α7nAChR is expressed in satellite cells at different myogenic status during skeletal muscle wound healing in rats

Recent study has reported that α7 nicotine acetylcholine receptor (α7nAChR) is expressed in regenerated multinucleated myotubes. But the distribution of α7nAChR in satellite cells in different myogenic status is unknown. A preliminary study on the dynamic distribution of α7nAChR in satellite cells was performed by double indirect immunofluorescent procedures during skeletal muscle wound healing in rats. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male rats. Samples were taken at 1, 3, 5, 7, 9, 13, 17 and 21 days after injury, respectively (five rats in each posttraumatic interval). Five rats were employed as control. In normal muscle specimens, weak immunoreactivity for α7nAChR was detected in a few satellite cells (considered as quiescent). α7nAChR-positive signals were observed in proliferated and differentiated satellite cells and regenerated multinucleated myotubes in the wounded areas. By morphometric analysis, the average number of α7nAChR+/Pax7+ and α7nAChR+/MyoD+ cells climaxed at 5 days post-injury. The average number of α7nAChR+/myogenin+ cells was significantly increased from 3 to 9 days post-injury as compared with other posttraumatic intervals. The protein level of α7nAChR maximized at 9 days post-injury, which implies that α7nAChR was associated with the satellite cells status. Our observations on expression of α7nAChR in satellite cells from quiescence to myotube formation suggest that α7nAChR may be involved in muscle regeneration by regulating satellite cell status.