ABSTRACT
Objective:To evaluate the effect of activating adenosine A2B receptors on autophagy during myocardial ischemia-reperfusion (I/R) and the role of phosphatidylinositol 3-kinase/serine/threonine protein kinase (PI3K/Akt) signaling pathway in rats.Methods:Forty-eight clean-grade healthy male Sprague-Dawley rats, weighing 220-280 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), myocardial I/R group (group I/R), adenosine A2B receptor agonist BAY 60-6583 group (group BAY) and BAY 60-6583+ PI3K inhibitor LY 294002 group (group BAY+ LY). Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery for 30 min followed by 120-min reperfusion.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion in group BAY.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion and LY 294002 10 mg/kg was intraperitoneally injected at 10 min before reperfusion in group BAY+ LY.Blood samples were obtained at the end of reperfusion for determination of concentrations of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in serum (by enzyme-linked immunosorbent assay). The animals were sacrificed, and myocardial tissues were obtained for measurement of the percentage of myocardial infarct size (by Evan Blue and TTC double-staining) and for determination of the expression of microtubule-associated protein 1 light chain 3 (LC3Ⅰ), LC3Ⅱ, Beclin-1 and phosphorylated Akt (p-Akt) (by Western blot). The ratio of LC3Ⅱ/LC3Ⅰ was calculated. Results:Compared with group Sham, the serum LDH and CK-MB concentrations and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group I/R ( P<0.05). Compared with group I/R, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly decreased, the expression of p-Akt was up-regulated, the expression of Beclin-1 and LC3Ⅱ was down-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was decreased in the group BAY ( P<0.05), and no significant change was found in the parameters mentioned above in group BAY+ LY ( P>0.05). Compared with group BAY, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group BAY+ LY ( P<0.05). Conclusion:Activating adenosine A2B receptors can decrease autophagy of myocardial cells during myocardial I/R injury, and the mechanism may be related to activating PI3K/Akt signaling pathway in rats.
ABSTRACT
Objective To investigate the roles of neutral sphingomyelinase-2 (nSMase2) pathway on cerebral edema and cerebral injury in cerebral ischemia-reperfusion injury in rats. Methods Seventy-six adult male SD rats were randomly divided into sham operation group (n = 12), modeling group (n = 16), vehicle group (n = 16), SB203580 (a p38 mitogen activated protein kinase [MAPK] inhibitor) treatment group (n = 16) , and MRS1754 (a selective adenosine A2B receptor [A2B AR] antagonist) treatment group (n = 16) according to the random number table. A suture-occluded method was used to induce a middle cerebral artery ischemia-reperfusion model. Vehicle, SB203580, and MRS1754 were injected into the lateral ventricles 30 min before model preparation, the neurological function score was performed after ischemia-reperfusion for 24 h. 2,3,5 triphenyltetrazolium staining was used to detect the infarct volume. The water content of brain tissue was detected by dry-wet weight method. Western blot analysis was used to detect the expression of nSMase 2 and p38 MAPK in ischemic brain tissue. Immunohistochemical staining was used to detect the expression of nSMase 2 in ischemic brain tissue. Results MRS1754 significantly decreased neurobehavioral score (P < 0. 05) and reduced cerebral infarction volume (P < 0. 05) in rats. Both MRS1754 and SB203580 significantly decreased the water content of ischemic brain tissue (all P < 0. 05). In addition, MRS1754 also significantly decrease the phosphorylation of p38 MAPK after ischemia-reperfusion and decreased the expression level of nSMase 2 (P < 0. 01). Conclusion Regulation of A2BAR and p38 MAPK of nSMase upstream may play a neuroprotective role after cerebral ischemia-reperfusion injury.
ABSTRACT
Objective To investigate the role of A2B adenosine receptor(A2BAR)in 6% HES 130/0.4-induced reduction of pulmonary capillary permeability in a rat model of sepsis.Methods Fifty male SD rats weighing 250-300 g were randomly divided into 5 groups(n = 10 each): group Ⅰ sham operation(group S);group Ⅱ sepsis(group CLP);group Ⅲ ,Ⅳ,Ⅴ low,medium,high dose HES(group H1,2,3).The animals were anesthetized with intraperitoneal pentobarbital sodium 50 mg/kg.Left carotid artery and left femoral vein were cannulated for MAP and HR monitoring and fluid and drug administration.Sepsis was induced by cecal ligation and puncture (CLP).6% HES 130/0.4 7.5,15.0 and 30.0 ml/kg were infused iv over 2 h in group H1,2,3 respectively at 4 h after CLP.The animals were sacrificed at 6 h after CLP.The lungs were isolated for determination of pulmonary capillary permeability(by iv Evans blue injection),the expression of A2BAR and the contents of cAMP,protein kinase A(PKA),TNF-α,IL-6 and IL-10 in the lung tissue.Results CLP significantly increased pulmonary capillary permeability,A2BAR expression and cAMP,IL-6 and TNF-α contents in the lung tissue in group Ⅱ as compared with group S.0.6% HES 130/0.4 significantly reduced pulmonary capillary permeability,increased A2BAR expression,cAMP,PKA and IL-10 and decreased IL-6 and TNF-αcontents in the lung tissue in group H1,2,3 as compared with group CLP.6% HES 130/0.4 decreased pulmonary capillary permeability and up-regulated A2BAR expression in a dose-dependent manner.6% HES 130/0.4 15.0 ml/kg was most effective in increasing cAMP and PKA contents in the lung and depressing inflammatory response.Conclusion 6% HES 130/0.4 decreases pulmonary capillary permeability in a rat model of sepsis by up-regulating A2BAR expression in lung tissue.