OBJECTIVETo investigate the change in neuropeptide substance P (SP) in the burn wound skin in scalded rats.

METHODSThe SP distribution density in the rat skin samples from the burn wound, peri-wound area and remote area of scalded rats were determined by immunohistochemistry technique. The mRNA expression of SP was observed by in situ hybridization.

RESULTSThe distribution density of SP in the skin samples from the above three areas decreased obviously since 15 mins postburn, dropped to the lowest level during 6 - 12 postburn hou (PBH), and then recovered thereafter. Comparatively, the recovery in peri-wound area occurred earlier. In addition, there was emigration of macrophage-like large cells with positive SP immunoreactivity from local blood vessels in the dermal layer of the burn wound and peri-wound areas. The large cells were closely related to the local SP-containing nerve fibres at 12 PBHs. Intensified staining of the cells was identified at 24 PBHs with the disintegration of the cells into pieces with release of large amounts of positive SP immunoreactive granules, followed by disappearance of the cells at 48 PBHs. It was indicated by in situ hybridization that the preprotachykinin A (PPTA) mRNA encoding and synthesizing SP was expressed in various cells at 6 PBHs.

CONCLUSIONSP might be synthesized and released from cutaneous nerve ending or from local inflammatory cells after skin burn injury.