Identification of KiSS-1 product kisspeptin and steroid-sensitive sexually dimorphic kisspeptin neurons in medaka (oryzias latipes).
Recently, a novel physiologically active peptide, kisspeptin (metastin), has been reported to facilitate sexual maturation and ovulation by directly stimulating GnRH neurons in several mammalian species. Despite its importance in the neuroendocrine regulation of reproduction, kisspeptin neurons have only been studied in mammals, and there has been no report on the kisspeptin or kisspeptin neuronal systems in nonmammalian vertebrates. We used medaka for the initial identification of the KiSS-1 gene and the anatomical distribution of KiSS-1 mRNA expressing neurons (KiSS-1 neurons) in the brain of nonmammalian species. In situ hybridization for the medaka KiSS-1 gene cloned here proved that two kisspeptin neuronal populations are localized in the hypothalamic nuclei, the nucleus posterioris periventricularis and the nucleus ventral tuberis (NVT). Furthermore, NVT KiSS-1 neurons were sexually dimorphic in number (male neurons >> female neurons) under the breeding conditions. We also found that the number of KiSS-1 neurons in the NVT but not that in the nucleus posterioris periventricularis was positively regulated by ovarian estrogens. The fact that there were clear differences in the number of NVT KiSS-1 neurons between the fish under the breeding and nonbreeding conditions strongly suggests that the steroid-sensitive changes in the KiSS-1 mRNA expression in the NVT occur physiologically, according to the changes in the reproductive state. From the present results, we conclude that the medaka KiSS-1 neuronal system is involved in the central regulation of reproductive functions, and, given many experimental advantages, the medaka brain may serve as a good model system to study its physiology.
Kanda
Shinji
S
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
Akazome
Yasuhisa
Y
Matsunaga
Takuya
T
Yamamoto
Naoyuki
N
Yamada
Shunji
S
Tsukamura
Hiroko
H
Maeda
Kei-ichiro
K
Oka
Yoshitaka
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D059648:Kisspeptins; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009990:Oryzias / Q000235:genetics* / Q000378:metabolism; D012098:Reproduction / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012727:Sex Characteristics; D013256:Steroids / Q000494:pharmacology*; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins / Q000235:genetics
C106628:KISS1 protein, human; D059648:Kisspeptins; D013256:Steroids; D025521:Tumor Suppressor Proteins