不同季节对正常和吊尾达乌尔黄鼠的肌纤维比例的影响
首发时间:2013-04-02
摘要:目的:研究不同季节正常达乌儿黄鼠(Spermophilus dauricus)与吊尾黄鼠趾长伸肌(EDL)的肌肉湿重、肌纤维横截面积及肌纤维类型的变化,探讨非冬眠状态下,后肢废用(吊尾)对黄鼠EDL的影响。 方法:选取黄鼠42只,按体重配对原则,分为夏季组,秋季组,冬眠组,冬季活跃组,夏季吊尾组,秋季吊尾组,冬季吊尾组(活跃状态),每组6只。测量其EDL的湿重(wet weightiness)及肌重体重比(mg/g),以Ca2+-ATPase酸法测定EDL的mATP酶活性,计算?型和П型肌纤维的比例,测定EDL中?型和П型肌纤维的横截面积。 结果:(1)夏季,秋季,冬季(冬眠)正常黄鼠的趾长伸肌肌重体重比无显著变化。(2)三个季节正常黄鼠趾长伸肌肌纤维横截面积无显著性差异。(3)与夏季、冬季正常黄鼠相比,秋季正常黄鼠趾长伸肌I型肌纤维比例显著减少(p<0.01)。(4)与正常组相比,夏季,秋季吊尾组黄鼠的体重无显著性变化,冬季吊尾组黄鼠的体重下降了9.59%(p<0.01)。(5)与正常组相比,夏季吊尾组黄鼠EDL湿重、肌重体重无显著差异;秋季,冬季吊尾组黄鼠EDL湿重均明显降低(p<0.05),但EDL肌重体重比均无显著性变化。(6)与正常组相比,夏季、秋季、冬季吊尾组黄鼠EDL的I、II型肌纤维比例无显著性差异,即不同季节吊尾黄鼠肌纤维类型未发生转化。(7)与正常组相比,夏季吊尾组黄鼠EDL中I、II型肌纤维横截面分别减少了19.12%和19.97%(p<0.05);秋季吊尾组黄鼠EDL中I、II型肌纤维横截面分别减少了24.11%和21.51%(p<0.05);冬季吊尾组黄鼠EDL中I、II型肌纤维横截面分别减少了:24.99%、27.39%(p<0.05)。 结论:总之,黄鼠在冬眠过程中有防止骨骼肌萎缩的保护机制,这种机制在非冬眠季节不会被激活。
关键词: 动物学 趾长伸肌 肌纤维横截面积 肌纤维比例 冬眠 吊尾
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Seasonal effects on muscle fiber type distribution in unrestrained vs. tail-suspended ground squirrels
Abstract:Aim: We investigated extensor digitorum longus (EDL) changes with different seasons in normal (unrestrained) and tail-suspended daurian ground squirrels. Methods: 42 ground squirrels were matched for body size and randomly assigned to seven groups of six animals each: Summer-control, Autumn-control, Winter-control (Hibernation), Winter-active, Summer-TS (Tail suspension), Autumn-TS and Winter-TS. Muscle weight, muscle-to-body mass ratio, fiber cross sectional area (CSA, video analysis) and fiber type distribution (m-ATPase staining) were determined in specimens from all experimental animals. Results: (1) Muscle-to-body mass ratios and fiber CSA in EDL were similar in all control groups (Summer-control, Autumn-control and Hibernation) while the percentage of type I fibers was lower in the Autumn-control animals (p<0.01). (2) Compared to controls, body weight was 9.6% lower in Winter-TS (p<0.01) but not Summer-TS and Autumn-TS, respectively. (3) Muscle wet mass was lower in Autumn-TS and Winter-TS than in controls (p<0.05). (4) Neither muscle-to-body mass ratio nor fiber type distribution was different between control and TS groups. (5) In Summer-TS, fiber CSA was lower than in controls (type I -19.1%, type II -20.0%). Similarly, the numbers were -24.1% and -21.5% for Autumn-TS and -25.0% and -27.4% for Winter-TS, respectively. Conclusion: The unrestrained ground squirrels only showed lower EDL type I fiber percentage in the autumn group; after tail suspension, EDL fibers were slightly atrophied throughout seasons, indicated by decreased fiber CSA. In summary, ground squirrels have a protective mechanism against muscle atrophy during hibernation, and this mechanism is not triggered under non-hibernation (i.e. tail-suspension) conditions.
Keywords: zoology Extensor digitorum longus Fiber cross-sectional area Fiber type distribution Hibernation Tail suspension
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不同季节对正常和吊尾达乌尔黄鼠的肌纤维比例的影响
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