Kisspeptin system: into the heart of reproduction control

Since the discovery of its importance in reproduction, the system formed by the neuropeptide kisspeptin and its receptor (KISS1R) has been the object of intense research activities. The results obtained in mammals show that this system plays an important role in several aspects of reproduction. Considering the extent of available data, we have focused our attention on a limited number of points that allow anyhow drawing a general picture of the field. First, we will illustrate the neuroanatomical and physiological data that permitted to establish that the main action of the system is the regulation of GnRH neurons and of their secretion patterns (pulsatile or surge). Then we will describe evidence for the implication of this system in initiating puberty and triggering ovulation. Finally, we will sketch a picture of the possible applications of Kp system modulation to better manage reproduction or to treat pathologies of the reproductive system either in veterinary or human medicine.Depuis la découverte de son importance en physiologie de la reproduction, le système composé par le neuropeptide kisspeptine et son récepteur (KISS1R) a fait l’objet d’une intense activité de recherche. Chez les mammifères, il joue un rôle dans de nombreux aspects de la reproduction. En raison de la richesse des données disponibles, nous avons focalisé notre attention sur un nombre limité de points suffisants, néanmoins, pour en avoir une vision générale. Les données neuroanatomiques et physiologiques nous permettent d’illustrer la fonction principale de ce système, qui est de réguler l’activité des neurones à GnRH et notamment de leur mode de sécrétion (pulsatile ou pic préovulatoire aussi appelé surge). Puis, son implication dans le déclenchement de la puberté et le contrôle de l’ovulation est développée. Pour terminer, sont décrites les applications possibles de la modulation du système Kp en zootechnie, pour une meilleure maitrise de la reproduction des animaux d’élevage ou à forte valeur patrimoniale, et en médecine vétérinaire ou humaine, pour le traitement des troubles de la fonction de reproduction

GPR50 is the mammalian ortholog of Mel1c: Evidence of rapid evolution in mammals

<p>Abstract</p> <p>Background</p> <p>The melatonin receptor subfamily contains three members Mel1a, Mel1b and Mel1c, found in all vertebrates except for Mel1c which is found only in fish, Xenopus species and the chicken. Another receptor, the melatonin related receptor known as GPR50, found exclusively in mammals and later identified as a member of the melatonin receptor subfamily because of its identity to the three melatonin receptors despite its absence of affinity for melatonin. The aim of this study was to describe the evolutionary relationships between GPR50 and the three other members of the melatonin receptor subfamily.</p> <p>Results</p> <p>Using an <it>in silico </it>approach, we demonstrated that GPR50 is the ortholog of the high affinity Mel1c receptor. It was necessary to also study the synteny of this gene to reach this conclusion because classical mathematical models that estimate orthology and build phylogenetic trees were not sufficient. The receptor has been deeply remodelled through evolution by the mutation of numerous amino acids and by the addition of a long C-terminal tail. These alterations have modified its affinity for melatonin and probably affected its interactions with the other two known melatonin receptors MT1 and MT2 that are encoded by Mel1a and Mel1b genes respectively. Evolutionary studies provided evidence that the GPR50 group evolved under different selective pressure as compared to the orthologous groups Me11 a, b, and c.</p> <p>Conclusion</p> <p>This study demonstrated that there are only three members in the melatonin receptor subfamily with one of them (Me11c) undergoing rapid evolution from fishes and birds to mammals. Further studies are necessary to investigate the physiological roles of this receptor.</p

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Distribution of galanin receptor 1-immunoreactive neurons in the ovine hypothalamus: Colocalization with GnRH

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La somatostatine agit sur les neurones à kisspeptine du noyau arqué du rat mâle via le récepteur SSTR1 plutôt que via le récepteur SSTR2A

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Kisspeptin neurons from the arcuate nucleus express somatostatin receptor SSTR1 more frequently than SSTR2A in male rats

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Galanin receptor (GAL-R1, GAL-R2) immunoreactivity in the ovine hypothalamus: colocalization with GnRH

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