【作者】 刘利丹；

【导师】 赵书芬；

【作者基本信息】 中国医科大学 ， 生理学， 2005， 硕士

【摘要】 前言 生物体在生理或病理情况下致体温升高时通常不会超过41℃,此现象称为热限。目前的研究显示,体内存在有内源性解热物质如精氨酸加压素(arginine vasopressin,AVP)和α-黑色素细胞刺激素(α-melanocyte stimulating hormone,α-MSH)等,但有关热限的生物学机制还有许多不明之处。 当组织、细胞或机体暴露于高温时,温热刺激能够诱导细胞产生热休克蛋白质(heat shock proteins,HSPs),此过程称为热休克应答(heat shock reaction,HSR)。大量研究证明HSP70在细胞保护,炎症反应和自身免疫等生理病理过程中起重要作用。 本实验观察通过热应激诱导HSP70表达对肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)性发热的影响,并检测下丘脑中环磷酸腺苷酸(cyclic AMP,cAMP)含量的变化情况,以探索HSP70是否参与热限作用及可能的机制。 材料与方法 1.动物和手术 SD大鼠,雄性,体重220-250g,由中国医科大学动物中心提供。室温(22±2)℃,单笼饲养,自由进食水。在盐酸氯氨酮和盐酸甲苯噻嗪的联合麻醉下,参照大鼠脑图谱,用立体定位仪向一侧POA区插入一规格为23号的不锈钢管,用牙科水泥固定。大鼠单笼饲养,常规喂养一周后实验。测量体温:将温度探头插入直肠6cm处,待数字稳定后读数,以给药前1小时测得的三次体温的平均值为大鼠给药前基础体温,然后在注药后记录大鼠体温。实验结束后检查插管位置,舍掉插管位置不正确的数据。更多还原

【Abstract】 INTRODUCTIONBody temperature of organisms can’t exceed 41 ℃ in physiological or pathological condition. This phenomenon is called febrile ceiling. Present studies have demonstrated that there are endogenous antipyretic in organisms such as ar-ginine vasopressin ( AVP) andα - melanocyte stimulating hormone ( α - MSH). But biological mechanism of febrile ceiling is still unclear.Exposured to high temperature, cells, tissues or bodies can be induced to produce heat shock proteins (HSPs). This process is called heat shock reaction ( HSR). Several studies have demonstrated that HSP70 has an important role in cell protection, inflammatory reaction and immunization.This study observed the effects of HSP70 induced by heat stress on TNF -a - induced fever,and measured the change of cAMP level in hypothalamus, so as to explore whether HSP70 participates febrile ceiling and the possible mechanism.MATERIALS AND METHODS1. Animals and surgeryMale Sprague - Dawley rats, weighting 220 - 250g, purchased from China Medical University Animal Center, were housed individually. Room temperature was kept at (22 ± 2) ℃ Food and water were available ad libitum. Under intraperitoneal anesthesia (ketamine hydrochloride and xylazine) , a 23 bugle stainless steel was implanted into POA area by stereotaxic apparatus according to the rat brain atlas, and the cannula was anchored with dental acrylic. Rats were in-dividuaUy housed a week before experiments. Examine body temperature: digital thermometer probe was inserted 6 centimeters in rats’rectum. Value was recorded after stabilization. Mean of three values 1 hour before administration was taken as baseline of pre - handling. Record body temperature of rats after administration. When the experiment was over, cannula’s positions were checked to discard incorrect ones.2. The expression of HSP70 in rat hypothalamus tissue assay Hypothalamus tissue was homogenated, centrifuged and the supernatantswere used to measure the expression of HSP70 by Western blotting assay3. cAMP level assayRat brain tissue was put into liquid nitrogen. 50 mg hypothalamus tissue was weighted, homogenate, centrifuged and assay concentration of cAMP with radioimmunoassay.4. Statistical analysisResults were presented as mean ± SD ( x ± s). Changes in body temperature were presented and analyzed with AT and thermo - response index. Data were analyzed using t - test.RESULTS1. The maximum expression of HSP70 in hypothalamus was attained at 12h after heat stress.2. In the febrile rats induced by TNF - α, cAMP level in hypothalamus was significantly higher.3. Injection of TNF - α 12h after heat stress could inhibit febrile effects, and the content of cAMP in hypothalamus was lower than TNF - a group.DISSCUSSIONIn this study, POA administration of TNF - α induced increase of body temperature, and at the same time cAMP level in hypothalamus was significantly higher than control group. This was consistent with previous report . That dem-更多还原