Cloning and Characterization of Chicken 5-hydroxytryptamine (5-HT) Receptors 1A and 1B

Abstract

The aim of this study is to clone and characterize 5-hydroxytryptamine (5-HT; serotonin) receptors, HTR1A and HTR1B, from chicken. 5-HT is a monoamine neurotransmitter derived from tryptophan and is believed to be involved in a broad range of biological activity including mitogenesis of smooth muscle cells, psychological disorders like schizophrenia, anxiety and depression, and neuroendocrine functions like regulation of ACTH, glutamate and dopamine release, via interaction with a large family of G protein-coupled receptors. However, these receptors were not well studied in avian species. In this study, the fulllength genes were cloned from chicken by PCR. HTR1A gene encodes a putative 413-amino acid protein, which shares 80%, 80% and 78% identity with human, chimpanzee and mouse homologues, respectively. Similarly, HTR1B gene encodes a putative 379-amino acid protein, which shares 82%, 82% and 86% identity with human, chimpanzee and mouse homologues respectively. Using a pGL3-CRE luciferase reporter system, activation of both HTR1A and HTR1B by 5-HT were found to inhibit forskolin-stimulated luciferase activity in CHO cells, suggesting that both HTR1A and HTR1B are functionally coupled to Gi protein(s). Further characterization of HTR1A and HTR1B will shed light on the study of biological functions of 5-HT in chickens.