Adenosine A2A receptor stimulation potentiates nitric oxide release by activated microglia.
The absence of adenosine A2A receptors, or its pharmacological inhibition, has neuroprotective effects. Experimental data suggest that glial A2A receptors participate in neurodegeneration induced by A2A receptor stimulation. In this study we have investigated the effects of A2A receptor stimulation on control and activated glial cells. Mouse cortical mixed glial cultures (75% astrocytes, 25% microglia) were treated with the A2A receptor agonist CGS21680 alone or in combination with lipopolysaccharide (LPS). CGS21680 potentiated lipopolysaccharide-induced NO release and NO synthase-II expression in a time- and concentration-dependent manner. CGS21680 potentiation of lipopolysaccharide-induced NO release was suppressed by the A2A receptor antagonist ZM-241385 and did not occur on mixed glial cultures from A2A receptor-deficient mice. In mixed glial cultures treated with LPS + CGS21680, the NO synthase-II inhibitor 1400W abolished NO production, and NO synthase-II immunoreactivity was observed only in microglia. Binding experiments demonstrated the presence of A2A receptors on microglial but not on astroglial cultures. However, the presence of astrocytes was necessary for CGS21680 potentiating effect. In light of the reported neurotoxicity of microglial NO synthase-II and the neuroprotection of A2A receptor inhibition, these data suggest that attenuation of microglial NO production could contribute to the neuroprotection afforded by A2A receptor antagonists.
Saura
Josep
J
Department of Pharmacology and Toxicology, IIBB, CSIC, IDIBAPS, Barcelona, Spain. jsafat@iibb.csic.es
Angulo
Ester
E
Ejarque
Aroa
A
Casadó
Vicent
V
Tusell
Josep M
JM
Moratalla
Rosario
R
Chen
Jiang-Fan
JF
Schwarzschild
Michael A
MA
Lluis
Carme
C
Franco
Rafael
R
Serratosa
Joan
J
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D058917:Adenosine A2 Receptor Antagonists; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D007211:Indoles / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010627:Phenethylamines / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011869:Radioligand Assay / Q000379:methods; D043705:Receptor, Adenosine A2A / Q000502:physiology*; D013997:Time Factors; D014227:Triazines / Q000493:pharmacokinetics / Q000494:pharmacology; D014230:Triazoles / Q000493:pharmacokinetics / Q000494:pharmacology; D014316:Tritium / Q000493:pharmacokinetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D058917:Adenosine A2 Receptor Antagonists; D004791:Enzyme Inhibitors; D007211:Indoles; D008070:Lipopolysaccharides; D008301:Maleimides; D009573:Nitrites; D010627:Phenethylamines; D043705:Receptor, Adenosine A2A; D014227:Triazines; D014230:Triazoles; D014409:Tumor Necrosis Factor-alpha; C097270:ZM 241385; D014316:Tritium; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D009569:Nitric Oxide; D000241:Adenosine; C070515:bisindolylmaleimide I