title: Kisspeptin neurons mediate reflex ovulation in the musk shrew (Suncus murinus).
abstract: The present study investigated whether kisspeptin-G protein-coupled receptor 54 (GPR54) signaling plays a role in mediating mating-induced ovulation in the musk shrew (Suncus murinus), a reflex ovulator. For this purpose, we cloned suncus Kiss1 and Gpr54 cDNA from the hypothalamus and found that suncus kisspeptin (sKp) consists of 29 amino acid residues (sKp-29). Injection of exogenous sKp-29 mimicked the mating stimulus to induce follicular maturation and ovulation. Administration of several kisspeptins and GPR54 agonists also induced presumed ovulation in a dose-dependent manner, and Gpr54 mRNA was distributed in the hypothalamus, showing that kisspeptins induce ovulation through binding to GPR54. The sKp-29-induced ovulation was blocked completely by pretreatment with a gonadotropin-releasing hormone (GnRH) antagonist, suggesting that kisspeptin activates GnRH neurons to induce ovulation in the musk shrew. In addition, in situ hybridization revealed that Kiss1-expressing cells are located in the medial preoptic area (POA) and arcuate nucleus in the musk shrew hypothalamus. The number of Kiss1-expressing cells in the POA or arcuate nucleus was up-regulated or down-regulated by estradiol, suggesting that kisspeptin neurons in these regions were the targets of the estrogen feedback action. Finally, mating stimulus largely induced c-Fos expression in Kiss1-positive cells in the POA, indicating that the mating stimulus activates POA kisspeptin neurons to induce ovulation. Taken together, these results indicate that kisspeptin-GPR54 signaling plays a role in the induction of ovulation in the musk shrew, a reflex ovulator, as it does in spontaneous ovulators.
authors: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. ninoue@agr.nagoya-u.ac.jp
authors: Naoko
authors: N
authors: Inoue
authors: Karin
authors: K
authors: Sasagawa
authors: Kotaro
authors: K
authors: Ikai
authors: Yuki
authors: Y
authors: Sasaki
authors: Junko
authors: J
authors: Tomikawa
authors: Shinya
authors: S
authors: Oishi
authors: Nobutaka
authors: N
authors: Fujii
authors: Yoshihisa
authors: Y
authors: Uenoyama
authors: Yasushige
authors: Y
authors: Ohmori
authors: Naoyuki
authors: N
authors: Yamamoto
authors: Eiichi
authors: E
authors: Hondo
authors: Kei-ichiro
authors: K
authors: Maeda
authors: Hiroko
authors: H
authors: Tsukamura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects / Q000502:physiology; D001483:Base Sequence; D003307:Copulation / Q000502:physiology; D003338:Corpus Luteum / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D059648:Kisspeptins / Q000235:genetics / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D006080:Ovarian Follicle / Q000502:physiology; D010060:Ovulation / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012788:Shrews / Q000502:physiology*; D014018:Tissue Distribution
chemical_list: D018076:DNA, Complementary; D059648:Kisspeptins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol