Neuroprotection afforded by adenosine A2A receptor blockade is modulated by corticotrophin-releasing factor (CRF) in glutamate injured cortical neurons.
In situations of hypoxia, glutamate excitotoxicity induces neuronal death. The release of extracellular adenosine is also triggered and is accompanied by an increase of the stress mediator, corticotrophin-releasing factor (CRF). Adenosine A(2A) receptors contribute to glutamate excitoxicity and their blockade is effective in stress-induced neuronal deficits, but the involvement of CRF on this effect was never explored. We now evaluated the interaction between A(2A) and CRF receptors (CRFR) function, upon glutamate insult. Primary rat cortical neuronal cultures (9 days in vitro) expressing both CRF(1)R and CRF(2)R were challenged with glutamate (20-1000 μM, 24 h). CRF(1)R was found to co-localize with neuronal markers and CRF(2)R to be present in both neuronal and glial cells. The effects of the CRF and A(2A) receptors ligands on cell viability were measured using propidium iodide and Syto-13 fluorescence staining. Glutamate decreased cell viability in a concentration-dependent manner. Urocortin (10 pM), an agonist of CRF receptors, increased cell survival in the presence of glutamate. This neuroprotective effect was abolished by blocking either CRF(1)R or CRF(2)R with antalarmin (10 nM) or anti-Sauvagine-30 (10 nM), respectively. The blockade of A(2A) receptors with a selective antagonist SCH 58261 (50 nM) improved cell viability against the glutamate insult. This effect was dependent on CRF(2)R, but not on CRF(1)R activation. Overall, these data show a protective role of CRF in cortical neurons, against glutamate-induced death. The neuroprotection achieved by A(2A) receptors blockade requires CRF(2)R activation. This interaction between the adenosine and CRF receptors can explain the beneficial effects of using A(2A) receptor antagonists against stress-induced noxious effects.
Institute of Pharmacology and Neurosciences, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal.
Jorge S
JS
Valadas
Vânia L
VL
Batalha
Diana G
DG
Ferreira
Rui
R
Gomes
Joana E
JE
Coelho
Ana M
AM
Sebastião
Maria José
MJ
Diógenes
Luísa V
LV
Lopes
D058917:Adenosine A2 Receptor Antagonists / Q000494:pharmacology*; D000818:Animals; D002540:Cerebral Cortex / Q000473:pathology; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism / Q000633:toxicity*; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D061251:Primary Cell Culture; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology
C098657:5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine; D058917:Adenosine A2 Receptor Antagonists; D018696:Neuroprotective Agents; D011743:Pyrimidines; D011758:Pyrroles; D043705:Receptor, Adenosine A2A; D014230:Triazoles; C103016:antalarmin; D018698:Glutamic Acid; D003346:Corticotropin-Releasing Hormone