Protective effect of the combined treatment of pancreatic and neutrophil elastase inhibitors on acute pancreatitis elicited by lipopolysaccharide in rats given intraductal injection of taurocholate plus trypsin.

A severe acute pancreatitis was produced by intraperitoneal injection of lipopolysaccharide (LPS) in rats with preexisting hemorrhagic and necrotizing pancreatitis induced by retrograde injection of a 5% taurocholate plus 1% trypsin solution into the pancreatic duct. Mortality and time-course changes in pancreatic, hepatic, renal and pulmonary functions, and organ myeloperoxidase (MPO) levels were examined in this model. LPS at an intraperitoneal dose of 30 mg/kg, which scarcely caused death and had no marked effect on serum parameters and organ MPO levels in rats without pancreatitis, increased the mortality in rats with taurocholate plus trypsin-induced pancreatitis. Pancreatic weight and ascitic volume increased in rats with taurocholate plus trypsin-induced pancreatitis regardless of the presence or absence of LPS. Serum amylase and lipase levels were also significantly increased in rats with induced pancreatitis, but was higher in the group given LPS. Serum glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN) and creatinine levels were significantly elevated in LPS-treated rats with induced pancreatitis, whereas levels in rats with induced pancreatitis not given LPS were only slightly elevated. Renal weight was also significantly increased in rats with induced pancreatitis despite the presence or absence of LPS. In LPS-treated rats with induced pancreatitis, the arterial oxygen pressure, pulmonary weight and pulmonary MPO level were significantly elevated. However, the MPO level in the kidney in these rats was not different from that in control rats, indicating that the renal dysfunction was not produced by the infiltration of neutrophils into the kidney. Increase in the pancreatic MPO level was observed in rats with induced pancreatitis, but combination treatment with LPS did not raise it. Protective effects of prophylactic treatment of 2-(3-methylsulfonylamino-2-oxo-6-phenyl-1,2-dihydro-1-pyridyl)-N-( 3,3,3-trifluoro-1-isopropyl-2-oxopropyl)acetamide (compound 1), a neutrophil elastase inhibitor, and trifluoroacetyl-L-lysyl-L-alaninanilide hydrochloride (compound 2), a pancreatic elastase inhibitor, on mortality were also examined in this model. Results were compared with that of the combined treatment of compound 1 and compound 2. In LPS-treated rats with taurocholate plus trypsin-induced pancreatitis, the combined treatment of compound 1 (2 mg/kg/h) and compound 2 (30 mg/kg/h) significantly reduced mortality, whereas single treatment of compound 1 or compound 2 did not show the beneficial effect. These results suggest that marked hepatic and renal dysfunction accompanies pancreatitis in this pancreatitis model rats, which may be good models for acute pancreatitis in humans. It is also suggested that neutrophil and pancreatic elastases may be synergistically involved in the pathogenesis of acute pancreatitis in this model.