title: Molecular cloning and pharmacological characterization of the guinea pig 5-HT1E receptor.
abstract: The human 5-HT(1E) receptor gene was cloned more than a decade ago. Little is known about its function, and there have been no reports of its existence in the genome of small laboratory animals. In this study, attempts to clone the 5-HT(1E) gene from the rat and mouse were unsuccessful. In fact, a search of the mouse genome database revealed that the 5-HT(1E) receptor gene is missing from the mouse genome. However, the 5-HT(1E) gene was cloned from guinea pig genomic DNA and was characterized. The guinea pig 5-HT(1E) receptor gene encodes a protein of 365 amino acids. It shares 88% (nucleic acid) and 95% (amino acid) homology with the human receptor. The guinea pig 5-HT(1E) receptor showed similar pharmacology to the human 5-HT(1E) receptor in radioligand binding assays. Serotonin (5-hydroxytryptamine, 5-HT) dose-dependently stimulated [35S]GTPgammaS binding to the guinea pig 5-HT(1E) receptor with an EC(50) of 13.6+/-1.92 nM, similar to that of the human 5-HT(1E) receptor (13.7+/-1.78 nM). Activation of the guinea pig 5-HT(1E) receptor was also achieved by ergonovine, alpha-methyl-5-HT, 1-naphthylpiperazine, methysergide, tryptamine, and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Methiothepin exhibited antagonist activity. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that 5-HT(1E) mRNA was present in the guinea pig brain with the greatest abundance in the hippocampus, followed by the olfactory bulb. Lower levels were detected in the cortex, thalamus, pons, hypothalamus, midbrain, striatum, and cerebellum. Our current study marks the first identification of the 5-HT(1E) receptor gene in a commonly used laboratory animal species. This finding should allow the elucidation of the receptor's role(s) in the complex coordination of central serotonergic effects.
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285, USA. fbai@iupui.edu
authors.forename: Fengju
authors.initials: F
authors.lastname: Bai
authors.forename: Tinggui
authors.initials: T
authors.lastname: Yin
authors.forename: Edward M
authors.initials: EM
authors.lastname: Johnstone
authors.forename: Chen
authors.initials: C
authors.lastname: Su
authors.forename: Gabor
authors.initials: G
authors.lastname: Varga
authors.forename: Sheila P
authors.initials: SP
authors.lastname: Little
authors.forename: David L
authors.initials: DL
authors.lastname: Nelson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular / Q000379:methods*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005849:Gerbillinae; D006168:Guinea Pigs; D000882:Haplorhini; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000502:physiology; D011817:Rabbits; D011985:Receptors, Serotonin / Q000235:genetics* / Q000378:metabolism*; D018490:Serotonin Agents / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D013552:Swine
chemical_list: D011985:Receptors, Serotonin; D018490:Serotonin Agents; C076396:serotonin 1E receptor