雄激素拮抗糖皮质激素引起的大鼠骨骼肌萎缩的作用与机制研究

发布时间：2018-01-10 22:30

本文关键词：雄激素拮抗糖皮质激素引起的大鼠骨骼肌萎缩的作用与机制研究　出处：《中国人民解放军军医进修学院》2007年博士论文　论文类型：学位论文

【摘要】： 目的：糖皮质激素是引起骨骼肌萎缩的重要介质。多种原因如严重烧伤、脓毒症等均可引起糖皮质激素大量释放，导致骨骼肌萎缩。业已明确，骨骼肌萎缩对机体危害极大，如导致机体免疫力下降、感染率增加、患者活动延迟等，这都严重影响了患者的生存质量和疾病预后。因此，预防和治疗糖皮质激素引起的骨骼肌萎缩具有重要的临床意义。研究发现，雄激素作为一种促合成代谢激素可能具有拮抗糖皮质激素引起的骨骼肌萎缩的作用，但其作用仍不明确，机制也尚未阐明。该研究通过动物实验旨在阐明雄激素对糖皮质激素引起的大鼠骨骼肌萎缩(特别是骨骼肌蛋白高分解代谢)的拮抗作用，并探讨与骨骼肌蛋白代谢密切相关的IGF-1信号传导通路在雄激素拮抗糖皮质激素引起的骨骼肌萎缩中的作用。方法：雌性SD大鼠160只，随机分为四组：(1)对照组注射生理盐水与香油(分别为地塞米松与睾酮的溶剂)；(2)地塞米松组注射地塞米松与香油；(3)睾酮组注射生理盐水与睾酮；(4)睾酮+地塞米松组注射地塞米松与睾酮。分别在开始注射地塞米松或生理盐水后1天、3天、5天、10天麻醉后处死动物，每个时间点10只动物，留取肌肉(腓肠肌、趾长伸肌、比目鱼肌、胫骨前肌、跖肌)、血浆与尿标本。实验过程中每日称量体重，，实验结束时称量肌肉重量。肌纤维横断面在HE染色或免疫组化染色之后采用图像采集与分析系统计算横断面面积；骨骼肌中与尿中3-甲基组氨酸(3-MH)采用高效液相色谱分析技术进行检测；血浆睾酮水平采用放射免疫学方法进行检测；血浆IGF-1蛋白水平采用酶联免疫吸附试验(ELISA)进行检测；骨骼肌中蛋白激酶B(Akt)、糖原合成酶激酶-3β(GSK-3β)、70kDa核糖体蛋白S6激酶(p70S6K)的活性采用Western blot方法进行检测；骨骼肌中胰岛素样生长因子-1(IGF-1)与二种泛素蛋白连接酶muscle atrophy F-box(MAFbx)、muscle RING finger-1(MuRF1)mRNA的表达采用定量PCR方法进行检测。结果：1．地塞米松使大鼠体重和多种肌肉重量进行性降低，并使多种肌肉的肌纤维横断面面积减小。睾酮可以部分拮抗地塞米松引起的大鼠体重、肌肉重量的降低和肌纤维横断面面积的减小。2．睾酮可以部分拮抗地塞米松引起的大鼠腓肠肌中3-MH含量和尿中3-MH释放量的增加。3．睾酮可以拮抗地塞米松引起的大鼠腓肠肌中IGF-1 mRNA表达的下降，但不能拮抗地塞米松引起的大鼠血浆中IGF-1蛋白水平的下降。4．地塞米松可以明显降低大鼠腓肠肌中Akt、p70S6K的活性；睾酮可以增加腓肠肌中Akt、p70S6K的活性，降低GSK-3p的活性，并可以部分拮抗地塞米松对Akt、p70S6K活性的影响。5．地塞米松可使大鼠腓肠肌中泛素蛋白连接酶MuRF1与MAFbx mRNA表达明显上调，而睾酮并不能拮抗地塞米松对这二种基因表达的影响。结论：1．雄激素可以减轻糖皮质激素引起的骨骼肌萎缩。2．雄激素可以部分拮抗糖皮质激素引起的骨骼肌蛋白高分解代谢。3．雄激素拮抗糖皮质激素致骨骼肌萎缩的作用至少部分是通过雄激素对IGF-1信号通路中与骨骼肌蛋白合成代谢有关的信号分子(Akt、GSK-3β、p70S6K)的调控实现的。4．雄激素拮抗糖皮质激素引起的骨骼肌蛋白高分解代谢的作用可能并不是通过对IGF-1下游与骨骼肌蛋白分解代谢有关的泛素蛋白连接酶MuRF1与MAFbx的调控实现的。
[Abstract]:Objective: glucocorticoids are important mediators to cause muscle atrophy. A variety of reasons such as severe burns, sepsis and other induce glucocorticoid release, leading to skeletal muscle atrophy. Clear, skeletal muscle atrophy and does great harm to the body, such as lead to decreased immunity, infection rate increased in patients with active delay, this have a serious impact on the quality of life of patients and the prognosis of the disease. Therefore, prevention and treatment of glucocorticoid induced skeletal muscle atrophy has important clinical significance. The study found that androgen as an anabolic hormone can antagonize glucocorticoid induced atrophy of skeletal muscle function, but its function is still not clear. The mechanism also has not yet been elucidated. The study by animal experiments aimed at elucidating androgen on glucocorticoid induced rat skeletal muscle atrophy (especially skeletal muscle protein catabolism) antagonist The effect of IGF-1 signaling pathway, which is closely related to skeletal muscle protein metabolism, is explored in the action of androgen antagonism on skeletal muscle atrophy induced by glucocorticoid.
Methods: 160 female SD rats were randomly divided into four groups: (1) control group were injected with saline and sesame oil (respectively, dexamethasone and testosterone solvent); (2) dexamethasone injection of dexamethasone and sesame oil; (3) testosterone group were injected with saline and testosterone; (4) testosterone + dexamethasone injection dexamethasone and testosterone. Respectively before injection of dexamethasone or saline after 1 days, 3 days, 5 days, 10 days after anesthesia were sacrificed animal, 10 rats at each time point for animal muscle (gastrocnemius muscle, extensor digitorum longus and soleus, tibialis anterior muscle, plantaris muscle), plasma and urine samples experiments. In the process of daily weighing, weighing at the end of the experiment. The muscle fiber cross-sectional muscle weight after HE staining and immunohistochemical staining using image acquisition and analysis system to calculate the cross-sectional area; in skeletal muscle and urine 3- methylhistidine (3-MH) analysis by HPLC To detect; plasma testosterone levels were detected by radioimmunoassay method; plasma levels of IGF-1 protein by enzyme-linked immunosorbent assay (ELISA) were detected; protein kinase B in skeletal muscle (Akt), glycogen synthase kinase -3 beta (GSK-3 beta), 70kDa ribosomal protein S6 kinase (p70S6K) activity by Western blot method detection; insulin-like growth factor -1 in skeletal muscle (IGF-1) and two muscle atrophy F-box ubiquitin protein ligase (MAFbx), muscle RING finger-1 (MuRF1) mRNA expression was detected by quantitative PCR method.
Results: 1. dexamethasone make weight and muscle weights of rats were decreased, and the muscle fiber CSA decreased. Testosterone can cause weight part of dexamethasone treated rats, reduce muscle weight and muscle fiber cross-sectional area decreased.2. testosterone may cause a part of dexamethasone in gastrocnemius muscles of rats 3-MH content the release amount of 3-MH in urine and.3. increased testosterone can express IGF-1 mRNA antagonist induced by dexamethasone in gastrocnemius muscles of rats decreased, but the level of IGF-1 protein caused not dexamethasone in rat plasma by.4. dexamethasone can significantly reduce rat gastrocnemius in Akt, the activity of p70S6K; testosterone can increase the gastrocnemius in Akt and the activity of p70S6K, decreased the activity of GSK-3p, and can antagonize the effects of dexamethasone on Akt, dexamethasone p70S6K activity can influence.5. The expression of ubiquitin protein ligase MuRF1 and MAFbx mRNA in the gastrocnemius muscle of rats was obviously up-regulated, but testosterone did not antagonize the effect of dexamethasone on the expression of these two genes.
Conclusion: 1. can reduce androgen induced by glucocorticoid in skeletal muscle atrophy.2. androgen can partially prevent glucocorticoid induced skeletal muscle protein catabolism of androgen antagonist.3. glucocorticoid induced by skeletal muscle atrophy, at least in part by signaling molecules associated with androgen on skeletal muscle protein synthesis and metabolism in the IGF-1 signaling pathway (Akt GSK-3, beta, p70S6K).4. androgen antagonist of glucocorticoid induced regulation of skeletal muscle protein catabolism may not be achieved through the regulation of IGF-1 downstream and skeletal muscle protein catabolism of the ubiquitin protein ligase MuRF1 and MAFbx.

【学位授予单位】：中国人民解放军军医进修学院
【学位级别】：博士
【学位授予年份】：2007
【分类号】：R363

【引证文献】