Effect of early administration of exogenous basic fibroblast growth factor on acute edematous pancreatitis in rats

AIM: To observe the therapeutic effect of early administration of exogenous Basic fibroblast growth factor (bFGF) on acute edematous pancreatitis (AEP) in rats. METHODS: Thirty male Sprague-Dawley rats were randomly divided into three (n = 10): normal control group (groupⅠ), AEP group (groupⅡ) and AEP with bFGF treatment group (groupⅢ). AEP was induced by subcutaneous injection of cerulein (5.5μg/kg and 7.5μg/kg) at 1 h interval into rats of groupsⅡandⅢ. Three hours after induction of AEP, 100μg/kg bFGF was administrated intraperitoneally for 1h to groupⅢrats. For test of DNA synthesis in acinar cells, 5-bromo-2'-deoxyuridine (BrdU) labeling solution was intraperitoneally injected into the rats of groupsⅡandⅢ24 h after bFGF treatment. The changes in serum amylase, lipase, pancreatic tissue wet/dry ratio were detected. RESULTS: In bFGF treatment group, there was a significant decrease in the volume of serum amylase, lipase and the pancreatic wet/dry weight ratio(1383.0±94.6 U/L, 194.0±43.6 U/L, 4.32±0.32) compared to AEP group (3464±223.7 U/L, 456±68.7 U/L, 6.89±0.47) (P < 0.01), and no significant difference was found between bFGF treatment and control group (1289±94.0 U/L, 171±23.4 U/L, 4.12±0.26, P > 0.05). The inflammatory changes such as interstitial edema, polymorphonuclear neutrophils (PMNs) and vacuolization were significantly ameliorated compared to AEP group (P < 0.01). A small number of BrdU-labeled nuclei were observed in acinar cells of AEP rats (1.8±0.3 nuclei/microscopic field, n = 10) while diffuse BrdU-labeled nuclei were found in bFGF-treated rats (18.9±1.4 nuclei/microscopic field, n = 10) {P < 0.01). Immunohistochemical study showed increased DNA synthesis in pancreatic acinar cells. CONCLUSION: Early administration of exogenous bFGF has significant therapeutic effect on cerulein-induced acute edematous pancreatitis in rats. Its mechanism is related to the amelioration of inflammation and facilitation of pancreatic regeneration.     

Effects of short-term administration of the CCK receptor antagonist,KSG-504, on regeneration of pancreatic acinar cells in acute pancreatitis in rats

Cholecystokinin (CCK) receptor antagonists have been reported on have an inhibitory effect on acute experimental pancreatitis, but their long-term administration is also reported to block pancreatic regeneration. We examined whether the short-term administration of KSG-504 )KSG), a synthetic CCK-A receptor antagonist, inhibited the regeneration of pancreatic acinar cells after ethionine-induced acute pancreatitis in rats. KSG (50 mg/kg), given 12 times by subcutaneous injection at 6-h intervals, prevented the reduction of protein, amylase, and trypsinogen levels, and the DNA content of the pancreas and facilitated the recovery of these values. Ornithine decarboxylase activity in pancreatic tissue and a 5-bromo-2′-deoxyuridine labeling study indicated that DNA synthesis was accelerated in rats treated with KSG. These findings suggest that the short-term administration of KSG inhibits the development of ethionine-induced acute pancreatitis and facilitates the regeneration of acinar cells.     

Induction of pancreatic acinar cell proliferation by thyroid hormone

Thyroid hormone is known to elicit diverse cellular and metabolic effects in various organs, including mitogenesis in the rat liver. In the present study, experiments were carried out to determine whether thyroid hormone is able to stimulate cell proliferation in another quiescent organ such as the pancreas. 3,5,3'-L-tri-iodothyronine (T3) added to the diet at a concentration of 4 mg/kg caused a striking increase in nuclear bromodeoxyuridine (BrdU) incorporation of rat acinar cells 7 days after treatment (the labeling index was 46.7% in T3-treated rats vs 7.1% in controls). BrdU incorporation was limited to the acinar cells, with duct cells and islet cells being essentially negative. The increase in DNA synthesis was accompanied by the presence of several mitotic figures. Histological examination of the pancreas did not exhibit any sign of T3-induced toxicity. Determination of the apoptotic index, measurement of the serum levels of alpha-amylase and lipase, and glycemia determination did not show any increase over control values, suggesting that the enhanced proliferation of acinar cells was a direct effect induced by T3 and not a regenerative response consequent to acinar or beta-cell injury. Additional experiments showed that DNA synthesis was induced as early as 2 days after T3 treatment (the labeling index was 9.4 vs 1.9% in controls) and was associated with increased protein levels of cyclin D1, cyclin A and proliferating cell nuclear antigen, with no substantial differences in the expression of the cyclin-dependent kinase inhibitor p27. The mitogenic effect of T3 on the pancreas was not limited to the rat, since extensive acinar cell proliferation was also observed in the pancreas of mice treated with T3 for 1 week (the labeling index was 28% in T3-treated mice vs 1.8% in controls). Treatment with three other ligands of nuclear receptors, ciprofibrate, all-trans retinoic acid and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, induced little or no pancreatic cell proliferation. These results demonstrated that T3 is a powerful inducer of cell proliferation in the pancreas and suggested that pancreatic acinar cell proliferation by selected agents may have potential for therapeutic use.     

Pancreatic exocrine function in unconscious rats treated with submaximal, maximal, and supramaximal doses of bombesin tetradecapeptide

Supramaximal stimulation of the rat pancreas in vivo with caerulein elicits a sharp decline in pancreatic juice volume and protein outputs and initiates acute edematous pancreatitis within 30 min. Because of the similar effects of caerulein and bombesin on pancreatic exocrine function, we examined in unconscious rats (a) the effects of a continuous, 4-h intravenous infusion of varying doses (0.2-40.0 nmol/kg/h) of bombesin on pancreatic juice volume and protein output, and (b) whether supramaximal doses of bombesin produce acute edematous pancreatitis. A maximal, fivefold and 17-fold rise in pancreatic juice volume and protein output was achieved with intravenous doses of 1.0 and 4.0 nmol of bombesin/kg/h, respectively. Pancreas weights in rats infused with bombesin as high as 40.0 nmol/kg/h were not significantly different from control animal values (no bombesin infusion) and serum amylase concentrations were only moderately (twofold) elevated over control values in rats i.v. infused with 4.0-40.0 nmol of bombesin/kg/h. The pancreas in rats treated with the highest dose of bombesin (40.0 nmol/kg/h) revealed sparsely scattered microvacuoles in a few acinar cells and minor evidence of interacinar edema. It is concluded that supramaximal stimulation of the rat pancreas in vivo with bombesin fails to elicit acute edematous pancreatitis and appears to be related to the ability of bombesin, in contrast to supramaximal doses of caerulein, to continuously stimulate maximal pancreatic juice secretion.     

Continuous infusion of cholecystokinin leads to down-regulation of the cholecystokinin-A receptor in the rat pancreas

BACKGROUND: Infusion of sulphated cholecystokinin-8 (CCK-8S) in rats transiently increased the proliferation of pancreatic acinar cells, whereas the CCK-A receptor antagonist devazepide decreased such proliferation. This effect ceased after 3 days. CCK-8S or devazepide injected twice daily induced a persistent effect on the cell proliferation involving the major cells of the exocrine pancreas. The aim of this study was to examine the effect of continuous infusion of CCK-8S and devazepide on CCK-A receptor gene expression. METHODS: Male Sprague-Dawley rats received subcutaneous continuous infusion of 5 microg/kg/h CCK-8S, 200 microg/kg/h devazepide, or 1% bovine serum albumin (BSA) by means of osmotic minipumps. The rats were killed after 4 days; I h before being killed they received 5-bromo-2-deoxyuridine (BrdU) intraperitoneally. Plasma was collected for analysis of CCK. The pancreas was dissected, and indirect immunofluorescence for BrdU and CCK-A receptor was performed. In situ hybridization to CCK-A receptor mRNA was performed for examination and semiquantification of receptor gene expression. RESULTS: Continuous infusion of CCK-8S led to a sixfold increase in plasma CCK and a 40% increase in pancreatic weight. Devazepide did not affect the CCK level but decreased the pancreatic weight by 24% compared with BSA-infused rats. The BrdU labeling indicated that CCK-8S had no effect on cell proliferation. Immunofluorescence for the CCK-A receptor showed a decreased labeling intensity after CCK-8S infusion. The mean optical density of in situ hybridization labeling of the sections from CCK-8S-treated rats was decreased to 37% +/- 3% of that in controls. Devazepide did not affect the CCK-A receptor gene expression. CONCLUSIONS: Continuous stimulation of the CCK-A receptor led to a downregulation of the receptor gene expression in pancreatic acinar cells and decreased labeling of the receptor at immunohistochemistry. The results suggest that down-regulation of the receptor is a protective mechanism against overstimulation.     

Epidermal growth factor protects against pancreatic damage in cerulein-induced pancreatitis.

Epidermal growth factor (EGF) exhibits gastroprotective and ulcer-healing action. These observations prompted us to determine the influence of EGF on cerulein-induced pancreatitis (CIP) in the rat. Acute pancreatitis was induced by subcutaneous infusion of cerulein (10 microg/kg/h) for 5 h. Initially EGF was administrated twice at doses of 1, 5, 10 or 100 microg/kg s.c. (first injection 30 min prior to cerulein infusion, and the second injection 2.5 h after the start of cerulein infusion) and from this part of study 10 microg/kg was chosen for the next experiments. CIP led to a significant decrease in DNA synthesis and a reduction in pancreatic blood flow (PBF) by 42 and 30%, respectively, as well as a significant increase in pancreatic weight, plasma amylase concentration, plasma interleukin-1beta (IL-1beta) level and the development of the histological signs of pancreatic damage with marked edema, leukocyte infiltration and vacuolization of acinar cells. Treatment with EGF attenuated the pancreatic tissue damage in CIP as manifested by partial reversal of the drop in DNA synthesis and improvement of pancreatic histology. Moreover, EGF administration attenuated the fall in PBF and significantly reduced the cerulein-evoked increase in pancreatic weight. Also plasma amylase and IL-1beta were decreased in rats treated with EGF. We conclude that: (1) EGF exerts a protective effect against CIP, and (2) the beneficial activity of EGF in CIP seems to depend on the increase in pancreatic cell proliferation, the reduction in cytokine generation and the attenuation of the fall in PBF.     

Apoptosis of acinar cells is involved in chronic pancreatitis in Wbn/Kob rats: role of glucocorticoids

The involvement of pancreatic acinar cell apoptosis and its relation to glucocorticoid exposure were investigated in spontaneously occurring chronic pancreatitis in male Wistar Bonn/Kobori (WBN/Kob) rats. Although most lobules were not inflamed in 10-week-old WBN/Kob, increased apoptosis of pancreatic acinar cells, confirmed by TUNEL staining was focally observed (0.10 +/- 0.10 vs. 0.05 +/- 0.10/field in 10-week Wistar rats). Localized hemorrhagic lesions and brown foci in the splenic lobes were apparent, with significant decrease in pancreas weight in 20-week WBN/Kob rats along with marked apoptosis (1.95 +/- 0.31 vs. 0.07 +/- 0.04/field in 20-week Wistar rats). Electron microscopy revealed apoptotic bodies to be present in acinar cells. Pancreatic myeloperoxidase activities, indirect indices of granulocyte infiltration, as well as histologic scores were significantly increased at 15 and 20 weeks, and endogenous corticosterone levels were significantly decreased at 10, 15, and 20 weeks as compared with values for age-matched Wistar rats. Prednisolone in the drinking water (0.01 mg/mL; calculated dose, 1.03 0.03 mg/kg/d) for 10 weeks significantly attenuated increases in numbers of apoptotic acinar cells and pancreatic myeloperoxidase activities and tended to reduce the histologic scores in 20-week WBN/Kob rats as compared with the vehicle group. In summary, (a) apoptosis of pancreatic acinar cells is involved in chronic pancreatitis, (b) endogenous corticosterone is decreased, and (c) prednisolone treatment attenuates both apoptosis of pancreatic acinar cells and chronic pancreatitis in male WBN/Kob rats. We conclude that apoptosis of acinar cells related to decreased corticosterone may be a trigger of chronic pancreatitis in this model.     

Effect of buprenorphine on pancreatic enzyme synthesis and secretion in normal rats and rats with acute edematous pancreatitis

Pancreatic enzyme secretion is inhibited during acute pancreatitis, resulting in an increase in acinar zymogen content. Since the premature activation of zymogens has been assigned a central role in the pathogenesis of acute pancreatitis, minimizing the amount of stored zymogens might lead to less severe acute pancreatitis. Inhibition of enzyme synthesis or stimulation of enzyme secretion would result in reduction of zymogen stores. Opiates have a varying effect on pancreatic secretion, depending on the dosage, site of administration, and presence of pancreatic stimulants. The effect of opiates and acute pancreatitis on individual pancreatic enzyme synthesis is unknown. The following study was undertaken in order to examine the effects of an opiate on pancreatic enzyme secretion and synthesis during experimental acute pancreatitis. Four groups of rats were studied. Group I received cerulein (25 µg/kg); group II received an opiate, buprenorphine (BPN, 0.5 mg/kg); and group III received cerulein and BPN. Drugs were dissolved in gelatin/saline and injected subcutaneously. A control group (group IV) received only gelatin/saline. Rats were sacrificed 4 hr after injection, and pancreatic mass was measured. Pancreatic acini were prepared and assayed for amylase and DNA content. Amylase, trypsinogen, chymotrypsinogen and lipase synthesis, and amylase secretion were measured for 2 hr. Results showed that, compared to controls, acini of rats with AP had increased amylase content, a finding consistent with decreasedin vivo amylase secretion. Total protein and individual enzyme synthesis rates were significantly lower in the acini of the rats with AP than in those of the controls. Negative feedback inhibition of enzyme synthesis due to the increased stores of intracellular enzymes may account for these findings. BPN reduced pancreatic edema in rats with acute pancreatitis (AP). Acinar amylase content of rats with AP treated with BPN was significantly lower than in acini of rats with AP. As amylase secretion was lower in the AP + BPN rats, the reduced acinar amylase content was probably solely due to the reduction in enzyme synthesis observed in the AP + BPN rats. The results suggest that BPN may have a moderating effect on the development of AP.This study was supported by a research grant from the South African Medical Research Council.     

奥曲肽治疗急性坏死性胰腺炎作用机制的实验研究

目的 探讨奥曲肽治疗急性坏死性胰腺炎（ＡＮＰ）的作用机制。方法 作者采用核素示踪和放射自显影技术,研究了奥曲肽对正常大鼠和大鼠ＡＮＰ时胰腺泡细胞氨基酸摄取、酶蛋白合成及分泌功能的影响。结果 奥曲肽对正常胰腺腺泡细胞和呈点同血坏死的ＡＶＰ胰腺腺细胞氨基酸摄取、酶蛋白合成均无明显影响,但可明显抑制胰腺腺胞细胞的外作泌功能,导致细胞内酶原颗粒积聚,ＡＮＰ时胰腺腺泡细胞出现底膜及侧膜异位分泌,奥曲肽能够减     

Time course and cellular source of pancreatic regeneration following acute pancreatitis in the rat

The regenerative capacity of the different cell types in the rat exocrine pancreas has been studied in a model of hormone-induced acute pancreatitis in which pancreatic edema, inflammation, and acinar cell destruction were induced within 12 h of infusion of supramaximal concentrations of cerulein (5 micrograms/kg/h). A sequential biochemical and structural analysis of the pancreas in daily intervals was combined with the autoradiographic quantitation of labeling indices of five cell populations following 3H-thymidine injection at days 1-7 after induction of pancreatitis. Desquamation of acinar cell apical cytoplasm and release of cytoplasmic segments into the acinar lumen on the first day following induction of pancreatitis led to formation of duct-like tubular complexes. Enzyme content in the pancreas decreased progressively following the formation of the edema to levels 15-20% of controls and remained reduced during the initial 5 days. Thymidine incorporation into total DNA showed a biphasic pattern with a distinct peak at day 1 and a second broader peak between days 4 and 7. Autoradiographic quantitation of labeling indices demonstrated the exclusive incorporation into intercalated duct cells and interstitial cells during the initial 24 h, while the second peak was predominantly due to labeling of acinar cells. Larger interlobular ducts and islets did not show changes in labeling index. In vivo labeling with 3H-thymidine during the first day and analysis of labeling indices 14 days later showed the persistence of label in intercalated duct cells and interstitial cells and argued against the stem cell hypothesis and against transformation of duct cells into acinar cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of nitric oxide in caerulein-induced acute pancreatitis and the recovery process after inflammatory damage.

OBJECTIVES: Nitric oxide (NO) is involved in the control of pancreatic blood flow and secretion, and its role in the maintenance of pancreatic tissue has been suggested. The aim of our study was to evaluate the influence of NO on pancreatic trophic parameters during acute pancreatitis induction and the pancreas recovery process. DESIGN/METHODS: Acute pancreatitis was induced in rats by a supramaximal dose of caerulein. During acute pancreatitis induction, rats were treated with L-arginine (a substrate for NO synthesis), glyceryl trinitrate (NTG, NO donor), glycine, N(G)-nitro-L-arginine (L-NNA, NO synthase inhibitor), L-arginine + L-NNA, or saline. Pancreatic weight, total contents of RNA, DNA, protein, amylase and chymotrypsin as well as pancreas histology and the number of proliferating acinar cells were evaluated after pancreatitis induction in all groups and additionally after 7 and 14 days of recovery in untreated acute pancreatitis rats or those injected with L-NNA and/or L-arginine. RESULTS: Pancreas destruction after acute pancreatitis was evidenced by similar decreases of all parameters in untreated acute pancreatitis rats or those treated with L-NNA or glycine when compared to control healthy animals. The recovery process after acute pancreatitis was not affected by L-NNA injections; however, the increased cell proliferation occurred later than in untreated rats. NTG and especially L-arginine treatment resulted in significant attenuation of pancreas damage (partially prevented by L-NNA treatment) as evidenced by biochemical data with a slight improvement in morphology. Treatment with L-arginine alone or in combination with L-NNA resulted in augmented cell proliferation after acute pancreatitis induction followed by earlier recovery in comparison to untreated acute pancreatitis rats or the L-NNA-injected group. CONCLUSION: The present study suggests the involvement of NO in mild acute pancreatitis and in the recovery process after inflammatory damage.     

Primary Culture of Pancreatic (Human) Acinar Cells

The acinar cell culture plays a very important role in research of pancreatic pathophysiology. The aim of this study was to establish a long-term culture of human (foetal) pancreatic acinar cells in standardized nutrient media with supplements. Acinar cells were prepared from pancreatic tissues obtained from aborted foetus (> or =35 weeks) with no prior pancreatic complications by collagenase digestion and cultured using different media and supplements. The purity and phenotype of acinar cells was confirmed by various staining techniques and FACS. The acinar cell proliferation was determined at different time intervals by Bromo-deoxyuridine (BrdU) incorporation, and metabolic enzyme activity was analysed. The acini could be cultured and maintained in Ham's F-12 K/M199 media in the presence of 5% BSA, 0.1 mg/ml STI, 10 ng/ml EGF, and 10% FCS with the same morphological appearance as that of freshly prepared for 12 days with maximum viability of 80-85% and formation of monolayer without extracellular matrix. A significant BrdU incorporation of acinar cells in primary culture was observed which was maximum (105%) at day four. Higher amylase and lipase activity was seen in freshly isolated acinar cells which decreased with time of the culture. The established human pancreatic acinar cell culture may act as an excellent model to study exocrine dysfunction or pancreatitis in response to acinar cell injury.     

Mechanism of octreotide in acute necrotizing pancreatitis (ANP) of rats: An experimental study

OBJECTIVE : To study the action of octreotide in acute necrotizing pancreatitis (ANP) in rats. METHODS : The effect of octreotide on pancreatic acinar cells with respect to amino acid uptake, protein synthesis and secretion of enzymes was observed by using radioactive tracing and autoradiography on both healthy rats and rats with ANP. RESULTS : It was shown that octreotide has no effect on pancreatic acinar cells with respect to amino acid uptake and protein synthesis in both ANP and in control rats. However, octreotide was able to inhibit the secretion of enzyme‐proteins. There were secretions from the basolateral membrane of the acinar cells in ANP rats, which could be reduced by treatment with octreotide. CONCLUSIONS : Octreotide has no effect on pancreatic acinar cells with respect to amino acid uptake and enzyme‐protein synthesis, but it can inhibit the secretion of enzyme‐proteins, in particular, from the basolateral membrane of ANP rats and prevent the accumulation of zymogen granules in the interstitium.     

Effects and mechanisms of somatostatin analogs on apoptosis of pancreatic acinar cells in acute pancreatitis in mice

AIM: To investigate the effects of somatostatin analogs (SSa) on apoptosis of pancreatic acinar cells and apoptosis-regulated gene bax, and p53 in treating acute pancreatitis in mice. METHODS: In cerulein-induced pancreatitis, with or without treatment of somatostatin, analogs (Octreotide) in CD-1 (BALB/c x DBetaAlpha/1) mice, apoptosis of pancreatic acinar cells was detected by using the TdT-mediated dUTP nick-end labeling (TUNEL) method, and the expression of apoptosis-regulated gene bax and p53 was determined by using the streptavidin-peroxidase immunohistochemical technique and the RT-PCR method, respectively. RESULTS: On HE staining, acinar cells in the pancreas showed pyknotic nuclei and the formation of apoptotic bodies, which are the typical morphological features of apoptosis. Regarding TUNEL use, the apoptotic index of pancreatic acinar cells in the non-treated group at 5 and 14 h after induction of acute pancreatitis was significantly lower than those of the SSa-treated group, respectively (P < 0.01). On immunohistochemistry and RT-PCR, there was an expression of neither bax nor p53 in normal pancreatic tissues. The expression of bax in the SSa-treated group at 5 and 14 h after treatment of SSa was markedly higher than those of the non-treated group, respectively (P < 0.01), but there was no significant difference in the expression of p53 between the SSa-treated group and the non-treated group. CONCLUSIONS: The induction of apoptosis in pancreatic acinar cells injury to reduce inflammatory reaction might be one of the mechanisms of SSa in treating acute pancreatitis in mice, and the mechanisms of apoptosis probably correlated with the expression of apoptosis-regulated gene bax, but have no relationship with the expression of p53.     

Tubular complexes in cerulein- and oleic acid-induced pancreatitis in rats: glycoconjugate pattern, immunocytochemical, and ultrastructural findings

Ductlike tubular complexes in cerulein-induced pancreatitis and oleic acid-induced pancreatic insufficiency were studied to analyze further their origin and development. Immunocytochemistry for pancreatic enzymes, lectin-binding studies, and ultrastructural investigations were combined with autoradiographic quantitation of labeling indices of ductlike cells in tubular complexes. In one group of rats, pancreatitis was induced by infusion of cerulein (10 micrograms kg-1 h-1). In a second group, pancreatic insufficiency was induced by intraductal injection of oleic acid (50 microliters). The investigations were carried out at distinct intervals following induction of pancreatic injury. In both groups of animals, after 3 days, a significant widening of acinar lumina was paralleled by a decreasing height of acinar cells, which showed pronounced retrogressive changes. At this time, acinar cells bound all of the lectins used and retained their immunoreactivity for amylase, trypsinogen, chymotrypsinogen, and lipase. At further intervals, acinar structures formed typical ductlike complexes, with a progressive loss of immunoreactivity for pancreatic enzymes and a reduced lectin-binding for L-fucose and N-acetylgalactosamine. Autoradiographic quantitation demonstrated no significant labeling of acinar cells undergoing tubular dedifferentiation. In both models, tubular complexes were removed by macrophages. It is concluded that lining cells in tubular complexes represent degenerating acinar cells that have no regenerative potency and have lost their secretory and membrane characteristics.     

Proliferative response of different exocrine pancreatic cells after surgical pancreaticobiliary diversion in the rat

Pancreaticobiliary diversion (PBD) is known to induce chronic, endogenous hypercholecystokininemia causing pancreatic growth in rats. In the present study the proliferative response of the different exocrine pancreatic cells was studied by administration of 3H-thymidine, 1 mCi/kg, given 1 h before the rats were killed and 5, 10, 20, and 40 days after PBD. DNA and 3H-thymidine uptake, both expressed per 1 mg of pancreatic tissue, were significantly increased on day 5. The nuclear labeling index was increased fivefold in both the acinar and ductal cell group. In the centroacinar cell group the labeling index was increased on day 10. In conclusion, we found that the proliferative activity after PBD occurred during the first 10 days and that the ductal cells were forced into proliferation to the same extent as the acinar ones. These findings are of interest for future studies of hormonal influences on the development of pancreatic carcinoma.     

New model of acute necrotizing pancreatitis induced by excessive doses of arginine in rats

We examined the biological and histologic characteristics of a new experimental model of acute necrotizing pancreatitis induced by excessive doses of arginine in rats. Rats were given a single intraperitoneal injection of 500 mg/100 g body weight of L-arginine. At 12-24 hr after the arginine injection, serum levels of amylase, lipase, and anionic trypsin(ogen) reached respective peak values 2, 5, and 20 times those of control rats without arginine and returned to control levels after 24-48 hr. The contents of pancreatic protein, DNA, and digestive enzymes were markedly reduced after the arginine injection and reached their nadirs at 72 hr. After 14 days these levels were almost normal. Histologic examination revealed a number of small vesicles within acinar cells at 6 hr, which were identified as markedly swollen mitochondria by the electron microscope. Other intracellular organelles and nuclei also showed degenerative changes. At 12 hr interstitial edema appeared, and acinar cell necrosis was seen after 24 hr. The extent and severity of necrotic changes of pancreatic exocrine tissue with inflammatory cell infiltration were maximal at 72 hr. At seven days, pancreatic acinar cells began to regenerate, and pancreatic architecture appeared almost normal after 14 days. The present study has demonstrated that the administration of excessive doses of arginine induces a new, noninvasive experimental model of acute necrotizing pancreatitis.     

川芎嗪诱导急性胰腺炎胰腺细胞凋亡及其机制的初步研究

目的研究川芎嗪（tetramethylpyrazine,TMP）对大鼠急性胰腺炎（acutepancreatitis,AP）的治疗作用,并探讨川TMP治疗AP的机理。方法采用腹腔内注射蛙皮素制备急性水肿型胰腺炎（acuteedematouspancreatitis,AEP）模型,腹腔内注射TMP,端口标记法（triphosphate-biotinnick-endlabeling,TUNEL）检测胰腺腺泡细胞凋亡,免疫组化法检测Bax基因表达,同时观察IL-6、TNF-α、CRP、AMY等变化,并进行胰腺组织形态学检查。结果采用蛙皮素腹腔注射造成AEP,发现AEP胰腺存在明显细胞凋亡。TMP可以抑制IL-6、TNF-α、CRP等表达,上调促凋亡基因Bax的表达,诱导AEP胰腺细胞凋亡。结论TMP对AEP有明显疗效,其机制与降低IL-6、TNF-α含量,抑制CRP等表达,上调促凋亡基因Bax表达,促进胰腺细胞凋亡有关。     

Pancreatic exocrine function during acute exacerbation in WBN/Kob rats with spontaneous chronic pancreatitis

Summary Conclusion Pancreatic exocrine hypofunction is markedly deteriorated during acute exacerbation in a rat model with chronic pancreatitis. Background Little is known about pancreatic exocrine function during acute exacerbation in patients with chronic pancreatitis. We investigated changes in pancreatic exocrine function after inducing acute pancreatitis in an animal model of spontaneous chronic pancreatitis. Methods WBN/Kob rats with chronic pancreatitis sequentially underwent pancreatic exocrine function test 1–6 d after surgical preparation with external pancreatic fistula. We induced acute pancreatitis in another WBN/Kob rats by iv administration of cerulein at a rate of 10 μg/kg/h for 4 h 4 after surgical preparation. Pancreatic exocrine function test was undertaken in a conscious state 1 d before and after cerulein administration. Results In WBN/Kob rats not given cerulein, pancreatic exocrine function remained almost constant, at 3–6 d after surgery. Marked hyperamylasemia developed immediately after cerulein administration. After its administration, the pancreas microscopcially showed prominent intersitial edema and intracellular vacuolization of acinar cells in addition to the finding of pre-existing chronic pancreatitis. Basal and chole-cystokinin-stimulated flow rate, bicarbonate output, and protein output, which were substantially impaired 1 d before cerulein administration, were further reduced 1 d after its administration.     

Pioglitazone, a specific ligand of peroxisome proliferator-activated receptor-gamma, protects pancreas against acute cerulein-induced pancreatitis

ABM: To determine the effect of pioglitazone, a specific peroxisome proliferator-activated receptor-γ(PPARγ) ligand, on the development of acute pancreatitis (AP) and on the expression of heat shock protein 70 (HSP70) in the pancreas. METHODS: AP was induced in rats by subcutaneous infusion of cerulein for 5 h. Pancreatic blood flow was measured by laser Doppler flowmetry. Plasma lipase activity, interleukin-1β (IL-1β) and IL-10 were determined, Pancreatic weight and histology were evaluated and pancreatic DNA synthesis and blood flow as well as pancreatic mRNA for IL-1β and HSP70 were assessed in rats treated with pioglitazone alone or in combination with cerulein. RESULTS: Pioglitazone administered (10-100 mg/kg i.g.) 30 min before cerulein, attenuated dose-dependently the pancreatic tissue damage in cerulein-induced pancreatitis (CIP) as demonstrated by the improvement of pancreatic histology, reduction in plasma lipase activity, plasma concentration of pro-inflammatory IL-1β and its gene expression in the pancreas and attenuation of the pancreatitis-evoked fall in pancreatic blood flow. CIP increased pancreatic HSP70 mRNA and protein expression in the pancreas and this effect was enhanced by pioglitazone treatment. CONCLUSION: Pioglitazone attenuates CIP and the beneficial effect of this pioglitazone is multifactorial probably due to its anti-inflammatory activities, to the suppression of IL-1β and to the over-expression of HSP70. PPARγ ligands could represent a new therapeutic option in the treatment of AP.