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Valerie Simonneaux - One of the best experts on this subject based on the ideXlab platform.

  • Kisspeptin and the seasonal Control of Reproduction in hamsters.
    Peptides, 2008
    Co-Authors: Valerie Simonneaux, Florent G Revel, Paul Pevet, Laura Ansel, Paul Klosen, Jens D Mikkelsen
    Abstract:

    Reproduction is a complex and energy demanding function. When internal and external conditions might impair reproductive success (negative energy balance, stress, harsh season) reproductive activity has to be repressed. Recent evidence suggests that these inhibitory mechanisms operate on Kiss1-expressing neurons, which were recently shown to be implicated in the regulation of GnRH release. Hamsters are seasonal rodents which are sexually active in long photoperiod and quiescent in short photoperiod. The photoperiodic information is transmitted to the reproductive system by melatonin, a pineal hormone whose secretion is adjusted to night length. The photoperiodic variation in circulating melatonin has been shown to synchronize reproductive activity with seasons, but the mechanisms involved in this effect of melatonin were so far unknown. Recently we have observed that Kiss1 mRNA level in the arcuate nucleus of the Syrian hamster is lower in short photoperiod, when animals are sexually quiescent. Notably, intracerebroventricular infusion of Kiss1 gene product, kisspeptin, in hamsters kept in short photoperiod is able to override the inhibitory photoperiod and to reactivate sexual activity. The inhibition of Kiss1 expression in short photoperiod is driven by melatonin because pinealectomy prevents decrease in Kiss1 mRNA level in short photoperiod and melatonin injection in long photoperiod down regulates Kiss1 expression. Whether melatonin acts directly on arcuate Kiss1 expressing neurons or mediates its action via interneurons is the subject of the current investigations.

  • kisspeptin mediates the photoperiodic Control of Reproduction in hamsters
    Current Biology, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, M Massonpevet, Paul Pevet, Jens D Mikkelsen, Valerie Simonneaux
    Abstract:

    Summary The KiSS-1 gene encodes kisspeptin, the endogenous ligand of the G-protein-coupled receptor GPR54 [1–4]. Recent data indicate that the KiSS-1/GPR54 system is critical for the regulation of Reproduction and is required for puberty onset [5–10]. In seasonal breeders, Reproduction is tightly Controlled by photoperiod (i.e., day length) [11, 12]. The Syrian hamster is a seasonal model in which reproductive activity is promoted by long summer days (LD) and inhibited by short winter days (SD) [12–14]. Using in situ hybridization and immunohistochemistry, we show that KiSS-1 is expressed in the arcuate nucleus of LD hamsters. Importantly, the KiSS-1 mRNA level was lower in SD animals but not in SD-refractory animals, which spontaneously reactivated their sexual activity after several months in SD. These changes of expression are not secondary to the photoperiodic variations of gonadal steroids. In contrast, melatonin appears to be necessary for these seasonal changes because pineal-gland ablation prevented the SD-induced downregulation of KiSS-1 expression. Remarkably, a chronic administration of kisspeptin-10 restored the testicular activity of SD hamsters despite persisting photoinhibitory conditions. Overall, these findings are consistent with a role of KiSS-1/GPR54 in the seasonal Control of Reproduction. We propose that photoperiod, via melatonin, modulates KiSS-1 signaling to drive the reproductive axis.

  • KiSS-1: a likely candidate for the photoperiodic Control of Reproduction in seasonal breeders
    Chronobiology International, 2006
    Co-Authors: Florent Revel, Michel Saboureau, Paul Pevet, Mireille Masson-pevet, Jens Mikkelsen, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

  • KiSS‐1: A Likely Candidate for the Photoperiodic Control of Reproduction in Seasonal Breeders
    Chronobiology international, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, Paul Pevet, Jens D Mikkelsen, Mireille Masson-pevet, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

Jens D Mikkelsen - One of the best experts on this subject based on the ideXlab platform.

  • Kisspeptin and the seasonal Control of Reproduction in hamsters.
    Peptides, 2008
    Co-Authors: Valerie Simonneaux, Florent G Revel, Paul Pevet, Laura Ansel, Paul Klosen, Jens D Mikkelsen
    Abstract:

    Reproduction is a complex and energy demanding function. When internal and external conditions might impair reproductive success (negative energy balance, stress, harsh season) reproductive activity has to be repressed. Recent evidence suggests that these inhibitory mechanisms operate on Kiss1-expressing neurons, which were recently shown to be implicated in the regulation of GnRH release. Hamsters are seasonal rodents which are sexually active in long photoperiod and quiescent in short photoperiod. The photoperiodic information is transmitted to the reproductive system by melatonin, a pineal hormone whose secretion is adjusted to night length. The photoperiodic variation in circulating melatonin has been shown to synchronize reproductive activity with seasons, but the mechanisms involved in this effect of melatonin were so far unknown. Recently we have observed that Kiss1 mRNA level in the arcuate nucleus of the Syrian hamster is lower in short photoperiod, when animals are sexually quiescent. Notably, intracerebroventricular infusion of Kiss1 gene product, kisspeptin, in hamsters kept in short photoperiod is able to override the inhibitory photoperiod and to reactivate sexual activity. The inhibition of Kiss1 expression in short photoperiod is driven by melatonin because pinealectomy prevents decrease in Kiss1 mRNA level in short photoperiod and melatonin injection in long photoperiod down regulates Kiss1 expression. Whether melatonin acts directly on arcuate Kiss1 expressing neurons or mediates its action via interneurons is the subject of the current investigations.

  • kisspeptin mediates the photoperiodic Control of Reproduction in hamsters
    Current Biology, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, M Massonpevet, Paul Pevet, Jens D Mikkelsen, Valerie Simonneaux
    Abstract:

    Summary The KiSS-1 gene encodes kisspeptin, the endogenous ligand of the G-protein-coupled receptor GPR54 [1–4]. Recent data indicate that the KiSS-1/GPR54 system is critical for the regulation of Reproduction and is required for puberty onset [5–10]. In seasonal breeders, Reproduction is tightly Controlled by photoperiod (i.e., day length) [11, 12]. The Syrian hamster is a seasonal model in which reproductive activity is promoted by long summer days (LD) and inhibited by short winter days (SD) [12–14]. Using in situ hybridization and immunohistochemistry, we show that KiSS-1 is expressed in the arcuate nucleus of LD hamsters. Importantly, the KiSS-1 mRNA level was lower in SD animals but not in SD-refractory animals, which spontaneously reactivated their sexual activity after several months in SD. These changes of expression are not secondary to the photoperiodic variations of gonadal steroids. In contrast, melatonin appears to be necessary for these seasonal changes because pineal-gland ablation prevented the SD-induced downregulation of KiSS-1 expression. Remarkably, a chronic administration of kisspeptin-10 restored the testicular activity of SD hamsters despite persisting photoinhibitory conditions. Overall, these findings are consistent with a role of KiSS-1/GPR54 in the seasonal Control of Reproduction. We propose that photoperiod, via melatonin, modulates KiSS-1 signaling to drive the reproductive axis.

  • KiSS‐1: A Likely Candidate for the Photoperiodic Control of Reproduction in Seasonal Breeders
    Chronobiology international, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, Paul Pevet, Jens D Mikkelsen, Mireille Masson-pevet, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

Paul Pevet - One of the best experts on this subject based on the ideXlab platform.

  • Kisspeptin and the seasonal Control of Reproduction in hamsters.
    Peptides, 2008
    Co-Authors: Valerie Simonneaux, Florent G Revel, Paul Pevet, Laura Ansel, Paul Klosen, Jens D Mikkelsen
    Abstract:

    Reproduction is a complex and energy demanding function. When internal and external conditions might impair reproductive success (negative energy balance, stress, harsh season) reproductive activity has to be repressed. Recent evidence suggests that these inhibitory mechanisms operate on Kiss1-expressing neurons, which were recently shown to be implicated in the regulation of GnRH release. Hamsters are seasonal rodents which are sexually active in long photoperiod and quiescent in short photoperiod. The photoperiodic information is transmitted to the reproductive system by melatonin, a pineal hormone whose secretion is adjusted to night length. The photoperiodic variation in circulating melatonin has been shown to synchronize reproductive activity with seasons, but the mechanisms involved in this effect of melatonin were so far unknown. Recently we have observed that Kiss1 mRNA level in the arcuate nucleus of the Syrian hamster is lower in short photoperiod, when animals are sexually quiescent. Notably, intracerebroventricular infusion of Kiss1 gene product, kisspeptin, in hamsters kept in short photoperiod is able to override the inhibitory photoperiod and to reactivate sexual activity. The inhibition of Kiss1 expression in short photoperiod is driven by melatonin because pinealectomy prevents decrease in Kiss1 mRNA level in short photoperiod and melatonin injection in long photoperiod down regulates Kiss1 expression. Whether melatonin acts directly on arcuate Kiss1 expressing neurons or mediates its action via interneurons is the subject of the current investigations.

  • kisspeptin mediates the photoperiodic Control of Reproduction in hamsters
    Current Biology, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, M Massonpevet, Paul Pevet, Jens D Mikkelsen, Valerie Simonneaux
    Abstract:

    Summary The KiSS-1 gene encodes kisspeptin, the endogenous ligand of the G-protein-coupled receptor GPR54 [1–4]. Recent data indicate that the KiSS-1/GPR54 system is critical for the regulation of Reproduction and is required for puberty onset [5–10]. In seasonal breeders, Reproduction is tightly Controlled by photoperiod (i.e., day length) [11, 12]. The Syrian hamster is a seasonal model in which reproductive activity is promoted by long summer days (LD) and inhibited by short winter days (SD) [12–14]. Using in situ hybridization and immunohistochemistry, we show that KiSS-1 is expressed in the arcuate nucleus of LD hamsters. Importantly, the KiSS-1 mRNA level was lower in SD animals but not in SD-refractory animals, which spontaneously reactivated their sexual activity after several months in SD. These changes of expression are not secondary to the photoperiodic variations of gonadal steroids. In contrast, melatonin appears to be necessary for these seasonal changes because pineal-gland ablation prevented the SD-induced downregulation of KiSS-1 expression. Remarkably, a chronic administration of kisspeptin-10 restored the testicular activity of SD hamsters despite persisting photoinhibitory conditions. Overall, these findings are consistent with a role of KiSS-1/GPR54 in the seasonal Control of Reproduction. We propose that photoperiod, via melatonin, modulates KiSS-1 signaling to drive the reproductive axis.

  • KiSS-1: a likely candidate for the photoperiodic Control of Reproduction in seasonal breeders
    Chronobiology International, 2006
    Co-Authors: Florent Revel, Michel Saboureau, Paul Pevet, Mireille Masson-pevet, Jens Mikkelsen, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

  • KiSS‐1: A Likely Candidate for the Photoperiodic Control of Reproduction in Seasonal Breeders
    Chronobiology international, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, Paul Pevet, Jens D Mikkelsen, Mireille Masson-pevet, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

Florent G Revel - One of the best experts on this subject based on the ideXlab platform.

  • Kisspeptin and the seasonal Control of Reproduction in hamsters.
    Peptides, 2008
    Co-Authors: Valerie Simonneaux, Florent G Revel, Paul Pevet, Laura Ansel, Paul Klosen, Jens D Mikkelsen
    Abstract:

    Reproduction is a complex and energy demanding function. When internal and external conditions might impair reproductive success (negative energy balance, stress, harsh season) reproductive activity has to be repressed. Recent evidence suggests that these inhibitory mechanisms operate on Kiss1-expressing neurons, which were recently shown to be implicated in the regulation of GnRH release. Hamsters are seasonal rodents which are sexually active in long photoperiod and quiescent in short photoperiod. The photoperiodic information is transmitted to the reproductive system by melatonin, a pineal hormone whose secretion is adjusted to night length. The photoperiodic variation in circulating melatonin has been shown to synchronize reproductive activity with seasons, but the mechanisms involved in this effect of melatonin were so far unknown. Recently we have observed that Kiss1 mRNA level in the arcuate nucleus of the Syrian hamster is lower in short photoperiod, when animals are sexually quiescent. Notably, intracerebroventricular infusion of Kiss1 gene product, kisspeptin, in hamsters kept in short photoperiod is able to override the inhibitory photoperiod and to reactivate sexual activity. The inhibition of Kiss1 expression in short photoperiod is driven by melatonin because pinealectomy prevents decrease in Kiss1 mRNA level in short photoperiod and melatonin injection in long photoperiod down regulates Kiss1 expression. Whether melatonin acts directly on arcuate Kiss1 expressing neurons or mediates its action via interneurons is the subject of the current investigations.

  • kisspeptin mediates the photoperiodic Control of Reproduction in hamsters
    Current Biology, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, M Massonpevet, Paul Pevet, Jens D Mikkelsen, Valerie Simonneaux
    Abstract:

    Summary The KiSS-1 gene encodes kisspeptin, the endogenous ligand of the G-protein-coupled receptor GPR54 [1–4]. Recent data indicate that the KiSS-1/GPR54 system is critical for the regulation of Reproduction and is required for puberty onset [5–10]. In seasonal breeders, Reproduction is tightly Controlled by photoperiod (i.e., day length) [11, 12]. The Syrian hamster is a seasonal model in which reproductive activity is promoted by long summer days (LD) and inhibited by short winter days (SD) [12–14]. Using in situ hybridization and immunohistochemistry, we show that KiSS-1 is expressed in the arcuate nucleus of LD hamsters. Importantly, the KiSS-1 mRNA level was lower in SD animals but not in SD-refractory animals, which spontaneously reactivated their sexual activity after several months in SD. These changes of expression are not secondary to the photoperiodic variations of gonadal steroids. In contrast, melatonin appears to be necessary for these seasonal changes because pineal-gland ablation prevented the SD-induced downregulation of KiSS-1 expression. Remarkably, a chronic administration of kisspeptin-10 restored the testicular activity of SD hamsters despite persisting photoinhibitory conditions. Overall, these findings are consistent with a role of KiSS-1/GPR54 in the seasonal Control of Reproduction. We propose that photoperiod, via melatonin, modulates KiSS-1 signaling to drive the reproductive axis.

  • KiSS‐1: A Likely Candidate for the Photoperiodic Control of Reproduction in Seasonal Breeders
    Chronobiology international, 2006
    Co-Authors: Florent G Revel, Michel Saboureau, Paul Pevet, Jens D Mikkelsen, Mireille Masson-pevet, Valerie Simonneaux
    Abstract:

    In seasonal species, photoperiod exerts tight regulation of Reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the Control of seasonal Reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal Control of Reproduction.

Andrzej Bartke - One of the best experts on this subject based on the ideXlab platform.

  • Role of growth hormone and prolactin in the Control of Reproduction: What are we learning from transgenic and knock-out animals?1
    Steroids, 1999
    Co-Authors: Andrzej Bartke
    Abstract:

    Growth hormone (GH), insulin-like growth factor (IGF-I), and prolactin (PRL) can influence various aspects of reproductive functions in both females and males. However, the physiological role of PRL and the GH-IGF-I axis in the Control of Reproduction has been difficult to define, and the recent availability of knock-out (KO) animals allows re-examination of this issue. PRL-receptor (R)-KO and PRL-KO females are sterile because of luteal failure. In addition, these mice have severe deficits in the development of oocytes and early embryos. However, male fertility is not affected in the PRL-KO and in most of the PRL-R-KO animals. IGF-KO animals have an infantile reproductive system and are sterile. GH-R-KO mice can reproduce, but their breeding performance is reduced, particularly in females. These data indicate that IGF-I signaling is required for normal reproductive development and confirm the requirement for PRL for fertility in the female mouse. GH resistance leads to quantitative deficits in reproductive development and functions, but does not preclude fertility in either sex. We suspect that PRL and the GH-IGF-I axis provide partially overlapping (redundant) regulatory inputs to the hypothalamic-pituitary-gonadal axis, and consequently, targeted disruption of either signaling pathway has relatively mild consequences on many functions related to Reproduction. Overexpression of heterologous or homologous GH in transgenic animals can lead to severe reproductive deficits, including female sterility in some of the lines. Studies in GH transgenics should allow the identification of mechanisms that mediate the effects of chronic overexposure to GH on Reproduction.

  • Neuroendocrine Control of Reproduction.
    Advances in experimental medicine and biology, 1995
    Co-Authors: Richard W. Steger, Andrzej Bartke
    Abstract:

    The gametogenic and steroidogenic functions of the ovaries and the testes are Controlled by numerous humoral, paracrine and neural signals. of paramount importance are the pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and, to a lesser extent, prolactin (Prl). The biosynthesis and release of these hormones are regulated by gonadal products and by a number of hypothalamic hormones or modulatory agents. This chapter will review some of the more important mechanisms Controlling the release of these hypothalamic substances. Limitations of time and space prevent an exhaustive review of all hypothalamic factors that have been shown to influence LH, FSH and Prl release in view of the fact that the number of endogenous compounds reported to have these actions probably exceeds a 100. However, the number of substances that have proven or at least strongly suspected physiological effects is much smaller.