Aim: 

The aim of present work was to perform a comparative analysis of gene expression of several connexins (Cx37, Cx39, Cx40, Cx43 and Cx45) in the adult regenerating skeletal muscle in response to injury promoting activation of satellite cells involved in myofibers repair and regeneration.

Methods: 

Using in situ hybridization and immunohistochemistry procedures we examined the spatial and temporal expression pattern of above listed connexins in the regenerating gastrocnemious muscle following a mechanical injury.

Results: 

Cx43 and Cx45 mRNAs were up-regulated by 3 hour following muscle injury, and were localised in satellite cells, M-cadherin positive cells, distributed surrounding the area of lesion. Three days after lesion Cx43 and Cx45 mRNAs were found colocalised in myogenin positive cells inside the area of lesion. Cx39 expression, appeared 3 days following lesion, was mainly localised in myogenin positive cells forming clusters or rows of closely apposed cell nuclei committed to form myotubes. Cx40 mRNA labelled cells were observed within 24 hours from injury in the endothelial cells of blood vessels surrounding the area of lesion. After 3 days these cells were localised inside the area of lesion forming clusters or rows of closely apposed cell nuclei myogenin positive. Cx37 mRNA expression appeared by 24 hrs from lesion and never was colocalised in myogenin positive cells, but it was detected in cells involved in new blood vessels formation.

Conclusions: 

Taken together these results support the suggestion that, in regenerating skeletal muscle several connexins may be differentially involved in communication of myogenic cells during the process of cell proliferation, aggregation and fusion to form new myotubes.