Influence of bile on the severity of acute experimental pancreatitis induced by closed duodenal loop in rat.

The study was performed to assess the ethiological role of bile in acute pancreatitis provoked by closed duodenal loop in rat. In group I a closed duodenal loop was created by method of Nevalainen. A similar operation was performed in group II, but the common pancreatico-biliary duct was ligated just under the liver. In the control group (group C) only the mobilization of duodenum was performed. After 24 hours the mortality rate was 20% in group I, but 0% in group II and C. The amount of ascitic fluid showed significant elevation in group I versus II and group C, and in group II as compared to group C, too. The serum amylase was significantly higher in group I than group II and group C, and in group II was also higher as compared to group C. Serum total protein differed significantly between all groups, while albumin and total calcium were significantly lower in group I than group II, but group II was only slightly reduced versus group C. Histology showed no differences between groups I and II, but both differed significantly from group C. In conclusion bile seems to be an aggressive factor in pathogenesis of acute pancreatitis induced by closed duodenal loop in rat, but other factors may play more important roles.     

Influence of intraluminal trypsin activity on the course of acute experimental pancreatitis

In short-term experiments (25 or 72 h) oral trypsin inhibitor administration to pancreatitic rats significantly decreased survival rate, whereas oral trypsin administration had no effect in this respect. Neither treatment influenced the activities of amylase in serum, pancreatic tissue or ascites. Trypsin given in excess together with the trypsin inhibitor abolished the deleterious effects on survival caused by the trypsin inhibitor. In a long-term experiment in healthy rats oral trypsin inhibitor ingestion caused a significant increase in pancreatic wet weight, protein concentration and activities of amylase, lipase and trypsinogen in pancreatic tissue; again, trypsin administration had no effect. The data support the idea that oral trypsin inhibitor administration causes release of cholecystokinin (CCK) or CCK-like factors from the intestine by interfering with the negative feedback regulation exerted by intraluminal trypsin. The results of the short-term experiments further indirectly suggest that even small amounts of trypsin within the intestine - as in acute pancreatitis - can exert the feedback regulation. Finally, the results of the long-term experiment suggest that oral administration of trypsin does not exert any suppressive effects on pancreatic wet weight and pancreatic enzyme content.     

Prostaglandin E1 treatment in experimental acute pancreatitis in the rat

Prostaglandin E1 (PGE1) was tested for cytoprotective activity against the development of experimental acute pancreatitis in the rat induced by the closed duodenal loop technique. Sham-operated, untreated and PGE1-treated pancreatic rats were investigated. All rats received an initial bolus of 3 ml 5% dextrose in normal saline (D5NS) via jugular catheter 30 min prior to surgery, and a continuous subcutaneous infusion of 35 ml D5NS over 24 h. Each treated rat received 10 micrograms/kg PGE1 in the initial bolus and a maintenance dosage of 10 micrograms/kg/h via the infusate. Serum amylase rose significantly in all pancreatic rats with no significant difference between treated and untreated. Pancreatic edema was more pronounced in PGE1-treated than in untreated rats. The ischemic and autolytic damage to acinar cells and vascular endothelial cells typical of untreated pancreatitis was delayed by PGE1. Mortality rates were unaffected by PGE1.     

皮下注射蛙皮缩胆囊肽诱发急性胰腺炎的早期胰腺微循环损伤特征

目的探索急性胰腺炎（ＡＰ）实验动物模型的早期胰腺局部微循环损伤特征及其规律。方法用异硫氰酸荧光素（ＦＩＴＣ）标记红细胞（ＦＩＴＣＲＢＣ）活体微循环技术、微血管树脂和墨汁灌注光镜和扫描电镜技术,对蛙皮缩胆囊肽（ｃａｅｒｕｌｅｉｎ）诱发ＡＰ早期胰腺局部微循环改变进行动态观察。结果实验组血淀粉酶均增高;光镜及扫描电镜显示胰腺小叶内动脉括约肌早期出现损伤,细胞胞浆内大量空泡形成,表现为持续痉挛,所属微动脉支配区域毛细血管床构形紊乱;ＦＩＴＣＲＢＣ显示胰腺微循环的流速减慢、流量减少（Ｐ＜００１）;机能毛细血管密度减少、出现灌注不稳定和不规则间歇性灌流（Ｐ＜００５）。结论ＡＰ早期胰腺微循环紊乱的始动环节是胰腺小叶内动脉括约肌损伤及其痉挛,是导致胰腺缺血、微循环障碍的早期关键因素。     

Changes of lysosomal and digestive enzymes in rat caerulein pancreatitis]

We evaluated the changes of lysosomal and digestive enzymes in the exocrine pancreas after caerulein induced acute pancreatitis in rats. The serum amylase levels and water content as well as pancreatic amylase and cathepsin B contents increased significantly in the early stage (0-12 h) after caerulein was administered, however, returned to the normal levels at 36 h. In the early stage, colocalization of lysosomal enzyme and digestive enzyme was found. Histologically, in the early stage, there were remarkable changes such as acinar cell vacuolization and interstitial edema, but these changes disappeared at 36 h. Furthermore, amylase and cathepsin B outputs decreased significantly in the early stage (12 h) but at 24 h, these increased significantly. LDH discharge from dispersed acini and cathepsin B leakage from lysosomes also increased in the early stage (0-12 h), but these values returned to the normal levels at 36 h. These results indicate that exocrine pancreas needs about 36 h to recover from the caerulein induced acute pancreatitis, and in this recovering process, secretion of colocalized digestive enzyme and lysosomal enzyme seem to play an important role.     

Apoptotic cell death of hepatocytes in rat experimental severe acute pancreatitis

BACKGROUND: Apoptosis of hepatocytes has been reported to be involved in liver failure complicated with systemic manifestations such as endotoxemia. We hypothesized that hepatocyte apoptosis occurs in severe acute pancreatitis. METHODS: Induction of apoptosis was evaluated in the liver from rats with necrotizing pancreatitis. Apoptosis-inducing activity of the pancreatitis-associated ascitic fluid on hepatocytes was evaluated in vivo by intraperitoneal injection of the ascitic fluid and in vitro using rat primary hepatocyte culture. RESULTS: Apoptosis was detected in hepatocytes in the rats both with severe acute pancreatitis and with the intraperitoneal injection of the ascitic fluid by in situ nick-end labeling and DNA fragmentation. Apoptotic change and hepatic injury were ameliorated by administration of an interleukin-1 beta-converting enzyme inhibitor. The ascitic fluid exhibited cytocidal activity in rat primary hepatocyte culture via apoptosis, which was confirmed by DNA fragmentation, by cell cycle analysis, and by nuclear fragmentation. The neutralizing antibody for transforming growth factor-beta 1 partially blocked the apoptosis induction but the antibody to tumor necrosis factor-alpha had no effect. CONCLUSIONS: Apoptotic cell death occurs in hepatocytes in severe acute pancreatitis partially via transforming growth factor-beta 1 in the pancreatitis-associated ascitic fluid.     

The effect of interleukin-10 on acute pancreatitis induced by cerulein in a rat experimental model.

To investigate whether interleukin-10, a potent anti-inflammatory cytokine, could have a therapeutic effect on rats on that were made pancreatitis by cerulein. Thirty Wistar Albino rats were randomized into sham, pancreatitis, and therapy groups (n = 10 in each). Nothing was applied to the sham group; pancreatitis by inject-ing cerulein (50 micro/g/kg/h) was induced in the pancreatitis and therapy groups. Interleukin-10 (10.000 U) was injected at 1 and 4 h after pancreatitis inductions in the therapy group. The rats were sacrificed at postoperative hour 24. The following parameters were investigated: the leukocyte count, blood glucose, amylase, lipase and tumor necrosis factor-alpha levels in the blood samples; histopathological search, and wet/dry weight ratios of the pancreas tissues. The ratio of wet/dry pancreatic tissue weight, serum tumor necrosis factor-alpha, amylase and lipase lev-els, and histologic damage scores in the pancreatitis and therapy groups were significantly higher when they were compared with the sham group(p < .01). However, all of these values were significantly lower in the therapy groups than in the pancreatitis group (p < .01). Interleukin-10 decreases pancreatic tissue injury induced by cerulein-induced pancreatitis in rats. Nevertheless, more experimental studies are needed to compare endogenous interleukin-10 with exogenous interleukin-10 effects before clinical usage of this drug.     

Platelet function in acute experimental pancreatitis induced by ischaemia-reperfusion

BACKGROUND: Ischaemia-reperfusion (IR)-associated microcirculatory changes play a major role in acute post-transplantation pancreatitis. The pathophysiological role of platelets in these events is unknown. The aim of this study was to examine platelet adhesion and function during early reperfusion after pancreatic ischaemia. METHODS: Rats were subjected to warm pancreatic ischaemia by cross-clamping of the pancreatic vessels for 1 h. After 1 h of reperfusion, platelet-endothelium interaction was evaluated after platelet separation and staining by fluorescence microscopy. Amylase levels and pancreatic histology were evaluated 24 h after reperfusion. Animals treated according to an identical protocol, but without ischaemia, served as controls. RESULTS: Mild pancreatitis had developed by 24 h after IR; serum amylase levels were significantly higher than those in control animals. The numbers of adherent platelets in capillaries and venules were significantly increased, and platelet velocity in capillaries was significantly decreased, in the IR group compared with controls. There was significantly more oedema and inflammation in pancreatic tissue after IR. CONCLUSION: Warm ischaemia for 1 h followed by reperfusion for 24 h caused mild pancreatitis in this experimental model. The pancreatic microcirculation was characterized by pronounced platelet-endothelium interaction in capillaries and venules. These results suggest that platelet activation may play an important role in acute post-transplantation pancreatitis.     

Effects of the specific cholecystokinin antagonist L 364,718 in experimental acute pancreatitis in the rat

Cholecystokinin (CCK) has been suggested to be involved in the pathogenesis of acute pancreatitis. To test this hypothesis, we administered the highly selective and specific CCK receptor antagonist L 364,718 to rats in which acute experimental pancreatitis had been induced by the use of transduodenal pancreatic duct injection of taurocholate. It was, however, found that despite the use of L 364,718 at a high dose level (1 mg/kg body weight given three times), and also given prior to induction of pancreatitis, the mortality rate, the serum or ascites amylase activity, the pancreatic concentrations of lysosomal enzymes or the morphology of the pancreas were not affected. This suggests that the CCK receptors are not involved in the pathogenesis of acute pancreatitis in this experimental model, and, consequently, that CCK receptor antagonists have no place in the therapy of this condition.     

Trophic effect of caerulein on the normal pancreas and enhancement in experimental pancreatic cancer by caerulein in the Syrian golden hamster

The author investigated the hyperplastic and hypertrophic effect of caerulein in the pancreas of normal syrian golden hamsters, and the promoting effect of experimental pancreatic cancer in hamster induced by N-nitroso-bis (2-hydroxypropyl) amine (BHP). The results are as follow: Repeated subcutaneous injections of caerulein in every 12 hours for 10 days elicited a marked trophic effect on the pancreas, characterized by increased pancreatic weight and pancreatic weight/DNA ratios with an enhanced content of DNA and amylase in the pancreas in treated hamsters. DNA synthesis, as measured by histoautoradiography of tritiated thymidine labeled tissues, was increased in pancreatic acinar but little in islet nor in ductal cells. Weekly subcutaneous administration of BHP with caerulein brought pancreatic carcinomas earlier and in higher incidence than BHP alone. The majority of induced carcinomas were well differentiated adenocarcinomas, and acinar cell carcinoma was seen in neither groups. In addition, a further investigation was performed in search target cells of both BHP and caerulein. Repeated injections of caerulein in every 12 hours for 5 days before one shot of subcutaneous BHP administration led to increase both mitotic and labeling index using tritiated thymidine in most acinar cells. These results suggested that caerulein has a trophic action on the pancreas, and acts as a promotor in experimental pancreatic carcinoma.     

Influence of portal blood on the development of systemic inflammation associated with experimental acute pancreatitis

BACKGROUND: The liver is a source of systemic proinflammatory mediators in acute pancreatitis. We have investigated the effects of blood from the pancreas and intestine in liver activation and lung inflammation during early stages of experimental acute pancreatitis in a rat model. METHODS: A portosystemic shunt and a mesosystemic shunt were created to prevent the passage of blood coming from the pancreas and the intestine, respectively, to the liver. Pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. After 3 hours, the inflammatory process in the lung and intestine, plasma levels of tumor necrosis factor (TNF)-alpha and their soluble receptor, and mRNA expression of inflammatory mediators in the lung were evaluated. RESULTS: Portocaval shunting of blood prevented the inflammatory process in the lung, an increase in plasma TNF-alpha concentration, and the expression of TNF-alpha, interleukin (IL)-1beta, and heat-shock protein (HSP)-72 in the lung, but had no effect on plasma levels of soluble TNF-alpha receptor or on expression of inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein (MIP)-2 in the lung. In contrast, mesocaval shunting of blood did not modify any of the parameters evaluated. CONCLUSIONS: Pancreatic blood, but not intestinal blood, plays a key role in liver activation during experimental acute pancreatitis.     

Acute experimental suppurative pancreatitis in the rat

Acute pancreatitis was induced in rats by infusing sodium taurodeoxycholate with or without Escherichia coli and Bacteroides fragilis into the bile-pancreatic duct. Survival did not differ between the 'noninfected bile group' (NIB) and the 'infected bile group' (IB). At standardized macroscopic evaluation, pancreatitis was more severe in the IB group (p less than 0.05). Histologic examination on day 7 showed suppuration of pancreatic tissue in 6/7 IB and 3/14 NIB rats (p less than 0.05). Bacteriologic culture of pancreatic tissue was positive in 6/8 IB and 3/17 NIB rats (p less than 0.01). Bacterial culture of blood, peritoneal fluid of pulmonary tissue was seldom positive. Concordance between microscopically observed suppuration and positive bacterial culture was almost total. Recall antigen skin testing indicated anergy in the IB group, while the NIB group showed moderately diminished reaction (p less than 0.001). Similar increase of S-fibrinogen was found on day 3 in both groups, but complement factor C3 was reduced only in the IB group. This experimental model, with suppurative pancreatitis induced by intraductal infusion of an infected bile salt, may be useful for studies of systemic complications in acute pancreatitis.     

Lipid metabolism in experimental acute pancreatitis

In order to study the changes of lipid metabolism in acute pancreatitis, the following experiments were performed in monogrel dogs. Bile-induced pancreatitis (severe type) and collagenase-induced pancreatitis (mild type) were prepared, and changes of FFA, TG, IRI and IRG were determined for one week. In addition, IVFTT and PHLA were determined at 24th hour, on the 3rd day and 7th day. A rise of FFA was observed during the first 24 hours, which was considered the lypolytic stage. On the 3rd day TG reached the maximal level, while K values in IVFTT and PHLA showed the lowest levels. The above results suggest that the elimination mechanism of TG was impaired on the 3rd day. Changes of FFA, TG, IRI and IRG showed marked differences between the two groups. Therefore it is thought that lipid metabolism in acute pancreatitis is regulated by balance of endogenous pancreatic hormones.     

The proteolytic proenzymes in the peritoneal exudate during acute experimental pancreatitis of the rat.

Precursors of proteolytic enzymes were demonstrated in the peritoneal inflammatory exudate during acute experimental pancreatitis of the rat. This was done by separating the proteinase inhibitors and proenzymes by gel filtration on Sephadex G-200. After elution the proenzymes could be demonstrated by activating them with enterokinase or with trypsin. The proenzymes were eluted after the main protein bulk and proteinase inhibitors. Enzyme precursors were absent from the exudate of formalin-induced peritonitis, which suggests that the proenzymes present in the exudate of pancreatitis are of pancreatic origin. The demonstration of proenzymes in perripheral blood during pancreatitis was tested with the several modifications of the same methods, but the results were not convincing, probably owing to the insensitivity of the methods used.     

川芎嗪对急性胰腺炎的作用

目的观察急性胰腺炎（AP）时大鼠体液因子和组织病理学的表达及川芎嗪对其的影响，探讨川芎嗪（TMP）对AP的治疗作用。方法采用十二指肠胆胰管逆行加压注射5％牛磺胆酸钠的方法制备大鼠AP模型，动态观察大鼠血浆丙二醛（MDA）、血栓素B2／6-酮-前列腺素F1a（TXB2／6-Keto—PGF1α）比值（TIP）、胰腺细胞凋亡指数（AI）、胰腺组织形态及大鼠72h死亡率、平均生存时间等各项指标。结果川芎组大鼠血浆MDA：1．45±0．22（12h）、T／P比值：6．52±0．96（12h）、胰腺组织病理评分：4．85±0．98（6h）、AI：9．88±0．98（6h）与胰腺炎组比较差距有统计学意义（P〈0．05）。结论TMP对AP治疗作用与其纠正TXA2、PGI2失衡，改善AP大鼠的微循环，减少自由基造成的损伤，诱导细胞凋亡，减少胰腺细胞坏死有关。     

高脂血症对大鼠急性胰腺炎发生的影响

目的: 研究高脂血症对大鼠急性胰腺炎发生的影响,即高脂血症是否是急性胰腺炎的高危因素.方法: 在中剂量Cerulein造成一定比例的急性胰腺炎发病率的基础上,通过研究高脂血症对急性胰腺炎发病率的影响来确定高脂血症是否是急性胰腺炎的高危因素.Wistar雄性大鼠随机分为:①Bal组,均衡饲料饲养2 w;②NS组,均衡饲料饲养2 w,手术日腹腔注射生理盐水0.5 ml/kg,每小时1次,共4次;③M组,均衡饲料饲养2 w,手术日腹腔注射Cerulein 10 μg/kg(0.5 ml/kg),每小时1次,共4次;④H组,高脂饲料饲养2 w;⑤H+NS组,高脂饲料饲养2 w,手术日腹腔注射生理盐水0.5 ml/kg,每小时1次,共4次;⑥H+M组,高脂饲料饲养2 w,手术日腹腔注射Cerulein 10 μg/kg(0.5 ml/kg),每小时1次,共4次.剖腹主动脉采血检测血清淀粉酶、血甘油三脂,并取胰腺组织做胰腺病理切片观察.结果: 高脂血症增加急性胰腺炎的发病率,H+M组与M组有明显差异(P<0.05).结论: 较正常稍高的高脂血症并不能单独诱发急性胰腺炎,但是增加Cerulein诱发的急性胰腺炎的发病率,证明高脂血症是急性胰腺炎的高危因素.     

The effect of caerulein induced pancreatitis on the hepatic microvasculature.

A three-dimensional morphological study of the hepatic microvasculature in caerulein induced oedematous pancreatitis was performed using scanning electron microscopy (SEM) vascular casts and transmission electron microscopy (TEM) of hepatocytes and hepatic sinusoids. TEM studies provided ultrastructural evidence of hepatocellular damage while SEM views demonstrated gross irregularity of the sinusoidal outline with abruptly terminating sinusoidal buds and extravasation of cast material, findings which were similar to those previously reported in the pancreas itself using the same model and which were supported by TEM cross-sectional views of the hepatic sinusoids. The results suggest that caerulein induced pancreatitis is associated with extrapancreatic microvascular damage which may be an important factor in the pathogenesis of extrapancreatic organ impairment associated with acute pancreatitis.