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AIM To investigate the effects and possible mechanism s of Glycyrrhizin on rat pancreatic fibrosis induced by TNBS (trinitrobenzenesulfonic acid, TNBS ). METHODS Chronic pancreatitis model was induced in male Sprague -Dawley rats by injection of 2% TNBS into bile duct. All the rats were randomly divided into two groups. The rats in Glycyrrhizin intervention group were treat ed with Glycyrrhizin 8 mg?kg -1 by injection into tail vein from day 3 to day 28, while the rats in control group were administrated with same volume of saline vehicle. Ten rats in the Glycyrrhizin intervention group and eight rats in the control group wer e sacrificed on day 29, the blood was collected to determine amylase and hyaluro nic acid by enzyme dynamic and RIA method. The histological change of pancreatic tissue was evaluated by H&E stain and modified Van-Gieson stain. Mast cell in pancreas was stained by thionine blue. Expression of TGF-? 1,Collagen Ⅰ and ?-SMA in pancreas were assessed by immunohistochemistry and western blot. RESULTS In the Glycyrrhizin intervention group, the mast cell number and the percentage of degranulation decreased significantly, and the expression of ?-SMA protein also decreased compared to the control group, but there was no difference in amylase or hyaluronic acid between the treatment group and the control group. In the Glycyrrhizin intervention group, inflammation and fibrosis were ameliorated and expression of collageⅠ and TGF-? 1 was also decreased significantly compared to the control group. CONCLUSION Glycyrrhizin inhibits pancreatic fibrosis in chronic pancreatitis rats induced by TNBS. This action might be related to protecting pancreatic acinus cells from being destructed by mast cell activation and inhibiting extracellular matrix synthesis stimulated by pancreatic stellate cell.
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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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AIM: To determine the effects of NF-?B on the development of rat pancreatic fibrosis mediated by angiotensin II. METHODS: Spraque-Dawley rats (200-300g) were randomly divided into normal group, control group and losartan-treatment group. Pancreatic fibrosis was induced by injection of 2% TNBS into biliopancreatic duct. Rats in losartan-treatment group and control group were respectively treated with losartan (10 mg?kg~(-1)?d~(-1)) by gavage and the same volume of saline vehicle. The expression, distribution, and activation of NF-?B were studied by Western blot, immunohistochemistry and TransAM~(TM). Toluidine blue staining and transmission electron microscopy were also used to observe the number, distribution and degranulation of mast cells. In addition, RT-PCR was performed to detect the intrapancreatic ICAM-1 mRNA expression. RESULTS: The expression and activity of intrapancreatic NF-?B p65 protein were significantly increased on day 3 after operation, reaching peak on day 7 [(0.406?0.086) mg/g total protein]. Mast cell activation was observed and ICAM-1 mRNA levels on day 3 and 7 were up-regulated in control group. Losartan treatment inhibited NF-?B expression and activation, reduced mast cell infiltration and degranulation and decreased ICAM-1 mRNA expression compared with control rats. CONCLUSION: It might be associated with the expression and activation of NF-?B that angiotensin II mediates inflammation and fibrosis in the early stage of pancreatic fibrosis. [
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AIM: To examine the effects of PPAR? activation on the growth of human pancreatic carcinoma in vitro and to explore the role of NF-?B and activator protein-1 (AP-1) in this process. METHODS: SW-1990 pancreatic cancer cells were treated with ligand of RXR?, 9-cis-RA, ligand of PPAR?, 15d-PGJ_2, and both. Antiproliferative effect was evaluated by using MTT assay; the expression of NF-?B p65 active protein was assayed by using TransAM~TM technique. Expression of c-jun and c-fos by SW1990 cells, which were treated with 15d-PGJ_2, 9-cis-RA and both at varying concentrations, were detected by RT-PCR. RESULTS: MTT assay demonstrated that 15d-PGJ_2, 9-cis-RA and the combination of both had a potent inhibitory effect on the growth of SW1990 cells in a dose-dependent manner. 9-cis-RA had a synergic action with 15d-PGJ_2 on the growth inhibition of pancreatic carcinoma. TransAM~TM showed a down-regulation trend of P65 active protein in SW1990 cells treated with 15d-PGJ_2, 9-cis-RA and both. RT-PCR demonstrated that the expression of c-jun mRNA in 15d-PGJ_2, 9-cis-RA and the combination of both-treated cells were firstly increased and then decreased, the expression of c-fos was decreased in 15d-PGJ_2 or 9-cis-RA treated SW1990 cells, but increased in cells treated with both 15d-PGJ_2 and 9-cis-RA. CONCLUSION: Activation of PPAR? exerts a negative regulatory effect on the growth of pancreatic carcinoma in vitro. Activation of RXR? has a synergic action with PPAR? agonist. The mechanism is probably associated with down-regulating the expression of NF-?B and AP-1. [