alpha,beta-amyrin, a natural triterpenoid ameliorates L-arginine-induced acute pancreatitis in rats

Abstract

Aim: To study the beneficial effects of triterpene alpha,beta-amyrin and the underlying mechanisms in an experimental pancreatitis model.

Methods: Acute pancreatitis was induced in five groups of rats (n = 8) by L-arginine (2 x 2.5 g/kg, intraperitoneal, 1 h apart) and 1 h later, they received a single oral dose of alpha,beta-amyrin (10, 30 and 100 mg/kg), methylprednisolone (30 mg/kg) and vehicle (3% Tween 80). A saline (0.9% NaCl) treated group served as a normal control. Efficacy was assessed at 24 h by determination of serum levels of amylase, lipase and pro-inflammatory cytokines [tumor necrosis factor (TNF)-alpha and interleukin (IL)-6], pancreatic myeloperoxidase (MPO) activity, lipid peroxidation [thiobarbituric acid reactive substances (TBARS)], nitrate/nitrite levels, and the wet weight/body weight ratio. Tissue histology and the immunoreactivity for TNF-alpha and inducible nitric oxide synthetase (iNOS) were performed.

Results: alpha,beta-amyrin and methylprednisolone treatments significantly (P < 0.05) attenuated the L-arginine-induced increases in pancreatic wet weight/body weight ratio, and decreased the serum levels of amylase and lipase, and TNF-alpha and IL-6, as compared to the vehicle control. Also, pancreatic levels of MPO activity, TBARS, and nitrate/nitrite were significantly lower. Histological findings and TNF-alpha and iNOS immunostaining further confirmed the amelioration of pancreatic injury by alpha,beta-amyrin.

Conclusion: alpha,beta-amyrin has the potential to combat acute pancreatitis by acting as an anti-inflammatory and antioxidant agent.

Figure 1

Effects of α,β-amyrin treatment on serum amylase (A), lipase (B) and on pancreatic edema (C) in rats on L-arginine-induced acute pancreatitis. Each column represents mean ± SE (n = 8). ^aP < 0.05 vs saline control group; ^cP < 0.05 vs vehicle control group. Pred: Methylprednisolone.

Figure 2

Effect of α,β-amyrin treatment on the serum tumor necrosis factor α (A) and interleukin-6 (B) in L-arginine induced acute pancreatitis. Each column represents mean ± SE (n = 8). ^aP < 0.05 vs saline control group; ^cP < 0.05 vs vehicle control group. Pred: Methylprednisolone; TNF-α: Tumor necrosis factor α; IL-6: Interleukin-6.

Figure 3

Effects of α,β-amyrin treatment on the pancreatic myeloperoxidase activity (A), thiobarbituric acid-reactant substances (B) and nitrate/nitrite levels (C) in L-arginine induced acute pancreatitis. Each column represents mean ± SE (n = 8). ^aP < 0.05 vs saline control group; ^cP < 0.05 vs vehicle control group. Pred: Methylprednisolone; MPO: Myeloperoxidase; TBARS: Thiobarbituric acid-reactant substances.

Figure 4

Effect of α,β-amyrin on tumor necrosis factor α immunoreactivity in L-arginine-induced acute pancreatitis (× 400). A: Normal control group; B: Vehicle + L-arginine; C: α,β-amyrin (100 mg/kg) + L-arginine; D: Methylprednisolone (30 mg/kg) + L-arginine.

Figure 5

Effect of α,β-amirin on inducible nitric oxide synthetase immunoreactivity in L-arginine-induced acute pancreatitis (× 400). A: Normal control group; B: Vehicle + L-arginine; C: α,β-amyrin (100 mg/kg) + L-arginine; D: Methylprednisolone (30 mg/kg) + L-arginine.

Figure 6

Representatives microphotographs of pancreatic sections (× 400). A: Normal control group; B: Vehicle + L-arginine; C: α,β-amyrin (100 mg/kg) + L-arginine; D: Methylprednisolone (30 mg/kg) + L-arginine.