The subnuclear distribution of 5-HT₃ receptors in the human nucleus of the solitary tract and other structures of the caudal medulla

The distribution of 5-HT₃ receptors was examined in the human medulla using [³H]LY278584, a highly selective 5-HT₃ receptor antagonist. The highest density of 5-HT₃ receptors was found in the substantia gelatinosus subnucleus of nucleus of the solitary tract (NTS) throughout its rostrocaudal extent, followed by the dorsal subnucleus, the area postrema (AP), the commissural sub nucleus, the medial subnucleus, and in an arc correspondingto the gelatinosus of the spinal trigeminal nucleus (nSp5). The distribution of 5-HT₃ receptors in the brain may help explain some of the reported CNS activities of 5-HT₃-selective drugs. The anti-emetic and antinociceptive activities of 5-HT₃ antagonists may be mediated by receptors in sensory areas of the brainstem.