Differential skeletal muscle gene expression after SCI as compared to denervation

• Published in: The FASEB journal 2007, Vol.21 (6), p.A1307-A1307
• Main Authors: cardozo, christopher, Zhao, Jingbo A., Wu, Yong, Zhao, Weidong, Zhang, Yuanfei, Wecht, Jill M, Wen, Xialing, Zeman, Richard, Bauman, William A.
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.6.A1307-c

Denervation is distinguished from SCI by loss after denervation of lower motor neurons and reflex arcs, and the absence of spasticity. Purpose: characterize effects of SCI on expression of genes that regulate muscle atrophy and/or hypertrophy and to compare these changes to those after denervation. Methods: Male Wistar rats underwent transection of the spinal cord or sciatic nerve followed 3, 7 or 14 days later by assessments of muscle size and gene expression. Results: Rates of atrophy after denervation for EDL and soleus were low at 3 days, increased at 7 days then were relatively constant; rates of atrophy after SCI were low at 3 days, high at 7 days, and lowest at 14 days. The peak in rate of atrophy after SCI was preceded in both EDL and soleus by high expression levels of MAFbx and MuRF1 that, initially, were greater by at least 2‐fold than those observed after denervation. Expression of MAFbx and MuRF1 then declined at 14 days, approaching normal levels. By contrast, expression of these genes after denervation remained elevated from 3 to 14 days. Three days after SCI, large, transient increases in expression of GADD45, myogenin and Runx1 were also observed whereas large and sustained increases in expression of these genes was observed after denervation. Conclusions: These differences are likely to be due to the distinct patterns of muscle electrical activity after denervation or SCI. Funded by the Department of Veterans Affairs RR&D Service.