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Uenoyama Y, Nonogaki M, Tsuchida H, Takizawa M, Matsuzaki S, Inoue N, Tsukamura H. Central δ/κ opioid receptor signaling pathways mediate chronic and/or acute suckling-induced LH suppression in rats during late lactation. J Reprod Dev 2024; 70:327-337. [PMID: 39155080 PMCID: PMC11461525 DOI: 10.1262/jrd.2024-045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 07/16/2024] [Indexed: 08/20/2024] Open
Abstract
In mammals, secretion of tonic (pulsatile) gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) is often suppressed during lactation. Suppression of GnRH/LH pulses in lactating dams is assumed to be caused by suckling stimuli and a chronic negative energy balance due to milk production. The present study aimed to investigate whether the central enkephalin-δ opioid receptor (DOR) signaling mediated the suppression of LH secretion by acute suckling stimuli and/or chronic negative energy balance due to milk production in rats during late lactation when dams were under a heavy energy demand. On postpartum day 16, the number of Penk (enkephalin mRNA)-expressing cells in the arcuate nucleus was significantly higher in lactating rats than in non-lactating control rats. Pulsatile LH secretion was suppressed in rats with chronic suckling or acute 1-h suckling stimuli 6 h after pup removal on day 16 of lactation. Central DOR antagonism significantly increased the mean LH concentrations and the baseline of LH pulses in rats with chronic suckling but not with acute suckling stimuli on day 16 of lactation. Besides, central κ opioid receptor (KOR) antagonism increased the amplitude of LH pulses in rats with the acute suckling stimuli on day 16 of lactation. These results suggest that central DOR signaling mediates the suppression of LH secretion caused by a negative energy balance in rats receiving chronic suckling during late lactation. On the other hand, central KOR signaling likely mediates acute suckling stimuli-induced suppression of LH secretion in rats during late lactation.
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Affiliation(s)
- Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Miku Nonogaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Sena Matsuzaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Tsuchida H, Takizawa M, Nonogaki M, Inoue N, Uenoyama Y, Tsukamura H. Enkephalin-δ opioid receptor signaling partly mediates suppression of LH release during early lactation in rats. J Reprod Dev 2023; 69:192-197. [PMID: 37331801 PMCID: PMC10435526 DOI: 10.1262/jrd.2023-006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/12/2023] [Indexed: 06/20/2023] Open
Abstract
Gonadal function is often suppressed during lactation in mammals including rodents, ruminants, and primates. This suppression is thought to be mostly due to the inhibition of the tonic (pulsatile) release of gonadotropin-releasing hormone (GnRH) and consequent gonadotropin. Accumulating evidence suggests that kisspeptin neurons in the arcuate nucleus (ARC) play a critical role in the regulation of pulsatile GnRH/gonadotropin release, and kisspeptin mRNA (Kiss1) and/or kisspeptin expression in the ARC are strongly suppressed by the suckling stimuli in lactating rats. This study aimed to examine whether the central enkephalin-δ-opioid receptor (DOR) signaling mediates the suckling-induced suppression of luteinizing hormone (LH) release in lactating rats. Central administration of a selective DOR antagonist increased the mean plasma LH levels and baseline of LH pulses in ovariectomized lactating mother rats compared to vehicle-injected control dams on day 8 of lactation without affecting the number of Kiss1-expressing cells and the intensity of Kiss1 mRNA signals in the ARC. Furthermore, the suckling stimuli significantly increased the number of enkephalin mRNA (Penk)-expressing cells and the intensity of Penk mRNA signals in the ARC compared to non-lactating control rats. Collectively, these results suggest that central DOR signaling, at least in part, mediates the suppression of LH release induced by suckling stimuli in lactating rats via indirect and/or direct inhibition of ARC kisspeptin neurons.
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Affiliation(s)
- Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Miku Nonogaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Uenoyama Y, Inoue N, Tsukamura H. Kisspeptin and lactational anestrus: Current understanding and future prospects. Peptides 2023; 166:171026. [PMID: 37230188 DOI: 10.1016/j.peptides.2023.171026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/18/2023] [Accepted: 05/22/2023] [Indexed: 05/27/2023]
Abstract
Lactational anestrus, characterized by the suppression of pulsatile gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) release, would be a strategic adaptation to ensure survival by avoiding pregnancy during lactation in mammals. In the present article, we first provide a current understanding of the central regulation of reproduction in mammals, i.e., a fundamental role of arcuate kisspeptin neurons in mammalian reproduction by driving GnRH/LH pulses. Second, we discuss the central mechanism inhibiting arcuate Kiss1 (encoding kisspeptin) expression and GnRH/LH pulses during lactation with a focus on suckling stimulus, negative energy balance due to milk production, and the role of circulating estrogen in rats. We also discuss upper regulators that control arcuate kisspeptin neurons in rats during the early and late lactation periods based on the findings obtained by a lactating rat model. Finally, we discuss potential reproductive technology for the improvement of reproductive performance in milking cows.
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Affiliation(s)
- Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Tsuchida H, Nonogaki M, Inoue N, Uenoyama Y, Tsukamura H. Dynorphin-κ-opioid receptor signaling, but not µ-opioid receptor signaling, partly mediates the suppression of luteinizing hormone release during late lactation in rats. Neurosci Lett 2022; 791:136920. [DOI: 10.1016/j.neulet.2022.136920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/24/2022] [Accepted: 10/13/2022] [Indexed: 11/27/2022]
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Tsukamura H. Kobayashi Award 2019: The neuroendocrine regulation of the mammalian reproduction. Gen Comp Endocrinol 2022; 315:113755. [PMID: 33711315 DOI: 10.1016/j.ygcen.2021.113755] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 02/05/2023]
Abstract
Mammalian reproductive function is a complex system of many players orchestrated by the hypothalamus-pituitary-gonadal (HPG) axis. The hypothalamic gonadotropin-releasing hormone (GnRH) and the consequent pituitary gonadotropin release show two modes of secretory patterns, namely the surge and pulse modes. The surge mode is triggered by the positive feedback action of estrogen secreted from the mature ovarian follicle to induce ovulation in females of most mammalian species. The pulse mode of GnRH release is required for stimulating tonic gonadotropin secretion to drive folliculogenesis, spermatogenesis and steroidogenesis and is negatively fine-tuned by the sex steroids. Accumulating evidence suggests that hypothalamic kisspeptin neurons are the master regulator for animal reproduction to govern the HPG axis. Specifically, kisspeptin neurons located in the anterior hypothalamus, such as the anteroventral periventricular nucleus (AVPV) in rodents and preoptic nucleus (POA) in ruminants, primates and others, and the neurons located in the arcuate nucleus (ARC) in posterior hypothalamus in most mammals are considered to play a key role in generating the surge and pulse modes of GnRH release, respectively. The present article focuses on the role of AVPV (or POA) kisspeptin neurons as a center for GnRH surge generation and of the ARC kisspeptin neurons as a center for GnRH pulse generation to mediate estrogen positive and negative feedback mechanisms, respectively, and discusses how the estrogen epigenetically regulates kisspeptin gene expression in these two populations of neurons. This article also provides the mechanism how malnutrition and lactation suppress GnRH/gonadotropin pulses through an inhibition of the ARC kisspeptin neurons. Further, the article discusses the programming effect of estrogen on kisspeptin neurons in the developmental brain to uncover the mechanism underlying the sex difference in GnRH/gonadotropin release as well as an irreversible infertility induced by supra-physiological estrogen exposure in rodent models.
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Affiliation(s)
- Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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SUGIMOTO A, TSUCHIDA H, NAGAE M, INOUE N, UENOYAMA Y, TSUKAMURA H. Central somatostatin-somatostatin receptor 2 signaling mediates lactational suppression of luteinizing hormone release via the inhibition of glutamatergic interneurons during late lactation in rats. J Reprod Dev 2022; 68:190-197. [PMID: 35249910 PMCID: PMC9184827 DOI: 10.1262/jrd.2022-009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reproductive function is suppressed during lactation owing to the suckling-induced suppression of the kisspeptin gene (Kiss1) expression in the arcuate nucleus (ARC) and
subsequent suppression of luteinizing hormone (LH) release. Our previous study revealed that somatostatin (SST) neurons mediate suckling-induced suppression of LH release via SST receptor 2
(SSTR2) in ovariectomized lactating rats during early lactation. This study examined whether central SST-SSTR2 signaling mediates the inhibition of ARC Kiss1 expression and
LH release in lactating rats during late lactation and whether the inhibition of glutamatergic neurons, stimulators of LH release, is involved in the suppression of LH release mediated by
central SST-SSTR2 signaling in lactating rats. A central injection of the SSTR2 antagonist CYN154806 (CYN) significantly increased ARC Kiss1 expression in lactating rats on
day 16 of lactation. Dual in situ hybridization revealed that few ARC Kiss1-positive cells co-expressed Sstr2, and some of the ARC
Slc17a6 (a glutamatergic neuronal marker)-positive cells co-expressed Sstr2. Furthermore, almost all ARC Kiss1-positive cells
co-expressed Grin1, a subunit of N-methyl-D-aspartate (NMDA) receptors. The numbers of Slc17a6/Sstr2 double-labeled and
Slc17a6 single-labeled cells were significantly lower in lactating dams than in non-lactating rats whose pups had been removed after parturition. A central injection of an
NMDA antagonist reversed the CYN-induced increase in LH release in lactating rats. Overall, these results suggest that central SST-SSTR2 signaling, at least partly, mediates the suppression
of ARC Kiss1 expression and LH release by inhibiting ARC glutamatergic interneurons in lactating rats.
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Affiliation(s)
- Arisa SUGIMOTO
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Hitomi TSUCHIDA
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Mayuko NAGAE
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Naoko INOUE
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Yoshihisa UENOYAMA
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Hiroko TSUKAMURA
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
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Sugimoto A, Tsuchida H, Ieda N, Ikegami K, Inoue N, Uenoyama Y, Tsukamura H. Somatostatin-Somatostatin Receptor 2 Signaling Mediates LH Pulse Suppression in Lactating Rats. Endocrinology 2019; 160:473-483. [PMID: 30544226 DOI: 10.1210/en.2018-00882] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/07/2018] [Indexed: 01/09/2023]
Abstract
Follicular development and ovulation are profoundly suppressed during lactation in mammals. This suppression is suggested to be mainly due to the suckling-induced inhibition of kisspeptin gene (Kiss1) expression in the arcuate nucleus (ARC) and consequent inhibition of pulsatile GnRH/LH release. We examined whether central somatostatin (SST) signaling mediates the suckling-induced suppression of pulsatile LH secretion. SST has been reported to be expressed in the posterior intralaminar thalamic nucleus (PIL), where the suckling stimulus is postulated to be relayed to the hypothalamus during lactation. SST inhibitory receptors (SSTRs) are abundantly expressed in the ARC, where kisspeptin/neurokinin B/dynorphin A (KNDy) neurons are located. Histological and quantitative studies revealed that the suckling stimulus increased the number of SST-expressing cells in the PIL, and Sstr2 expression in the ARC. Furthermore, a central injection of an SSTR2 antagonist caused a significant increase in pulsatile LH release in lactating rats. Double labeling of Sstr2 and the neurokinin B gene, as a marker for ARC KNDy neurons, showed Sstr2 expression was abundantly detected in the ARC, but few KNDy neurons coexpressed Sstr2 in lactating rats. Taken together, these findings suggest the suckling-induced activation of SST-SSTR2 signaling mediates, at least in part, the suppression of pulsatile LH secretion during lactation in rats, probably via the indirect effects of SST on KNDy neurons. These results provide a new aspect on the role of central SST-SSTR signaling in understanding the mechanism underlying lactational anestrus.
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Affiliation(s)
- Arisa Sugimoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Hitomi Tsuchida
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Nahoko Ieda
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Kana Ikegami
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
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Assadullah, Ieda N, Kawai N, Ishii H, Ihara K, Inoue N, Uenoyama Y, Tsukamura H. Co-expression of the calcitonin receptor gene in the hypothalamic kisspeptin neurons in female rats. Reprod Med Biol 2018; 17:164-172. [PMID: 29692674 PMCID: PMC5902471 DOI: 10.1002/rmb2.12085] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 12/20/2017] [Indexed: 11/25/2022] Open
Abstract
Purpose Hypothalamic kisspeptin neurons are considered to play a critical role in regulating mammalian reproduction and integrating humoral and neuronal inputs that control gonadotropin‐releasing hormone (GnRH)/gonadotropin release. The present study aimed to investigate the upstream regulator candidates for kisspeptin neurons. Methods Visualized kisspeptin neurons that were taken from the arcuate nucleus (ARC) of Kiss1‐tdTomato rats were subjected to next‐generation sequencing (NGS) analysis. In situ hybridization (ISH) for the calcitonin receptor gene (Calcr) was performed throughout the whole forebrain of ovariectomized wild‐type female rats that had been implanted with a negative feedback level of estrogen, because the Calcr expression was evident in the ARC kisspeptin neurons from the NGS analysis. Then, a double ISH was performed for the Calcr and kisspeptin gene (Kiss1) in the brain regions, containing either the anteroventral periventricular nucleus (AVPV) or ARC of the female rats. Results The NGS analysis revealed that the Calcr was highly expressed in the ARC kisspeptin neurons. It was found that the Calcr was co‐expressed in 12% and 22% of the Kiss1‐expressing cells in the ARC and AVPV, respectively. Conclusion The present study suggests that calcitonin receptor signaling could be involved in the regulation of reproductive function through the direct control of the ARC and/or AVPV kisspeptin neurons, and then GnRH/gonadotropin release.
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Affiliation(s)
- Assadullah
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
| | - Nahoko Ieda
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
| | - Narumi Kawai
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
| | - Hirotaka Ishii
- Department of Anatomy and Neurobiology Nippon Medical School Tokyo Japan
| | - Kunio Ihara
- Center for Gene Research Nagoya University Nagoya Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan
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Bardóczi Z, Wilheim T, Skrapits K, Hrabovszky E, Rácz G, Matolcsy A, Liposits Z, Sliwowska JH, Dobolyi Á, Kalló I. GnRH Neurons Provide Direct Input to Hypothalamic Tyrosine Hydroxylase Immunoreactive Neurons Which Is Maintained During Lactation. Front Endocrinol (Lausanne) 2018; 9:685. [PMID: 30524376 PMCID: PMC6261975 DOI: 10.3389/fendo.2018.00685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 11/01/2018] [Indexed: 01/09/2023] Open
Abstract
Gonadotropin releasing hormone (GnRH) neurons provide neuronal input to the preoptic area (POA) and the arcuate nucleus (Arc), two regions involved critically in the regulation of neuroendocrine functions and associated behaviors. These areas contain tyrosine hydroxylase immunoreactive (TH-IR) neurons, which play location-specific roles in the neuroendocrine control of both the luteinizing hormone and prolactin secretion, as well as, sexually motivated behaviors. Concerning changes in the activity of GnRH neurons and the secretion pattern of GnRH seen under the influence of rising serum estrogen levels and during lactation, we tested the hypothesis that the functional state of GnRH neurons is mediated via direct synaptic connections to TH-IR neurons in the POA and Arc. In addition, we examined putative changes of these inputs in lactating mice and in mothers separated from their pups. Confocal microscopic and pre-embedding immunohistochemical studies on ovariectomized mice treated with 17β-estradiol (OVX+E2) provided evidence for direct appositions and asymmetric synapses between GnRH-IR fiber varicosities and TH-IR neurons in the POA and the Arc. As TH co-localizes with kisspeptin (KP) in the POA, confocal microscopic analysis was continued on sections additionally labeled for KP. The TH-IR neurons showed a lower level of co-labeling for KP in lactating mice compared to OVX+E2 mice (16.1 ± 5% vs. 57.8 ± 4.3%). Removing the pups for 24 h did not alter significantly the KP production in TH-IR neurons (17.3 ± 4.6%). The mean number of GnRH-IR varicosities on preoptic and arcuate TH cells did not differ in the three animal models investigated. This study shows evidence that GnRH neurons provide direct synaptic inputs to POA and Arc dopaminergic neurons. The scale of anatomical connectivity with these target cells was unaltered during lactation indicating a maintained GnRH input, inspite of the altered hormonal condition.
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Affiliation(s)
- Zsuzsanna Bardóczi
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- School of Ph.D. Studies, Semmelweis University, Budapest, Hungary
| | - Tamás Wilheim
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Katalin Skrapits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergely Rácz
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - András Matolcsy
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Joanna H. Sliwowska
- Laboratory of Neurobiology, Institute of Zoology, Poznan University of Life Sciences, Poznań, Poland
| | - Árpád Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Imre Kalló
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
- *Correspondence: Imre Kalló
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Sudsukh A, Taya K, Watanabe G, Wajjwalku W, Thongphakdee A, Thongtip N. Annual ovarian activity monitored by the noninvasive measurement of fecal concentrations of progesterone and 17β-estradiol metabolites in rusa deer (Rusa timorensis). J Vet Med Sci 2017; 78:1785-1790. [PMID: 27570098 PMCID: PMC5240755 DOI: 10.1292/jvms.15-0485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
To clarify the reproductive cycle of female Rusa deer (Rusa timorensis),
the fecal concentrations of progesterone and 17β-estradiol metabolites were measured.
Fecal samples were collected on a weekly basis for one year (between October, 2012 and
September, 2013) from five healthy adult hinds in Thailand. At the beginning of the study,
three hinds were pregnant. Two hinds delivered one healthy offspring, and one hind
delivered a stillborn calf. The mating period of Rusa hinds in Thailand is from November
to April. In pregnant hinds, fecal progesterone metabolite concentration was high in late
pregnancy and abruptly declined to the baseline around parturition, suggesting that the
placenta secretes a large amount of progesterone. Fecal 17β-estradiol metabolite
concentration remained elevated around the day of parturition. Both concentrations of
fecal progesterone and 17β-estradiol metabolites in non-lactating hinds were significantly
higher than those in lactating hinds, indicating that ovarian activity of lactating hinds
is suppressed by the suckling stimulus of fawn during lactation. The present study
demonstrated that monitoring of fecal steroid hormones is useful method for assessing
ovarian function in this species.
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Affiliation(s)
- Apichaya Sudsukh
- Center for Agricultural Biotechnology, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand
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Abstract
Successfully rearing young places multiple demands on the mammalian female. These are met by a wide array of alterations in maternal physiology and behavior that are coordinated with the needs of the developing young, and include adaptations in neuroendocrine systems not directly involved in maternal behavior or lactation. In this article, attenuations in the behavioral and neuroendocrine responses to stressors, the alterations in metabolic pathways facilitating both increased food intake and conservation of energy, and the changes in fertility that occur postpartum are described. The mechanisms underlying these processes as well as the factors that contribute to them and the relative contributions of these stimuli at different times postpartum are also reviewed. The induction and maintenance of the adaptations observed in the postpartum maternal brain are dependent on mother-young interaction and, in most cases, on suckling stimulation and its consequences for the hormonal profile of the mother. The peptide hormone prolactin acting on receptors within the brain makes a major contribution to changes in metabolic pathways, suppression of fertility and the attenuation of the neuroendocrine response to stress during lactation. Oxytocin is also released, both into the circulation and in some hypothalamic nuclei, in response to suckling stimulation and this hormone has been implicated in the decrease in anxiety behavior seen in the early postpartum period. The relative importance of these hormones changes across lactation and it is becoming increasingly clear that many of the adaptations to motherhood reviewed here reflect the outcome of multiple influences. © 2016 American Physiological Society. Compr Physiol 6:1493-1518, 2016.
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Affiliation(s)
- Barbara Woodside
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, Quebec, Canada
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Iijima N, Takumi K, Matsumoto K, Ozawa H. Visualization of Kisspeptin Binding to Rat Hypothalamic Neurons. Acta Histochem Cytochem 2015; 48:179-84. [PMID: 26855450 PMCID: PMC4731855 DOI: 10.1267/ahc.15017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/09/2015] [Indexed: 11/30/2022] Open
Abstract
The neuropeptide kisspeptin plays an important role in fertility and the onset of puberty, stimulating gonadotropin-releasing hormone (GnRH) neurons to activate the hypothalamic–pituitary–gonadal axis. Several studies have demonstrated a morphological interaction between kisspeptin- and GnRH-expressing neurons; however, few have addressed the interaction of kisspeptin with other neuronal subtypes. We recently showed that fibers immunoreactive for kisspeptin were densely distributed in the dorsal part of the arcuate nucleus. These fibers were found in close proximity to GnRH and tuberoinfundibular dopamine (TIDA) neurons. In the present study, using biotinylated kisspeptin, we established a visualization method for identifying kisspeptin binding sites on TIDA neurons. Biotinylated kisspeptin bound to the cell bodies of TIDA neurons and surrounding fibers, suggesting that TIDA neurons express sites of action for kisspeptin. Our assay also detected biotinylation signals from kisspeptin binding to GnRH fibers in the median eminence, but not to cell bodies of GnRH neurons in the medial preoptic area. Positive signals were completely eliminated by addition of excess non-labeled kisspeptin. This method enabled us to detect kisspeptin binding sites on specific neural structures and neuronal fibers.
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Affiliation(s)
- Norio Iijima
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School
| | - Ken Takumi
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School
| | - Keisuke Matsumoto
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School
| | - Hitoshi Ozawa
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School
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Higo S, Aikawa S, Iijima N, Ozawa H. Rapid modulation of hypothalamic Kiss1 levels by the suckling stimulus in the lactating rat. J Endocrinol 2015; 227:105-15. [PMID: 26446276 DOI: 10.1530/joe-15-0143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/09/2015] [Indexed: 12/11/2022]
Abstract
In mammals, lactation suppresses GnRH/LH secretion resulting in transient infertility. In rats, GnRH/LH secretion is rescued within 18-48 h after pup separation (PS) and rapidly re-suppressed by subsequent re-exposure of pups. To elucidate the mechanisms underlying these rapid modulations, changes in the expression of kisspeptin, a stimulator of GnRH secretion, in several lactating conditions (normal-lactating; 4-h PS; 18-h PS; 4-h PS +1-h re-exposure of pups; non-lactating) were examined using in situ hybridization. PS for 4 h or 18 h increased Kiss1 expressing neurons in both the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC), and subsequent exposure of pups re-suppressed Kiss1 in the AVPV. A change in Kiss1 expression was observed prior to the reported time of the change in GnRH/LH, indicating that the change in GnRH/LH results from changes in kisspeptin. We further examined the mechanisms underlying the rapid modulation of Kiss1. We first investigated the possible involvement of ascending sensory input during the suckling stimulus. Injection of the anterograde tracer to the subparafascicular parvocellular nucleus (SPFpc) in the midbrain, which relays the suckling stimulus, revealed direct neuronal connections between the SPFpc and kisspeptin neurons in both the AVPV and ARC. We also examined the possible involvement of prolactin (PRL). Administration of PRL for 1 h suppressed Kiss1 expression in the AVPV but not in the ARC. These results indicate that suckling stimulus rapidly modulates Kiss1 expression directly via neuronal connections and indirectly through serum PRL, resulting in modulation in GnRH/LH secretion.
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Affiliation(s)
- Shimpei Higo
- Department of Anatomy and NeurobiologyGraduate School of Medicine, Nippon Medical School, Sendagi 1-1-5, Bunkyo-ku, Tokyo 113-8602, Japan
| | - Satoko Aikawa
- Department of Anatomy and NeurobiologyGraduate School of Medicine, Nippon Medical School, Sendagi 1-1-5, Bunkyo-ku, Tokyo 113-8602, Japan
| | - Norio Iijima
- Department of Anatomy and NeurobiologyGraduate School of Medicine, Nippon Medical School, Sendagi 1-1-5, Bunkyo-ku, Tokyo 113-8602, Japan
| | - Hitoshi Ozawa
- Department of Anatomy and NeurobiologyGraduate School of Medicine, Nippon Medical School, Sendagi 1-1-5, Bunkyo-ku, Tokyo 113-8602, Japan
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14
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Abstract
The hypothalamic control of prolactin secretion is different from other anterior pituitary hormones, in that it is predominantly inhibitory, by means of dopamine from the tuberoinfundibular dopamine neurons. In addition, prolactin does not have an endocrine target tissue, and therefore lacks the classical feedback pathway to regulate its secretion. Instead, it is regulated by short loop feedback, whereby prolactin itself acts in the brain to stimulate production of dopamine and thereby inhibit its own secretion. Finally, despite its relatively simple name, prolactin has a broad range of functions in the body, in addition to its defining role in promoting lactation. As such, the hypothalamo-prolactin axis has many characteristics that are quite distinct from other hypothalamo-pituitary systems. This review will provide a brief overview of our current understanding of the neuroendocrine control of prolactin secretion, in particular focusing on the plasticity evident in this system, which keeps prolactin secretion at low levels most of the time, but enables extended periods of hyperprolactinemia when necessary for lactation. Key prolactin functions beyond milk production will be discussed, particularly focusing on the role of prolactin in inducing adaptive responses in multiple different systems to facilitate lactation, and the consequences if prolactin action is impaired. A feature of this pleiotropic activity is that functions that may be adaptive in the lactating state might be maladaptive if prolactin levels are elevated inappropriately. Overall, my goal is to give a flavour of both the history and current state of the field of prolactin neuroendocrinology, and identify some exciting new areas of research development.
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Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago, PO Box 913, Dunedin 9054, New ZealandMaurice Wilkins Centre for Molecular BiodiscoveryAuckland, New Zealand Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago, PO Box 913, Dunedin 9054, New ZealandMaurice Wilkins Centre for Molecular BiodiscoveryAuckland, New Zealand
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15
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Yamada S, Kawata M. Identification of neural cells activated by mating stimulus in the periaqueductal gray in female rats. Front Neurosci 2014; 8:421. [PMID: 25565950 PMCID: PMC4270180 DOI: 10.3389/fnins.2014.00421] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/02/2014] [Indexed: 11/13/2022] Open
Abstract
Induction of lordosis as typical female sexual behavior in rodents is dependent on a mount stimulus from males and blood levels of estrogen. Periaqueductal gray (PAG) efferent neurons have been suggested to be important for lordosis behavior; however, the neurochemical basis remains to be understood. In this study, we neuroanatomically examined (1) whether PAG neurons activated by mating stimulus project to the medullary reticular formation (MRF), which is also a required area for lordosis; and (2) whether these neurons are glutamatergic. Mating stimulus significantly increased the number of cFos-immunoreactive (ir) neurons in the PAG, particularly in its lateral region. Half of cFos-ir neurons in the lateral PAG were positive for a retrograde tracer (FluoroGold; FG) injected into the MRF. cFos-ir neurons also colocalized with mRNA of vesicular glutamate transporter 2 (vGLUT2), a molecular marker for glutamatergic neurons. Using retrograde tracing and in situ hybridization in conjunction with fluorescent microscopy, we also found FG and vGLUT2 mRNA double-positive neurons in the lateral PAG. These results suggest that glutamatergic neurons in the lateral PAG project to the MRF and are involved in lordosis behavior in female rats.
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Affiliation(s)
- Shunji Yamada
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine Kyoto, Japan
| | - Mitsuhiro Kawata
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine Kyoto, Japan
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16
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Ladyman SR, Woodside B. Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats. Reproduction 2014; 147:743-51. [PMID: 24492858 DOI: 10.1530/rep-13-0426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
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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Affiliation(s)
- Sharon R Ladyman
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Quebec, Canada
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17
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Liu X, Brown RSE, Herbison AE, Grattan DR. Lactational anovulation in mice results from a selective loss of kisspeptin input to GnRH neurons. Endocrinology 2014; 155:193-203. [PMID: 24169550 DOI: 10.1210/en.2013-1621] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In mammals, lactation is associated with a period of infertility characterized by the loss of pulsatile secretion of GnRH and cessation of ovulatory cycles. Despite the importance of lactational infertility in determining overall fecundity of a species, the mechanisms by which the suckling stimulus suppresses GnRH secretion remain unclear. Because kisspeptin neurons are critical for fertility, the aim of this study was to test the hypothesis that reduced kisspeptin expression might mediate the lactation-induced suppression of fertility, using mouse models. In the rostral periventricular area of the third ventricle (RP3V), a progressive decrease in RP3V Kiss1 mRNA levels was observed during pregnancy culminating in a 10-fold reduction during lactation compared with diestrous controls. This was associated with approximately 60% reduction in the numbers of kisspeptin-immunoreactive neurons in the RP3V detected during lactation. Similarly, in the arcuate nucleus there was also a significant decrease in Kiss1 mRNA levels during late pregnancy and midlactation, and a notable decrease in kisspeptin fiber density during lactation. The functional characteristics of the RP3V kisspeptin input to GnRH neurons were assessed using electrophysiological approaches in an acute brain slice preparation. Although endogenous RP3V kisspeptin neurons were found to activate GnRH neurons in diestrous mice, this was never observed during lactation. This did not result from an absence of kisspeptin receptors because GnRH neurons responded normally to 100 nM exogenous kisspeptin during lactation. The kisspeptin deficit in lactating mice was selective, because GnRH neurons responded normally to RP3V gamma aminobutryic acid inputs during lactation. These data demonstrate that a selective loss of RP3V kisspeptin inputs to GnRH neurons during lactation is the likely mechanism causing lactational anovulation in the mouse.
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Affiliation(s)
- X Liu
- Centre for Neuroendocrinology and Departments of Physiology (X.L., A.E.H.) and Anatomy (R.S.E.B., D.R.G.), School of Medical Sciences, University of Otago, Dunedin, 9054 New Zealand
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Hu J, Du G, Zhang W, Huang H, Chen D, Wu D, Wang X. Short-term neonatal/prepubertal exposure of dibutyl phthalate (DBP) advanced pubertal timing and affected hypothalamic kisspeptin/GPR54 expression differently in female rats. Toxicology 2013; 314:65-75. [DOI: 10.1016/j.tox.2013.09.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 09/13/2013] [Accepted: 09/13/2013] [Indexed: 11/29/2022]
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