Du Fangying, Wang Jun, Gao Yunfang, Wang Huiping, Wang Qi, Jiang Shanfeng, Goswami Nandu
Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Ministry of Education, Xi'an, China.
Aviat Space Environ Med. 2011 Jul;82(7):689-93. doi: 10.3357/asem.2984.2011.
This study aimed to examine the effects of a new hind limb disuse model on the morphology and fiber type distribution of the extensor digitorum longus (EDL) of rats. Quicker onset of disuse atrophy would reduce the amount of time the animals have to be subjected to tail suspension.
The new hind limb disuse mode was achieved by tail suspension (TS) and one hind limb fixed by plaster-casting (tail suspension-immobilization, TS+Im). There were 42 female Sprague-Dawley rats randomly divided into 7 groups (6 rats in each group) and exposed to the conditions for 0-6 wk, respectively. The cross-sectional area (CSA) and the types of muscle fiber of the rats' EDL were measured and classified by histochemical staining.
The decrease of EDL's CSA caused by TS+Im was more obvious (significant change was observed after 4 wk and Type I fiber's CSA decreased 27.3% after 6 wk) than that caused by TS only (significant change occurred after 6 wk and Type I fiber's CSA diminished 18.01% at that time). TS lead to the transition of Type IIB fibers to Type I and IIA fibers while TS+Im led to Type I and IIA fibers getting converted to Type IIB fibers.
When compared to TS only, TS+Im caused faster and greater reduction of the EDL's CSA in rats. TS+Im can also lead to a shift from oxidative to glycolytic metabolism of the EDL muscle fiber. Tail suspension-immobilization is a new hind limb disuse model for the EDL and may be more effective.
本研究旨在探讨一种新的后肢废用模型对大鼠趾长伸肌（EDL）形态及纤维类型分布的影响。废用性萎缩更快出现将减少动物接受尾部悬吊的时间。
通过尾部悬吊（TS）和用石膏固定一条后肢（尾部悬吊-固定，TS+Im）建立新的后肢废用模型。将42只雌性Sprague-Dawley大鼠随机分为7组（每组6只），分别暴露于相应条件0至6周。通过组织化学染色测量并分类大鼠EDL的横截面积（CSA）和肌纤维类型。
TS+Im导致的EDL的CSA降低比仅TS导致的更明显（4周后观察到显著变化，6周后I型纤维的CSA降低27.3%）（仅TS在6周后出现显著变化，此时I型纤维的CSA减少18.01%）。TS导致IIB型纤维向I型和IIA型纤维转变，而TS+Im导致I型和IIA型纤维转变为IIB型纤维。
与仅TS相比，TS+Im导致大鼠EDL的CSA更快且更大程度地降低。TS+Im还可导致EDL肌纤维从氧化代谢向糖酵解代谢转变。尾部悬吊-固定是一种用于EDL的新的后肢废用模型，可能更有效。
