Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types
Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types
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DOI：
10.1113/jphysiol.2007.127639
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发表时间：
2007-08-01
影响因子：
5.5
通讯作者：
Schjerling, P.
中科院分区：
文献类型：
--
作者：
Heinemeier, K. M.;Olesen, J. L.;Schjerling, P.
急性运动诱导肌腱和肌肉中的胶原蛋白合成，表明肌肉-肌腱单位的结缔组织中的适应性反应。然而，这种适应的机制，可能涉及胶原诱导生长因子（如转化生长因子-β-1（TGF-β-1）），以及与胶原加工相关的酶，尚不清楚。此外，尚未研究特定收缩类型对胶原调节的可能差异效应。通过刺激坐骨神经，使雌性Sprague-Dawley大鼠的内侧腓肠肌经受4天的同心、离心或等长训练（每组n = 7-9）。在最后一次训练后24 h从内侧腓肠肌和跟腱组织中提取RNA，并通过北方印迹和/或实时PCR测量胶原蛋白I和III、TGF-β 1、结缔组织生长因子（CTGF）、赖氨酰氧化酶（LOX）、金属蛋白酶（MMP-2和-9）及其抑制剂（TIMP-1和2）的mRNA水平。在肌腱中，TGF-β-1和I型和III型胶原蛋白（但不包括CTGF）的表达在所有类型的训练中都有所增加。类似地，参与胶原蛋白加工的酶/因子在肌腱中被诱导，特别是LOX（高达37倍），这可能表明肌腱胶原蛋白交联的负荷诱导的增加。在骨骼肌中，观察到类似的基因表达调控，但与肌腱反应相反，离心训练的效果显着大于同心训练对几个转录本表达的影响。总之，该研究支持TGF-β-1参与肌肉-肌腱单元中负荷诱导的胶原蛋白合成，重要的是，它表明肌肉组织比肌腱对特定的机械刺激更敏感。
Acute exercise induces collagen synthesis in both tendon and muscle, indicating an adaptive response in the connective tissue of the muscle-tendon unit. However, the mechanisms of this adaptation, potentially involving collagen-inducing growth factors (such as transforming growth factor-beta-1 (TGF-beta-1)), as well as enzymes related to collagen processing, are not clear. Furthermore, possible differential effects of specific contraction types on collagen regulation have not been investigated. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve. RNA was extracted from medial gastrocnernius and Achilles tendon tissue 24 h after the last training bout, and mRNA levels for collagens I and III, TGF-beta-1, connective tissue growth factor (CTGF), lysyl oxidase (LOX), metalloproteinases (MMP-2 and -9) and their inhibitors (TIMP-1 and 2) were measured by Northern blotting and/or real-time PCR. In tendon, expression of TGF-beta-1 and collagens I and III (but not CTGF) increased in response to all types of training. Similarly, enzymes/factors involved in collagen processing were induced in tendon, especially LOX (up to 37-fold), which could indicate a loading-induced increase in cross-linking of tendon collagen. In skeletal muscle, a similar regulation of gene expression was observed, but in contrast to the tendon response, the effect of eccentric training was significantly greater than the effect of concentric training on the expression of several transcripts. In conclusion, the study supports an involvement of TGF-beta-1 in loading-induced collagen synthesis in the muscle-tendon unit and importantly, it indicates that muscle tissue is more sensitive than tendon to the specific mechanical stimulus.