目的 探讨被动转移重症肌无力(PTMG)大鼠模型眼外肌的受累情况.方法 腹腔注射mAb35建立SD大鼠PTMG模型并观察其眼部症状,取大鼠眼外肌(EOM)行HE染色、琥珀酸脱氢酶染色、免疫组化以及置透射电镜下观察EOM神经-肌肉接头(NMJ)处病理变化,并与生理盐水对照组比较.结果 PTMG大鼠出现睑裂缩小和眼球内陷充血、眼部流出血性分泌物的现象；HE染色显示出现眼部症状的PTMG大鼠EOM肌纤维轻度萎缩,肌细胞周围间质有较多淋巴细胞浸润；与对照组比较,琥珀酸脱氢酶染色显示PTMG组大鼠EOM Ⅰ型肌纤维比例下降,ⅡA型肌纤维比例上升；免疫组化显示PTMG大鼠EOM上可与银环蛇毒结合的乙酰胆碱受体数量显著减少；透射电镜发现PTMG组大鼠EOM出现NMJ突触皱褶短缩,皱褶数量减少等类似重症肌无力的病理改变.结论 PTMG大鼠EOM确有受累并出现重症肌无力典型病理变化,可为进一步在此模型上研究EOM易感机制提供实验基础.%Objective To investigate the involvement of extraocular muscles (EOM) in the passive transferred experimental myasthenia gravis ( PTMG) in rats. Methods PTMG model was built by intraperitoneally injecting purified monoclonal antibody-mAb35 to rats and their ocular symptoms were observed. HE staining and the succinate dehydrogenase staining were adopted on EOM. The amount of acetylcholine receptors (AChR) marked by alpha bungarotoxin immunohistology was detected, and their neuromuscular junctions were observed by transmission electron microscope. The above parameters were compared with those in control group, who took normal saline injection intraperitoneally. Results The monoclonal antibody-mAb35 treated rats showed smaller eyelid crack, congestive eyeball and bloody secretions. HE staining showed that some nuclei congregated in EOM cells and more lymphocytes appeared in interstitial substances surrounding the muscles. The succinate dehydrogenase staining showed decreased proportion of type I and increased proportion of type II fibers in EOMs in PTMG group compared with control group. The amount of AChR, which was marked by alpha bungarotoxin, decreased in the PTMG group, and ultrastructure of neuromuscular junctions in EOMs in the PTMG rats showed particular pathological changes similar to those in clinical myasthenia gravis (MG), such as less synaptic folds and larger synaptic gaps. Conclusions Our findings suggested that the EOMs were exactly involved in the PTMG rats and showed pathological changes similar to clinical MG, which could be a nice experimental basement for further studies of EOM susceptibility in MG.
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