Abstract: In this study, we examined the protective effects of low-molecular-weight soybean polypeptides (LMWSPs) against gastric mucosal injury in mice induced by water-immersion restraint stress (WIRS) and anhydrous alcohol, respectively. A total of 60 clean male IRC mice were randomly assigned into 6 groups: normal group, model control group, positive drug control group (ranitidine ＋ VE), and high-, medium- and low-dosage LMWSP groups (administered at the dosages of 7.5, 5.0 g/(kg ·d) and 2.5 g/(kg ·d) once daily for 10 consecutive days, respectively). After the last administration, all the mice were killed to observe ulcer index and assay malondialdehyde (MDA) content in the liver, alanine transaminase (ALT) in the serum, and the levels of MDA and SOD in the gastric mucosa. The results showed that WIRS-induced and anhydrous alcohol-induced gastric mucosal injury models were set up in mice successfully. UI was significantly decreased in the high- and medium-dosage LMWSP and positive drug control groups compared with the model control groups (P ＜0.01) and the UI-reducing effect of LMWSPs was better at the high dosage and consequently followed a dose-dependent pattern. Meanwhile, both dosages of LMWSPs markedly decreased ALT activity in the liver and serum of mice with WIRS-induced gastric mucosal injury, and increased SOD activity and reduced MDA level in mouse gastric mucosa with anhydrous alcohol-induced injury. Based on these findings, we conclude that LMWSPs can function to protect against gastric mucosal injury in mice.

Key words: soybean polypeptide, stress-induced stomach ulcer, gastric mucosa, ulcer index