PANCREATITIS-ASSOCIATED PROTEIN IS UP-REGULATED IN MOUSE PANCREAS DURING ACUTE-PANCREATITIS

Pancreatitis-associated protein I (PAP I) is a pancreatic secretory pr otein strongly expressed during acute pancreatitis in the rat and huma n. We hypothesized that its expression was part of a general and coord inated response of the organ against aggression. An opposite pattern o f PAP I mRNA expression has recently been described in the mouse. The murine PAP I mRNA was described to be highly expressed in normal pancr eas and down-regulated during pancreatitis, The important implications of these unexpected findings led us to investigate the expression of murine PAP I in cerulein-induced pancreatitis. Northern blot analysis demonstrated a very low level of PAP I mRNA in the healthy mouse pancr eas and strong overexpression during acute pancreatitis. Western blot analysis confirmed that changes in pancreatic PAP I levels were parall el to those of the mRNA and the protein was localized by immunohistoch emistry to the acinar cells, It was concluded that, during the course of acute pancreatitis, the pattern of PAP I expression in the mouse pa ncreas was comparable to that already observed in the rat and human. A lthough we have no explanation for the discrepancy between our results and those recently reported, the expression pattern of PAP I in the m ouse exocrine pancreas described in the present study suggests that th e pancreatic response to aggression might be conserved in mammals.