Effects of Photoperiod on Kisspeptin Neuronal Populations of the Ewe Diencephalon in Connection with Reproductive Function

Chalivoix, Stephanie; Bagnolini, Alexandre; Caraty, Alain; Cognié, Juliette; Malpaux, Benoît; Dufourny, Laurence

doi:10.1111/j.1365-2826.2009.01939.x

Cited by 51 publications

(42 citation statements)

References 51 publications

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“…Furthermore, during the last week of lactation, Kiss1 mRNA in the arcuate nucleus was low in the AL-fed lactating rats and food-restricted dams, despite increases in overall LH concentrations. Increases in AVPV kisspeptin expression across pubertal development in rodents (Han et al 2005, Clarkson & Herbison 2006, Takase et al 2009, Clarkson et al 2010) and increases in POA kisspeptin expression across the photoperiodic transition from long days to short days in ewes (Chalivoix et al 2010) have been reported to be associated with the activation or reactivation respectively of the HPG axis. By contrast, in the AL-fed lactating rats, Kiss1 mRNA levels in the AVPV remained stable, between day 15 pp and day 20 pp, and were similar to those in the nonlactating controls, even though basal LH concentrations increased over this period.…”

Section: Discussionmentioning

confidence: 99%

Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats

Ladyman¹,

Woodside²

2014

Reproduction

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Among the numerous physiological changes that accompany lactation is the suppression of the reproductive axis. The aim of this study was to investigate a possible role for the kisspeptin system in the restoration of the hypothalamic-pituitary-gonadal axis during late lactation in rats using a food restriction model that allows manipulation of the duration of lactational anovulation. Kiss1 mRNA expression and kisspeptin-immunoreactive cell counts were examined in both food-restricted dams and ad libitum (AL)-fed dams across late lactation when LH concentrations begin to increase. In the arcuate nucleus, Kiss1 mRNA expression and kisspeptin-positive cell counts were suppressed during late lactation. In the anteroventral periventricular (AVPV), day 15 food-restricted dams had significantly lower AVPV Kiss1 mRNA expression and a decreased LH response to exogenous kisspeptin compared with the AL-fed dams. Following 5 days of ad libitum food intake, these values were restored to levels similar to those in dams that had been fed ad libitum throughout lactation. In conclusion, this study shows that delayed restoration of the reproductive axis due to food restriction is associated with a decrease in kisspeptin sensitivity and low AVPV Kiss1 mRNA in late lactation.

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Section: Discussionmentioning

confidence: 99%

Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats

Ladyman¹,

Woodside²

2014

Reproduction

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“…However, it has been shown in sheep that there are more than 40 fewer ARC Kiss1-positive neurons during the non-breeding season compared with the breeding season [28] and that the expression of Kiss1 in the ARC is markedly decreased by transition of sheep from short days (8L:16D) to long days (16L:8D) [29], whereas that from long days to short days increases the number of kisspeptin-positive neurons by approximately 50% [30]. Therefore, although we did not examine histology in ewes in the breeding season, it is plausible to think that the population of kisspeptin neurons observed in this study would be still considerably smaller than that during the breeding season.…”

Section: Discussionmentioning

confidence: 99%

Central Administration of Neurokinin B Activates Kisspeptin/NKB Neurons in the Arcuate Nucleus and Stimulates Luteinizing Hormone Secretion in Ewes During the Non-Breeding Season

et al. 2012

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Abstract. Human genetic studies have suggested that kisspeptin and neurokinin B (NKB) play pivotal roles in the control of gonadotropin-releasing hormone (GnRH) secretion. However, the role of NKB in this context is less clear compared with that of kisspeptin. In the present study, we investigated the ratio of colocalization of kisspeptin and NKB in neurons in the arcuate nucleus (ARC), the effects of intracerebroventricular infusion of NKB on luteinizing hormone (LH) secretion and whether the treatment activates ARC kisspeptin/NKB neurons in seasonally anestrous ewes. Double-labeling immunohistochemistry revealed that the majority of kisspeptin neurons coexpressed NKB in the ARC. Infusion of NKB for 2 h into the lateral ventricle elicited a discharge of LH, which resulted in significant increases in LH concentrations between 20 and 50 min after the start of infusion compared with a saline-infused control. Animals were sacrificed immediately after the end of infusion, and Fos expression in ARC kisspeptin neurons was immunohistochemically examined. The NKB treatment activated kisspeptin neurons throughout the ARC, and approximately 70% of kisspeptin neurons expressed Fos immunoreactivity at the caudal portion of the nucleus. The present study demonstrated that a central infusion of NKB elicited a discharge of LH, which was associated with the activation of a large population of ARC kisspeptin/NKB neurons in seasonally anestrous ewes. The results suggest that NKB plays a stimulatory role in the control of pulsatile GnRH secretion and that the population of ARC kisspeptin/NKB neurons is one of sites of the NKB action in sheep. Key words: Gonadotropin-releasing hormone, Kisspeptin, Neurokinin B, Seasonal anestrus, Sheep (J. Reprod. Dev. 58: [700][701][702][703][704][705][706] 2012) I nactivating mutations of not only Kiss1R, which encodes the kisspeptin receptor (GPR54), but also Tac3 and Tacr3, which encode neurokinin B (NKB) and its receptor (NK3R), respectively, produce gonadotropin deficiency and pubertal failure in humans [1][2][3][4]. These studies document that kisspeptin and NKB signaling play pivotal roles in the control of gonadotropin-releasing hormone (GnRH) secretion. Growing evidence indicates that kisspeptin acts as a potent stimulator of GnRH secretion in a variety of species [5], whereas the physiological role of NKB in this context is less clear.Human genetic studies [3,4] suggest that NKB would act to stimulate pulsatile GnRH/luteinizing hormone (LH) secretion.Indeed, it was demonstrated that a bolus intravenous (iv) injection of NKB or an agonist of NK3R, senktide, elicited a distinct LH discharge in castrated juvenile monkeys [6]. We also showed that a bolus intracerebroventricular (icv) administration of NKB induced a distinct LH pulse in ovariectomized (OVX) goats treated with estradiol (E2) and progesterone (P) [7]. However, in the goat study, the same treatment resulted in an overall reduction in LH secretion in the absence of gonadal steroids. A similar inhibitory effect of senktide was ...

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“…The intra-and inter-assay coefficients of variation of the control averaged 8% and 12%, respectively. Five ewes were killed on day 0 when LH levels were < 1 ng/ml for three consecutive samples (all our ewes had LH levels at 0 ng/ml on the day of killing) and five were killed on day 112 when LH levels were > 1 ng/ml for three consecutive blood samples (the mean LH concentration at D112 was 3.1 ng/ ml, with a maximum reaching 7.5 ng/ml in one ewe, as reported previously) (17).…”

Section: Animals and Treatmentsmentioning

confidence: 94%

“…Kiss is indeed one of the most potent stimulators of GnRH secretion, and is able to induce ovulation in ewes during both the breeding and anoestrous seasons (15). More interestingly, Kiss levels in the ARC fluctuate with photoperiod (16,17) and the number of Kiss appositions on GnRH neurones is seasonally regulated (16). Kiss neurones express a large number of oestrogen receptors a (18), although whether or not they may also be under the influence of thyroid hormones remains to be established.…”

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confidence: 98%

The Content of Thyroid Hormone Receptor α in Ewe Kisspeptin Neurones is not Season‐Dependent

Dufourny

Gennetay

Martinet

et al. 2016

J Neuroendocrinology

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Seasonal reproduction is grounded in several mechanisms, among which are plasticity in both hormone synthesis and neuronal networks. Increased daylength on long days (LD) translates into local tri-iodothyronin (T3) production in the mediobasal hypothalamus that will enable the transition to the anoestrus season in sheep. The photoperiod also strongly affects the content of kisspeptin (Kiss), a hypothalamic neuropeptide exerting a potent stimulatory effect on gonadotrophin-releasing hormone release. Our hypothesis was that T3 directly inhibits Kiss release during LD. Using double immunocytochemistry, we first searched for coexpression of thyroid hormone receptor (THR)α in Kiss neurones in ewes with an active or inactive gonadotrophic axis. In both the preoptic area and the arcuate nucleus, most Kiss neurones were labelled by THR antibody under both physiological/photoperiodic conditions. These results suggest thyroid hormones may affect Kiss synthesis and release all through the year. We then attempted to assess the influence of T3 on Kiss content in hypothalamic explants sampled from ewes with an active gonadotrophic axis. Kiss produced by hypothalamic explants cultured with different doses of T3 (300 or 600 pg) and subjected to different times of incubation (2 or 24 h) was measured. No significant effects of T3 on Kiss tissular content were observed for the two doses of T3 and for the two incubation times. In light of these findings, potential reasons for the divergent effects of thyroid hormones on Kiss content are discussed. Our data emphasise that the effects of thyroid hormone on Kiss synthesis are not one-sided and may affect a wide range of functions.

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Effects of Photoperiod on Kisspeptin Neuronal Populations of the Ewe Diencephalon in Connection with Reproductive Function

Cited by 51 publications

References 51 publications

Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats

Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats

Central Administration of Neurokinin B Activates Kisspeptin/NKB Neurons in the Arcuate Nucleus and Stimulates Luteinizing Hormone Secretion in Ewes During the Non-Breeding Season

The Content of Thyroid Hormone Receptor α in Ewe Kisspeptin Neurones is not Season‐Dependent

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