STRUCTURE FUNCTIONAL EXPRESSION AND SPATIAL-DISTRIBUTION OF A CLONED CDNA-ENCODING A RAT 5-HT1D-LIKE RECEPTOR

Using polymerase chain reaction (PCR) a complementary DNA (cDNA) encoding a 5-hydroxytryptamine (5-HT) receptor was isolated from rat forebrain. The amplified cDNA specifies an open reading frame of 374 amino acids comprising seven putative transmembrane regions. Expression of the cloned cDNA in human embryonic kidney cells (HEK 293) was used to established the pharmacological profile of the coded receptor polypeptide. Membranes containing the cloned receptor showed high affinity binding of [H-3]-5-HT. Competition binding experiments with a variety of serotonin receptor ligands displayed a rank order of affinities corresponding to 5-HT1D subtype: 5-CT > %-HT = metergoline > CGS 12066 > methysergide > sumatriptan > mianserin = (-)alpha-Me-5-HT = yohimbine > 8-OH-DPAT greater-than-or-equal-to rauwolscine > spiperone > DOI > propranolol greater-than-or-equal-to ICS 205930. Ketanserin and ritanserin displaced [H-3]-5-HT-binding in a biphasic manner. In situ hybridization revealed highest expression of the corresponding RNA in the pyramidal layer of the olfactory tubercle and the nucleus caudatus and accumbens.