• 来稿:陈琳   北京市虹天济神经科学研究院

  • Am J Physiol Cell Physiol. 2000  Dec;279(6):C1677-84. 

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  • Mechanisms leading to restoration of  muscle size with exercise and transplantation after spinal cord  injury

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  • Dupont-Versteegden EE, Murphy RJ, Houlé JD, Gurley CM,  Peterson CA.

  • Department of Geriatrics,  University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205,  USA.

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  • We have shown that cycling exercise  combined with fetal spinal cord transplantation restored muscle mass reduced as  a result of complete transection of the spinal cord. In this study, mechanisms  whereby this combined intervention increased the size of atrophied soleus and  plantaris muscles were investigated. Rats were divided into five groups (n = 4,  per group): control, nontransected; spinal cord transected at T10 for 8 wk (Tx);  spinal cord transected for 8 wk and exercised for the last 4 wk (TxEx); spinal  cord transected for 8 wk with transplantation of fetal spinal cord tissue into  the lesion site 4 wk prior to death (TxTp); and spinal cord transected for 8 wk,  exercised for the last 4 wk combined with transplantation 4 wk prior to death  (TxExTp). Tx soleus and plantaris muscles were decreased in size compared with  control. Exercise and transplantation alone did not restore muscle size in  soleus, but exercise alone minimized atrophy in plantaris. However, the  combination of exercise and transplantation resulted in a significant increase  in muscle size in soleus and plantaris compared with transection alone.  Furthermore, myofiber nuclear number of soleus was decreased by 40% in Tx and  was not affected in TxEx or TxTp but was restored in TxExTp. A strong  correlation (r = 0.85) between myofiber cross-sectional area and myofiber  nuclear number was observed in soleus, but not in plantaris muscle, in which  myonuclear number did not change with any of the experimental manipulations.  5'-Bromo-2'-deoxyuridine-positive nuclei inside the myofiber membrane were  observed in TxExTp soleus muscles, indicating that satellite cells had divided  and subsequently fused into myofibers, contributing to the increase in  myonuclear number. The increase in satellite cell activity did not appear to be  controlled by the insulin-like growth factors (IGF), as IGF-I and IGF-II mRNA  abundance was decreased in Tx soleus and plantaris, and was not restored with  the interventions. These results indicate that, following a relatively long  postinjury interval, exercise and transplantation combined restore muscle size.  Satellite cell fusion and restoration of myofiber nuclear number contributed to  increased muscle size in the soleus, but not in plantaris, suggesting that  cellular mechanisms regulating muscle size differ between muscles with different  fiber type composition.


中枢神经系统再生的概念与策略
神经组织移植的法律道德方面

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脊髓损伤后促进肌体积恢复的锻炼和移植机制