Pancreatic damage and regeneration in the course of ischemia-reperfusion induced pancreatitis in rats

The objective of this study was to assess the biochemical and histological signs of pancreatic damage development and pancreatic recovery in the course of ischemia-reperfusion induced pancreatitis. Acute pancreatitis was induced in rats by limitation of pancreatic blood flow (PBF) in inferior splenic artery for 30 min using microvascular clips, followed by reperfusion. Rats were sacrificed at the time: 1 h, 12 h, 24 h, and 2, 3, 5, 7, 10, 14, 21 and 28 days after ischemia. PBF was measured using laser Doppler flowmeter. Plasma amylase, interleukin 1beta (IL-1beta) and interleukin 10 (IL-10) concentration, pancreatic DNA synthesis, as well as, morphological features of pancreatic damage were examined. Ischemia with reperfusion caused acute necrotizing pancreatitis followed by pancreatic regeneration. After removal of microvascular clips, PBF was reduced and the maximal fall of PBF was observed 24 h after ischemia, then PBF grew reaching the control value at 28th day. Plasma amylase activity was increased between 12th h and 3rd day with maximum at 24 h after ischemia. Also plasma IL-1beta and IL-10 were elevated with maximal value at the first and second day after ischemia, respectively. DNA synthesis was maximally reduced at the first day (by 70%) and from second day the reversion of this tendency was observed with full restoration of pancreatic DNA synthesis within four weeks. Morphological features of pancreatic tissue showed necrosis, strongly pronounced edema and leukocyte infiltration. Maximal intensity of morphological signs of pancreatic damage was observed between first and second day of reperfusion. During pancreatic regeneration between second and tenth day after ischemia the temporary appearance of chronic pancreatitis-like features such as fibrosis, acinar cell loss, formation of tubular complexes and dilatation of ducts was observed. The regeneration was completed within four weeks after pancreatitis development. We conclude that partial and temporary pancreatic ischemia followed by reperfusion causes acute necrotizing pancreatitis with subsequent regeneration within four weeks. Pancreatic repair after necrotizing pancreatitis is connected with the increase in plasma IL-10 concentration and transitory formation of tubular complexes.