后肢去负荷对大鼠比目鱼肌肌梭神经末梢的影响

Influence of Hindlimb-unloading on the Morphology of Nerve Endings in Soleus Muscle Spindles.

目的观察后肢去负荷对大鼠比目鱼肌肌梭神经末梢形态的影响。方法采用大鼠尾部悬吊法建立后肢去负荷动物模型,按体重配对原则随机将大鼠分为5组,即后肢去负荷7 d组1、4 d组、21 d组、28 d组和正常同步对照组。分离单一肌梭,采用快速的银染方法,光镜下对肌梭的形态及其神经末梢进行观察并拍照。结果正常对照组大鼠比目鱼肌肌梭形态完整,包囊光滑,边缘清晰,赤道部和两极部神经末梢清晰完整,梭内肌横纹亦清晰可见;后肢去负荷7 d后肌梭神经末梢与对照组相比未见明显异常;后肢去负荷14 d后肌梭赤道部神经纤维淡染,末梢出现轻微的溶解,断裂;后肢去负荷21 d后肌梭内神经末梢密度明显减少,肌梭赤道部神经纤维断裂,溶解;后肢去负荷28 d后肌梭神经末梢呈严重的退行性改变,出现断裂,迂曲。结论后肢去负荷可引起肌梭赤道部与极部神经末梢的退行性改变,且随去负荷时间的延长而加重。

Objective To investigate changes induced by hindlimb unloading in morphology of nerve endings in soleus muscle spindles. Method Hindlimb unloading model was simulated by tail suspension in female rats. Fast silver-staining was used to observe morphology of nerve endings of single muscle spindle in 7 d,14 d,21 d and 28 d tail-suspended and control rats. Result Nerve endings of muscle spindles in control rats were intact and clear,and there was no obvious abnormality in single soleus muscle spindle of 7 d tail-suspended rats. Slight fragmentation of nerve endings was observed in Equatorial Region of soleus muscle spindle in 14 d tail-suspended rats,while reduction in density and disruption of nerve endings were observed in soleus muscle spindle in 21 d tail-suspended rats. Serious degeneration and distortion of nerve endings were found in soleus muscle spindle in 28 d tail-suspended rats. Conclusion Hindlimb-unloading can induce time-related changes in morphology of nerve endings of muscle spindle in rats soleus muscle.