OBJECTIVE: Growth, regeneration and reparation of gastric mucosal epithelium may relate to the expression of peptides. This study aimed to investigate the effect of pS2, TGF-α and PCNA in endotoxin-induced acute gastric mucosal injury in young rats. METHODS: Eighteen-day-old Wistar rats were randomly injected intraperitoneally with lipopolysaccharide (LPS) (5 mg/kg) or normal saline (control). The gastric mucosal specimens were harvested 1.5, 3, 6, 24, 48, and 72 hrs after LPS or normal saline injection (n=8 each). The pathological changes of the gastric mucosa were observed by hematoxylin-eosin staining. The expression of pS2,TGF-α and PCNA was measured by immunohistochemistry SP method. RESULTS: Gastric mucosal injuries were the most serious 6 hrs after LPS injection, characterized by massive erosion, bleeding and cord necrosis of the gastric mucosa paralleling with gastric longitudinal axis. PCNA expression in the gastric mucosa in the LPS group 3, 6, 24 and 48 hrs after LPS injection was significantly lower than that in the control group (P<0.01). pS2 expression in the gastric mucosa weakened 1.5 hrs after LPS injection, recovered to the control level at 3 hrs and was significantly higher than the control at 6, 24, 48 and 72 hrs of LPS injection (P<0.01). TGF-α expression in the gastric mucosa in the LPS group increased significantly 6, 24 and 48 hrs after LPS injection when compared with the control group (P<0.01). CONCLUSIONS: PCNA expression may be associated with the proliferation activity of the gastric mucosa in the process of gastric mucosal injury/reparation. pS2 and TGF-α might participate in the defense and reparation of gastric mucosal cells through mediating cell proliferation following acute gastric mucosal injury.