The role of nitric oxide in caerulein-induced acute pancreatitis and the recovery process after inflammatory damage.

Abstract

Nitric oxide (NO) is involved in the control of pancreatic blood flow and secretion, and its role in the maintenance of pancreatic tissue has been suggested. The aim of our study was to evaluate the influence of NO on pancreatic trophic parameters during acute pancreatitis induction and the pancreas recovery process. Acute pancreatitis was induced in rats by a supramaximal dose of caerulein. During acute pancreatitis induction, rats were treated with L-arginine (a substrate for NO synthesis), glyceryl trinitrate (NTG, NO donor), glycine, N(G)-nitro-L-arginine (L-NNA, NO synthase inhibitor), L-arginine + L-NNA, or saline. Pancreatic weight, total contents of RNA, DNA, protein, amylase and chymotrypsin as well as pancreas histology and the number of proliferating acinar cells were evaluated after pancreatitis induction in all groups and additionally after 7 and 14 days of recovery in untreated acute pancreatitis rats or those injected with L-NNA and/or L-arginine. Pancreas destruction after acute pancreatitis was evidenced by similar decreases of all parameters in untreated acute pancreatitis rats or those treated with L-NNA or glycine when compared to control healthy animals. The recovery process after acute pancreatitis was not affected by L-NNA injections; however, the increased cell proliferation occurred later than in untreated rats. NTG and especially L-arginine treatment resulted in significant attenuation of pancreas damage (partially prevented by L-NNA treatment) as evidenced by biochemical data with a slight improvement in morphology. Treatment with L-arginine alone or in combination with L-NNA resulted in augmented cell proliferation after acute pancreatitis induction followed by earlier recovery in comparison to untreated acute pancreatitis rats or the L-NNA-injected group. The present study suggests the involvement of NO in mild acute pancreatitis and in the recovery process after inflammatory damage.