Differential induction of HSP60 and HSP72 by different stress situations in rats. Correlation with cerulein-induced pancreatitis.

We previously reported that water-immersion stress specifically induced the synthesis of a 60-kDa heat-shock protein (HSP60, chaperonin homolog) in pancreatic cells and preinduction of HSP60 completely prevented development of cerulein-induced pancreatitis in the rat in an HSP60 quantitatively dependent manner. In order to study the cytoprotective function of a 72-kDa heat-shock protein (HSP72, stress-inducible hsp70), the effect of specific preinduction of HSP72 by hyperthermia on cerulein-induced pancreatitis was investigated and compared with the effect of preinduction of HSP60 in this study. Expression of HSP60 and HSP72 in the pancreas was investigated by immunoblot before and after water immersion or hyperthermia. Following pretreatment with water-immersion stress or hyperthermia, the rats were injected with cerulein (40 micrograms/kg, intraperitoneally). The pancreas wet weight and serum amylase concentration were measured before and after cerulein injection. Hyperthermia (42.5 degrees C, 20 min) specifically induced HSP72 in the pancreas. The synthesis of HSP60 was specifically induced by water-immersion stress in the pancreas. Cerulein-induced pancreatitis was clearly prevented by specific preinduction of HSP60 by water-immersion stress. However, preinduction of HSP72 by hyperthermia had no preventive effect on cerulein-induced pancreatitis. Our findings suggest that HSP60 and HSP72 have distinct functions in the pancreas, and their induction mechanisms are also different in vivo. These results could be important for understanding the mechanism of "adaptive cytoprotection" in the pancreas mediated by heat-shock proteins.