阻力訓練與北冬蟲夏草攝食對大鼠骨骼肌IGF-1Ea、MGF和MSTN基因表現的影響

Abstract

前言：阻力訓練對於骨骼肌肌力發展基因表現的提升具有正面的效果，如果訓練同時增補具有活化肌力發展基因調控之增補物，可能提升負重運動表現。北冬蟲夏草 (Cordyceps militaris，以下簡稱蟲草) 中之蟲草素 (cordycepin) 可能誘發老鼠骨骼肌脂肪代謝基因表現，而對於肌力表現的調節因子如IGF-1Ea、MGF和myostatin (MSTN) 則尚無研究發表，如以動物模式輔以負重訓練，是否能如預期誘發肌力基因表現，需要進一步證實。目的：探討負重階梯攀爬訓練對攝食北冬蟲夏草大鼠骨骼肌肌力發展基因表現之影響。方法：將32隻7週齡SD大鼠分成4組：1.控制組 (C, n=8)：無處理。2.蟲草組 (CM, n=8)：灌食劑量200 mg/kg/d北冬蟲夏草粉劑。3.訓練組 (T, n=8)：負重訓練。4.蟲草訓練組 (TCM, n=8)：灌食劑量200 mg/kg/d北冬蟲夏草粉劑外加負重訓練。訓練組實施3次/週，共6週之負重階梯攀爬訓練，3週時各組犧牲4隻 (中測)，6週結束前各組實施負重測試後犧牲 (後測)。取腓腸肌 (快縮肌) 和比目魚肌 (慢縮肌) 實施半定量反轉錄-聚合酶鏈鎖反應 (semi-quantitative SqRT-PCR) 分析肌力發展調控基因之表現。統計以二因子變異數分析以及杜凱氏事後比較，顯著水準為p＜.05。結果：6週蟲草攝食和負重訓練對於體重和負重運動表現無顯著影響，但上調腓腸肌IGF-1Ea (後測) 和MGF (中測和後測) 基因，同時下調MSTN (中測和後測) 基因，且TCM在MSTN基因的下調具有協同效應 (synergistic effect)；對比目魚肌IGF-1Ea和MGF的調控影響不大，只有TCM下調MSTN (後測) 基因。結論：蟲草攝食和負重訓練對大鼠快縮肌群IGF-1Ea 和MGF基因具有正向調控效果，但對慢縮肌群的表現影響較小；無論在快縮或慢縮肌，蟲草攝食和負重訓練對MSTN基因的下調表現皆有顯著影響。Introduction：Recent studies have confirmed that resistance training can regulate the gene expression of muscle strength growth factors (MSGF). It has been demonstrated that Cordycepin of Cordyceps militaris (CM) can induce the fatty-acid metabolism gene in rat muscles , such as AMPK, PGC-1α and PPAR-δ. However, the effects on genes involved in muscle strength, such as the genes coding for IGF-1Ea、MGF and myostatin (MSTN) have not been examined. The effects of resistance training with CM supplementation to enhance muscle strength factor needs further investigation. Purpose: To investigate the effects of resistance training on MSGF gene expression in CM supplemented rats. Methods: Thirty-two 7-wk-old Sprague-Dawley rats were divided into 4 groups: 1.Control group (C, n=8): general feeding. 2. CM feeding group (CM, n=8): general feeding mixed with 200mg/kg/d CM extract. 3. Training group (T, n=8): loaded resistance training on climbing ladder. 4. Training with CM feeding group (TCM, n=8): general feeding mixed with 200mg/kg/d CM extract, and loaded resistance training on climbing ladder. A progressive exercise training protocol was adopted 3 days/week on T and TCM for 6 weeks. Four rats from each group were sacrificed after 3 weeks of experimentation as middle-testing. The others were sacrificed after the loading-test at the end of the experiment as final-testing. Semi-quantative RT-PCR was used to analyse the expression of muscle strength genes on gastrocnemius (fast twitch muscle) and soleus (slow twitch muscle). A 2-way ANOVA and Tukey’s test was used to compare the differences among the groups. Significant level was set at p<.05. Results: CM supplementation and resistance training for 6 weeks had no significantly effects on the body weight and the loading-test results. However, IGF-1Ea was up-regulated in gastrocnemius in the final-test, and MGF was up-regulated in both middle- and final-tests. MSTN was down-regulated in gastrocnemius in both middle- and final-tests. Resistance training and CM supplementation had synergistic effect on down-regulating the MSTN. In soleus, no significant effect on regulation of IGF-1Ea and MGF was observed, but down-regulation of MSTN was detected in TCM. Conclusions：CM supplementation and resistance training had positive effects on IGF-1Ea and MGF expressions, and negative effects on MSTN expressions of fast twitch muscles in rats, as well as minor effects on slow twitch muscles.