正常婴幼儿手内肌与肱二头肌神经肌接头发育特征比较的实验研究

Clinically in obstetric brachial plexus palsy (OBPP), the atrophy of the intrinsic muscles of the hand (IMH) turns irreversible much faster than that of the biceps. We have successfully established the rat model to simulate these clinical phenomena, and in further study we found that denervated intrinsic muscles of the forepaw (IMF) and biceps had their own characteristics of specifically dysregulated mRNA, which participate in constructive and functional regulation of neuromuscular junctions (NMJs), respectively, as compared with control. Thus physiological studies have shown that the occurrence of fine action dominated by intrinsic musculature of the hand was far later than the original action dominated by biceps after born. As the experiments confirmed that the maturation process of NMJs relied on the movement, we hypothesize that the development of biceps' NMJ is close to be matured, but the NMJ of intrinsic musculature of the hand require the constantly stimulated of external conditions to be matured. The difference between the NMJ of these two kinds of muscles leads to the result that the intrinsic musculature of the hand is more vulnerable to the harmful effects such as denervation. We will compare the difference of basement membrane, the postsynaptic membrane and terminal Schwann cells of NMJ between the intrinsic musculature of the forepaw and the biceps of newborn rats, and further analysis for the difference of protein and gene expression relating to construction and function of NMJ in normal state. The purpose of this study is to clarify the construction basis of the different characteristics of the NMJ between the intrinsic musculature and the biceps in development progress of infants, as well as the expression roles of genes and proteins. This study may provide histological basis for pathological studies in the future.

在分娩性臂丛损伤中，婴幼儿失神经手内肌较肱二头肌更快发生不可逆萎缩。本人已成功建立模拟上述现象的大鼠模型，且通过全基因组基因芯片筛查发现，上述二种失神经肌肉差异表达的mRNA，多数涉及神经肌接头（NMJ）结构与功能的自我调节。鉴于出生后手内肌所支配精细动作的出现时间远晚于肱二头肌所支配的粗大动作，且NMJ成熟呈活动依赖性，假设：出生后手内肌NMJ的发育较肱二头肌NMJ不成熟；正是这两种肌肉NMJ发育上的差异，导致手内肌更易遭受失神经后炎症凋亡等有害因素的影响，而成熟的肱二头肌则有较完善的自我保护机制。将采用正常新生大鼠，比较其前肢爪內肌与肱二头肌NMJ突触前膜、基底膜、乙酰胆碱受体、终末雪旺细胞的形态特征，并研究两种肌肉NMJ结构与功能相关基因和蛋白的表达差异。研究目标是阐明新生大鼠前肢爪内肌和肱二头肌NMJ的发育特征及相关分子机制，为后续有关的病理研究提供组织学基础。

临床上分娩性臂丛损伤中的手内肌较肱二头肌更快进入不可逆萎缩状态。前期动物实验发现，大鼠爪内肌与肱二头肌在失神经5周后的mRNA与miRNA表达各具特征，且多数涉及神经肌肉接头（NMJ）的结构与功能调节。已有研究发现，出生后手内肌所支配精细动作的出现时间远晚于肱二头肌所支配的原始动作。因此假设：出生后肱二头肌NMJ的发育已较完善，而手内肌NMJ则需经外界条件的不断刺激才能逐渐成熟，正是这两种肌肉NMJ发育上的差异，导致手内肌更易遭受失神经等有害因素的影响。将比较新生大鼠前肢正常爪內肌与肱二头肌NMJ的基底膜、突触后膜和终末雪旺细胞空间和数量分布、及形态上的不同，以及两种肌肉NMJ结构与功能相关基因和蛋白的表达差异，最终进行体外体内验证。这将阐明引起婴幼儿手内肌与肱二头肌NMJ发育过程差异的形态基础，以及造成这种差异的分子机制，找到导致手内肌NMJ更易受到失神经不利影响的关键基因。