RESUMO
Objective To investigate the pathologic changes in the pancreas of rats after intraperitoneal injection of DETC,a kind of superoxide dismutase (SOD) inhibitor,and to compared that with another model of chronic pancreatitis by pancreatic duct injection of TNBS.Methods The rats were randomly divided into DETC group,DETC control group,TNBS group,TNBS control group,normal control group.Rats in DETC group received an intra-peritoneal injection of DETC twice a week,and rats in DETC control group received an intra-peritoneal injection of same amount of normal saline.Rats in TNBS group was injected with 2％ TNBS ethanol phosphate buffer into the pancreatic duct,while rats in TNBS control group was treated with injection of same amount of ethanol phosphate buffer,and rats in normal control group received no treatment.The rats were sacrificed after 2 w,4 w,6 w and 8 w.The serum levels of amylase were determined,and pathological and ultrastructure changes of the pancreas were measured.The levels of SOD,GSH-PX activity and MDA content were detected.The expressions of α-SMA,Desmin,Collagen Ⅰ,Collagen Ⅲ,TGF-β1,FN in tissue were detected by immunohistochemical assay.The TGF-β1 mRNA expression was detected by RTPCR.Results No rat died in DETC group.The mortality rate of TNBS group was 15％.The serum levels of amylase were not statistically different between the 2 groups.The fibrosis scores of rat in DETC group at 4 w was 3.4 ± 1.l,which was significantly higher than that in TNBS group (3.0 ± 1.3,t =3.462,P ＜ 0.05).At 6 w,the damage scores of rat in DETC group was 9.1 ± 1.8,which was significantly higher than that in TNBS group (8.4 ± 1.8,t =2.943,P ＜ 0.05).Scores of vacuolar degeneration and fatty infiltration of rat in DETC group were higher than those in TNBS group,but the difference between the two groups was not statistically significant.Two weeks later,ultrastructure changes of pancreas could be observed,and large amounts of regenerative or mature collagen could be seen at 4 w.The SOD activity of DETC group was significantly decreased when compared with those in TNBS group (t =5.468,P ＜ 0.01).The GSH-PX activity of DETC group at 2 w,6w was significantly decreased when compared with those in TNBS group (t =6.497,10.125,P＜0.01).While the activity of MDA at 6 w,8 w was significantly increased when compared with those in TNBS group (t =3.350,5.407,P ＜0.05).The differences at other time points were not statistically significant.The expressions of (a)-SMA,Desmin,Collagen Ⅰ,Collagen Ⅲ,TGF-β1,FN,and TGF-β1 mRNA were not statistically significant between the 2 groups.Conclusions Sustained suppression of SOD activity can successfully induce chronic pancreatitis.Fatty infiltration and fibrosis in pancreas in DETC group occurs earlier with more severe presentation than that in TNBS group.Intraperitoneal injection of DETC is easy with low mortality rate,which is an ideal method for chronic pancreatitis model induction.
RESUMO
PURPOSE: Because previous studies have reported depleted antioxidant capacity in patients with chronic pancreatitis (CP), prevention of free radical production has gained importance in antifibrotic treatment strategies for CP. The aim of this study was to investigate the effects of ascorbic acid on oxidative capacity and pancreatic damage in experimental CP. MATERIALS AND METHODS: CP was induced in male Sprague-Dawley rats by infusion of dibutyltin dichloride (DBTC) into the tail vein. Ascorbic acid was given intraperitoneally at a daily dose of 10mg/kg body weight. The treatment groups were as follows: group 1, DBTC plus intraperitoneal physiologic saline; group 2, DBTC plus intraperitoneal ascorbic acid; group 3, solvent plus intraperitoneal physiologic saline; group 4, no operation plus intraperitoneal physiologic saline. Each group contained 15 animals. Treatment was started after CP was established. After 4 weeks of treatment, serum hyaluronic acid and laminin levels were determined by radioimmunoassay, pancreatic tissue oxidative stress was analyzed, and the degree of pancreatic damage was determined. RESULTS: Ascorbic acid treatment markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). Significant serum hyaluronic acid and laminin reductions were observed in group 2 as compared with group 1 (p < 0.05). However, the serum hyaluronic acid and laminin levels remained elevated when compared with those of groups 3 and 4 (p < 0.05). Histopathologic scores were also lower in animals with CP that underwent ascorbic acid-treatment (p < 0.05). CONCLUSION: Ascorbic acid treatment alleviated the degree of oxidative stress and pancreatic damage in rat CP. Antioxidant treatment might be considered a potential option to improve the pathologic process in CP.