Activation of Erk mitogen-activated protein kinase proteins by vascular serotonin receptors.
We previously demonstrated that 5-hydroxytryptamine 2A (5-HT 2A ) receptor-mediated rat arterial contraction was dependent on activation of tyrosine kinases, including mitogen-activated protein kinase (MAPK) kinase. In the current study, we examined arterial smooth muscle for the presence of serotonin (5-hydroxytryptamine, 5-HT) 5-HT 1B, 5-HT 1D, 5-HT 1F, 5-HT 2A, 5-HT 2B, and 5-HT 7 receptor mRNA and hypothesized that, if present, activation of these receptors would stimulate the extracellular signal-regulated kinase (Erk) MAPK pathway and an Erk MAPK-dependent contraction. RT-PCR analyses of rat aortic smooth muscle cells, cultured and fresh, indicated the presence of 5-HT 1B, 5-HT 1D, 5-HT 1F, 5-HT 2A, 5-HT 2B, and 5-HT 7 receptor mRNA. The 5-HT 1B agonists RU24969 and CGS12066B, 5-HT 1B/1D/1F receptor agonist sumatriptan, and 5-HT 2B receptor agonist BW723C86 (10(-9) - 10(-4) M ) did not contract the aorta, nor did the 5-HT 7 receptor antagonist LY215840 leftward shift 5-HT-induced contraction. The 5-HT 1E/1F receptor agonist BRL54443 induced contraction, but this was abolished by the 5-HT 2A/2C receptor antagonist ketanserin (10 nM ); contraction was not observed with a different 5-HT 1F receptor agonist, LY344864. 5-HT and alpha-methyl-5-HT produced a concentration-dependent increase in Erk MAPK activity in cultured aortic smooth muscle cells and in aorta contracted with these agonists. All other agonists were inactive; a high concentration of BRL54443 (10 microM ) stimulated Erk MAPK activation (150% basal). Thus, while mRNA and possibly protein for multiple 5-HT receptors are present in aortic smooth muscle, only the 5-HT 2A receptor plays a significant role in directly modulating contractility and activating the Erk MAPK pathway.
Watts
S W
SW
Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824-1317, USA. wattss@msu.edu
Yang
P
P
Banes
A K
AK
Baez
M
M
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D012333:RNA, Messenger; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D020928:Mitogen-Activated Protein Kinases