The effects of 5-HT1A, 5-HT1B and 5-HT1D receptor agonists on trigeminal nociceptive neurotransmission in anaesthetized rats

Pre-clinical studies have suggested that one mechanism of antimigraine acti on of the 'triptan' 5-HT1B/1D receptor agonists may be through inhibition o f central nociceptive transmission in the trigeminal dorsal horn. In anaest hetized rats, the 5-HT1B/1D receptor agonist, zolmitriptan (up to 3 mg kg(- 1), i.v.), inhibited the action potential discharge of single trigeminal ne urones to noxious electrical stimulation of the middle meningeal artery. In contrast, the selective 5-HT1B receptor agonist, CP-93,129 (3-(1,2,5,6-tet rahydropyrid-4-yl)pyrrolo[3,2-b]pyrid-5-one), and the 5-HT1B receptor selec tive agonist 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) had no eff ect in this assay at up to 3 mg kg(-1), i.v.. Brain penetrant, triptan 5-HT 1B/1D receptor agonists may therefore mediate their central trigeminal anti -nociceptive action in the rat via 5-HT1D, but not 5-HT1B or 5-HT1A, recept ors. (C) 1998 Elsevier Science B.V. All rights reserved.