尾部悬吊对大鼠比目鱼肌梭内外肌纤维乙酰胆碱酯酶活性的影响

目的：研究尾部悬吊对大鼠比目鱼肌肌型和梭内外肌纤维胆碱酯酶活性的影响，探讨失重或模拟失重状态下肌肉萎缩和肌型转换的机制。方法：选用雌性大鼠，以尾部悬吊法模拟失重。实验分为尾部悬吊7d、14d、21d组及相应的同步饲养对照组。以琥珀酸脱氢酶（SDH）确定肌型，检测不同类型梭内外肌纤维乙酰胆碱酯酶（AChE）活性。结果：悬吊使肌肉萎缩、梭外肌纤维构成比发生改变，Ⅰ型纤维减少而Ⅱ型纤维增多。Ⅰ、Ⅱ型梭外肌纤维和梭内肌纤维乙酰胆碱酯酶活性均减弱。结论：模拟失重可导致神经-肌接头胆碱酯酶活性减弱。这种变化可能与运动神经元活动下降有关。

Acetylcholinesterase Activity in Soleus Muscle Intrafusal and Extrafusal Fibres in Tail Suspended Rats (in English)

Objective To explore the mechanisms involved in muscle atrophy and conversion of the fiber types induced by simulated weightlessness. Method Weightlessness was simulated by tail suspension of female rats. Intrafusal and extrafusal fibers of soleus muscles in the rat were examined histochemically for their activity of acetylcholinesterase (AChE) and succinic dehydrogenase (SDH) in 7 d,14 d,21 d tail suspended groups and control groups. Result Staining for succinic dehydrogenase showed that simulated weightlessness caused obvious atrophy and change in fiber type composition in soleus muscle, with decrease of the proportion of type I fiber and increase of type II fiber. Acetylcholinesterase activities of intrafusal and extrafusal fibers were both decreased significantly after 21 d tail suspension. Conclusion Simulated weightlessness could induce decrease of AChE activity in neuromuscular junctions, which might be linked with decrease in motor neuron activity.