Evidence for 5-HT(1B/1D) and 5-HT(2A) Receptors Mediating Constriction of the Canine Internal Carotid Circulation
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The present study has investigated the preliminary pharmacological profile of the receptors mediating vasoconstriction to 5-hydroxytryptamine (5-HT) in the internal carotid bed of vagosympathectomised dogs. One minute intracarotid infusions of the agonists 5-HT (0.1 - 10 microg min(-1)), sumatriptan (0.3 - 10 microg min(-1); 5-HT(1B/1D)), 5-methoxytryptamine (1 - 100 microg min(-1); 5-HT(1), 5-HT(2), 5-HT(4), 5-ht(6) and 5-HT(7)) or DOI (0.31 - 10 microg min(-1); 5-HT(2)), but not 5-carboxamidotryptamine (0.01 - 0.3 microg min(-1); 5-HT(1), 5-ht(5A) and 5-HT(7)), 1-(m-chlorophenyl)-biguanide (mCPBG; 1 - 1000 microg min(-1); 5-HT(3)) or cisapride (1 - 1000 microg min(-1); 5-HT(4)), resulted in dose-dependent decreases in internal carotid blood flow, without changing blood pressure or heart rate. The vasoconstrictor responses to 5-HT, which remained unaffected after saline, were resistant to blockade by i.v. administration of the antagonists ritanserin (100 microg kg(-1); 5-HT(2A/2B/2C)) in combination with tropisetron (3000 microg kg(-1); 5-HT(3/4)) or the cyclo-oxygenase inhibitor, indomethacin (5000 microg kg(-1)), but were abolished by the 5-HT(1B/1D) receptor antagonist, GR127935 (30 microg kg(-1)). Interestingly, after administration of GR127935, the subsequent administration of ritanserin unmasked a dose-dependent vasodilator component. GR127935 or saline did not practically modify the vasoconstrictor effects of 5-MeO-T. In animals receiving GR127935, the subsequent administration of ritanserin abolished the vasoconstrictor responses to 5-MeO-T unmasking a dose-dependent vasodilator component. The vasoconstriction induced by sumatriptan was antagonized by GR127935, but not by ritanserin. Furthermore, ritanserin (100 microg kg(-1)) or ketanserin (100 microg kg(-1); 5-HT(2A)), but not GR127935, abolished DOI-induced vasoconstrictor responses. The above results suggest that 5-HT-induced internal carotid vasoconstriction is predominantly mediated by 5-HT(1B/1D) and 5-HT(2A) receptors.
Tsujino T, Isayama H, Nakai Y, Ito Y, Togawa O, Toda N J Gastroenterol. 2012; 48(8):982-8.
PMID: 23090004 DOI: 10.1007/s00535-012-0698-5.
5-HT(1F) Receptor agonists: a new treatment option for migraine attacks?.
Neeb L, Meents J, Reuter U Neurotherapeutics. 2010; 7(2):176-82.
PMID: 20430316 PMC: 5084098. DOI: 10.1016/j.nurt.2010.03.003.
Villalon C, Centurion D Naunyn Schmiedebergs Arch Pharmacol. 2007; 376(1-2):45-63.
PMID: 17703282 DOI: 10.1007/s00210-007-0179-1.
Centurion D, Sanchez-Lopez A, de Vries P, Saxena P, Villalon C Br J Pharmacol. 2001; 132(5):991-8.
PMID: 11226129 PMC: 1572652. DOI: 10.1038/sj.bjp.0703913.