title: mRNA levels of kisspeptins, kisspeptin receptors, and GnRH1 in the brain of chub mackerel during puberty.
abstract: Kisspeptin (Kiss) and its cognate receptor (Kiss1R), implicated in the neuroendocrine control of GnRH secretion in mammals, have been proposed to be the key factors in regulating puberty. However, the mechanisms underlying the initiation of puberty in fish are poorly understood. The chub mackerel Scomber japonicus expresses two forms of Kiss (kiss1 and kiss2) and two Kiss receptor (kissr1 and kissr2) genes in the brain, which exhibit sexually dimorphic changes during the seasonal reproductive cycle. This indicates that the kisspeptin system plays an important role in gonadal recrudescence of chub mackerel; however, the involvement of the kisspeptin system in the pubertal process has not been identified. In the present study, we examined the mRNA expression of kiss1, kiss2, kissr1, kissr2, and gnrh1 (hypophysiotropic form) in the brain of a chub mackerel during puberty. In male fish, kiss2, kissr1 and kissr2 levels increased significantly at 14weeks post-hatch (wph), synchronously with an increase in type A spermatogonial populations in the testis; kiss2 and gnrh1 levels significantly increased at 22wph, just before the onset of meiosis in the testes. In female fish, kiss2 increased significantly at 14wph, synchronously with an increase in the number of perinucleolar oocytes in the ovary; kiss1 and kiss2 levels significantly increased concomitantly with an increase in the kissr1, kissr2, and gnrh1 levels at 24wph, just before the onset of vitellogenesis in oocytes. The present results suggest positive involvement of the kisspeptin-GnRH system in the pubertal process in the captive reared chub mackerel.
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ohga
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Adachi
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Kojiro
authors.initials: K
authors.lastname: Matsumori
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Kodama
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nyuji
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Sethu
authors.initials: S
authors.lastname: Selvaraj
authors.affiliation: Fisheries Laboratory of Kinki University, Shirahama, Wakayama 649-2211, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Kato
authors.affiliation: Fisheries Laboratory of Kinki University, Shirahama, Wakayama 649-2211, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamaguchi
authors.affiliation: Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: rinya_m@agr.kyushu-u.ac.jp.
authors.forename: Michiya
authors.initials: M
authors.lastname: Matsuyama
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics* / Q000378:metabolism; D006066:Gonads / Q000254:growth & development / Q000378:metabolism; D059648:Kisspeptins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D010473:Perciformes / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000378:metabolism; D012741:Sexual Maturation / Q000235:genetics*
chemical_list: D059648:Kisspeptins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D007987:Gonadotropin-Releasing Hormone
keywords: GnRH1; Kisspeptin; Kisspeptin receptor; Puberty; Scombridae; Teleost