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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.
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Objective To observe the activation of pancreatic stellate cells (PSC) during the formation of pancreatic fibrosis induced by the pancreatic injection of trinitrobenzene sulfonic acid (TNBS). Meanwhile, the effects of PSC-related factors, such as transforming growth factor ? 1 (TGF-? 1), collagen Ⅰ and MMP-2 on the pathogenesis of pancreatic fibrosis in rats were also evaluated. Methods Pancreatic fibrosis model in rats was induced by the injection of 2% TNBS in ethanolate-phosphate buffer solution into the pancreatic duct. The rats were sacrificed and the pancreata were removed at the 72nd hour, 3rd week, 4th week, 5th week, 6th week and 7th week after the operation respectively. Expressions of ?-smooth muscle actin (?-SMA), transforming growth factor ? 1 (TGF-? 1), collagen Ⅰ and MMP-2 were determined by either immunohistochemistry or RT-PCR, or Western blot respectively. The ultrastructure of pancreas was studied by electron microscope at different time points. Results The inflammation, swelling and necrosis were the major pathological changes of the pancreas at the early stage after the injection of 2% TNBS. Subsequently, the fibrotic manifestations such as proliferation of the fibrosis, atrophy of vesicles, deposition of collagen because prominent at the 3rd week after the operation, which peaked at 4th week. The expression of TGF-? 1 was increased significantly at the 3rd week after the operation and reached maximum at the 4th week. The expression of ?-SMA, which indicated the activation of PSC, could be detected at the 3rd week and also reached the peak value at the 4th week. After wards, it was decreased gradually. During the first 72 hours, the expression of MMP-2 mRNA was increased significantly and then was fluctuated but still higher than that in normal rats. The deposition of type Ⅰ collagen was increased in the areas of fibrotic tissues. Conclusions PSC might involve in the courses of the development and progression of TNBS induced pancreatic fibrosis in rats. This action was achieved via the activation of PSC by TGF-? 1, the production of those extracellular matrix metabolic associated enzymes such as the synthesis of collagen Ⅰ and the secretion of MMP-2.
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Objectives To analyze the role and mechanisms of mast cells in the inflammation and fibrosis of 2 ,4, 6-trinitrobenzene sulfonic acid (TNBS)-induced rat pancreatic fibrosis. Methods Rats were received the aseptic instillation of TNBS in ethanol via bilo-pancreatic duct, and then injected with nedocromil sodium, a mast cell stabilizer, and compound 18/80, a mast cell activator, or saline. Rats were sacrificed respectively on 3, 7, 14, 21 or 28 days. Pancreatic inflammation and fibrosis were assessed by gross and histopathological evaluation. Pancreatic fibrosis were observed by Van Gieson. Pancreatic mast cells distribution, number and their state of activation (toluidine blue) were evaluated. The activation of pancreatic stellate cells (PSCs) were assessed by the expression of a-smooth muscle actin (?-SMA) through immunohistochemistry. The expression of angiotensin Ⅱ AT1 and AT2 receptors and transforming growth factor (TGF) ? 1 raRNA, which were the factors of fibrogenesis, were also assessed. Results Typical pancreatic fibrosis changes occurred in the model of rats received TNBS at 4th week by morphological evaluation. The positive expression of ?-SMA and TGF?1 in the pancreatic tissues were detected at day 3, especially at 4th week. The expression of angiotensin Ⅱ AT1 and AT2 receptors mRNA increased gradually in all the three groups, also especially at 4th week. Compared to the control group, there were more higher expression of ?-SMA, TGF?1, angiotensin Ⅱ AT1 and AT2 receptor in the compound 48/80 group, while there were lower expression of these proteins in the nedocromil group. Conclusions Mast cells are involved in TNBS-induced pancreatic inflammation and fibrosis in rats. After being activated, mast cells will promote the activation and proliferation of PSCs and upregulate the expression of angiotensin Ⅱ AT1 receptor and AT2 receptor, and then lead to pancreatic fibrosis gradually.