Differential discrimination of G-protein coupling of serotonin1A receptors from bovine hippocampus by an agonist and an antagonist

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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‐HT1A 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‐HT1A receptors from bovine hippocampus.