Abstract: Objective To investigate the effect of psychological stress on the healing process of experimental oral mucositis in rats. Methods 80 male rats (Sprague-Dawley) were randomly divided into four groups:5 rats in control group (Control), 75 rats in ulcer group (U), ulcer and stress group (U+S), and ulcer and stress + drug group (U+S+M), with 25 rats in each group. The rats with ulceration were euthanized at 0, 24, 48, 72, and 120 h (5 rats per experimental period). Psychological stress was induced by subjecting rats to restraint stress (6 h/d) for 7 consecutive days. Oral ulcer was induced by using a 4-mm tip monopolar electrode to cauterize in U, U+S, U+S+M groups. Then, psychological stress was given to the rats in both U+S and U+S+M groups at point-in-time continually. Also, diazepam was given to U+S+M group 1 mg/kg daily. The body weight gained，behavior tests and serum tests were used to testify stressed condition. Histological examinations were used to evaluate the changes of periodontal tissues and immunohistochemistry was used to evaluate the expression of HSP70. Results The stressed rats showed less body weight gained, abnormal behavioral changes and increased serum corticosterone (CORT)and adrenocorticotropic hormone (ACTH)( P＜0.05). The surface of inflammatory infiltrate of the stress group was significantly higher than other groups and the expression of hsp70 in control and ulcer group was lower than in stress group (P＜0.05). Conclusion Psychological stress can result in delayed healing process of the tissue in oral ulcer while diazepam might antagonize the stress and alleviate its negative effect．

Key words: stress, cauterization, experimental oral mucositis, wound repair, diazepam