title: Modulation of 5-hydroxytryptamine1A receptor density by nonhydrolyzable GTP analogues.
abstract: Co-incubation of rat cortical membranes with 10(-4) M GTP results in a competitive inhibition of 5-hydroxytryptamine1A (5-HT1A) receptor binding sites labeled by [3H]8-hydroxy-2-(di-n-propylamino)tetralin [( 3H]8-OH-DPAT). Preincubation of cortical membranes with 10(-4) M GTP does not significantly change either KD or Bmax values, indicating that the effect of GTP is reversible. By contrast, GTP gamma S and 5'-guanylylimidodiphosphate (GppNHp) are nonhydrolyzable analogues of GTP which lengthen the time course of guanine nucleotide activation of guanine nucleotide binding proteins (G proteins) and thereby alter G protein-receptor interactions. These nonhydrolyzable GTP analogues were used to characterize the effects of persistent alterations in G proteins on [3H]8-OH-DPAT binding to 5-HT1A receptors. Co-incubation of rat cortical membranes with either 10(-4) M GTP gamma S or GppNHp results in a decrease in both the affinity and apparent density of 5-HT1A binding sites. Co-incubation with the nonhydrolyzable nucleotides reduces the affinity of [3H]8-OH-DPAT binding by 65-70% and lowers the density of the binding site by 53-61%. Similarly, preincubation of membranes with a 10(-4) M concentration of either GTP gamma S or GppNHp significantly increases the KD value and reduces the Bmax value of [3H]8-OH-DPAT binding. These results indicate that GTP gamma S and GppNHp induce persistent changes in 5-HT1A receptor-G protein interactions that are reflected as a decrease in the density of binding sites labeled by [3H]8-OH-DPAT.
authors: Department of Neurology, Stanford University Medical Center, California 94305.
authors: M A
authors: MA
authors: Harrington
authors: S J
authors: SJ
authors: Peroutka
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D007700:Kinetics; D008962:Models, Theoretical; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D013764:Tetrahydronaphthalenes / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D013873:Thionucleotides; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins