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McIlwraith EK, Loganathan N, Mak KWY, He W, Belsham DD. Phoenixin knockout mice show no impairment in fertility or differences in metabolic response to a high-fat diet, but exhibit behavioral differences in an open field test. J Neuroendocrinol 2024:e13398. [PMID: 38733120 DOI: 10.1111/jne.13398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 03/27/2024] [Accepted: 04/21/2024] [Indexed: 05/13/2024]
Abstract
Phoenixin (PNX) is a conserved secreted peptide that was identified 10 years ago with numerous studies published on its pleiotropic functions. PNX is associated with estrous cycle length, protection from a high-fat diet, and reduction of anxiety behavior. However, no study had yet evaluated the impact of deleting PNX in the whole animal. We sought to evaluate a mouse model lacking the PNX parent gene, small integral membrane protein 20 (Smim20), and the resulting effect on reproduction, energy homeostasis, and anxiety. We found that the Smim20 knockout mice had normal fertility and estrous cycle lengths. Consistent with normal fertility, the hypothalamii of the knockout mice showed no changes in the levels of reproduction-related genes, but the male mice had some changes in energy homeostasis-related genes, such as melanocortin receptor 4 (Mc4r). When placed on a high-fat diet, the wildtype and knockout mice responded similarly, but the male heterozygous mice gained slightly less weight. When placed in an open field test box, the female knockout mice traveled less distance in the outer zone, indicating alterations in anxiety or locomotor behavior. In summary, the homozygous knockout of PNX did not alter fertility and modestly alters a few neuroendocrine genes in response to a high-fat diet, especially in the female mice. However, it altered the behavior of mice in an open field test. PNX therefore may not be crucial for reproductive function or weight, however, we cannot rule out possible compensatory mechanisms in the knockout model. Understanding the role of PNX in physiology may ultimately lead to an enhanced understanding of neuroendocrine mechanisms involving this enigmatic peptide.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Neruja Loganathan
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Kimberly W Y Mak
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Wenyuan He
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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2
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Nagae M, Yamada K, Enomoto Y, Kometani M, Tsuchida H, Panthee A, Nonogaki M, Matsunaga N, Takizawa M, Matsuzaki S, Hirabayashi M, Inoue N, Tsukamura H, Uenoyama Y. Conditional Oprk1-dependent Kiss1 deletion in kisspeptin neurons caused estrogen-dependent LH pulse disruption and LH surge attenuation in female rats. Sci Rep 2023; 13:20495. [PMID: 37993510 PMCID: PMC10665460 DOI: 10.1038/s41598-023-47222-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 11/10/2023] [Indexed: 11/24/2023] Open
Abstract
The gonadotropin-releasing hormone (GnRH) pulse and surge are considered to be generated by arcuate kisspeptin/neurokinin B/dynorphin A (KNDy) neurons and anteroventral periventricular nucleus (AVPV) kisspeptin neurons, respectively, in female rodents. The majority of KNDy and AVPV kisspeptin neurons express κ-opioid receptors (KORs, encoded by Oprk1) in female rodents. Thus, this study aimed to investigate the effect of a conditional Oprk1-dependent Kiss1 deletion in kisspeptin neurons on the luteinizing hormone (LH) pulse/surge and fertility using Kiss1-floxed/Oprk1-Cre rats, in which Kiss1 was deleted in cells expressing or once expressed the Oprk1/Cre. The Kiss1-floxed/Oprk1-Cre female rats, with Kiss1 deleted in a majority of KNDy neurons, showed normal puberty while having a one-day longer estrous cycle and fewer pups than Kiss1-floxed controls. Notably, ovariectomized (OVX) Kiss1-floxed/Oprk1-Cre rats showed profound disruption of LH pulses in the presence of a diestrous level of estrogen but showed apparent LH pulses without estrogen treatment. Furthermore, Kiss1-floxed/Oprk1-Cre rats, with Kiss1 deleted in approximately half of AVPV kisspeptin neurons, showed a lower peak of the estrogen-induced LH surge than controls. These results suggest that arcuate and AVPV kisspeptin neurons expressing or having expressed Oprk1 have a role in maintaining normal GnRH pulse and surge generation, the normal length of the estrous cycle, and the normal offspring number in female rats.
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Affiliation(s)
- Mayuko Nagae
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
- Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan
| | - Koki Yamada
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Yuki Enomoto
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Mari Kometani
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Arvinda Panthee
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Miku Nonogaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Nao Matsunaga
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Sena Matsuzaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Masumi Hirabayashi
- Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
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3
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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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Hellier V, Dardente H, Lomet D, Cognié J, Dufourny L. Interactions between β-endorphin and kisspeptin neurons of the ewe arcuate nucleus are modulated by photoperiod. J Neuroendocrinol 2023; 35:e13242. [PMID: 36880357 DOI: 10.1111/jne.13242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023]
Abstract
Opioid peptides are well-known modulators of the central control of reproduction. Among them, dynorphin coexpressed in kisspeptin (KP) neurons of the arcuate nucleus (ARC) has been thoroughly studied for its autocrine effect on KP release through κ opioid receptors. Other studies have suggested a role for β-endorphin (BEND), a peptide cleaved from the pro-opiomelanocortin precursor, on food intake and central control of reproduction. Similar to KP, BEND content in the ARC of sheep is modulated by day length and BEND modulates food intake in a dose-dependent manner. Because KP levels in the ARC vary with photoperiodic and metabolic status, a photoperiod-driven influence of BEND neurons on neighboring KP neurons is plausible. The present study aimed to investigate a possible modulatory action of BEND on KP neurons located in the ovine ARC. Using confocal microscopy, numerous KP appositions on BEND neurons were found but there was no photoperiodic variation of the number of these interactions in ovariectomized, estradiol-replaced ewes. By contrast, BEND terminals on KP neurons were twice as numerous under short days, in ewes having an activated gonadotropic axis, compared to anestrus ewes under long days. Injection of 5 μg BEND into the third ventricle of short-day ewes induced a significant and specific increase of activated KP neurons (16% vs. 9% in controls), whereas the percentage of overall activated (c-Fos positive) neurons, was similar between both groups. These data suggest a photoperiod-dependent influence of BEND on KP neurons of the ARC, which may influence gonadotropin-releasing hormone pulsatile secretion and inform KP neurons about metabolic status.
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Affiliation(s)
- Vincent Hellier
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
| | - Hugues Dardente
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
| | - Didier Lomet
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
| | - Juliette Cognié
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
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Cho-Clark MJ, Watkins A, Wu TJ. The role of GnRH metabolite, GnRH-(1-5), in endometrial cancer. Front Endocrinol (Lausanne) 2023; 14:1183278. [PMID: 37124730 PMCID: PMC10140499 DOI: 10.3389/fendo.2023.1183278] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
From the time of its discovery and isolation in the mammalian hypothalamus, the decapeptide, gonadotropin-releasing hormone (GnRH), has also been found to be expressed in non-hypothalamic tissues and can elicit a diverse array of functions both in the brain and periphery. In cancer, past studies have targeted the gonadotropin-releasing hormone receptors (GnRHR) as a way to treat reproductive cancers due to its anti-tumorigenic effects. On the contrary, its metabolite, GnRH-(1-5), behaves divergently from its parental peptide through putative orphan G-protein coupled receptor (oGPCR), GPR101. In this review, we will focus on the potential roles of GnRH-(1-5) in the periphery with an emphasis on its effects on endometrial cancer progression.
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Luna-García LA, Meza-Herrera CA, Pérez-Marín CC, Corona R, Luna-Orozco JR, Véliz-Deras FG, Delgado-Gonzalez R, Rodriguez-Venegas R, Rosales-Nieto CA, Bustamante-Andrade JA, Gutierrez-Guzman UN. Goats as Valuable Animal Model to Test the Targeted Glutamate Supplementation upon Antral Follicle Number, Ovulation Rate, and LH-Pulsatility. BIOLOGY 2022; 11:biology11071015. [PMID: 36101396 PMCID: PMC9311901 DOI: 10.3390/biology11071015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/28/2022] [Accepted: 07/02/2022] [Indexed: 11/16/2022]
Abstract
The potential effect of intravenous administration of glutamate on the ovarian activity and the LH secretion pattern, considering the anestrous yearling goat as an animal model, were assessed. In late April, yearling goats (n = 20) were randomly assigned to either (1) Glutamate supplemented (GLUT; n = 10, Live Weight (LW) = 29.6 ± 1.02 kg, Body Condition (BCS) = 3.4 ± 0.2 units; i.v. supplemented with 7 mg GLUT kg−1 LW) or (2) Non-supplemented (CONT; n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2 units; i.v. saline). The oats were estrus-synchronized; blood sampling (6 h × 15 min) was carried out for LH quantification. Response variables included pulsatility (PULSE), time to first pulse (TTFP), amplitude (AMPL), nadir (NAD), and area under the curve (AUC) of LH. Ovaries were ultra-sonographically scanned to assess ovulation rate (OR), number of antral follicles (AF), and total ovarian activity (TOA = OR + AF). LH-PULSE was quantified with the Munro algorithm; significant treatment x time interactions were evaluated across time. The variables LW and BCS did not differ (p > 0.05) between the experimental groups. Nevertheless, OR (1.77 vs. 0.87 ± 0.20 units), TOA (4.11 vs. 1.87 ± 0.47 units) and LH-PULSE (5.0 vs. 2.2 pulses 6 h-1) favored (p < 0.05) to the GLUT group. Our results reveal that targeted glutamate supplementation, the main central nervous system neurotransmitter, arose as an interesting strategy to enhance the hypothalamic−hypophyseal−ovarian response considering the anestrous-yearling goat as an animal model, with thought-provoking while promising translational applications.
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Affiliation(s)
- Luis A. Luna-García
- Universidad Autónoma Chapingo, Unidad Regional Universitaria de Zonas Áridas, Bermejillo 35230, Durango, Mexico;
- Departamento de Medicina y Cirugía Animal, Campus Rabanales, Universidad de Córdoba, 14014 Córdoba, Spain;
| | - César A. Meza-Herrera
- Universidad Autónoma Chapingo, Unidad Regional Universitaria de Zonas Áridas, Bermejillo 35230, Durango, Mexico;
- Correspondence: or
| | - Carlos C. Pérez-Marín
- Departamento de Medicina y Cirugía Animal, Campus Rabanales, Universidad de Córdoba, 14014 Córdoba, Spain;
| | - Rebeca Corona
- Departamento de Neurobiología Celular y Molecular, Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología, UNAM, Querétaro 76230, Mexico;
| | - Juan R. Luna-Orozco
- Centro de Bachillerato Tecnológico Agropecuario No. 1, Torreón 27000, Coahuila, Mexico;
| | - Francisco G. Véliz-Deras
- Universidad Autónoma Agraria Antonio Narro, Unidad Laguna, Torreón 27054, Coahuila, Mexico; (F.G.V.-D.); (R.D.-G.); (R.R.-V.)
| | - Ramón Delgado-Gonzalez
- Universidad Autónoma Agraria Antonio Narro, Unidad Laguna, Torreón 27054, Coahuila, Mexico; (F.G.V.-D.); (R.D.-G.); (R.R.-V.)
| | - Rafael Rodriguez-Venegas
- Universidad Autónoma Agraria Antonio Narro, Unidad Laguna, Torreón 27054, Coahuila, Mexico; (F.G.V.-D.); (R.D.-G.); (R.R.-V.)
| | - Cesar A. Rosales-Nieto
- Facultad de Agronomía y Veterinaria, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78321, Mexico;
| | - Jorge A. Bustamante-Andrade
- Facultad de Agricultura y Zootecnia, Universidad Juárez del Estado de Durango, Venecia Durango 35111, Mexico; (J.A.B.-A.); (U.N.G.-G.)
| | - Ulises N. Gutierrez-Guzman
- Facultad de Agricultura y Zootecnia, Universidad Juárez del Estado de Durango, Venecia Durango 35111, Mexico; (J.A.B.-A.); (U.N.G.-G.)
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7
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Sex-specific hypothalamic expression of kisspeptin, gonadotropin releasing hormone, and kisspeptin receptor in progressive demyelination model. J Chem Neuroanat 2022; 123:102120. [PMID: 35718292 DOI: 10.1016/j.jchemneu.2022.102120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/24/2022] [Accepted: 06/13/2022] [Indexed: 11/21/2022]
Abstract
Demyelinating diseases, such as multiple sclerosis, decrease the quality of life of patients and can affect reproduction. Assisted reproductive therapies are available, which although effective, aggravate motor symptoms. For this reason, it is important to determine how the control of the hypothalamus-pituitary-gonadal axis is affected in order to develop better strategies for these patients. One way to determine this is using animal models such as the taiep rat, which shows progressive demyelination of the central nervous system, and was used in the present study to characterize the expression of gonadotrophin-releasing hormone (GnRH), Kisspeptin, and kisspeptin receptor (Kiss1R) and luteinizing hormone (LH) secretion. The expression of kisspeptin, GnRH, and Kiss1R was determined at the hypothalamic level by immunofluorescence and serum LH levels were determined by ELISA. The expression of kisspeptin at the hypothalamic level showed sexual dimorphism, where there was an increase in males and a decrease in females during oestrus. There was no change in the expression of GnRH or kisspeptin receptor, regardless of sex. However, a decrease in serum LH concentration was observed in both sexes. The taiep rat showed changes in the expression of kisspeptin at the hypothalamic level. These changes are different from those reported in the literature with the use of animals with experimental allergic encephalomyelitis, this is because both animal models represent different degrees of progression of multiple sclerosis. Our results suggest that the effects on the hypothalamus-pituitary-gonadal axis depend on the differences between the demyelinating processes, their progression, and even individual factors, and it is thus important that fertility treatments are individualized to maximize therapeutic effects.
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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: 27] [Impact Index Per Article: 13.5] [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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Ikegami K, Watanabe Y, Nakamura S, Goto T, Inoue N, Uenoyama Y, Tsukamura H. Cellular and molecular mechanisms regulating the KNDy neuronal activities to generate and modulate GnRH pulse in mammals. Front Neuroendocrinol 2022; 64:100968. [PMID: 34808231 DOI: 10.1016/j.yfrne.2021.100968] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/18/2021] [Accepted: 11/15/2021] [Indexed: 12/30/2022]
Abstract
Accumulating findings during the past decades have demonstrated that the hypothalamic arcuate kisspeptin neurons are supposed to be responsible for pulsatile release of gonadotropin-releasing hormone (GnRH) to regulate gametogenesis and steroidogenesis in mammals. The arcuate kisspeptin neurons express neurokinin B (NKB) and dynorphin A (Dyn), thus, the neurons are also referred to as KNDy neurons. In the present article, we mainly focus on the cellular and molecular mechanisms underlying GnRH pulse generation, that is focused on the action of NKB and Dyn and an interaction between KNDy neurons and astrocytes to control GnRH pulse generation. Then, we also discuss the factors that modulate the activity of KNDy neurons and consequent pulsatile GnRH/LH release in mammals.
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Affiliation(s)
- Kana Ikegami
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Youki Watanabe
- Graduate School of Applied Life Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Sho Nakamura
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan
| | - Teppei Goto
- RIKEN Center for Biosystems Dynamics Research, Hyogo 650-0047, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan.
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11
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Duittoz A, Cayla X, Fleurot R, Lehnert J, Khadra A. Gonadotrophin-releasing hormone and kisspeptin: It takes two to tango. J Neuroendocrinol 2021; 33:e13037. [PMID: 34533248 DOI: 10.1111/jne.13037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 01/06/2023]
Abstract
Kisspeptin (Kp), a family of peptides comprising products of the Kiss1 gene, was discovered 20 years ago; it is recognised as the major factor controlling the activity of the gonadotrophin-releasing hormone (GnRH) neurones and thus the activation of the reproductive axis in mammals. It has been widely documented that the effects of Kp on reproduction through its action on GnRH neurones are mediated by the GPR54 receptor. Kp controls the activation of the reproductive axis at puberty, maintains reproductive axis activity in adults and is involved in triggering ovulation in some species. Although there is ample evidence coming from both conditional knockout models and conditional-induced Kp neurone death implicating the Kp/GPR54 pathway in the control of reproduction, the mechanism(s) underlying this process may be more complex than a sole direct control of GnRH neuronal activity by Kp. In this review, we provide an overview of the recent advances made in elucidating the interplay between Kp- and GnRH- neuronal networks with respect to regulating the reproductive axis. We highlight the existence of a possible mutual regulation between GnRH and Kp neurones, as well as the implication of Kp-dependent volume transmission in this process. We also discuss the capacity of heterodimerisation between GPR54 and GnRH receptor (GnRH-R) and its consequences on signalling. Finally, we illustrate the role of mathematical modelling that accounts for the synergy between GnRH-R and GPR54 in explaining the role of these two receptors when defining GnRH neuronal activity and GnRH pulsatile release.
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Affiliation(s)
- Anne Duittoz
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Xavier Cayla
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Renaud Fleurot
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Jonas Lehnert
- Department of Quantitative Life Sciences, McGill University, Montreal, QC, Canada
| | - Anmar Khadra
- Department of Quantitative Life Sciences, McGill University, Montreal, QC, Canada
- Department of Physiology, McGill University, Montréal, QC, Canada
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Tsuchida H, Kawai N, Yamada K, Takizawa M, Inoue N, Uenoyama Y, Tsukamura H. Central µ-Opioid Receptor Antagonism Blocks Glucoprivic LH Pulse Suppression and Gluconeogenesis/Feeding in Female Rats. Endocrinology 2021; 162:6322534. [PMID: 34270714 DOI: 10.1210/endocr/bqab140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Indexed: 12/27/2022]
Abstract
Energetic status often affects reproductive function, glucose homeostasis, and feeding in mammals. Malnutrition suppresses pulsatile release of the gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) and increases gluconeogenesis and feeding. The present study aims to examine whether β-endorphin-μ-opioid receptor (MOR) signaling mediates the suppression of pulsatile GnRH/LH release and an increase in gluconeogenesis/feeding induced by malnutrition. Ovariectomized female rats treated with a negative feedback level of estradiol-17β (OVX + low E2) receiving 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, intravenously (iv) were used as a malnutrition model. An administration of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), a selective MOR antagonist, into the third ventricle blocked the suppression of the LH pulse and increase in gluconeogenesis/feeding induced by iv 2DG administration. Histological analysis revealed that arcuate Kiss1 (kisspeptin gene)-expressing cells and preoptic Gnrh1 (GnRH gene)-expressing cells co-expressed little Oprm1 (MOR gene), while around 10% of arcuate Slc17a6 (glutamatergic marker gene)-expressing cells co-expressed Oprm1. Further, the CTOP treatment decreased the number of fos-positive cells in the paraventricular nucleus (PVN) in OVX + low E2 rats treated with iv 2DG but failed to affect the number of arcuate fos-expressing Slc17a6-positive cells. Taken together, these results suggest that the central β-endorphin-MOR signaling mediates the suppression of pulsatile LH release and that the β-endorphin may indirectly suppress the arcuate kisspeptin neurons, a master regulator for GnRH/LH pulses during malnutrition. Furthermore, the current study suggests that central β-endorphin-MOR signaling is also involved in gluconeogenesis and an increase in food intake by directly or indirectly acting on the PVN neurons during malnutrition in female rats.
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Affiliation(s)
- Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Narumi Kawai
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Koki Yamada
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Direct evidence that KNDy neurons maintain gonadotropin pulses and folliculogenesis as the GnRH pulse generator. Proc Natl Acad Sci U S A 2021; 118:2009156118. [PMID: 33500349 DOI: 10.1073/pnas.2009156118] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The gonadotropin-releasing hormone (GnRH) pulse is fundamental for mammalian reproduction: GnRH pulse regimens are needed as therapies for infertile women as continuous GnRH treatment paradoxically inhibits gonadotropin release. Circumstantial evidence suggests that the hypothalamic arcuate KNDy neurons expressing kisspeptin (encoded by Kiss1), neurokinin B (encoded by Tac3), and d ynorphin A serve as a GnRH pulse generator; however, no direct evidence is currently available. Here, we show that rescuing >20% KNDy neurons by transfecting Kiss1 inside arcuate Tac3 neurons, but not outside of these neurons, recovered folliculogenesis and luteinizing hormone (LH) pulses, an indicator of GnRH pulses, in female global Kiss1 knockout (KO) rats and that >90% conditional arcuate Kiss1 KO in newly generated Kiss1-floxed rats completely suppressed LH pulses. These results first provide direct evidence that KNDy neurons are the GnRH pulse generator, and at least 20% of KNDy neurons are sufficient to maintain folliculogenesis via generating GnRH/gonadotropin pulses.
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McIlwraith EK, Belsham DD. Hypothalamic reproductive neurons communicate through signal transduction to control reproduction. Mol Cell Endocrinol 2020; 518:110971. [PMID: 32750397 DOI: 10.1016/j.mce.2020.110971] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/11/2020] [Accepted: 07/28/2020] [Indexed: 12/11/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus coordinate fertility and puberty. In order to achieve successful reproductive capacity, they receive signals from the periphery and from other hypothalamic neurons that coordinate energy homeostasis. Hormones, such as estradiol, insulin, leptin, and adiponectin, act directly or indirectly on GnRH and its associated reproductive neurons. Nutrients like glucose and fatty acids can also affect reproductive neurons to signal nutrient availability. Additionally, acute and chronic inflammation is reported to detrimentally affect GnRH and kisspeptin expression. All of these cues activate signal transduction pathways within neurons that lead to the changes in GnRH neuronal function. The signalling pathways can also be dysregulated by endocrine disrupting chemicals, which impair fertility by misappropriating common signalling pathways. The complex mechanisms controlling the levels of GnRH during the reproductive cycle rely on a carefully orchestrated set of signal transduction events to regulate the positive and negative feedback arms of the hypothalamic-pituitary-gonadal axis. If these signalling events are dysregulated, this will result is a downregulatory event leading to hypogonadal hypogonadism with decreased or absent fertility. Therefore, an understanding of the mechanisms involved in distinct neuronal signalling could provide an advantage to inform therapeutic interventions for infertility and reproductive disorders.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada; Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, ON, Canada.
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Babwah AV. The wonderful and masterful G protein-coupled receptor (GPCR): A focus on signaling mechanisms and the neuroendocrine control of fertility. Mol Cell Endocrinol 2020; 515:110886. [PMID: 32574585 DOI: 10.1016/j.mce.2020.110886] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/08/2020] [Accepted: 05/20/2020] [Indexed: 12/18/2022]
Abstract
Human GnRH deficiency, both clinically and genetically, is a heterogeneous disorder comprising of congenital GnRH deficiency with anosmia (Kallmann syndrome), or with normal olfaction [normosmic idiopathic hypogonadotropic hypogonadism (IHH)], and adult-onset hypogonadotropic hypogonadism. Our understanding of the neural mechanisms underlying GnRH secretion and GnRH signaling continues to increase at a rapid rate and strikingly, the heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) continue to emerge as essential players in these processes. GPCRs were once viewed as binary on-off switches, where in the "on" state they are bound to their Gα protein, but now we understand that view is overly simplistic and does not adequately characterize GPCRs. Instead, GPCRs have emerged as masterful signaling molecules exploiting different physical conformational states of itself to elicit an array of downstream signaling events via their G proteins and the β-arrestins. The "one receptor-multiple signaling conformations" model is likely an evolved strategy that can be used to our advantage as researchers have shown that targeting specific receptor conformations via biased ligands is proving to be a powerful tool in the effective treatment of human diseases. Can biased ligands be used to selectively modulate signaling by GPCR regulators of the neuroendocrine axis in the treatment of IHH? As discussed in this review, the grand possibility exists. However, while we are still very far from developing these treatments, this exciting likelihood can happen through a much greater mechanistic understanding of how GPCRs signal within the cell.
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Affiliation(s)
- Andy V Babwah
- Department of Pediatrics, Laboratory of Human Growth and Reproductive Development, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States; Child Health Institute of New Jersey, New Brunswick, NJ, United States.
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16
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Ikegami K, Goto T, Nakamura S, Watanabe Y, Sugimoto A, Majarune S, Horihata K, Nagae M, Tomikawa J, Imamura T, Sanbo M, Hirabayashi M, Inoue N, Maeda KI, Tsukamura H, Uenoyama Y. Conditional kisspeptin neuron-specific Kiss1 knockout with newly generated Kiss1-floxed and Kiss1-Cre mice replicates a hypogonadal phenotype of global Kiss1 knockout mice. J Reprod Dev 2020; 66:359-367. [PMID: 32307336 PMCID: PMC7470906 DOI: 10.1262/jrd.2020-026] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The present study aimed to evaluate whether novel conditional kisspeptin neuron-specific Kiss1 knockout (KO) mice utilizing the Cre-loxP system could recapitulate
the infertility of global Kiss1 KO models, thereby providing further evidence for the fundamental role of hypothalamic kisspeptin neurons in regulating mammalian
reproduction. We generated Kiss1-floxed mice and hypothalamic kisspeptin neuron-specific Cre-expressing transgenic mice and then crossed these two
lines. The conditional Kiss1 KO mice showed pubertal failure along with a suppression of gonadotropin secretion and ovarian atrophy. These results indicate that
newly-created hypothalamic Kiss1 KO mice obtained by the Cre-loxP system recapitulated the infertility of global Kiss1 KO models, suggesting that
hypothalamic kisspeptin, but not peripheral kisspeptin, is critical for reproduction. Importantly, these Kiss1-floxed mice are now available and will be a valuable
tool for detailed analyses of roles of each population of kisspeptin neurons in the brain and peripheral kisspeptin-producing cells by the spatiotemporal-specific manipulation of
Cre expression.
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Affiliation(s)
- Kana Ikegami
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Teppei Goto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.,Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Sho Nakamura
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Youki Watanabe
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Arisa Sugimoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Sutisa Majarune
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Kei Horihata
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Mayuko Nagae
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Junko Tomikawa
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Takuya Imamura
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8526, Japan
| | - Makoto Sanbo
- Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Masumi Hirabayashi
- Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Kei-Ichiro Maeda
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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