Pancreatic Ischemia-reperfusion Research Articles

Oleuropein Relieves Pancreatic Ischemia Reperfusion Injury in Rats by Suppressing Inflammation and Oxidative Stress through HMGB1/NF-κB Pathway.

Oleuropein (OLP) is a naturally occurring phenolic compound in olive plant with antioxidant and anti-inflammatory potential and can possibly be used in treating pancreatic injuries. This investigation aimed to follow the molecular mechanism behind the potential therapeutic effect of OLP against pancreatic injury persuaded by ischemia-reperfusion (I/R). Pancreatic I/R injury was induced by splenic artery occlusion for 60 min followed by reperfusion. Oral administration of OLP (10 and 20 mg/kg) for 2 days significantly alleviated I/R-persuaded oxidative damage and inflammatory responses in pancreatic tissue as indicated by the decreased malondialdehyde (MDA) content and increased glutathione peroxidase (GPx) activity, accompanied by the suppression of myeloperoxidase (MPO) activity and reduced levels of interleukin-1beta (IL-1β), nuclear factor kappa B (NF-κB), and tumor necrosis factor alpha (TNF-α) in pancreatic tissues. Furthermore, OLP treatment markedly restored the serum levels of amylase, trypsinogen-activated peptide (TAP), and lipase, with concurrent improvement in pancreatic histopathological alterations. Moreover, treatment with OLP regulated the pancreatic expression of inducible nitric oxide synthase (iNOS) and high-mobility group box 1 (HMGB1) relative to rats of the pancreatic IR group. Thus, OLP treatment significantly alleviates the I/R-induced pancreatic injury by inhibiting oxidative stress and inflammation in rats through downregulation of HMGB1 and its downstream NF-κB signaling pathway.

Dexmedetomidine's Effects on the Livers and Kidneys of Rats with Pancreatic Ischemia-Reperfusion Injury.

Pancreatic surgeries inherently cause ischemia-reperfusion (IR) injury, affecting not only the pancreas but also distant organs. This study was conducted to explore the potential use of dexmedetomidine, a sedative with antiapoptotic, anti-inflammatory, and antioxidant properties, in mitigating the impacts of pancreatic IR on kidney and liver tissues. A total of 24 rats were randomly divided into four groups: control (C), dexmedetomidine (D), ischemia reperfusion (IR), and dexmedetomidine ischemia reperfusion (D-IR). Pancreatic ischemia was induced in the IR and D-IR groups. Dexmedetomidine was administered intraperitoneally to the D and D-IR groups. Liver and kidney tissue samples were subjected to microscopic examinations after hematoxylin and eosin staining. The levels of thiobarbituric acid reactive substances (TBARS), aryllesterase (AES), catalase (CAT), and glutathione S-transferase (GST) enzyme activity were assessed in liver and kidney tissues. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine were measured. A comparison of the groups revealed that the IR group exhibited significantly elevated TBARS (p<0.0001), AES (p=0.004), and CAT enzyme activity (p<0.0001) levels in the liver and kidney compared to groups C and D. Group D-IR demonstrated notably reduced histopathological damage (p<0.05) and low TBARS (p<0.0001), AES (p=0.004), and CAT enzyme activity (p<0.0001) in the liver and kidney as well as low AST and ALT activity levels (p<0.0001) in the serum compared to the IR group. The preemptive administration of dexmedetomidine before pancreatic IR provides significant protection to kidney and liver tissues, as evidenced by the histopathological and biochemical parameters in this study. The findings underscored the potential therapeutic role of dexmedetomidine in mitigating the multiorgan damage associated with pancreatic surgeries.

Pancreatic Ischemia-Reperfusion Injury Following Endovascular Treatment of Symptomatic Celiac and Superior Mesenteric Artery Stenosis.

With endovascular therapy becoming the first-line treatment for symptomatic chronic mesenteric ischemia, acute pancreatitis within the context of abdominal ischemia-reperfusion injury may be seen more often in cross-sectional imaging following this kind of interventions and should therefore be kept in mind by the reading physician.

Correlation of Different Serum Biomarkers with Prediction of Early Pancreatic Graft Dysfunction Following Simultaneous Pancreas and Kidney Transplantation.

Background: Despite recent advances and refinements in perioperative management of simultaneous pancreas–kidney transplantation (SPKT) early pancreatic graft dysfunction (ePGD) remains a critical problem with serious impairment of early and long-term graft function and outcome. Hence, we evaluated a panel of classical blood serum markers for their value in predicting early graft dysfunction in patients undergoing SPKT. Methods: From a prospectively collected database medical data of 105 patients undergoing SPKT between 1998 and 2018 at our center were retrospectively analyzed. The primary study outcome was the detection of occurrence of early pancreatic graft dysfunction (ePGD), the secondary study outcome was early renal graft dysfunction (eRGD) as well as all other outcome parameters associated with the graft function. In this context, ePGD was defined as pancreas graft-related complications including graft pancreatitis, pancreatic abscess/peritonitis, delayed graft function, graft thrombosis, bleeding, rejection and the consecutive need for re-laparotomy due to graft-related complications within 3 months. With regard to analyzing ePGD, serum levels of white blood cell count (WBC), C-reactive protein (CRP), procalcitonin (PCT), pancreatic lipase as well as neutrophil–lymphocyte ratio (NLR) and platelet–lymphocyte ratio (PLR) were measured preoperatively and at postoperative days (POD) 1, 2, 3 and 5. Further, peak serum levels of CRP and lipase during the first 72 h were evaluated. Receiver operating characteristics (ROC) curves were performed to assess their predictive value for ePGD and eRGD. Cut-off levels were calculated with the Youden index. Significant diagnostic biochemical cut-offs as well as other prognostic clinical factors were tested in a multivariate logistic regression model. Results: Of the 105 patients included, 43 patients (41%) and 28 patients (27%) developed ePGD and eRGD following SPKT, respectively. The mean WBC, PCT, NLR, PLR, CRP and lipase levels were significantly higher on most PODs in the ePGD group compared to the non-ePGD group. ROC analysis indicated that peak lipase (AUC: 0.82) and peak CRP levels (AUC: 0.89) were highly predictive for ePGD after SPKT. The combination of both achieved the highest AUC (0.92; p < 0.01) in predicting ePGD. Concerning eRGD, predictive accuracy of all analyzed serological markers was moderate (all AUC < 0.8). Additionally, multivariable analysis identified previous dialysis/no preemptive transplantation (OR 2.4 (95% CI: 1.41–4.01), p = 0.021), donor age (OR 1.07 (95% CI: 1.03–1.14), p < 0.010), donor body mass index (OR 1.32 (95% CI: 1.01–1.072), p = 0.04), donors cerebrovascular cause of death (OR 7.8 (95% CI: 2.21–26.9), p < 0.010), donor length of ICU stay (OR 1.27 (95% CI: 1.08–1.49), p < 0.010), as well as CIT pancreas (OR 1.07 (95% CI: 1.03–1.14), p < 0.010) as clinical relevant prognostic predictors for ePGD. Further, a peak of lipase (OR 1.04 (95% CI: 1.02–1.07), p < 0.010), peak of CRP levels (OR 1.12 (95% CI: 1.02–1.23), p < 0.010), pancreatic serum lipase concentration on POD 2 > 150 IU/L (OR 2.9 (95% CI: 1.2–7.13), p = 0.021) and CRP levels of ≥ 180 ng/mL on POD 2 (OR 3.6 (95% CI: 1.54–8.34), p < 0.01) and CRP levels > 150 ng/mL on POD 3 (OR 4.5 (95% CI: 1.7–11.4), p < 0.01) were revealed as independent biochemical predictive variables for ePGD after transplantation. Conclusions: In the current study, the combination of peak lipase and CRP levels were highly effective in predicting early pancreatic graft dysfunction development following SPKT. In contrast, for early renal graft dysfunction the predictive value of this parameter was less sensitive. Intensified monitoring of these parameters may be helpful for identifying patients at a higher risk of pancreatic ischemia reperfusion injury and various IRI- associated postoperative complications leading to ePGD and thus deteriorated outcome.

The effects of profound hypothermia on pancreas ischemic injury: a new experimental model.

Pancreatic ischemia-reperfusion (IR) has a key role in pancreas surgery and transplantation. Most experimental models evaluate the normothermic phase of the IR. We proposed a hypothermic model of pancreas IR to evaluate the benefic effects of the cold ischemic phase. We performed a reproducible model of hypothermic pancreatic IR. The ischemia was induced in the pancreatic tail portion (1-hour ischemia, 4-hour reperfusion) in 36 Wistar rats. They are divided in 3 groups as follows: group 1 (control), sham; group 2, normothermic IR; and group 3, hypothermic IR. In group 3, the temperature was maintained as close to 4.5°C. After reperfusion, serum amylase and lipase levels, inflammatory mediators (tumor necrosis factor α, interleukin 6), and pancreas histology were evaluated. In pancreatic IR groups, amylase, cytokines, and histological damage were significantly increased when compared with group 1. In the group 3, we observed a significant decrease in tumor necrosis factor α (P = 0.004) and interleukin 6 (P = 0.001) when compared with group 2. We did not observe significant difference in amylase (P = 0.867), lipase (P = 0.993), and histology (P = 0.201). In our experimental model, we reproduced the cold phase of pancreas IR, and the pancreas hypothermia reduced the inflammatory mediators after reperfusion.

Upregulation of IL-1β, IL-6, and CCL-2 by a novel mouse model of pancreatic ischemia-reperfusion injury.

Little is known about the immunologic events surrounding pancreatic ischemia-reperfusion injury (IRI) because of a lack of established experimental models. The purpose of this study was to develop a mouse model for pancreatic IRI to serve as a basis for the immunologic characterization of pancreatic organ damage at transplantation. Reversible ischemia was surgically induced by vascular isolation of the distal pancreas for 0, 10, 20, or 30 min. Mice receiving laparotomy without clamping served as sham-operated controls. After reperfusion, mice were serially assayed for biochemical and histologic evidence of inflammation, proinflammatory cytokine and chemokine production, and inflammatory gene upregulation. After induction of pancreatic IRI, serum amylase and lactate dehydrogenase peaked at 6 hr and returned to baseline by 120 hr after injury in all groups. Mice undergoing 30 min of IRI demonstrated the greatest biochemical evidence of inflammation. Histologic scoring similarly demonstrated marked inflammation in mice subjected to 30-min IRI compared with controls. Serum cytokine/chemokine analysis demonstrated significant upregulation of granulocyte colony-stimulating factor, interferon γ, tumor necrosis factor α, interleukin (IL)-2, IL-1β, IL-6, chemokine (C-C motif) ligand-2, chemokine (C-C motif) ligand-5, chemokine (C-X-C motif) ligand-1, and macrophage inflammatory protein 2. A similar upregulation of ccl2, il1b, il6, fos, hspa1a, hspd1, and cd14 gene expression was detected by real-time polymerase chain reaction analysis of pancreatic tissue. This novel model of distal pancreatic IRI in the mouse demonstrates time-limited pancreatic inflammation and injury by histologic and biochemical indices. Inflammation may be, in part, a result of the immunologic effects of IL-1β, IL-6, and CCL-2. This model provides a method by which immunologic mechanisms of pancreatic IRI can be elucidated.

Blood Modulates the Kinetics of Reactive Oxygen Release in Pancreatic Ischemia-Reperfusion Injury

Reason for the unsuccessful use of antioxidants in transplantation might be the unknown kinetics of reactive oxygen species (ROS) release. In this study, we compared the kinetics of ROS release from rat pancreata in the presence and absence of blood. In vivo, ischemia-reperfusion injury (IRI) was induced in pancreata of male Wistar rats by occlusion of the arterial blood supply for 1 or 2 hours. In vitro, isolated pancreata were single-pass perfused with Krebs-Henseleit bicarbonate solution. Reactive oxygen species were quantified by electron spin resonance spectroscopy using CMH (1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine) as spin label. Thiols (glutathione), nicotinamide adenine dinucleotide phosphate-oxidase activity, myeloperoxidase activity, and adenosine triphosphate content were measured. During reperfusion, an increase in IRI-induced ROS in arterial blood was noted after 2 hours of warm ischemia. In sharp contrast, ROS release was immediate and short lived in blood-free perfused organs. The degree of tissue damage correlated with nicotinamide adenine dinucleotide phosphate-oxidase activity and adenosine triphosphate content. Antioxidative capacity of tissues was reduced. Electron spin resonance spectroscopy in conjunction with spin labels allows for the detection of ROS kinetics in pancreatic IRI. Reactive oxygen species kinetics are dependent on the length of the ischemic period and the presence or absence of blood.

Protective Effects of Deferoxamine Mesylate Preconditioning on Pancreatic Tissue in Orthotopic Liver Autotransplantation in Rats

Background Deferoxamine mesylate is known to ameliorate tissue ischemia–reperfusion injury. This study was designed to explore the impact of deferoxamine mesylate preconditioning (DMP) on pancreatic tissue and its possible effects during orthotopic liver autotransplantation. Methods A modified orthotopic liver autotransplantation model was used to simulate pancreatic ischemia–reperfusion injury. Sprague-Dawley rats (0.25–0.30 kg) were randomly divided into normal control, autotransplantation (AT), systemic deferoxamine mesylate preconditioning (SDMP), and partial deferoxamine mesylate conditioning (PDMC) groups. The SDMP group was injected with deferoxamine mesylate (75–90 mg; 300 mg/kg), via the celiac artery at 24 and 48 hours before surgery. During surgery, the PDMC group underwent liver perfusion by means of deferoxamine mesylate solution (20 ml; 0.6 mmol/L) rather than Ringer's lactate solution, with no prior preconditioning. At 6, 24, and 48 hours after surgery, the rats were sacrificed to sample their pancreatic tissues for the expression of hypoxia-inducible factor-1α (HIF-1α) and malondialdehyde (MDA) content. The samples were subjected to blood chemistry analyses, light and transmission electron microscopic morphological studies, and quantitative measurement of HIF-1α expression. Results The serum levels of amylase, lipase, and MDA in SDMP and PDMC groups were significantly lower than those in the AT group at 6, 24, and 48 hours after orthotopic liver autotransplantation ( P < .05). Light and electron microscopic analyses showed much more severe pancreatic injury in the autotransplantation than in the SDMP and PDMC groups. The HIF-1α expression was increased in the SDMP and PDMC groups more than in the autotransplantation group ( P < .05). Conclusions Deferoxamine mesylate preconditioning protected pancreatic tissue in orthotopic liver autotransplantation in rats. Inhibition of oxidative toxic reactions and up-regulated expression of HIF-1α protein are possible mechanisms.

Cytokine Suppressive Agent Prevents Pancreatic Injuries Induced by Ischemia-Reperfusion in Rats.

This study was designed to evaluate the possible role of cytokines (IL-1 and TNF-alpha) in the pathogenesis of pancreatic injuries induced by pancreatic ischemia-reperfusion and to evaluate the protective effect of the cytokine suppressive agent, FR167653, against pancreatic injuries. Pancreatic ischemia-reperfusion was induced in rats by ligating the celiac and caudate mesenteric arteries by small metallic clips for 45 min, after this ischemia, the metal clips were removed. Four hours after removing the metal clips, the animals were used for the experiments. In this model, mild hyperamylsemia and significant increases in pancreatic water and trypsin content were observed. Significant increases in serum IL-1 and TNF-alpha were also observed, as compared with the control rats. Pancreatic subcellular redistribution of lysosomal enzyme cathepsin B from the lysosomal fraction to the zymogen fraction was also observed. However, treatment with FR167653 at a dose of 0.5 mg/kg.hr significantly prevented all these pancreatic injuries. These results indicate that cytokines such as IL-1 and TNF-alpha might be involved in the pathogenesis of pancreatic injuries induced by ischemia-reperfusion, and that a cytokine suppressive agent might be of therapeutic value for the treatment of pancreatic ischemia.

Beneficial Effects of N-Acetyl Cysteine on Pancreas and Kidney Following Experimental Pancreatic Ischemia-Reperfusion in Rats

OBJECTIVE:To evaluate the protective effects of N-acetyl cysteine on the pancreas and kidney after pancreatic ischemia reperfusion injury in a rat model.METHODS AND MATERIALS:Pancreatic ischemia reperfusion was performed in Wistar rats for 1 hour. Revascularization was achieved followed by 4 h of reperfusion. A total of 24 animals were divided into four groups: Group 1: sham; Group 2: pancreatic ischemia reperfusion without treatment; Group 3: pancreatic ischemia reperfusion plus N-acetyl cysteine intravenously; and Group 4: pancreatic ischemia reperfusion plus N-acetyl cysteine per os. Blood and tissue samples were collected after reperfusion.RESULTS:There were significant differences in amylase levels between Group 1 (6.11±0.55) and Group 2 (10.30±0.50) [p=0.0002] as well as between Group 2 (10.30±0.50) and Group 4 (7.82±0.38) [p=0.003]; creatinine levels between Group 1 (0.52 ± 0.07) and Group 2 (0.77±0.18) [p=0.035] as well as between Group 2 (0.77±0.18) and Group 3 (0.48±0.13) [p=0.012]; and pancreatic tissue thiobarbituric acid reactive substance levels between Group 1 (1.27±0.96) and Group 2 (2.60±3.01) [p=0.026] as well as between Group 2 (2.60±3.01) and Group 4 (0.52±0.56) [p=0.002]. A decrease in pancreatic tissue GST-α3 gene expression was observed in Group 2 in comparison to Group 1 (p =0.006), and an increase was observed in Groups 3 and 4 when compared to Group 2 (p= 0.025 and p=0.010, respectively).CONCLUSION:This study provides evidence that N-acetyl cysteine has a beneficial effect on pancreatic ischemia reperfusion injury and renal function in a rat model.

Sirolimus Improves Early Microcirculation, but Impairs Regeneration After Pancreatic Ischemia-Reperfusion Injury

Ischemia and reperfusion injury remains a relevant problem in clinical pancreas transplantation. We investigated the effect of sirolimus (SRL) in a rodent model of 90-min warm pancreatic ischemia. Four groups were studied: (1) sham surgery and vehicle; (2) sham surgery and SRL; (3) warm ischemia and vehicle; (4) warm ischemia and SRL. SRL (1.5 mg/kg/day) and vehicle were administered intraperitoneally for 3 days prior to surgery until the animals were killed. Microcirculation was assessed immediately after reperfusion by means of intravital fluorescence microscopy. Histopathological injury, apoptosis, proliferation and biochemical parameters were analyzed at 2 h, 1 day and 5 days after surgery. Ninety minutes after ischemia, intravital microscopy revealed an improved functional capillary density (p < 0.05) and reduction of adherent leucocytes (p < 0.01) and platelets (p < 0.05) in the SRL-treated group compared to the vehicle-treated controls. In contrast, on day 5 after ischemia, the pancreatic tissue of SRL-treated animals showed a higher grade of histological injury (p < 0.05) and higher rate of apoptotic cells (p < 0.05) than the vehicle controls. In summary, our data indicate that administration of SRL improves microcirculation at a very early stage, but results in an impairment of the recovery phase after pancreatic ischemia-reperfusion injury.

Protective Effect of Endotoxin Preconditioning in Pancreas: Analysis With DNA Chip Arrays

Recently we demonstrated a protective effect of endotoxin preconditioning 24 hours before pancreatic ischemia-reperfusion injury, which has also been described for other organs. The mechanisms underlying this phenomenon, such as differential gene expression, are poorly investigated. We chose to approach this question by investigating differential gene expression in the rat pancreas over the time course of endotoxin pretreatment. Male Wistar rats (5 groups, 5 animals per group) were pretreated with endotoxin intraperitoneally (1 mg/kg of body weight). After treatment at 30 minutes, and at 3 and 24 hours the pancreas was removed. Untreated animals and animals with injection of saline solution served as controls. After RNA isolation, RNA was pooled and hybridized to Affymetrix chips to measure the relative mRNA levels of 7000 genes and 1000 expression sequence tags. Three hours after administration of endotoxin there was an activation of proinflammatory transcription factors and other proinflammatory genes. After 24 hours there was a clear decrease of these proinflammatory genes, but a remaining and increasing upregulation of important antiapoptotic genes, antiproteases, and other probably protective genes. There was also a significant upregulation of complement factors. It was surprising that heat-shock proteins and other typical immediate early genes of the AP-1 complex were not upregulated. Our data show that 24 hours after endotoxin stress there is a regulation of a network of genes that represents a multifaceted preconditioning. As most important factors, inhibition of apoptosis and antiproteatic strategies are identified. Heat-shock proteins seem to play no important role in the mechanism of endotoxin preconditioning.

Pancreatic Trypsin Increases Matrix Metalloproteinase-9 Accumulation and Activation during Acute Intestinal Ischemia-Reperfusion in the Rat

Ischemia-reperfusion of the intestine produces a set of inflammatory mediators, the origin of which has recently been shown to involve pancreatic digestive enzymes. Matrix metalloproteinase-9 (MMP-9) participates in a variety of inflammatory processes including myocardial, hepatic, and pancreatic ischemia-reperfusion. In the present study, we explore the role of neutrophil-derived MMP-9 in acute intestinal ischemia-reperfusion and its interaction with pancreatic trypsin. Male Sprague-Dawley rats were subjected to 45 minutes of superior mesenteric arterial occlusion followed by 90 minutes of reperfusion. In situ zymography of the proximal jejunum reveals increased gelatinase activity in the intestinal wall after ischemia-reperfusion. Gel electrophoresis zymography and immunofluorescence co-localization suggests that this gelatinase activity is derived from MMP-9 released from infiltrating neutrophils. The role of intraluminal trypsin in this process was investigated using an in vivo isolated jejunal loop model of intestinal ischemia-reperfusion. Trypsin increased the inflammatory response after reperfusion, with an augmented neutrophil infiltration of the intestinal wall. Furthermore, trypsin stimulated a rapid conversion of neutrophil-released proMMP-9 into the lower molecular weight enzymatically active MMP-9. This process represents a powerful in vivo pathophysiological mechanism for trypsin-induced MMP-9 activation and is likely to play a central role in the development of acute intestinal inflammation and shock.

Characterization of microcirculatory disturbance in a novel model of pancreatic ischemia-reperfusion using intravital fluorescence-microscopy.

Microcirculatory disturbances caused by ischemia-reperfusion injury (IRI) are the crucial hallmarks of pancreatitis following pancreas transplantation. To develop a novel rodent model of normothermic in situ ischemia of a pancreatic tail-segment that simulates the clinical situation of pancreas transplantation by flushing the organ via an inserted microcatheter and thus enables selective treatment of the organ via this access. Four experimental groups were investigated (n = 7 Wistar rats/group): sham animals without ischemia and dissection of the pancreas; control animals with dissection of a pancreatic tail segment pedunculated on the splenic vessels and flushing od this segment with saline via a microcatheter; and two groups of animals treated like controls with a pancreatic ischemia time of 1 hour or 2 hours. With use of intravital epifluorescence microscopy, the microcirculatory damage was characterized by investigation of functional capillary density (FCD) and leukocyte adherence in postcapillary venules (LAV) before ischemia and during a reperfusion time of 2 hours. Dry:wet ratio determinations, light microscopy, and electron microscopic investigations were performed to characterize the histologic organ damage. FCD decreased significantly (p < 0.05) 2 hours after reperfusion in the groups of 1-hour (-29.21%) and 2-hour ischemia (-42.73%), in comparison with baseline values. LAV increased significantly (p < 0.05), 4.3- and 5.8-fold, after 1-hour and 2-hour ischemia during the observation time. The histologic damage was similar to posttransplantation pancreatitis in humans 1 hour after reperfusion. In sham and control animals these alterations were not significant. The rodent in situ model of pancreatic IRI showed standardized microcirculatory damage dependent on the ischemia time. Offering the possibility of selective treatment by the direct artery access to the ischemic pancreatic area, the model enables investigations of questions related to human pancreas transplantation.

Effect of FR167653 on pancreatic ischemia-reperfusion injury in dogs

Background. The role of inflammatory cytokines is still unclear in ischemia-reperfusion injury of the pancreas. We investigated the effect of FR167653 (FR), a newly developed compound that is a potent suppressor of interleukin (IL)-1β and tumor necrosis factor (TNF)-α on ischemia-reperfusion injury of the isolated pancreatic tail in dogs. Methods. The tail of the pancreas was subjected to ischemia for 90 minutes. During occlusion of the vascular inflow, the head of the pancreas was removed. A control group (n = 14) and an FR treatment group (n = 11) were evaluated for survival rate, tissue blood flow, arterial oxygen pressure (Pao2), serum amylase and lipase levels, glucose and insulin, liver enzymes, creatinine, IL-1β mRNA in the peripheral blood, and histopathology. Results. Six of the 14 control animals and 2 of the 11 FR-treated animals died. The FR treatment group showed lower amylase (P=.037) and lipase (P =.030) levels, lower IL-1β mRNA expression (P =.033), and less pancreatic tissue damage (P =.041) than did the control group, but there was no remarkable change in endocrine function (P =.422). Pao2 during the acute phase in the FR treatment group was maintained (P=.009), but pulmonary tissue was damaged. Results of biochemical and histologic examinations of the liver and kidneys were unremarkable. Conclusions. FR ameliorates ischemia-reperfusion injury of the pancreas and reduces the production of inflammatory cytokines that may contribute to secondary damage to distant organs. (Surgery 2001;129:309-17)

Cytokine Suppressive Agent Prevents Pancreatic Injuries Induced by Ischemia-Reperfusion in Rats

This study was designed to evaluate the possible role of cytokines (IL-1 and TNF-α) in the pathogenesis of pancreatic injuries induced by pancreatic ischemia-reperfusion and to evaluate the protective effect of the cytokine suppressive agent, FR167653, against pancreatic injuries. Pancreatic ischemia-reperfusion was induced in rats by ligating the celiac and caudate mesenteric arteries by small metallic clips for 45 min, after this ischemia, the metal clips were removed. Four hours after removing the metal clips, the animals were used for the experiments. In this model, mild hyperamylsemia and significant increases in pancreatic water and trypsin content were observed. Significant increases in serum IL-1 and TNF-α were also observed, as compared with the control rats. Pancreatic subcellular redistribution of lysosomal enzyme cathepsin B from the lysosomal fraction to the zymogen fraction was also observed. However, treatment with FR167653 at a dose of 0.5 mg/kg.hr significantly prevented all these pancreatic injuries. These results indicate that cytokines such as IL-1 and TNF-α might be involved in the pathogenesis of pancreatic injuries induced by ischemia-reperfusion, and that a cytokine suppressive agent might be of therapeutic value for the treatment of pancreatic ischemia.

Possible Involvement of Nitric Oxide (NO) as a Free Radical in the Pathogenesis of Pancreatic Ischemia-Reperfusion Injuries in Rats

This study was designed to evaluate the role of nitric oxide (NO) as a free radical in the pathogenesis of pancreatic injuries induced by pancreatic ischemia-reperfusion in rats. Pancreatic ischemia-reperfusion was accomplished by reducing the mean arterial blood pressure approximately to 60% of the control values for 45 minutes with blood removal and by restoring normotension by reinfusion of the shed blood. In this model of pancreatic ischemia-reperfusion, serum amylase concentrations, pancreatic water content, and pancreatic trypsin content were significantly increased as compared with the control animals. Pancreatic superoxide dismutase (SOD) content was significantly decreased. However, pancreatic lipid peroxide (LPO) levels were significantly increased. Moreover, pancreatic subcellular redistribution of lysosomal enzyme, cathepsin B, from the lysosomal fraction to the zymogen fraction was also observed. Pretreatment with NO synthase inhibitor, N ω-nitro-L-arginine (NNA) at a dose of 20 mg/kg, significantly inhibited these changes. These results indicate that NO seems to play an important role as a free radical in the pathogenesis of pancreatic injuries induced by pancreatic ischemia-reperfusion and that NO seems to be involved in the intracellular sorting of lysosomal enzymes in the pancreatic acinar cells during pancreatic ischemia-reperfusion.

Detection of nitric oxide production and its role in pancreatic ischemia-reperfusion in rats.

Partial ischemia of rat pancreas body and tail was obtained by occlusion of the celiac axis for 1 h after gastrectomy. The plasma level of nitrite plus nitrate in both systemic and portal venous blood after reperfusion was significantly higher than that after sham operation and ischemia alone. The elevation after reperfusion was significantly decreased by NG-nitro-L-arginine methyl ester (L-NAME). Simultaneous administration of L-arginine counteracted the L-NAME-induced decrease in the level of nitric oxide (NO) end products. Generation of NO was further demonstrated by nitrosylhemoglobin detection by electron spin resonance in the blood after reperfusion. On the other hand, the plasma level of lipase, a marker of damage to pancreatic exocrine tissue, was significantly increased after ischemia-reperfusion and further increased by administration of L-NAME. This increase in lipase correlated with a decrease in tissue blood flow in the pancreas. These results suggest that NO is generated during and may have a protective role in ischemia-reperfusion of the rat pancreas.

Role of xanthine oxidase and eicosanoids in development of pancreatic ischemia-reperfusion injury

The implication of different eicosanoids and oxygen free radicals in the development of pancreatic injury after an ischemia-reperfusion process has been evaluated. For this purpose we have compared the effect of allopurinol and indomethacin administration on the pancreatic levels of eicosanoids in a rat model of pancreatic ischemia-reperfusion. After 60 min of pancreatic ischemia and 2 h of reperfusion, significant increases in 6-keto-PGF1 alpha, PGE2, and LTB4 in pancreas tissue were detected. Allopurinol before the ischemic period reduced 6-keto-PGF1 alpha, PGE2, and LTB4 levels to the range of basal values, while prior indomethacin treatment significantly reduced 6-keto-PGF1 alpha and PGE2 levels, with LTB4 remaining unmodified. Increased postischemic plasma lipases were also significantly reduced by allopurinol to the range of sham-operated animals whereas indomethacin did not modify these levels. The data suggest a role for lipoxygenase metabolites in the development of pancreatic injury and the importance of the enzyme xanthine oxidase as an inductor of eicosanoid biosynthesis.