WHAT INTRACRANIAL TISSUES IN HUMANS CONTAIN SUMATRIPTAN-SENSITIVE SEROTONIN 5-HT1-TYPE RECEPTORS

We investigated the presence of sumatriptan-sensitive serotonin (5-HT)(1) receptors in different human tissues by using a radioligand-binding technique with [H-3]5-HT. Sumatriptan displaced [H-3]5-HT from frontal cortical and striatal membranes in a biphasic manner, with a high-affinity site corresponding to binding to the 5-HT1D receptor. In blood platelet membranes, sumatriptan displaced [H-3]S-HT with a 100-fold lower affinity. Sumatriptan failed to displace [H-3]5-HT in membranes from large cerebral arteries, pial vessels, coronary arteries and dura mater. These findings suggest that either there are no sumatriptan-sensitive 5-HT1 receptors on intracranial blood vessels or they are so small in number that they cannot be detected by the radioligand-binding technique. Other mechanisms, possibly centrally mediated, may be responsible for the antimigraine action of sumatriptan.