Effects of apotesis-related proteins in the size and phenotypes of rat skeletal msucles

1.对大鼠比目鱼肌进行14天的后肢卸载(14U)和14天的再负荷，观察其对细胞凋亡的影响。HU后，比目鱼肌纤维大小和肌核数/纤维数显著减小，而凋亡肌核数显著增加。在HU后14天的动态恢复过程中，纤维大小和肌核数目逐渐增大，伴随着凋亡核的减少，我们的结果提示，比目鱼肌纤维萎缩是由于肌核数目的减少，部分是通过细胞凋亡反应。2.进一步分析了热应激(HS)对比目鱼肌纤维再生的影响。注射布比卡因后比目鱼肌纤维变性。与未加HS的再生纤维相比，HS再生纤维的横截面积和肌核数目较多。此外，在HS再生的比目鱼肌纤维中，卫星细胞的激活以及热休克蛋白(HSP)72和钙调神经磷酸酶(CaN)的表达水平也增加。我们的结果表明，热应激可能通过促进卫星细胞的激活来加速再生纤维的生长。

1. To investigate the apoptotic responses, rat soleus muscles were subjected to 14-day of hindlimb unloading (14U)and 14-day reloading. After HU, soleus fiber size and the myonuclear number/fiber were significantly decreased, while the apoptotic myonuclear number increased. During ambulatory recovery day〜14 after HU, fiber size and myonuclear number were gradually increased, concomitant with the decrease in apoptotic nuclei Our results suggested that soleus fiber atrophy was induced by the decrement of myonuclear number via, in part, by apoptotic response.2.We further analyzed the effects of heat stress (HS)on regenerating soleus fibers. The soleus fibers were degenerated by bupivacaine injection. Compared with regenerating fibers without HS, regenerating fibers with HS were greater in cross-sectional area and myonuclear numbers. Also, activation of satellite cells and the expression levels of heat shock protein (Hsp)72 and calcineurin were enhanced in HS-regenerating soleus fibers. Our results suggest that the growth of regenerating fibers is possible to be accelerated by heat stress via enhancement of satellite cell activation.