模拟失重对不同性别大鼠背根神经节失营养的影响

Effects of simulated weightlessness on nutritional loss of dorsal root ganglion of different gender rats

目的 探索模拟失重雌、雄性大鼠背根神经节（dorsal root ganglion,DRG）神经失营养的机制,为航天员飞行后神经肌肉系统改变的相关研究提供实验基础. 方法 3月龄雌、雄性Sprague Dawley（SD）大鼠各20只,按性别及随机数分为4组：雄性对照组、雄性失重组、雌性对照组、雌性失重组,每组10只.模拟失重组保持-30°头低位及后肢自由悬垂不负重的状态,悬吊4周后,麻醉大鼠,取腰5双侧DRG,冷冻切片,苏木精伊红染色观测DRG细胞形态,甲苯胺蓝染色观察DRG细胞、尼氏体形态,电镜观测DRG髓鞘、线粒体微观结构,免疫组织化学及Western-blot观察退变的髓鞘碱性蛋白（degenerated myelin basic protein,DegenMBP）及胶质细胞源性神经营养因子（glial cell line-derived neurotrophic factor,GDNF）含量及表达. 结果 组织染色,失重组大鼠DRG细胞间隙轻度增宽,与卫星细胞分离,尼氏体结构蓬松、肿胀.电镜下失重组大鼠DRG线粒体形态肿大、变形,呈损伤性改变,髓鞘结构紊乱、松散.失重组大鼠DegenMBP含量较对照组明显增多（P＜0.01）,且雌性高于雄性,差异有统计学意义（P＜0.05）.失重组大鼠GDNF含量及表达均较对照组降低（P＜0.01）,且雌性较雄性降低更明显（P＜0.05）. 结论 模拟失重4周后,SD大鼠DRG表现出神经失营养状态.雌性失重大鼠神经失营养较雄性组明显,提示未来的航天医学研究工作应注意性别差异.

Objective To study the effects of simulated weightlessness on nutritional loss of dorsal root ganglion （DRG） of male and female rats and to provide the experimental basis for studying the neuromuscular sysiem changes after long-term space flight.Methods Twenty male and 20 female 3-month Sprague Dawley （SD） rats were randomly and averagely divided into 4 groups by sex：male control group,male weightlessness group,female control group and female weightlessness group.The simulated weightlessness was adopted by-30° head down and hind limbs load free tail suspension models （TS）.After 4-week suspension,the rats were anaesthetized and resected the DRG of bilateral L5,and the samples were frozen for sections.DRG was respectively hematoxylin eosin and Toluidine blue stained for observing cell morphology and Nissl bodies.Electron microscopy was used to observe DRG lamellar structure of myelin and the microstructure of mitochondria.Immunohistochemistry and Western-blot were applied for observing degenerated myelin basic protein （Degen MBP） and glial cell line-derived neurotrophic factor （GDNF） protein content and expression.Results By the analysis of staining,the intercellular space of DRG cells was slightly widened,the ganglion cells and satellite cells were separated partly,and Nissl body structure became fluffy and swelled in simulated weightlessness group.Electron microscopy analysis showed that the shape of DRG mitochondria was swelled and deformed which indicated the injury changes in weightlessness groups.Disordered and loose lamellar structure of myelin was also observed.Immunohistochemistry and Western-blot showed that the Degen MBP content of weightlessness groups was significantly higher than that of control groups （P〈0.01）,and the female＇s was higher than the male＇s （P〈0.05）.The GDNF protein content and expression of weightlessness groups was lower than that of control groups （P 〈 0.01）,and the female group decreased more significantly than the male （P 〈 0.05）.Conclusions For 4-week simulated weightlessness,the DRG cells of SD rats show serious nutritional loss.Weightlessness causes female SD rats more serious neurological loss than the male.It reveals the attention on sex difference in future research of space medicine.