Pathological changes of pancreas and changes of serum amylase and lipase in septic rat

Abstract

Objective To systematically observe the damage of pancreas and changes of serum amy-lase and lipase in septic rat at different time points after the septic rat model being established. Methods Fifty-four male rats were randomly divided into sham group, sepsis group and normal control group. In the sepsis group, rats were given cecal ligation and puncture so as to produce a model of the rat′s intestinal septic shock. In sham group, after opening the abdominal cavity of the rats, only the cecum was pulled out of the abdominal cavity, then the abdominal cavity was satisfied and stitched. The arterial blood and pancreatic tissues of the rats in both sepsis and sham groups were collected for detection of serum amylase and lipase and observation of damage of pancreas by light and electron microscopy at 3 h, 6 h, 12 h, 24 h after the model being established. Results The levels of serum amylase of sepsis group showed a rising trend over time, and peaked at 24 h (2 779.83 U/L), which showed no difference among 4 time points. There was no significant difference of serum amylase among 3 groups at each time point except for 12 h value. The levels of serum lipase in both sepsis and sham group were higher than that in normal control group at 3 h (P<0.05), while decreased to the level of normal control group at 24 h. By light microscope, pathological changes of pancreas in the sham groups were that lobule was slightly widened; mild interstitial edema, vasodilation and a little inflammatory cell infiltration were occasionally found; most of the lobular structure was complete. In the sepsis group, pancreatic pathological changes aggravated with time prolonged. Pancreatic lobules gap widened, interstitial were infiltrated by the inflammatory cell, flocculus brim structure was fuzzy, focal necrosis was found occasionally, islet structure was complete at 3 h. Pancreatic lobule was significantly wider, more inflammatory cell infiltrated, necrosis enlarged at 6 h, and pancreatic lobule was obvious edema, more inflammatory cell infiltration and focal necrosis were found at 12 h. Vascular of pancreatic lobule was dilatation and congestion, pancreatic lobule and islet edge blurred, more lobular necrosis at 24 h. The modified Schmidt scoring of sham group and sepsis group at 3 h, 6 h, 12 h, 24 h were 2.0, 3.6, 3.4, 3.6 and 4.6, 6.0, 6.8, 7.6, respectively. By transmission electron microscope, the ultrastructure of pancreatic cell in sham group was normal, mitochondrial and lysosomal swelling were found occasionally. When in the sepsis group, the nucleus was normal, some mitochondria was swelling and cracking, lysosomes was swelling at 3 h, nucleus was complete, a part of swelling mitochondria and lysosomes appeared vacuolated necrosis at 6 h, and karyopyknosis and chromatin condensation were found, more mitochondria and lysosomes were swelling necrosis and vacuolar degenerated, rough endoplasmic reticulum was swelling at 12 h, cell karyopyknosis and chromatin condensation were obvious, a large number of mitochondria and lysosome, endoplasmic reticulum were swelling, dilatation and vacuolar necrosis at 24 h. The modified Schmidt scoring showed no significant correlation with the levels of serum amylase and lipase in sepsis group (r=0.472, P=0.199; r=0.260, P=0.499). Conclusion The pancreas was damaged in the septic rat. The pathological changes of pancreas were obvious at 6 h after sepsis onset. The characteristics of the pancreas ultrastructure change includes the changes of the mitochondria and lysosome in the early period, clear vacuoles necrosis of mitochondria and lysosome, and destruction of nucleus and the endoplasmic reticulum. There is no significant correlation between pancreatic pathological changes and serum amylase as well as lipase, serum amylase and lipase can′t indicate the extent of pancreas damage in sepsis. Key words: Sepsis; Pancreatic damage; Amylase; Lipase; Rat