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Abstract(s)
Gonadotrophin-releasing hormone (GnRH) is the main neurohormone controlling gonadotrophin release in all
vertebrates, and in teleost fish also of growth hormone and possibly of other adenohypophyseal hormones. Over 20
GnRHs have been identified in vertebrates and protochoordates and shown to bind cognate G-protein couple
receptors (GnRHR). We have searched the puffer fish, Fugu rubripes, genome sequencing database, identified five
GnRHR genes and proceeded to isolate the corresponding complementary DNAs in European sea bass, Dicentrachus
labrax. Phylogenetic analysis clusters the European sea bass, puffer fish and all other vertebrate receptors into two
main lineages corresponding to the mammalian type I and II receptors. The fish receptors could be subdivided in two
GnRHR1 (A and B) and three GnRHR2 (A, B and C) subtypes. Amino acid sequence identity within receptor subtypes
varies between 70 and 90% but only 50–55% among the two main lineages in fish. All European sea bass receptor
mRNAs are expressed in the anterior and mid brain, and all but one are expressed in the pituitary gland. There is
differential expression of the receptors in peripheral tissues related to reproduction (gonads), chemical senses (eye
and olfactory epithelium) and osmoregulation (kidney and gill). This is the first report showing five GnRH receptors in
a vertebrate species and the gene expression patterns support the concept that GnRH and GnRHRs play highly
diverse functional roles in the regulation of cellular functions, besides the ‘‘classical’’ role of pituitary function regulation.
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Citation
Moncaut, N.; Somoza, G. M.; Power, D. M.; Canario, A. V. M.Five gonadotrophin-releasing hormone receptors in a teleost fish: isolation, tissue distribution and phylogenetic relationships, Journal of Molecular Endocrinology, 34, 3, 767-779, 2005