)and cold water immersion group 2(HEC2).The high temperature exercise group is EHS model group.The rat model of EHS was established by exercising to exhaustion and raising rectal temperature to about 42℃ in the high temperature environment of 36℃.Cold water immersion for 5 min at 19℃ was used as cooling treatment for EHS rats.After anesthesia,blood and hypothalamus were taken.Hematocrit and hemoglobin were measured by automatic blood cell analyzer.Arginine vasopressin in serum was measured by Enzyme-Linked Immunosorbnent Assay method.Quantitative Real Time Polymerase Chain Reaction method was used for testing AVP mRNA expression in hypothalamus.AVP protein expression in hypothalamus was detected by Western Blot.Results:When EHS occurs,core temperature rised significantly,Hematocrit level increased significantly,while Hemoglobin showed no significant change.To regulate water metabolism,AVP,AVPmRNA expression and AVP protein expression were significantly up-regulated.Immediately and 60 minutes after cold water immersion,core temperature decreased significantly,while Hct,Hb and AVP did not change significantly.Immediately after cold water immersion,AVP mRNA expression in HEC1 group was significantly down-regulated than that in HE group,and there was a significant difference between HER1 group and HEC1 group;AVP protein expression in HEC1 group was significantly down-regulated than that in HE group.60 minutes after cold immersion,AVP mRNA expression and AVP protein expression in HEC2 group were significantly down-regulated than those in HE group.Conclusions:Cold water immersion can quickly reduce the core temperature of EHS rats;significantly down-regulated AVP mRNA expression and AVP protein expression to improve the synthesis of AVP in the hypothalamus;but it has no significant effect on AVP and Hct to improve the release of AVP in the hypothalamus and dehydration status in the body.