title: Dual effect of serotonin on growth of bovine pulmonary artery smooth muscle cells in culture.
abstract: We have previously reported that serotonin (5-hydroxytryptamine [5HT]) alters cultured bovine pulmonary artery smooth muscle cell (SMC) configuration through two different regulatory mechanisms. We now report that 5HT also regulates SMC growth through these same two mechanisms--a stimulatory event initiated intracellularly and inhibition of growth resulting from a cell surface action. 5HT (1 microM) plus 0.1 mM iproniazid (a 5HT metabolic inhibitor) produced a severalfold stimulation of DNA synthesis (as measured by [3H]thymidine incorporation) of SMCs after a 17-24-hour incubation with only a slight elevation of cellular cAMP. This stimulatory effect responded synergistically with other growth factors including platelet-derived growth factor, fibroblast growth factor, and epidermal growth factor and was effectively reversed by 5HT uptake inhibition. It was not produced by 5-hydroxyindoleacetic acid, a metabolite of 5HT. In the presence of 1 microM 5HT plus 0.1 mM isobutylmethylxanthine (IBMX), cAMP was elevated eightfold, dendritic formation occurred, and [3H]thymidine labeling of SMCs was inhibited. Inhibition of labeling by [3H]thymidine was mimicked by other agents that elevated cellular cAMP (10 microM histamine, 1 microM isoproterenol plus 0.1 mM IBMX, and 10 microM forskolin) and by 1 mM dibutyryl cAMP. This inhibitory effect was not blocked by either inhibition of 5HT uptake or 5HT-receptor antagonists ketanserin (5HT2); methiothepin, spiperone, and mianserin (5HT1/5HT2); and 3-tropanyl-indole-3-carboxylate and 3-tropanyl-3,5-dichlorobenzoate (5HT3). However, similar to 5HT, the 5HT1A agonist, (+/-)-8-hydroxy-(+/-)-2-dipropylamino-8-hydroxy-1,2,3, 4-tetrahydronaphthalenehydrobromide, in association with IBMX, produced an elevation in cAMP and inhibition of labeling by [3H]thymidine. 5HT, in the presence of either iproniazid or IBMX, did not alter [Ca2+]i, indicating that [Ca2+]i was not a signal for either of these actions.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, New England Medical Center, Boston, Mass. 02111.
authors.forename: S L
authors.initials: SL
authors.lastname: Lee
authors.forename: W W
authors.initials: WW
authors.lastname: Wang
authors.forename: B J
authors.initials: BJ
authors.lastname: Moore
authors.forename: B L
authors.initials: BL
authors.lastname: Fanburg
mesh_terms: D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000032:analysis; D007490:Iproniazid / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects; D011651:Pulmonary Artery / Q000166:cytology* / Q000187:drug effects; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011985:Receptors, Serotonin; D012701:Serotonin; D007490:Iproniazid; D000242:Cyclic AMP