肌肉游离移植后运动终板区乙酰胆碱能受体分布的变化

Changes of acetylcholine receptor distribution at the motor end-plates following muscle transfer

目的探讨吻合血管神经的肌肉移植后运动终板区乙酰胆碱能受体(acetylcholinereceptor,AChR)分布的变化。方法建立Wistar大鼠股薄肌原位移植模型,以荧光染色激光共聚焦显微镜观察和放射性碘标记γ记数器测定γ放射线强度,对吻合血管神经的肌肉移植前和移植后的不同时间运动终板区AChR分布的变化进行定性和定量研究。结果①正常运动终板区AChR二维和三维图像为连续光滑、精细分支的网络状结构。移植术后早期终板区呈弥散模糊的片状荧光图像;随失神经时间延长,呈现不规则间断的图像,亮度减弱。术后5周时,新生的运动终板图像为不规则的斑点,以后,斑点逐渐面积增大、数量增多,相互间衔接形成分支样立体结构。到术后30周时,新生运动终板的图像仍达不到移植前的精细程度。②AChR数量从最初的失神经支配期急剧下降,到神经再支配初期短时间内骤然上升,随后平缓上升形成平台。但术后30周时,AChR的数量仍低于对照组的水平。相反,终板外区AChR量由失神经支配初期的明显增多到神经再支配早期的快速降低直至基本消失。结论吻合血管神经的肌肉移植后运动终板区AChR受体分布和数量不能恢复到移植前的水平。

Objective To investigate the changes of acetylcholine receptor (AChR) distribution at the neuromuscular junction (i.e. motor end-plate) following the free neurovascular muscle transfer. Methods AChR in the gracilis muscle of the Wistar rat following free neurovascular transfer were labeled by fluorescent α-bungarotoxin and radioiodinated α-bungarotoxin. Then confocal microscope and γ-counting were estimated to ACHR, qualitatively and quantitatively. Results The junctional AChR numbers decreased to a minimum at the fourth week postoperatively, whereas the extrajunctional receptor numbers increased. From the fifth week postoperatively, the number of junctional AChR's increased. Even at 30 weeks after transfer, the morphology of the neuromuscular junction failed to return to the preoperative style. The number of acetylcholine receptors at the reinnervated neuromuscular junction also remained lower than the control. Conclusion The persistent weakness following free neurovascular muscle transfer may be attributed to these qualitative and quantitative changes at the neuromuscular junction.