Pharmacological characterization of regulation of phosphoinositide metabolism by recombinant 5-HT2 receptors of the rat.
Transfection of 5-HT2 receptor cDNA in 293 cells induced the expression of a protein binding domain, exhibiting the classical 5-HT2 receptor transduction mechanism. Both [3H]DOB and [3H]spiperone high affinity binding sites were present in membranes of sense but not of antisense, 5-HT2 receptor cDNA transfected cells. Addition of 1 microM 5-HT induced a time-dependent increase of phosphoinositide (PI) metabolism in sense but not in antisense, 5-HT2 receptor cDNA transfected cells. Graded concentrations of 5-HT and of different serotonergic agonists showed different potencies (DOI greater than 5-HT greater than quipazine greater than DOM greater than alpha-methyl-5-HT greater than 8-OH-DPAT greater than 2-methyl-5-HT greater than CGS-12066B) in stimulating turnover of PI in cells transfected with cDNA encoding for 5-HT2 receptors of the rat. The ability of different antagonists to inhibit 5-HT-stimulated turnover of PI bore a direct relationship with their potency to inhibit 5-HT2 receptor binding in cells transfected with 5-HT2 receptor cDNA (spiperone greater than ketanserin greater than ritanserin greater than mianserin greater than haloperidol). Preincubation of transfected 293 cells with pertussis toxin failed to modify either 5-HT- or DOI-induced activation of metabolism of PI. Pretreatment of transfected 293 cells with DOI (100 nM) for 2 hr or more, significantly reduced activation of turnover of PI elicited by graded doses of 5-HT. When the transfected 293 cells were exposed to DOI (100 nM) for 12 hr and the challenge was performed after a 2-hr wash-out period, the desensitization of the response to 5-HT was virtually abolished.(ABSTRACT TRUNCATED AT 250 WORDS)
Apud
J A
JA
FIDIA-Georgetown Institute for the Neurosciences, Georgetown University, School of Medicine, Washington, DC 20007.
Grayson
D R
DR
De Erausquin
E
E
Costa
E
E
D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011985:Receptors, Serotonin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012701:Serotonin / Q000502:physiology; D012702:Serotonin Antagonists / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D010716:Phosphatidylinositols; D011985:Receptors, Serotonin; D011994:Recombinant Proteins; D012702:Serotonin Antagonists; D010566:Virulence Factors, Bordetella; D012701:Serotonin; D004247:DNA; D037342:Pertussis Toxin