Inhibition of the constitutive activity of human 5-HT1A receptors by the inverse agonist, spiperone but not the neutral antagonist, WAY 100,635.
At recombinant human 5-hydroxytryptamine (5-HT)5-HT1A receptors expressed in Chinese hamster ovary cells (CHO-5-HT1A), 5-carboxamidotryptamine (5-CT), acted as a full agonist (relative to 5-HT = 100%) for stimulation of receptor-mediated [35S]-GTP gamma S (guanylyl 5'-[gamma-thio]-tryphosphate) binding. In contrast, spiperone inhibited basal [35S]-GTP gamma S binding by 30.2% (IC50 = 55.5 nM) in CHO-5-HT1A membranes but not in control untransfected membranes. The antagonist, N-[2-[4-(2-methoxyphenyl) -1-piperazinyl]ethyl]-N-(2-pyridinyl)-cyclohexane-carboxamide (WAY 100,635), blocked both 5-CT-induced stimulation and spiperone-induced inhibition of [35S]-GTP gamma S binding without itself modifying [35S]-GTP gamma S binding. It is concluded that, in this heterologous expression system, 5-HT1A receptors display 'constitutive' activation of G-proteins and that spiperone displays inverse agonist activity whereas WAY 100,635 acts as a 'neutral' antagonist at this site.
Newman-Tancredi
A
A
Department of Psychopharmacology, Institut de Recherches Servier, Croissy-sur-Seine (Paris), France.
Conte
C
C
Chaput
C
C
Spedding
M
M
Millan
M J
MJ
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D010879:Piperazines / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D011869:Radioligand Assay; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013134:Spiperone / Q000494:pharmacology*; D013462:Sulfur Radioisotopes
D010879:Piperazines; D011725:Pyridines; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D011994:Recombinant Proteins; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D013462:Sulfur Radioisotopes; D012701:Serotonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013134:Spiperone; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; C047087:5-carboxamidotryptamine