title: Lack of pulse and surge modes and glutamatergic stimulation of luteinising hormone release in Kiss1 knockout rats.
abstract: Kisspeptin, encoded by the Kiss1 gene, has attracted attention as a key candidate neuropeptide in controlling puberty and reproduction via regulation of gonadotrophin-releasing hormone (GnRH) secretion in mammals. Pioneer studies with Kiss1 or its cognate receptor Gpr54 knockout (KO) mice showed the indispensable role of kisspeptin-GPR54 signalling in the control of animal reproduction, although detailed analyses of gonadotrophin secretion, especially pulsatile and surge-mode of luteinising hormone (LH) secretion, were limited. Thus, in the present study, we have generated Kiss1 KO rats aiming to evaluate a key role of kisspeptin in governing reproduction via pulse and surge modes of GnRH/LH secretion. Kiss1 KO male and female rats showed a complete suppression of pulsatile LH secretion, which is responsible for folliculogenesis and spermatogenesis, and an absence of puberty and atrophic gonads. Kiss1 KO female rats showed no spontaneous LH/follicle-stimulating hormone surge and an oestrogen-induced LH surge, suggesting that the GnRH surge generation system, which is responsible for ovulation, does not function without kisspeptin. Furthermore, challenge of major stimulatory neurotransmitters, such as monosodium glutamate, NMDA and norepinephrine, failed to stimulate LH secretion in Kiss1 KO rats, albeit they stimulated LH release in wild-type controls. Taken together, the results of the present study confirm that kisspeptin plays an indispensable role in generating two modes (pulse and surge) of GnRH/gonadotrophin secretion to regulate puberty onset and normal reproductive performance. In addition, the present study suggests that kisspeptin neurones play a critical role as a hub integrating major stimulatory neural inputs to GnRH neurones, using newly established Kiss1 KO rats, which serve as a useful model for detailed analysis of hormonal profiles.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Uenoyama
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Hayakawa
authors.forename: K
authors.initials: K
authors.lastname: Ikegami
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: C
authors.initials: C
authors.lastname: Deura
authors.forename: S
authors.initials: S
authors.lastname: Minabe
authors.forename: J
authors.initials: J
authors.lastname: Tomikawa
authors.forename: T
authors.initials: T
authors.lastname: Goto
authors.forename: N
authors.initials: N
authors.lastname: Ieda
authors.forename: N
authors.initials: N
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Sanbo
authors.forename: C
authors.initials: C
authors.lastname: Tamura
authors.forename: M
authors.initials: M
authors.lastname: Hirabayashi
authors.forename: K-I
authors.initials: KI
authors.lastname: Maeda
authors.forename: H
authors.initials: H
authors.lastname: Tsukamura
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D018698:Glutamic Acid / Q000502:physiology*; D059648:Kisspeptins / Q000235:genetics / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D018345:Mice, Knockout; D016202:N-Methylaspartate / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology; D051381:Rats; D012741:Sexual Maturation / Q000235:genetics / Q000502:physiology*
chemical_list: C491406:Kiss1 protein, rat; D059648:Kisspeptins; D018698:Glutamic Acid; D016202:N-Methylaspartate; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D009638:Norepinephrine
keywords: GPR54; knockout rats; metastin; puberty; rat embryonic stem cells