任俊婵, 樊小力*, 宋新艾, 石磊
西安交通大学医学院生理学与病理生理学教研室，西安 710061；西安电子科技大学生命科学技术学院生物技术系，西安 710071
本研究旨在探讨模拟失重对大鼠比目鱼肌肌梭神经营养因子3 (neurotrophin-3, NT‑3)表达的影响。采用大鼠尾部悬吊法建立模拟失重动物模型，按体重配对原则随机将大鼠分为5组，即尾悬吊3 d组、7 d组、14 d组、21 d组和正常同步对照组。采用免疫组织化学ABC染色法及酶联免疫吸附实验法(ELISA)检测大鼠比目鱼肌肌梭NT-3的表达。结果显示，大鼠比目鱼肌梭外肌中未见到NT-3表达；正常对照组大鼠比目鱼肌肌梭中，核袋1和核袋2纤维NT-3呈现强阳性表达；模拟失重后，梭内肌纤维的NT-3免疫染色反应进行性降低；NT-3的ELISA定量检测结果显示，正常组、尾悬吊3 d组、7 d组、14 d组和21 d组大鼠比目鱼肌NT-3的含量分别为(14.23±1.65)、(14.11±1.53)、(13.09±1.47)、(12.45±1.51)和(9.85±1.52) pg/mg。统计比较显示，尾悬吊14 d后，大鼠比目鱼肌NT-3的含量较正常对照组明显减少(P<0.05)；而尾悬吊21 d后，大鼠比目鱼肌NT-3的表达进一步减少(P<0.01)。以上结果表明，模拟失重可致大鼠比目鱼肌肌梭NT-3 的表达明显减少，并且随着模拟失重时间的延长，梭内肌NT-3的表达量进行性减少。提示微重力环境下本体感觉的适应性变化可能与肌梭NT-3的表达减少有关。
[Decreased neurotrophin-3 expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness.] [Article in Chinese]
REN Jun-Chan, FAN Xiao-Li*, SONG Xin-Ai, SHI Lei
Department of Physiology and Pathophysiology, Medical College of Xi’an Jiaotong University, Xi’an 710061, China； Department of Biotechnology, School of Life Sciences and Technology, Xidian University, Xi’an 710071, China
The present study aimed to study the changes of neurotrophin-3 (NT-3) expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness. The tail-suspension (SUS) rat model was used to simulate weightlessness. Forty mature female Sprague-Dawley rats were randomly assigned to ambulatory control (CON), 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups. Immunohistochemistry ABC staining method and enzyme linked immunosorbent assay (ELISA) were used to detect the NT-3 expression of intrafusal muscle fibers in rat soleus muscles. The results from the immunohistochemistry staining technique showed that the extrafusal muscle fibers did not exhibit the NT-3-like immunoreactivity, and NT-3-like immunoreactivity was mainly expressed in nuclear bag 1 and nuclear bag 2 fibers of the muscle spindles. The ELISA results showed that the expression quantity of NT-3 in rat soleus muscles in control, 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups were (14.23±1.65), (14.11±1.53), (13.09±1.47), (12.45±1.51) and (9.85±1.52) pg/mg of tissue respectively. Compared to the control group, the expression quantity of NT-3 was significantly decreased after 14 days of SUS (P<0.05). After 21 days of SUS, the NT-3 expression was further reduced (P<0.01). These results suggest that simulated weightlessness induces an obvious decrease in the NT-3 expression level of intrafusal fibers in rat soleus muscles. Accompanying the simulated weightlessness extension, NT-3 expression in rat soleus muscle spindles is progressively decreased. These changes may contribute to the proprioceptive adaptations to microgravity.
Key words: weightlessness; soleus muscle; muscle spindles; neurotrophin-3
通讯作者：樊小力 E-mail: firstname.lastname@example.org
任俊婵, 樊小力, 宋新艾, 石磊. 模拟失重条件下大鼠比目鱼肌肌梭神经营养因子3表达降低[J]. 生理学报 2011; 63 (1): 75-80.
REN Jun-Chan, FAN Xiao-Li, SONG Xin-Ai, SHI Lei. [Decreased neurotrophin-3 expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness.] [Article in Chinese]. Acta Physiol Sin 2011; 63 (1): 75-80 (in Chinese with English abstract).