Protection against kainate-induced excitotoxicity by adenosine A2A receptor agonists and antagonists.
The neuroprotective role of adenosine receptor agonists in various models of ischaemia and neuronal excitotoxicity has been attributed to adenosine A1 receptor activation. In this study we examine the role of the A2A receptor in the kainate model of excitotoxicity. Kainate (10 mg/kg) was administered systemically 10 min after the intraperitoneal injection of adenosine analogues. The A2A agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS21680) protected the hippocampus at concentrations of 0.1 and 0.01 mg/kg, but not at 2 microg/kg. The addition of the centrally acting adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine partially reduced protection only in the CA3a region, suggesting that only a small proportion of the protection was attributable to the A1 receptor. A less potent A2A agonist, N6-[2-(3,5-dimethyoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (1 mg/kg), provided only partial protection against kainate. 4-(2-[7-Amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl -amino]ethyl)phenol, a selective A2A antagonist, also showed protection against kainate-induced neuronal death, when administered alone or in combination with CGS21680. These results show that adenosine A2A receptor activation is protective against excitotoxicity. The protection is largely independent of A, receptor activation or blockade.
Jones
P A
PA
Division of Neuroscience and Biomedical Systems, Institute of Biomedical and Life Sciences, University of Glasgow, UK.
Smith
R A
RA
Stone
T W
TW
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology; D010627:Phenethylamines / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D014227:Triazines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018696:Neuroprotective Agents; D010627:Phenethylamines; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D014227:Triazines; D014230:Triazoles; D014970:Xanthines; C097270:ZM 241385; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C056426:CGS 24012; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine; D007608:Kainic Acid