Adaptive effects of the β2-agonist clenbuterol on expression of β2-adrenoceptor mRNA in rat fast-twitch fiber-rich muscles
Adaptive effects of the β2-agonist clenbuterol on expression of β2-adrenoceptor mRNA in rat fast-twitch fiber-rich muscles
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DOI：
10.1007/s12576-009-0075-1
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发表时间：
2010-03-01
影响因子：
2.3
通讯作者：
Imaizumi, Kazuhiko
中科院分区：
文献类型：
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作者：
Sato, Shogo;Nomura, Sachiko;Imaizumi, Kazuhiko
研究表明，给予 β(2) 激动剂克仑特罗可降低大鼠富含快肌纤维（趾长伸肌，EDL）的 β(2) 肾上腺素受体 (AR) mRNA 表达，而不会改变富含慢肌纤维（比目鱼肌，SOL）的肌肉。然而，克伦特罗诱导的肌纤维类型依赖性β(2)-AR mRNA表达下调的调节机制仍不清楚。因此，通过实时逆转录聚合酶链反应研究了给予克伦特罗（1.0 mg/kg体重/天，持续10天，皮下）的大鼠快肌纤维丰富（EDL和跖肌，PLA）和慢肌纤维丰富（SOL）肌肉中β（2）-AR mRNA水平的转录和转录后调节因子的mRNA表达。给予克伦特罗可显着降低 EDL 和 PLA 肌肉中 β(2)-AR mRNA 的表达，而不会改变 SOL 肌肉中的 mRNA 表达。给予克仑特罗还显着降低了 EDL 和 PLA 肌肉中转录调节因子（糖皮质激素受体）和 mRNA 稳定因子（Hu 抗原 R）的 mRNA 表达，而不改变 SOL 肌肉中的 mRNA 表达。这些结果表明，克仑特罗对β(2)-AR mRNA表达的肌纤维类型依赖性影响与β(2)-AR mRNA水平的转录和转录后调节因子的mRNA表达下调密切相关。
Administration of the beta(2)-agonist clenbuterol has been shown to reduce the expression of beta(2)-adrenoceptor (AR) mRNA in fast-twitch fiber-rich (extensor digitorum longus, EDL) muscle without changing that in slow-twitch fiber-rich (soleus, SOL) muscle in rats. However, the regulatory mechanism for muscle fiber type-dependent down-regulation of the expression of beta(2)-AR mRNA induced by clenbuterol is still unclear. Therefore, mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels in fast-twitch fiber-rich (EDL and plantaris, PLA) and slow-twitch fiber-rich (SOL) muscles in clenbuterol-administered (1.0 mg/kg body weight/day for 10 days, subcutaneous) rats was studied by real-time reverse transcription-polymerase chain reaction. Administration of clenbuterol significantly reduced expression of beta(2)-AR mRNA in EDL and PLA muscles without changing that in SOL muscle. Administration of clenbuterol also significantly reduced the mRNA expression of transcriptional regulatory factor (glucocorticoid receptor) and mRNA stabilizing factor (Hu antigen R) in EDL and PLA muscles without changing those in SOL muscle. These results suggest that muscle fiber type-dependent effects of clenbuterol on expression of beta(2)-AR mRNA are closely related to the down-regulation of mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels.