ABSTRACT
ObjectiveTo investigate the effects of autophagy on exocrine function of pancreas in rats with acute sepsis, and to determine whether the mitochondrial coenzyme Q (Mito Q) can prevent exocrine dysfunction of pancreas mediated by autophagy.Methods ExperimentⅠ: 30 Sprague-Dawley (SD) rats were randomly divided into three groups, with 10 rats in each group. All the rats were given lipopolysaccharide (LPS, 10 mg/kg) intraperitoneally, and Wortmannin (2 mg/kg), the specific inhibitor of autophagy (LPS+ Wortmannin group), Mito Q (6.5μmol/kg, LPS+Mito Q group), or the same volume of normal saline (LPS group) was respectively injected via the tail vein 1 hour later. Survival rate was assessed within 12 hours after LPS injection. ExperimentⅡ: another 100 male SD rats were randomly divided into ten groups with 10 rats in each group: namely control 4, 6 and 12 hours groups, LPS 4, 6 and 12 hours groups, and LPS+ Wortmannin 4 hours group, Wortmannin 4 hours group, LPS+ Mito Q 6 hours group, and Mito Q 6 hours group. The protocols of model reproduction and drug administration were the same as in the experimentⅠ. Blood samples were collected at each time point, and the amylase content was determined with the velocity method. The levels of reactive oxygen species (ROS) in the pancreases were measured with enzyme-linked immunosorbent assay (ELISA). The expression of the autophagy-related protein LC3 was determined with Western Blot. The pathological changes in the pancreas were observed with microscopy.Results① The survival time in the LPS+ Wortmannin group was significantly shorter than that in the LPS group (hours: 7.50±0.64 vs. 11.90±0.13,χ2= 19.847,P= 0.001). There was no significant difference in the survival time between LPS+ Mito Q and LPS groups (hours: 11.60±0.24 vs. 11.90±0.13,χ2= 1.055,P= 0.137).② The serum amylase in the LPS 6 hours, LPS+ Wortmannin 4 hours, and LPS+ Mito Q 6 hours groups were significantly higher than those in the control group at the same time points (U/L:2 881.00±550.12 vs. 2 099.20±249.57, 3 672.00±779.24 vs. 2 081.36±245.18, 2 975.20±687.03 vs. 2 099.20± 249.57, allP 0.05). Light microscopy showed that obvious pathological changes were found in the pancreas in the LPS 6 hours and 12 hours groups, LPS+Wortmannin 4 hours group, and LPS+ Mito Q 6 hours group. Electron microscopy showed that the number of autophagic vacuoles increased 6 hours after LPS administration. There was no difference at any time point in the number of autophagic vacuoles between LPS+ Mito Q 6 hours group and LPS 6 hours group, and the autophagic vacuoles were not found after Wortmannin intervention. It was demonstrated by Western Blot that the levels of LC3 protein in the LPS 6 hours and 12 hours groups, and LPS+ Mito Q 6 hours group were significantly higher than those of the control group at the same time points (A value: 0.34±0.02 vs. 0.17±0.02, 0.37±0.03 vs. 0.18±0.04, 0.36±0.02 vs. 0.17±0.02, allP 0.05).Conclusions Autophagy prevents exocrine dysfunction of pancreas in septic rats, and the autophagic capacity or autophagosome-formation rate may determine the development of exocrine pancreatic dysfunction. The mitochondria-targeted antioxidant Mito Q does not prevent exocrine dysfunction of pancreas.
ABSTRACT
Objective To investigate the effects of autophagy on cardiac function and to determine whether the mitochondrial coenzyme Q (MitoQ) prevents cardiac dysfunction,mediated by autophagy,in rats with acute sepsis.Methods Forty-five Sprague Dawley (SD) rats were randomly divided into 9 groups (n =5,each group):control group,4 h lipopolysaccharide(LPS) group,6 h LPS group,12 h LPS group,4 h LPS + Wortmannin group,4 h LPS + MitoQ group,6 h LPS + MitoQ group,MitoQ group and Wortmannin group.Rats in LPS + Wortmannin group and LPS + MitoQ group were intraperitoneally given LPS(10 mg/kg) and followed by an injection of Wortmannin(2 mg/kg) and MitoQ (6.5 μmol/kg) via tail vein 1 hour later,respectively.Rats in each group were given the same amount of normal sodium in addition to different intervention drugs.The cardiac function parameters were measured by a BL-420E + biosignal collection system.Blood samples from abdominal aorta were taken at each time point,and creatine kinase MB isoenzyme (CK-MB) content was detected by using the velocity method.The content of reactive oxygen species (ROS) in isolated myocardial tissues in rats was measured by enzyme-linked immunoadsorbent assay(ELISA).The protein expression of microtubule-associated protein 1 light chain 3 (LC3) was detected by Western blot method.The pathological changes of myocardial tissue were observed by light and electronic microscopy.Results Compared with the control group,the left ventricular systolic pressure(LVSP),the rate of the rise in left ventricular pressure (± dp/dt max) were significantly decreased in 6 h LPS group,6 h LPS + MitoQ group and 4 h LPS + Wortmannin group(P ＜0.05),left ventricular end-diastolic pressure(LVEDP) was significantly increased in these 3 groups(P ＜0.05).The contents of CKMB and ROS in 6 h LPS group,6 h LPS =MitoQ group and 4 h LPS + Wortmannin group were higher than those in the control group(P ＜ 0.05).Electron microscopy showed that the number of autophagic vacuoles increased 6 h after LPS was administered,but did not increase significantly thereafter to 12 h.There was no difference at any time point in the number of autophagic vacuoles in the group given MitoQ and LPS.Immunoblotting demonstrated that the levels of LC3Ⅱ protein in the LPS 6 h group and LPS + MitoQ 6 h group were higher than those in the control group(P ＜0.05),but there was no difference between the LPS 12 h and LPS 6 h groups (P ＞ 0.05).Conclusions The mitochondria-targeted antioxidant MitoQ does not prevent cardiac dysfunction.However,autophagy prevents cardiac dysfunction,and the autophagic capacity or autophagosome-formation rate may determine whether cardiac dysfunction develops.