單次運動對間歇性低氧誘發心肌微管相關蛋白1輕鏈3-II的影響

Effects of a single bout of exercise on intermittent hypoxia-induced microtubule-associated protein 1 light chain 3-II expression in rat left ventricle

探討運動後不同休息時間對間歇性低氧誘發心肌自噬反應的影響。方法：將8週齡Sprague-Dawley 雄性大鼠，隨機分成控制組 （control, CON）、運動組 （exercise,EXE）、間歇性低氧曝露組 （intermittent hypoxia, IH）、空氣曝露組 （room air, RA）、運動後1 （post-exercise 1 h, PE1h） 及3 小時 （PE3h） 合併RA 或IH 組。大鼠給予單次持續8 小時IH （氧氣濃度下降至2~6 %約1-2 秒/75 秒），單次運動方式以24 m/min 速度、2% 坡度之強度在跑步機上跑步60 min。動物犧牲後，檢測左心室心肌肝醣、自噬反應相關蛋白及粒腺體功能相關mRNA 表現量。結果：運動後心肌細胞微管相關蛋白1 輕鏈3-II（microtubule-associated protein 1 light chain 3-II, LC3-II） /LC3-I 表現量、肝醣含量下降 （p< .05），p62 表現量沒有變化 （p > .05）。IH 對心肌p62 表現量沒有影響 （p > .05），與RA比較，IH 之LC3-II/LC3-I、核內呼吸因子1 和2 （nuclear respiratory factor 1 and 2, NRF-1和NRF-2） mRNA 表現量上升 （p < .05）。與IH 比較，PE1h+RA、PE3h+RA 及PE3h+IH各組LC3-II/LC3-I 及NRF-1 和NRF-2 mRNA 表現量均下降 （p < .05），雖PE1h+IH 之NRF-1 和NRF-2 mRNA 表現量下降 （p > .05），但LC3-II/LC3-I 表現量沒有改變 （p > .05）。結論：IH 曝露前3 小時從事運動，可避免IH 造成心肌LC3-II/LC3-I 表現量上升的現象。

Investigating the effects of different time intervals after exercise on intermittent hypoxia (IH)-induced autophagy in rat left ventricle. Methods: Eight-week-old male Sprague-Dawley rats were randomly assigned to control (CON), exercise (EXE), IH, room air exposure (RA), post-exercise 1 and 3 h combined with RA (PE1h + RA and PE3h + RA) or IH (PE1h + IH and PE3h + IH) groups. Rats were exposed to a single IH bout (2% - 6% O2 for 1-2 sec/75 sec) for 8 h and a single exercise bout on treadmill (24 m/min, 2% grade) for 60 min. Myocardial glycogen, autophagy-related proteins and mitochondrial-related mRNAs were determined after euthanisation. Results: Immediately after exercise, microtubule-associated protein 1 light chain 3-II (LC3-II)/LC3-I protein levels decreased (p < .05) but p62 levels did not alter (p > .05). As compared with RA, IH did not alter p62 levels but did increase LC3-II/LC3-I protein and nuclear respiratory factor 1 and 2 (NRF-1 and NRF-2) mRN A levels (p < .05). Compared with IH, significantly lower LC3-II/LC3-I protein and NRF-1 and NRF2 mRNA levels were found in PE1h + RA, PE3h + RA and PE3h + IH (p < .05). NRF-1 and NRF-2 mRNA levels were lower in PE1h+IH than in IH (p < .05), although LC-II/LC3-I levels were similar (p > .05). Conclusion:Exercise at 3 h before IH exposure could prevent IH-induced increased myocardial LC3-II/LC3-I levels.