The time-dependent expression of [alpha]7nAChR during skeletal muscle wound healing in rats

The study on time-dependent expression of [alpha]7 nicotine acetylcholine receptor ([alpha]7nAChR) was performed by immunohistochemistry, Western blotting, and real-time PCR during skeletal muscle wound healing in rats. Furthermore, co-localization of [alpha]7nAChR with macrophage or myofibroblast marker was detected by double immunofluorescence. A total of 50 Sprague-Dawley male rats were divided into control and contusion groups (3 h, 6 h, 12 h, 1 day, 3 days, 5 days, 7 days, 10 days, and 14 days post-injury). In the uninjured controls, [alpha]7nAChR positive staining was observed in the sarcolemma and sarcoplasm of normal myofibers. In wounded specimens, a small number of polymorphonuclear cells, a number of macrophages and myofibroblasts showed positive reaction for [alpha]7nAChR in contused zones. Morphometrically, the average ratios of [alpha]7nAChR-positive cells were over 50 % from 3 to 10 days after contusion, and exceeded 60 % at 5 and 7 days post-injury. Besides, the positive ratios of [alpha]7nAChR were 2.13. Similarly, the relative quantity of [alpha]7nAChR mRNA expression peaked at 7 days post-wounding as compared with control by real-time PCR detection, showing a relative quantity of >2.65. In conclusion, the expression of [alpha]7nAChR is upregulated and temporally distributed in macrophages and myofibroblasts during skeletal muscle wound healing, which might be closely involved in inflammatory response and fibrotic repair after injury. Moreover, [alpha]7nAChR is promising as a useful marker for wound age determination of skeletal muscle.[PUBLICATION ABSTRACT]