Activity of serotonin (5-HT) receptor agonists, partial agonists and antagonists at cloned human 5-HT1A receptors that are negatively coupled to adenylate cyclase in permanently transfected HeLa cells.
The activity of serotonin (5-HT) receptor agonists, partial agonists and antagonists, and various other neurotransmitter receptor antagonists at human 5-HT1A receptors that are negatively coupled to adenylate cyclase in permanently transfected HeLa cells was investigated. 5-HT1A receptor-mediated inhibition of adenylate cyclase was studied by measuring inhibition of cAMP accumulation, induced by forskolin. At 100 microM forskolin produced a 100-fold increase in cAMP formation: 5-HT concentration dependently inhibited the cAMP formation; maximal inhibition was attained at 1 microM 5-HT and represented 90% of the stimulated cAMP formation. Full inhibition was observed with 5-HT1A receptor agonists: N,N-dipropyl-8-hydroxy-2-aminotetralin (8-OH-DPAT) and flesinoxan, and non-selective 5-HT receptor agonists: d-lysergic acid diethylamide (d-LSD), RU 24,969, bufotenine, methysergide and tryptamine. The rank order of potency of the compounds for inhibiting the cAMP formation corresponded to the rank order of the binding affinities of the drugs for the 5-HT1A receptor. Partial inhibition was obtained with submicromolar concentrations of buspirone, spiroxatrine and ipsapirone. A slight inhibition was observed with 1 microM 5-HT receptor agonist CP 93129 and 1 microM 5-HT receptor antagonists mesulergine and BW-501. No inhibition was found with: the 5-HT receptor agonists quipazine, sumatriptan and 1-(2,5-dimethoxy-4-methylphenyl)-2- aminopropane (DOM); the 5-HT receptor antagonist ICS-205,930; and other neurotransmitter receptor antagonists such as pindolol, CGP 20712-A, prazosin, sulpiride and pyrilamine. Spiperone and pindolol fully antagonized the agonist-mediated inhibition of forskolin-stimulated cAMP formation. Partial inhibition of the agonist-mediated inhibition of forskolin-stimulated cAMP formation was apparent with 1 microM ocaperidone and 1 microM ipsapirone. It can be concluded that HeLa cells, permanently expressing human 5-HT1A receptors, are a valid cellular system for studying the negative coupling of 5-HT1A receptors to adenylate cyclase and the action of compounds thereupon.
Pauwels
P J
PJ
Department of Biochemical Pharmacology, Janssen Research Foundation, Beerse, Belgium.
Van Gompel
P
P
Leysen
J E
JE
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D005576:Colforsin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology; D008954:Models, Biological; D010869:Pindolol / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013134:Spiperone / Q000494:pharmacology; D014162:Transfection
D000067956:Adenylyl Cyclase Inhibitors; D007211:Indoles; D010879:Piperazines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D005576:Colforsin; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D012701:Serotonin; C056895:flesinoxan; D013134:Spiperone; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D008238:Lysergic Acid Diethylamide; D010869:Pindolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases