Molecular cloning and characterization of a rat brain cDNA encoding a 5-hydroxytryptamine1B receptor.

Abstract

To date, there have been at least eight different receptors for the neurotransmitter serotonin (5‐HT) identified in the central nervous system. These receptors fall into four pharmacological classes: 5‐HT1, 5‐HT2, 5‐HT3 and 5‐HT4. The 5‐HT1 class has been shown to contain at least four pharmacologically distinct subtypes, 5‐HT1A‐D. Of these, cDNAs encoding the 5‐HT1A and 5‐HT1C receptors have been previously characterized. We now report the cloning and expression of a rat brain cDNA encoding another member of the 5‐HT1 receptor family. Transient expression of this clone demonstrated high‐affinity binding of [3H]5‐HT with a pharmacological profile corresponding to that of the 5‐HT1B subtype: 5‐CT, 5‐HT greater than propranolol greater than methysergide greater than rauwolscine greater than 8‐OH‐DPAT. In situ hybridization revealed expression of cognate mRNA within cells of the dorsal and median raphe nuclei, consistent with previous reports that the 5‐HT1B receptor acts as an autoreceptor on 5‐HT terminals in this species. mRNA expression was also detected in cells within the CA1 region of hippocampus, striatum, layer 4 of cortex and in the cerebellum, suggesting a previously unrecognized post‐synaptic role for the 5‐HT1B receptor.