Guanine nucleoside diphosphate and triphosphate modulate [³H]CGS 21680 binding to A₂ adenosine receptor in rat striatal membranes

Abstract

In striaturn and several other tissues, a guanine nucleotide binding protein (G,) couples A, adenosine receptor to activation of adenylyl cyclase. We have examined the effect of guanine nucleoside diphosphate and triphosphate on 13H]CGS 21680 binding to A, , adenosine receptors of rat striaturn. Both GDP and GTP inhibited specific 13H]CGS 21680 binding to rat striatal membranes by 50% at about 0.1 mM. GMP was inhibitory only at higher concentrations, and the estimated I C, , value was greater than 1 mM. The nonhydrolyzable analog of GTP, Gpp(NH)p, was as potent as GTP with an I C, , value of approximately 86 FM. These results suggest that the regulation of adenosine receptor binding properties by guanine nucleotides i s independent of G, activation, since inhibition of agonist binding is achieved by addition of both guanine nucleoside diphosphate and triphosphate. o 1993 Wiley-Liss, Inc.

Effect of serotonergic agents on adenosine A 2 receptor mediated catalepsy in mice

“…Numerous physiological (Parkinson and Fredholm 1990;Mazzoni et al 1993), biochemical (Ferre et al 1991c) and behavioral (Ferre et al 1991a;Hauber and Munkle 1997;Mandhane et al 1997) observations exist to indicate antagonistic adenosine A 2A -dopamine D 2 receptor interaction in the rat or mouse CNS, particularly in the striatal region. Likewise, in the human brain also, preferential distribution of A 2A receptors to the dopamine-rich regions has been observed (Martinez-Mir et al 1991).…”