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Citation
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HERO ID
7677921
Reference Type
Journal Article
Title
Binding of the prototypical adenosine A(2A) receptor agonist CGS 21680 to the cerebral cortex of adenosine A(1) and A(2A) receptor knockout mice
Author(s)
Lopes, LV; Halldner, L; Rebola, N; Johansson, B; Ledent, C; Chen, JF; Fredholm, BB; Cunha, RA
Year
2004
Is Peer Reviewed?
Yes
Journal
British Journal of Pharmacology
ISSN:
0007-1188
EISSN:
1476-5381
Volume
141
Issue
6
Page Numbers
1006-1014
Language
English
PMID
14993095
DOI
10.1038/sj.bjp.0705692
Abstract
1. 2-p-(2-carboxyethylphenethylamino-5'-ethylcarboxamidoadenosine) (CGS 21680) is considered the reference compound to study adenosine A(2A) receptors. However, CGS 21680 binding in the cerebral cortex, where adenosine A(1) receptors are predominant, displays a mixed A(2A)/A(1) receptor pharmacology. We now use adenosine A(1) and A(2A) receptor knockout mice to investigate the characteristics of cortical [(3)H]CGS 21680 binding. 2. [(3)H]CGS 21680 binding to the cerebral cortex was strongly reduced in adenosine A(1) receptor knockout mice, but only slightly reduced in A(2A) receptor knockout mice compared with the corresponding wild-type littermates. 3. Another selective A(2A) receptor ligand, [(3)H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine ([(3)H]SCH 58261), displayed a saturable binding to mouse cortical membranes, albeit with a binding density 20 times lower than that of striatal membranes, and this [(3)H]SCH58261 binding was abolished in both striatal and cortical membranes of A(2A) receptor knockout mice and unchanged in A(1) receptor knockout mice. 4. The presence of A(2A) receptors in cortical neurons was further confirmed by Western blot in mouse cortical nerve terminal membranes. 5. It is concluded that, although A(2A) receptors are present in the cerebral cortex, the purportedly selective A(2A) receptor agonist [(3)H]CGS 21680 binds in the cerebral cortex to an entity that requires the presence of adenosine A(1) receptors. Thus, CGS 21680 should be used with care in all preparations where adenosine A(1) receptors out-number A(2A) receptors.
Keywords
A 1 receptors; A 2A receptors; Adenosine; CGS 21680; Cortex; SCH 58261; Striatum
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