Differential discrimination of G-protein coupling of serotonin_1A receptors from bovine hippocampus by an agonist and an antagonist

Abstract

We have studied the effect of guanosine-5'-O-(3-thiotriphosphate) (GTP-γ -S), a non-hydrolyzable analogue of GTP, on agonist and antagonist binding to bovine hippocampal 5-hydroxytryptamine (5-HT)_1A receptor in native membranes. Our results show that the specific binding of the agonist is inhibited with increasing concentrations of GTP-γ -S along with a reduction in binding affinity. In sharp contrast to this, antagonist binding to 5-HT_1A receptor shows no significant reduction and remains invariant over a large range of GTP-γ -S concentrations. The binding affinity of the antagonist also remains unaltered. This shows that the agonist and the antagonist differentially discriminate G-protein coupling of 5-HT_1A receptors from bovine hippocampus.