Abstract: Objective To investigate the expression of M3 subtype of muscarinic receptors(M3R) during the incised wound healing of the skin in mice and the characteristics of its time-dependent.Methods The change of M3R in skin incised wound was detected by immunohistochemical staining and Western blot.Results M3R-positive cells were detected in epidermis,hair follicle,sebaceous glands,sweat glands,dermomuscular layer in normal mouse skin.Expression of M3R was mainly detectable in polymorphonuclear cells(PMNs) in the wound specimens aged from 6 h to 12 h after injury.Afterwards,the M3R-positive cells were mostly mononuclear cells(MNCs) and fibroblastic cells(FBCs) at 1 d to 3 d post-injury,whereas the M3R-positive cells were mostly FBCs aged from 5 d to 14 d.Morphometrically,the ratio of the M3R-positive cells increased aged from 6 h to 12 h after injury,with a peak at 12 h.The ratios kept a high relatively level aged from 1 d to 5 d,but significantly that lowered as compared with aged 12 h after injury.The ratio reached the peak at 7 d again after injury,and then decreased gradually.The M3R protein also revealed a time-dependent tendency with double peaks at 12 h and 7 d after injury as detected by Western blotting.Conclusion M3R is time-dependently expression in PMNs,MNCs and FBCs suggesting that it may play roles during the skin incised wound healing,and M3R may be used as a marker for wound age determination.

Key words: forensic pathology, wounds and injuries, skin, receptors, cholinergic, wound age, mice