Irisin attenuates intestinal injury, oxidative and endoplasmic reticulum stress in mice with L-arginine-induced acute pancreatitis

Figure 1 Mouse acute pancreatitis model schedule. Arginine-acute pancreatitis was induced by two hourly intraperitoneal injections of 4.0 g/kg L-arginine. At 2 h after the last injection of L-arginine, normal saline (vehicle) or 50 μg/kg or 250 μg/kg irisin were administered through intraperitoneal injection. The animals were sacrificed 69 h after irisin treatment (i.e. 72 h after the first injection of L-arginine). Blood and tissue samples were collected. Model schedule for each group of mice. n = 6. AP: Acute pancreatitis; i.p.: Intraperitoneal injection.

Figure 2 Irisin administration attenuates intestinal injury in experimental acute pancreatitis. A: Representative photos of hematoxylin and eosin staining; B: Intestinal injury scores. n = 6, mean ± standard error of mean; ^aP < 0.05 vs sham group; ^cP < 0.05 vs vehicle group. AP: Acute pancreatitis.

Figure 3 Irisin administration alleviates intestinal apoptosis in experimental acute pancreatitis. A: Representative photos of TUNEL staining (green) and corresponding nuclear counterstaining (blue) in the intestines; B: Quantitative analysis of TUNEL-positive cells; C-E: Western blot analysis of the expression of BAX, caspase-3 and cleaved caspase-3 in the intestines. n = 6, mean ± standard error of mean; ^aP < 0.05 vs sham group; ^cP < 0.05 vs vehicle group. AP: Acute pancreatitis; TUNEL: TdT-mediated dUTP nick-end labeling.

Figure 4 Irisin reduces intestinal oxidative stress in experimental acute pancreatitis. A: Representative images of dihydroethidium (DHE) fluorescence staining in the intestines; B: Relative fluorescence intensity of DHE fluorescence staining in the intestines; C: Superoxide dismutase levels in the intestinal tissue; D: Malondialdehyde levels in the intestinal tissue; E: Glutathione levels in the intestinal tissue. n = 6, mean ± standard error of mean; ^aP < 0.05 vs sham group; ^cP < 0.05 vs vehicle group. AP: Acute pancreatitis; DHE: Dihydroethidium; MDA: Malondialdehyde; GSH: Glutathione; SOD: Superoxide dismutase.

Figure 5 Irisin alleviates endoplasmic reticulum stress in experimental acute pancreatitis. Western blot analysis of the expression of glucose-regulated protein 78, protein disulfide isomerase, endoplasmic reticulum oxidoreductase 1-Lα, calnexin, C/EBP homologous protein and perilipin-2 in the intestines. n = 6, mean ± standard error of mean; ^aP < 0.05 vs sham group; ^cP < 0.05 vs vehicle group. AP: Acute pancreatitis; GRP78: Glucose-regulated protein 78; PDI: Protein disulfide isomerase; Ero1-Lα: Endoplasmic reticulum oxidoreductase 1-Lα; CHOP: C/EBP homologous protein; PLIN2: Perilipin-2.

Figure 6 Protective effects of irisin on multiple organ damage in acute pancreatitis. A: Serum IL-6 levels; B: Serum TNF-α levels; C: Representative photos of hematoxylin and eosin staining; D: Renal, hepatic, pancreatic and pulmonary injury scores. n = 6, mean ± standard error of mean; ^aP < 0.05 vs sham group; ^cP < 0.05 vs vehicle group. AP: Acute pancreatitis; IL-6: Interleukin-6; TNFα: Tumor necrosis factor-alpha.