5-Hydroxytryptamine(1F) receptors do not participate in vasoconstriction: lack of vasoconstriction to LY344864, a selective serotonin(1F) receptor agonist in rabbit saphenous vein.
Recently, several novel approaches to the treatment of migraine have been advanced, including selective 5-hydroxytryptamine (or serotonin) 1B/1D (5-HT(1B/1D)) receptor agonists such as sumatriptan and 5-HT(1F) receptor agonists such as LY344864. Many 5-HT(1B/1D) receptor agonists have been identified based on their ability to produce cerebral vascular contraction, whereas LY344864 was identified as an inhibitor of trigeminal nerve-mediated dural extravasation. In our study, several triptan derivatives were compared with LY344864 for their ability to contract the rabbit saphenous vein, a tissue used in the preclinical identification of sumatriptan-related agonists. Sumatriptan, zolmitriptan, rizatriptan, and naratriptan all contracted the rabbit saphenous vein from baseline tone, whereas LY344864 in concentrations up to 10(-4) M did not contract the rabbit saphenous vein. Furthermore, vascular contractions to sumatriptan were markedly augmented in the presence of prostaglandin F(2alpha) (PGF(2alpha)). However, even in the presence of PGF(2alpha) (3 x 10(-7) M), LY344864 did not contract the rabbit saphenous vein in concentrations well in excess of its 5-HT(1F) receptor affinity (pK(i) = 8.2). Only when concentrations exceeded those likely to activate 5-HT(1B) and 5-HT(1D) receptors (>10(-5) M) did modest contractile responses occur in the presence of PGF(2alpha). Use of these serotonergic agonists revealed a significant correlation between the contractile potency in the rabbit saphenous vein and the affinities of these agonists at 5-HT(1B) and 5-HT(1D) receptors, although contractile agonist potencies were not quantitatively similar to 5-HT(1B) or 5-HT(1D) receptor affinities. In contrast, no significant correlation existed between the contractile potencies of these serotonergic agonists in the rabbit saphenous vein and their affinity at 5-HT(1F) receptors. These data support the contention that activation of 5-HT(1F) receptors will not result in vascular contractile effects.
Cohen
M L
ML
Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA. cohenml@lilly.com
Schenck
K
K
D000818:Animals; D002227:Carbazoles / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005464:Fluorobenzenes / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D011485:Protein Binding; D011817:Rabbits; D011869:Radioligand Assay; D011985:Receptors, Serotonin / Q000145:classification / Q000378:metabolism / Q000502:physiology*; D012501:Saphenous Vein / Q000187:drug effects* / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000378:metabolism / Q000494:pharmacology*; D013379:Substrate Specificity; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D000096642:Receptor, Serotonin, 5-HT1F
D002227:Carbazoles; D005464:Fluorobenzenes; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D000096642:Receptor, Serotonin, 5-HT1F; C109453:LY 344864