Ischemia-Reperfusion of the Pancreas Induced Hyperresponsiveness of the Airways in Rats

Pulmonary function changes in rats with taurocholate-induced pancreatitis are attenuated by pretreatment with melatonin

Melatonin is a free radical scavenger and broad-spectrum antioxidant with immunomodulatory effects. We studied the effects of melatonin on changes in lung function, oxidative/nitrosative stress, and inflammatory cell sequestration in an acute pancreatitis (AP)-associated lung inflammation model. Acute pancreatitis was induced by injection of 5% sodium taurocholate into the pancreatic duct of rats. Animals were randomized into control, AP, and a melatonin pretreatment (10 mg/kg)/AP group. Functional residual capacity (FRC), lung compliance (Cchord), expiratory flow rate at 50% (FEF50), airway resistance index (RI), and peak expiratory flow rate (PEF) were evaluated. White blood cell count (WBC) and hydrogen peroxide, lung lavage fluid WBC, methylguanidine, protein, lactic dehydrogenase (LDH), nitric oxide (NO), and leukotriene B4 (LTB4) levels were determined. Lung wet-to-dry weight ratio, peroxynitrite, and inducible nitric oxide synthase (NOS) mRNA and protein were measured. AP induction resulted in reductions in FRC, Cchord, FEF50, and PEF, and increase in RI and lung wet-to-dry weight ratio. Blood and lung lavage fluid WBC, lavage fluid LDH, protein, and blood hydrogen peroxide also increased. Levels of hydroxyl radicals, nitric oxide, and LTB4 in lung lavage fluid, inducible NOS mRNA, protein expression, and peroxynitrite in lung tissue also were significantly elevated. Pretreatment with melatonin attenuated obstructive and restrictive ventilatory insufficiency induced by AP. Blood and lavage WBC, lavage LDH and protein, lung edema, oxidative/nitrosative stress, and lipoxygenase pathway derivatives were also significantly attenuated by melatonin. We conclude that melatonin decreases AP-induced obstructive and restrictive lung function changes via its antioxidant and anti-inflammatory properties.

Nimesulide may be more efficient than allopurinol in protecting pancreas from acute ischemia/reperfusion injury in an animal model

OBJECTIVE

To determine the influence of allopurinol and nimesulide in the protection of the pancreas from acute ischemia-reperfusion (I/R) injury.

MATERIALS AND METHODS

A total of 30 rabbits were divided into 3 groups, group A: acute I/R only; group B: allopurinol (30 mg/kg) was administered intravenously 10 minutes before ischemia; group C: nimesulide (50 mg/kg) was given intraperitoneally 20 minutes before ischemia. Neopterin and superoxide dismutase (SOD) levels were examined. Pancreatic biopsies were obtained for electron microscopy study.

RESULTS

The mean neopterin concentrations in group A are 3.56 ± 3.41, 7.74 ± 3.59, and 8.94 ± 2.86 ng/mL, respectively, in the stabilization, ischemia, and reperfusion phases; group B: 3.40 ± 3.03, 7.45 ± 8.89, and 10.64 ± 7.47 ng/mL; and group C: 3.41 ± 2.71, 5.67 ± 2.76, and 4.34 ± 2.87 ng/mL. The mean SOD concentrations in group A are 4.25 ± 1.79, 4.48 ± 1.60, and 5.57 ± 1.15 ng/mL; group B: 4.32 ± 0.81, 5.08 ± 1.10, and 4.45 ± 1.31 ng/mL; and group C: 4.10 ± 0.99, 5.23 ± 1.60, and 3.72 ± 1.30 ng/mL. Histopathology showed the least deterioration in group C.

CONCLUSION

Nimesulide is more efficient than allopurinol in protecting pancreas from acute I/R injury.

Oral melatonin attenuates lung inflammation and airway hyperreactivity induced by inhalation of aerosolized pancreatic fluid in rats

Melatonin is a free radical scavenger with potent antioxidant properties and immunomodulatory effects. The purpose of this study was to determine the effects of orally administered melatonin in a pancreatic fluid (PF)-induced lung inflammation and airway hyperreactivity model. Aerosolized PF was introduced into airways to induce inflammation in rats. Animals were randomized into three experimental groups: sham treated; PF treated (200 μL/kg); and PF with melatonin (10 mg/kg) pretreatment. Airway reactivity to methacholine, airflow and airway resistance, bronchoalveolar lavage (BAL) cellular differential, the tumor necrosis factor α (TNFα) level, lavage nitric oxide, hydroxyl radical, and lactic dehydrogenase (LDH) were compared among groups. mRNA expressions of inducible nitric oxide synthase (iNOS) and TNFα in lung tissues were determined by real-time polymerase chain reaction. Protein expressions of iNOS and nitrotyrosine and lung tissue myeloperoxidase (MPO) activity were determined using an ELISA assay. Oral melatonin treatment indicated anti-inflammatory efficacy as evidenced by decreased methacholine sensitivity by 24% and airway obstruction by 28%, reduction in BAL eosinophil (P < 0.01) and neutrophil counts (P < 0.05), LDH (P < 0.05), and TNFα concentrations (P < 0.05) when compared to levels in sham-treated rats. Melatonin-treated animals also had reduced nitric oxide and hydroxyl radical concentrations (P < 0.05) in lavage fluid. Oral melatonin significantly reduced mRNA and protein expression of iNOS (P < 0.05 and P < 0.01, respectively), TNFα (P < 0.05), nitrotyrosine (P < 0.05), and MPO activity (P < 0.05) in lung tissues when compared with the sham-treated animals. These results suggest that oral treatment with melatonin had a beneficial effect on PF-induced obstructive ventilatory insufficiency by attenuating nitrosative and oxidative stress.

Curcumin attenuates airway hyperreactivity induced by ischemia-reperfusion of the pancreas in rats

OBJECTIVES

Ischemia-reperfusion (I/R) of the rat pancreas induces acute pancreatitis with a systemic inflammatory response. Activated inflammatory cells are sequestered in the lung, and the consequent respiratory burst may increase airway reactivity. In this study, we characterized the effect of the antioxidant curcumin on airway hyperreactivity induced by pancreatic I/R.

METHODS

Ischemia of the pancreas was induced by clamping the gastroduodenal and the splenic artery for 2 hours followed by reperfusion for 6 hours. The pulmonary function data of Penh, a measurement of airway resistance, were used to show the airway responses to a methacholine challenge. The blood concentration of oxygen radicals, nitric oxide, and tumor necrosis factor-alpha (TNFalpha) were measured after pancreatic I/R. mRNA expressions of inducible nitric oxide synthase (iNOS) and TNFalpha in lung tissues were measured after pancreatic I/R. Pretreatment with curcumin (20 mg/kg) was administered by intraperitoneal injection 2 hours before pancreatic I/R.

RESULTS

The protocol resulted in significant elevations of the blood concentrations of amylase, hydroxyl radical, nitric oxide, TNFalpha, and white cells among the I/R group. iNOS and TNFalpha mRNA expressions also significantly increased in lung tissues. Pulmonary function data showed that pancreatic I/R induced significant increases in responses to methacholine challenge: Penh increased significantly in the I/R group when compared with the sham group. Pretreatment with curcumin significantly attenuated the inflammatory, oxidative, and nitrosative responses and lung tissue iNOS and TNFalpha expressions. Curcumin also attenuated airway reactivity to methacholine challenge.

CONCLUSIONS

I/R of the pancreas induced systemic inflammatory responses with respiratory burst, nitrosative stress, and hyperresponses in the airways. Curcumin, which has antioxidant and anti-inflammatory effects, significantly attenuated the inflammatory responses and airway hyperreactivity induced by pancreatic I/R.