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 [3H]5-HT. Sumatriptan displaced [3H]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 [3H]5-HT with a 100-fold lower affinity. Sumatriptan failed to displace [3H]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.