EFFECT OF PREINDUCTION OF HEAT-SHOCK PROTEINS ON ACETIC ACID-INDUCED COLITIS IN RATS

In order to study the cytoprotective function of heat shock proteins ( HSPs) in vivo, the effect of preinduction of HSPs by hyperthermia on a cetic acid-induced colitis was investigated. Expression of 60-kDa, 72- kDa, and 90-kDa heat shock proteins (HSP60, HSP72, and HSP90, respecti vely) in rat colonic mucosa was investigated by Western blot analysis and immunohistochemical study before and after hyperthermia. Following pretreatment with or without hyperthermia, the rats received intrarec tal infusion of various doses of acetic acid. The colonic mucosal dama ge was evaluated by macroscopic and microscopic assessments 24 hr afte r the intrarectal infusion of acetic acid. Expression of HSPs was sign ificantly increased by hyperthermia in rat colonic mucosa. Immunohisto chemical study also showed the increments of HSPs in the colonic mucos al cells after hyperthermia. Acetic acid-induced colitis was dramatica lly prevented by pretreatment with hyperthermia when HSP72 and HSP90 w ere preinduced. On the other hand, induction of HSP60 did not correlat e with mucosal protection. Our findings suggest that HSP72 and HSP90 m ay have cytoprotective function against acetic acid-induced mucosal da mage. These results may be important for understanding the mechanism o f ''adaptive cytoprotection'' mediated by HSPs.