8-(3-Chlorostyryl)caffeine (CSC) is a selective A2-adenosine antagonist in vitro and in vivo.
An adenosine antagonist, 8-(3-chlorostyryl)caffeine (CSC), was shown previously to be 520-fold selective for A2a-adenosine receptors in radioligand binding assays in the rat brain. In reversing agonist effects on adenylate cyclase, CSC was 22-fold selective for A2a receptors in rat phenochromocytoma cells (Kb 60 nM) vs. A1 receptors in rat adipocytes (Kb 1.3 microM). Administered i.p. in NIH mice at a dose of 1 mg/kg, CSC shifted the curve for locomotor depression elicited by the A2a-selective agonist APEC to the right (ED50 value for APEC shifted from 20 micrograms/kg i.p. to 190 micrograms/kg). CSC had no effect on locomotor depression elicited by an ED50 dose of the A1-selective agonist CHA. CSC alone at a dose of 5 mg/kg stimulated locomotor activity by 22% over control values. Coadministration of CSC and the A1-selective antagonist CPX, both at non-stimulatory doses, increased activity by 37% (P < 0.001) over CSC alone, suggesting a behavioral synergism of A1- and A2-antagonist effects in the CNS.
Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
K A
KA
Jacobson
O
O
Nikodijević
W L
WL
Padgett
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C
Gallo-Rodriguez
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M
Maillard
J W
JW
Daly
D000241:Adenosine / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D002110:Caffeine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008124:Locomotion / Q000187:drug effects; D008297:Male; D051379:Mice; D051381:Rats
D000067956:Adenylyl Cyclase Inhibitors; C081320:8-(3-chlorostyryl)caffeine; D002110:Caffeine; D000241:Adenosine