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Goadsby PJ, Classey JD: Evidence for serotonin (5-HT) 1B, 5-HT1D and 5-HT1F receptor inhibitory effects on trigeminal neurons with craniovascular input. Neuroscience. 2003;122(2):491-8.
Development of serotonin (5HT (1B/1D)) agonists for the acute attack of migraine resulted in considerable interest in their action. The superior sagittal sinus (SSS) was isolated in alpha-chloralose (60 mg/kg, i.p. and 20 mg/kg i.v.i. supplementary 2 hourly) anaesthetised cats. The SSS was stimulated electrically (100 V, 250 micros duration, 0.3 Hz) and neurons of the trigeminocervical complex monitored using electrophysiological methods. To test 5-HT (1B) receptor-mediated activity common carotid blood flow (CCF) was monitored with a transonic flow probe placed around the vessel. Naratriptan (5-HT (1B/1D/1F) receptor agonist) and alniditan (5-HT (1B/1D) receptor agonist) produced reductions in carotid blood flow of 38+/-5% and 42+/-6%, respectively. These effects were attenuated by the 5-HT (1B) receptor antagonist SB224289 (P <0.05). LY344864 (5-HT (1F) receptor agonist) had no effect on CCF. Naratriptan inhibited SSS-evoked activity (61+/-7%), an effect partially inhibited by the 5-HT (1B) receptor antagonist SB224289 (30+/-5%), or by the 5-HT (1D) receptor antagonist BRL-15572 (37+/-6%). There remained an inhibitory effect of naratriptan after both 5-HT (1B) and 5-HT (1D) receptor blockade (22+/-5%). Alniditan inhibited SSS-evoked trigeminal activity (53+/-6%), an effect abolished after 5-HT (1B) and 5-HT (1D) receptor blockade. LY344864 (5-HT (1F) receptor agonist) inhibited SSS-evoked trigeminal activity (28+/-5%), an effect unaltered by either SB224289 or BRL-15572. It can be concluded that there are inhibitory 5-HT (1B), 5-HT (1D) and 5-HT (1F) receptors in the trigeminocervical complex of the cat. 5-HT (1B) receptor-mediated inhibition is the most potent of the three in terms of inhibition of trigeminovascular nociceptive traffic. |
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