title: Adenosine and selective A(2A) receptor agonists reduce ischemia/reperfusion injury of rat liver mainly by inhibiting leukocyte activation.
abstract: To examine whether adenosine reduces ischemia/reperfusion (I/R)-induced liver injury by inhibiting leukocyte activation via A(2) receptor (A(2)R) stimulation, we investigated the effects of adenosine and selective A(2A) receptor (A(2A)R) agonists (YT-146 and CGS21680C) on I/R-induced liver injury in rats. Adenosine, YT-146, and CGS21680C, in the concentration of 10(-7) to 10(-5) M, significantly inhibited neutrophil elastase release by about 30 to 40% and increased intracellular Ca(2+) concentrations in isolated neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine (fMLP) in vitro. Adenosine, YT-146, and CGS21680C, in the concentration of 10(-7) to 10(-5) M, significantly inhibited tumor necrosis factor (TNF)-alpha production by monocytes stimulated with endotoxin by about 50%. Although ZM241385, a selective A(2A)R antagonist, significantly enhanced the increase in neutrophil elastase release and intracellular Ca(2+) concentrations in neutrophils stimulated with fMLP, this agent did not affect the endotoxin-induced TNF-alpha production by monocytes. Rats were subjected to liver ischemia for 60 min. Serum levels of transaminases increased after hepatic I/R, peaking at 12 h after reperfusion. The i.v. infusion of adenosine (1 and 10 mg/kg/h), YT-146 (0.1 and 1 mg/kg/h), and CGS21680C (0.1 and 1 mg/kg/h) significantly inhibited the I/R-induced increase in serum transaminase levels 12 h after reperfusion. The I/R-induced decrease in hepatic tissue blood flow was significantly prevented by adenosine and YT-146. Hepatic levels of TNF-alpha, cytokine-induced neutrophil chemoattractant (equivalent to human interleukin-8), and myeloperoxidase were significantly increased after I/R. These increases were significantly inhibited by the administration of adenosine, YT-146, and CGS21680C. Although the histological neutrophil accumulation in the liver was significantly increased after I/R as evaluated by the naphthol AS-D chloroacetate technique, the administration of adenosine, YT-146, and CGS21680C significantly inhibited this increase. These findings suggest that adenosine reduces I/R-induced liver injury both by inhibiting the synthesis of inflammatory mediators and by inhibiting neutrophil degranulation directly, probably through A(2A)R stimulation.
authors.affiliation: Department of Pharmacology, School of Medicine, Fukuoka University, Japan. naoha@Msat.fukuoka-u.ac.jp
authors.forename: N
authors.initials: N
authors.lastname: Harada
authors.forename: K
authors.initials: K
authors.lastname: Okajima
authors.forename: K
authors.initials: K
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Usune
authors.forename: C
authors.initials: C
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Ohshima
authors.forename: T
authors.initials: T
authors.lastname: Katsuragi
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000480:Alkynes / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007511:Ischemia / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019272:Leukocyte Elastase / Q000378:metabolism; D008070:Lipopolysaccharides; D008099:Liver / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D018375:Neutrophil Activation / Q000187:drug effects*; D009195:Peroxidase / Q000378:metabolism; D010627:Phenethylamines / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D043705:Receptor, Adenosine A2A; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D014227:Triazines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D000480:Alkynes; C475829:CXCL1 protein, human; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors; C513297:Cxcl1 protein, rat; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D010627:Phenethylamines; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D043705:Receptor, Adenosine A2A; D014227:Triazines; D014230:Triazoles; D014409:Tumor Necrosis Factor-alpha; C097270:ZM 241385; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C070494:YT 146; D009195:Peroxidase; D019272:Leukocyte Elastase; D000241:Adenosine; D002118:Calcium