1
|
McGrath BM, Norman ST, Gaspardis CA, Rose JL, Scott CJ. Characterizing the relationship between gonadotropin releasing hormone (GnRH), kisspeptin, and RFamide related peptide 3 (RFRP-3) neurons in the equine hypothalamus across the estrous cycle and in the anovulatory seasons. Theriogenology 2024; 219:157-166. [PMID: 38432143 DOI: 10.1016/j.theriogenology.2024.02.027] [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: 10/17/2023] [Revised: 02/26/2024] [Accepted: 02/26/2024] [Indexed: 03/05/2024]
Abstract
To understand better the role that kisspeptin plays in regulating seasonal and estrous cycle changes in the mare, this study investigated the number, location and interactions between GnRH, kisspeptin and RFRP-3 neurons in the equine hypothalamus. Hypothalami were collected from mares during the non-breeding season, vernal transition and various stages of the breeding season. Fluorescent immunohistochemistry was used to label the neuropeptides of interest. GnRH cells were observed primarily in the arcuate nucleus (ARC), while very few labeled cells were identified in the pre-optic area (POA). Kisspeptin cells were identified primarily in the ARC, with a small number of cells observed dorsal to the ARC, surrounding the third ventricle (3V). The mean number of kisspeptin cells varied between animals and typically showed no pattern associated with season or stage of estrous cycle, but a seasonal difference was identified in the ARC population. Small numbers of RFRP-3 cells were observed in the ARC, ventromedial hypothalamus (VMH) and dorsomedial hypothalamus (DMH). The mean number of RFRP-3 cells appeared higher in pre-ovulatory animals compared to all other stages. The percentage of GnRH cell bodies with kisspeptin appositions did not change with season or stage of estrous cycle. The percentage of kisspeptin cells receiving inputs from RFRP-3 fibers did not vary with season or stage of estrous cycle. These interactions suggest the possibility of the presence of an ultra-short loop feedback system between these three peptides. The changes in RFRP-3 neurons suggest the possibility of a role in the regulation of reproduction in the horse, but it is unlikely to be as a gonadotropin inhibitory factor.
Collapse
Affiliation(s)
- B M McGrath
- School of Dentistry & Medical Sciences, Locked bag 588, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.
| | - S T Norman
- School of Animal and Veterinary Sciences, Locked bag 588, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.
| | - C A Gaspardis
- School of Animal and Veterinary Sciences, Locked bag 588, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.
| | - J L Rose
- School of Dentistry & Medical Sciences, Locked bag 588, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.
| | - C J Scott
- School of Dentistry & Medical Sciences, Locked bag 588, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.
| |
Collapse
|
2
|
Silva MSB, Decoster L, Delpouve G, Lhomme T, Ternier G, Prevot V, Giacobini P. Overactivation of GnRH neurons is sufficient to trigger polycystic ovary syndrome-like traits in female mice. EBioMedicine 2023; 97:104850. [PMID: 37898094 PMCID: PMC10630624 DOI: 10.1016/j.ebiom.2023.104850] [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: 08/03/2023] [Revised: 09/18/2023] [Accepted: 10/12/2023] [Indexed: 10/30/2023] Open
Abstract
BACKGROUND Polycystic ovary syndrome (PCOS) is the most common endocrine disorder leading to anovulatory infertility. Abnormalities in the central neuroendocrine system governed by gonadotropin-releasing hormone (GnRH) neurons might be related to ovarian dysfunction in PCOS, although the link in this disordered brain-to-ovary communication remains unclear. Here, we manipulated GnRH neurons using chemogenetics in adult female mice to unveil whether chronic overaction of these neurons would trigger PCOS-like hormonal and reproductive impairments. METHODS We used adult Gnrh1cre female mice to selectively target and express the designer receptors exclusively activated by designer drugs (DREADD)-based chemogenetic tool hM3D(Gq) in hypophysiotropic GnRH neurons. Chronic chemogenetic activation protocol was carried out with clozapine N-oxide (CNO) i.p. injections every 48 h over a month. We evaluated the reproductive and hormonal profile before, during, and two months after chemogenetic manipulations. FINDINGS We discovered that the overactivation of GnRH neurons was sufficient to disrupt reproductive cycles, promote hyperandrogenism, and induce ovarian dysfunction. These PCOS features were detected with a long-lasting neuroendocrine dysfunction through abnormally high luteinizing hormone (LH) pulse secretion. Additionally, the GnRH-R blockade prevented the establishment of long-term neuroendocrine dysfunction and androgen excess in these animals. INTERPRETATION Taken together, our results show that hyperactivity of hypothalamic GnRH neurons is a major driver of reproductive and hormonal impairments in PCOS and suggest that antagonizing the aberrant GnRH signaling could be an efficient therapeutic venue for the treatment of PCOS. FUNDING European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement n◦ 725149).
Collapse
Affiliation(s)
- Mauro S B Silva
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Laurine Decoster
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Gaspard Delpouve
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Tori Lhomme
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Gaetan Ternier
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Vincent Prevot
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France
| | - Paolo Giacobini
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, FHU 1000 Days for Health, School of Medicine, Lille, France; Univ. Lille, Inserm, CHU Lille, Lille Neuroscience & Cognition, UMR-S 1172, Lille, France.
| |
Collapse
|
3
|
Ruddenklau A, Glendining K, Prescott M, Campbell RE. Validation of a new Custom Polyclonal Progesterone Receptor Antibody for Immunohistochemistry in the Female Mouse Brain. J Endocr Soc 2023; 7:bvad113. [PMID: 37693686 PMCID: PMC10492226 DOI: 10.1210/jendso/bvad113] [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: 05/07/2023] [Indexed: 09/12/2023] Open
Abstract
Immunohistochemical visualization of progesterone receptor (PR)-expressing cells in the brain is a powerful technique to investigate the role of progesterone in the neuroendocrine regulation of fertility. A major obstacle to the immunohistochemical visualization of progesterone-sensitive cells in the rodent brain has been the discontinuation of the commercially produced A0098 rabbit polyclonal PR antibody by DAKO. To address the unavailability of this widely used PR antibody, we optimized and evaluated 4 alternative commercial PR antibodies and found that each lacked the specificity and/or sensitivity to immunohistochemically label PR-expressing cells in paraformaldehyde-fixed female mouse brain sections. As a result, we developed and validated a new custom RC269 PR antibody, directed against the same 533-547 amino acid sequence of the human PR as the discontinued A0098 DAKO PR antibody. Immunohistochemical application of the RC269 PR antibody on paraformaldehyde-fixed mouse brain sections resulted in nuclear PR labeling that was highly distinguishable from background, specific to its antigen, highly regulated by estradiol, matched the known distribution of PR protein expression in the female mouse hypothalamus, and nearly identical to that of the discontinued A0098 DAKO PR antibody. In summary, the RC269 PR antibody is a specific and sensitive antibody to immunohistochemically visualize PR-expressing cells in the mouse brain.
Collapse
Affiliation(s)
- Amy Ruddenklau
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Kelly Glendining
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Melanie Prescott
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| |
Collapse
|
4
|
Gurule S, Sustaita-Monroe J, Padmanabhan V, Cardoso R. Developmental programming of the neuroendocrine axis by steroid hormones: Insights from the sheep model of PCOS. Front Endocrinol (Lausanne) 2023; 14:1096187. [PMID: 36755919 PMCID: PMC9899912 DOI: 10.3389/fendo.2023.1096187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/06/2023] [Indexed: 01/25/2023] Open
Abstract
The reproductive neuroendocrine system is a key target for the developmental programming effects of steroid hormones during early life. While gonadal steroids play an important role in controlling the physiological development of the neuroendocrine axis, human fetuses are susceptible to adverse programming due to exposure to endocrine disrupting chemicals with steroidal activity, inadvertent use of contraceptive pills during pregnancy, as well as from disease states that result in abnormal steroid production. Animal models provide an unparalleled resource to understand the effects of steroid hormones on the development of the neuroendocrine axis and their role on the developmental origins of health and disease. In female sheep, exposure to testosterone (T) excess during fetal development results in an array of reproductive disorders that recapitulate those seen in women with polycystic ovary syndrome (PCOS), including disrupted neuroendocrine feedback mechanisms, increased pituitary responsiveness to gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) hypersecretion, functional hyperandrogenism, multifollicular ovarian morphology, and premature reproductive failure. Similar to a large proportion of women with PCOS, these prenatally T-treated sheep also manifest insulin resistance and cardiovascular alterations, including hypertension. This review article focuses on the effects of prenatal androgens on the developmental programming of hypothalamic and pituitary alterations in the sheep model of PCOS phenotype, centering specifically on key neurons, neuropeptides, and regulatory pathways controlling GnRH and LH secretion. Insights obtained from the sheep model as well as other animal models of perinatal androgen excess can have important translational relevance to treat and prevent neuroendocrine dysfunction in women with PCOS and other fertility disorders.
Collapse
Affiliation(s)
- Sara Gurule
- Department of Animal Science, Texas A&M University, College Station, TX, United States
| | | | | | - Rodolfo Cardoso
- Department of Animal Science, Texas A&M University, College Station, TX, United States
| |
Collapse
|
5
|
Ovarian Response and Fertility after Short-Term Progestagen/eCG Treatments Are Compromised in Nulliparous Sheep during Non-Breeding Season. Vet Sci 2022; 9:vetsci9120663. [PMID: 36548824 PMCID: PMC9781245 DOI: 10.3390/vetsci9120663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/10/2022] [Accepted: 11/23/2022] [Indexed: 11/30/2022] Open
Abstract
The objective of this investigation was to determine the ovarian response, fertility, and prolificacy of nulliparous sheep when compared to multiparous sheep after a short-term (7 days) CIDR/eCG treatment which was administered during the non-breeding season. All the multiparous sheep, whereas only 54% of the nulliparous ewes, showed signs of estrus. However, 81.8% of the multiparous sheep and 100% of the nulliparous ewes ovulated. Fertility was also low after short-term progesterone treatments during the anestrous season in maiden sheep (30.8 vs. 72.7% in multiparous ewes). Such results indicate significant differences in the response to CIDR/eCG protocols for induction and synchronization of estrus and ovulation between nulliparous and multiparous sheep during the non-breeding season.
Collapse
|
6
|
González-Flores O, Pfaus JG, Luna-Hernández A, Montes-Narváez O, Domínguez-Ordóñez R, Tecamachaltzi-Silvarán MB, García-Juárez M. Estradiol and progesterone-induced lordosis behavior is modulated by both the Kisspeptin receptor and melanin-concentrating hormone in estradiol benzoate-primed rats. Horm Behav 2022; 146:105257. [PMID: 36115135 DOI: 10.1016/j.yhbeh.2022.105257] [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: 04/26/2022] [Revised: 08/22/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022]
Abstract
Intracerebroventricular (ICV) administration of estradiol benzoate (E2B) and progesterone (P) induces intense lordosis behavior in ovariectomized rats primed peripherally with E2B. The present study tested the hypothesis that the Kisspeptin (Kiss) and melanin-concentrating hormone (MCH) pathways regulate female sexual behavior induced by these steroid hormones. In Experiment 1, we tested the relevance of the Kiss pathway by ICV infusion of its inhibitor, kiss-234, before administration of E2B or P in estrogen-primed rats. Lordosis induced by E2B alone or with the addition of P was reduced significantly at 30, 120, and 240 min. In Experiment 2, ICV infusion of MCH 30 min before E2B or P significantly reduced lordosis in rats primed with E2B alone. These data support the hypothesis that the Kiss and MCH pathways, which can release or modulate gonadotropin-releasing hormone (GnRH), are involved in E2B- and P-induced lordosis.
Collapse
Affiliation(s)
- Oscar González-Flores
- Centro de Investigación en Reproducción Animal, Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, México
| | - James G Pfaus
- Department of Psychology and Life Sciences, Charles University, Prague, Czech Republic; Czech National Institute of Mental Health, Klecany, Czech Republic
| | - Ailyn Luna-Hernández
- Centro de Investigación en Reproducción Animal, Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, México; Maestría en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, México
| | - Omar Montes-Narváez
- Centro de Investigación en Reproducción Animal, Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, México; Doctorado en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, México
| | - Raymundo Domínguez-Ordóñez
- Centro de Investigación en Reproducción Animal, Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, México; Licenciatura en Ingeniería Agronómica y Zootecnia, CRC, Benemérita Universidad Autónoma de Puebla, México
| | | | - Marcos García-Juárez
- Centro de Investigación en Reproducción Animal, Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, México.
| |
Collapse
|
7
|
Silva MSB, Campbell RE. Polycystic Ovary Syndrome and the Neuroendocrine Consequences of Androgen Excess. Compr Physiol 2022; 12:3347-3369. [PMID: 35578968 DOI: 10.1002/cphy.c210025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a major endocrine disorder strongly associated with androgen excess and frequently leading to female infertility. Although classically considered an ovarian disease, altered neuroendocrine control of gonadotropin-releasing hormone (GnRH) neurons in the brain and abnormal gonadotropin secretion may underpin PCOS presentation. Defective regulation of GnRH pulse generation in PCOS promotes high luteinizing hormone (LH) pulsatile secretion, which in turn overstimulates ovarian androgen production. Early and emerging evidence from preclinical models suggests that maternal androgen excess programs abnormalities in developing neuroendocrine circuits that are associated with PCOS pathology, and that these abnormalities are sustained by postpubertal elevation of endogenous androgen levels. This article will discuss experimental evidence, from the clinic and in preclinical animal models, that has significantly contributed to our understanding of how androgen excess influences the assembly and maintenance of neuroendocrine impairments in the female brain. Abnormal central gamma-aminobutyric acid (GABA) signaling has been identified in both patients and preclinical models as a possible link between androgen excess and elevated GnRH/LH secretion. Enhanced GABAergic innervation and drive to GnRH neurons is suspected to contribute to the pathogenesis and early manifestation of neuroendocrine derangement in PCOS. Accordingly, this article also provides an overview of GABA regulation of GnRH neuron function from prenatal development to adulthood to discuss possible avenues for future discovery research and therapeutic interventions. © 2022 American Physiological Society. Compr Physiol 12:3347-3369, 2022.
Collapse
Affiliation(s)
- Mauro S B Silva
- Department of Medicine, Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Rebecca E Campbell
- Centre for Neuroendocrinology, Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| |
Collapse
|
8
|
Moore AM, Lohr DB, Coolen LM, Lehman MN. Prenatal Androgen Exposure Alters KNDy Neurons and Their Afferent Network in a Model of Polycystic Ovarian Syndrome. Endocrinology 2021; 162:bqab158. [PMID: 34346492 PMCID: PMC8402932 DOI: 10.1210/endocr/bqab158] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Indexed: 02/08/2023]
Abstract
Polycystic ovarian syndrome (PCOS), the most common endocrinopathy affecting women worldwide, is characterized by elevated luteinizing hormone (LH) pulse frequency due to the impaired suppression of gonadotrophin-releasing hormone (GnRH) release by steroid hormone negative feedback. Although neurons that co-express kisspeptin, neurokinin B, and dynorphin (KNDy cells) were recently defined as the GnRH/LH pulse generator, little is understood about their role in the pathogenesis of PCOS. We used a prenatal androgen-treated (PNA) mouse model of PCOS to determine whether changes in KNDy neurons or their afferent network underlie altered negative feedback. First, we identified elevated androgen receptor gene expression in KNDy cells of PNA mice, whereas progesterone receptor and dynorphin gene expression was significantly reduced, suggesting elevated androgens in PCOS disrupt progesterone negative feedback via direct actions upon KNDy cells. Second, we discovered GABAergic and glutamatergic synaptic input to KNDy neurons was reduced in PNA mice. Retrograde monosynaptic tract-tracing revealed a dramatic reduction in input originates from sexually dimorphic afferents in the preoptic area, anteroventral periventricular nucleus, anterior hypothalamic area and lateral hypothalamus. These results reveal 2 sites of neuronal alterations potentially responsible for defects in negative feedback in PCOS: changes in gene expression within KNDy neurons, and changes in synaptic inputs from steroid hormone-responsive hypothalamic regions. How each of these changes contribute to the neuroendocrine phenotype seen in in PCOS, and the role of specific sets of upstream KNDy afferents in the process, remains to be determined.
Collapse
Affiliation(s)
- Aleisha M Moore
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| | - Dayanara B Lohr
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| | - Lique M Coolen
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| | - Michael N Lehman
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| |
Collapse
|
9
|
Harlow K, Renwick AN, Shuping SL, Sommer JR, Lents CA, Knauer MT, Nestor CC. Evidence that pubertal status impacts KNDy neurons in the gilt. Biol Reprod 2021; 105:1533-1544. [PMID: 34643223 DOI: 10.1093/biolre/ioab189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/26/2022] Open
Abstract
Puberty onset is a complex physiological process which enables the capacity for reproduction through increased gonadotropin-releasing hormone (GnRH), and subsequently luteinizing hormone (LH), secretion. While cells that coexpress kisspeptin, neurokinin B (NKB), and dynorphin in the hypothalamic arcuate nucleus (ARC) are believed to govern the timing of puberty, the degree to which KNDy neurons exist and are regulated by pubertal status remains to be determined in the gilt. Hypothalamic tissue from prepubertal and postpubertal, early follicular phase gilts was used to determine the expression of kisspeptin, NKB, and dynorphin within the ARC. Fluorescent in situ hybridization revealed that the majority (> 74%) of ARC neurons that express mRNA for kisspeptin coexpressed mRNA for NKB and dynorphin. There were fewer ARC cells that expressed mRNA for dynorphin in postpubertal gilts compared to prepubertal gilts (P < 0.05), but the number of ARC cells expressing mRNA for kisspeptin or NKB was not different between groups. Within KNDy neurons, mRNA abundance for kisspeptin, NKB, and dynorphin of postpubertal gilts was the same as, less than, and greater than, respectively, prepubertal gilts. Immunostaining for kisspeptin did not differ between prepubertal and postpubertal gilts, but there were fewer NKB immunoreactive fibers in postpubertal gilts compared to prepubertal gilts (P < 0.05). Together, these data reveal novel information about KNDy neurons in gilts and supports the idea that NKB and dynorphin play a role in puberty onset in the female pig.
Collapse
Affiliation(s)
- KaLynn Harlow
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| | - Allison N Renwick
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| | - Sydney L Shuping
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| | - Jeffrey R Sommer
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| | - Clay A Lents
- USDA, ARS, U.S. Meat Animal Research Center, Livestock Biosystems Research Unit, Clay Center, NE 68966-0166, USA
| | - Mark T Knauer
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| | - Casey C Nestor
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695 USA
| |
Collapse
|
10
|
Stopa LRS, de Souza CF, Martins AB, Lopes GM, Costa NO, Gerardin DCC, de Carvalho GG, Zaia DAM, Zaia CTBV, Uchoa ET, Leite CM. Neonatal overfeeding reduces estradiol plasma levels and disrupts noradrenergic-kisspeptin-GnRH pathway and fertility in adult female rats. Mol Cell Endocrinol 2021; 524:111147. [PMID: 33388353 DOI: 10.1016/j.mce.2020.111147] [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: 10/14/2020] [Revised: 12/21/2020] [Accepted: 12/26/2020] [Indexed: 01/21/2023]
Abstract
This work evaluated the effects of neonatal overfeeding, induced by litter size reduction, on fertility and the noradrenaline-kisspeptin-gonadotrophin releasing hormone (GnRH) pathway in adult female rats. The litter size was adjusted to 3 pups with each mother in the small litters (SL) and 10 pups with each mother in the normal litters (NL). SL females exhibited metabolic changes associated with reproductive dysfunctions, shown by earlier vaginal opening and first estrus, later regular cyclicity onset, and lower and higher occurrences of estrus and diestrus phases, respectively, as well as reduced fertility, estradiol plasma levels, and mRNA expressions of tyrosine hydroxylase in the locus coeruleus, kisspeptin, and GnRH in the preoptic area in adult females in the afternoon of proestrus. These results suggest that neonatal overfeeding in female rats promotes reproductive dysfunctions in adulthood, such as lower estradiol plasma levels associated with impairments in fertility and noradrenaline-kisspeptin-GnRH pathway during positive feedback.
Collapse
Affiliation(s)
- Larissa Rugila S Stopa
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Camila F de Souza
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Andressa B Martins
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | | | - Nathália O Costa
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Daniela C Ceccatto Gerardin
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil; Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Giovana Gomes de Carvalho
- Programa de Pós-Graduação em Ciências Patológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | | | - Cássia Thaïs B V Zaia
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil; Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Ernane Torres Uchoa
- Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil; Departamento de Ciências Fisiológicas, Universidade Estadual de Londrina, Londrina, PR, Brazil.
| | | |
Collapse
|
11
|
Liu Y, Li X, Shen X, Ivanova D, Lass G, He W, Chen Q, Yu S, Wang Y, Long H, Wang L, Lyu Q, Kuang Y, O’Byrne KT. Dynorphin and GABAA Receptor Signaling Contribute to Progesterone's Inhibition of the LH Surge in Female Mice. Endocrinology 2020; 161:5808894. [PMID: 32181477 PMCID: PMC7153819 DOI: 10.1210/endocr/bqaa036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 02/28/2020] [Indexed: 01/02/2023]
Abstract
Progesterone can block estrogen-induced luteinising hormone (LH) surge secretion and can be used clinically to prevent premature LH surges. The blocking effect of progesterone on the LH surge is mediated through its receptor in the anteroventral periventricular nucleus (AVPV) of the hypothalamus. However, the underlying mechanisms are unclear. The preovulatory LH surge induced by estrogen is preceded by a significant reduction in hypothalamic dynorphin and gamma-aminobutyric acid (GABA) release. To test the detailed roles of dynorphin and GABA in an LH surge blockade by progesterone, ovariectomized and 17β-estradiol capsule-implanted (OVX/E2) mice received simultaneous injections of estradiol benzoate (EB) and progesterone (P) or vehicle for 2 consecutive days. The LH level was monitored from 2:30 pm to 8:30 pm at 30-minute intervals. Progesterone coadministration resulted in the LH surge blockade. A continuous microinfusion of the dynorphin receptor antagonist nor-BNI or GABAA receptor antagonist bicuculline into the AVPV from 3:00 pm to 7:00 pm reversed the progesterone-mediated blockade of the LH surge in 7 of 9 and 6 of 10 mice, respectively. In addition, these LH surges started much earlier than the surge induced by estrogen alone. However, 5 of 7 progesterone-treated mice did not show LH surge secretion after microinfusion with the GABAB receptor antagonist CGP-35348. Additionally, peripheral administration of kisspeptin-54 promotes LH surge-like release in progesterone treated mice. These results demonstrated that the progesterone-mediated suppression of the LH surge is mediated by an increase in dynorphin and GABAA receptor signaling acting though kisspeptin neurons in the AVPV of the hypothalamus in female mice.
Collapse
Affiliation(s)
- Yali Liu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
- Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Pudong New Area, Shanghai, China
| | - Xiaofeng Li
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
| | - Xi Shen
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
| | - Deyana Ivanova
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
| | - Geffen Lass
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
| | - Wen He
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Qiuju Chen
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Sha Yu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Yun Wang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Hui Long
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Li Wang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Qifeng Lyu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
| | - Yanping Kuang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Huangpu District, Shanghai, China
- Correspondence: Kevin O’Byrne, PhD, 2.92W Hodgkin Building, Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, Guy’s Campus, King’s College London, London, SE1 1UL. E-mail: ; or Yanping Kuang, Department of Assisted Reproduction, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People’s Republic of China. E-mail:
| | - Kevin T O’Byrne
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, Guy’s Campus, UK
- Correspondence: Kevin O’Byrne, PhD, 2.92W Hodgkin Building, Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, Guy’s Campus, King’s College London, London, SE1 1UL. E-mail: ; or Yanping Kuang, Department of Assisted Reproduction, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People’s Republic of China. E-mail:
| |
Collapse
|
12
|
Baker FC, Siboza F, Fuller A. Temperature regulation in women: Effects of the menstrual cycle. Temperature (Austin) 2020; 7:226-262. [PMID: 33123618 PMCID: PMC7575238 DOI: 10.1080/23328940.2020.1735927] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/17/2020] [Accepted: 02/24/2020] [Indexed: 02/08/2023] Open
Abstract
Core body temperature changes across the ovulatory menstrual cycle, such that it is 0.3°C to 0.7°C higher in the post-ovulatory luteal phase when progesterone is high compared with the pre-ovulatory follicular phase. This temperature difference, which is most evident during sleep or immediately upon waking before any activity, is used by women as a retrospective indicator of an ovulatory cycle. Here, we review both historical and current literature aimed at characterizing changes in core body temperature across the menstrual cycle, considering the assessment of the circadian rhythm of core body temperature and thermoregulatory responses to challenges, including heat and cold exposure, exercise, and fever. We discuss potential mechanisms for the thermogenic effect of progesterone and the temperature-lowering effect of estrogen, and discuss effects on body temperature of exogenous formulations of these hormones as contained in oral contraceptives. We review new wearable temperature sensors aimed at tracking daily temperature changes of women across multiple menstrual cycles and highlight the need for future research on the validity and reliability of these devices. Despite the change in core body temperature across the menstrual cycle being so well identified, there remain gaps in our current understanding, particularly about the underlying mechanisms and microcircuitry involved in the temperature changes.
Collapse
Affiliation(s)
- Fiona C. Baker
- Center for Health Sciences, SRI International, Menlo Park, USA
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Felicia Siboza
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| |
Collapse
|
13
|
Leonardi CEP, Dias FCF, Adams GP, Araujo ER, Singh J. Kisspeptin induces ovulation in heifers under low plasma progesterone concentrations. Theriogenology 2020; 141:26-34. [PMID: 31494459 DOI: 10.1016/j.theriogenology.2019.08.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 08/14/2019] [Accepted: 08/28/2019] [Indexed: 11/23/2022]
Abstract
The objective of the present study was to compare the effect of a single versus multiple doses of a 10-amino acid fragment of human (hKp) or murine (mKp) kisspeptin on LH secretion and the fate of the dominant follicle. In all experiments, a new wave was induced (Day 0) by ultrasound-guided ablation of >5 mm follicles, a progesterone device (CIDR) was placed in the vagina, animals given prostaglandin F2α analog im on Day 3.5 and 4, and hKp or mKp treatment given on Day 6. The experimental design maintained growth and ovulatory potential of the dominant follicle for 12 days and allowed hypothesis testing during the low-progesterone period (plasma progesterone ≤1.8 ng/ml on Day 6) wherein spontaneous wave emergence and ovulation did not occur between Day 6 and Day 12. In Experiment 1, heifers (n = 10/group) were given single iv dose of 45 mg hKp, 45 mg mKp, or 2 ml normal saline (control). Post-treatment plasma LH concentrations from 15 to 90 min were higher (P < 0.01) in hKp group than in the mKp and control groups. Two heifers ovulated in hKp group versus none in other groups. In Experiment 2, heifers (n = 6/group) were given 45 mg hKp over a 2 h period divided into multiple iv doses treatments or 2 ml normal saline (control). Post-treatment plasma LH concentrations were higher (P < 0.01) in all hKp treatment groups than in the control group. The ovulation rate was higher (P = 0.06) after hKp treatments (11/18) than in the control group (0/6). In Experiment 3, heifers (n = 6/group) were given 45 mg mKp over a 2 h period divided into multiple iv doses treatments or a single iv dose of gonadorelin acetate (positive control). Plasma LH concentration was higher (P < 0.01) and the ovulation rate was greater (P = 0.01) in the GnRH group (5/6) than mKp groups (1/12). In summary, hKp was more effective to induce ovulation than mKp. Human kisspeptin-10 given over a 2 h period induced ovulations at a rate similar to that of GnRH treatment in heifers under a low plasma progesterone state.
Collapse
Affiliation(s)
- Carlos E P Leonardi
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Fernanda C F Dias
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Gregg P Adams
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Estela R Araujo
- Department of Pathobiological Sciences, University of Wisconsin, Madison, USA
| | - Jaswant Singh
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| |
Collapse
|
14
|
Coyle C, Campbell RE. Pathological pulses in PCOS. Mol Cell Endocrinol 2019; 498:110561. [PMID: 31461666 DOI: 10.1016/j.mce.2019.110561] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/22/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a highly prevalent endocrine disorder associated with hyperandrogenism and anovulation. Although a spectrum disorder, many women with PCOS exhibit elevated luteinizing hormone (LH) pulse frequency and an elevated LH to follicle stimulating hormone ratio. This aberrant pattern of gonadotrophin signalling drives many of the downstream ovarian features of PCOS, including increased androgen synthesis, and indicates neuroendocrine impairments upstream. Decreased responsiveness to gonadal steroid hormone negative feedback in PCOS patients points toward dysfunction within the gonadotropin-releasing hormone (GnRH) neuronal network in the brain. Excessive androgen exposure during development or over pubertal onset can recapitulate the neuroendocrine pathology of PCOS in pre-clinical models, and these models have been fundamental in beginning to pick apart the specific central mechanisms involved. This mini-review will briefly describe the pathology of PCOS associated with high frequency GnRH/LH pulses and then highlight what is currently known, and yet to be discovered, about the central mechanisms involved.
Collapse
Affiliation(s)
- Christopher Coyle
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, 9054, New Zealand.
| |
Collapse
|
15
|
Porter DT, Moore AM, Cobern JA, Padmanabhan V, Goodman RL, Coolen LM, Lehman MN. Prenatal Testosterone Exposure Alters GABAergic Synaptic Inputs to GnRH and KNDy Neurons in a Sheep Model of Polycystic Ovarian Syndrome. Endocrinology 2019; 160:2529-2542. [PMID: 31415088 PMCID: PMC6779074 DOI: 10.1210/en.2019-00137] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 08/05/2019] [Indexed: 12/29/2022]
Abstract
Prenatal testosterone (T)-treated female sheep display reproductive deficits similar to women with polycystic ovarian syndrome (PCOS), including an increase in LH pulse frequency due to actions of the central GnRH pulse generator. In this study, we used multiple-label immunocytochemistry to investigate the possibility of changes in the γ-aminobutyric acid (GABA) neurotransmitter system at two key components of the GnRH pulse generator in prenatal T-treated sheep: kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus, and GnRH neurons in the preoptic area (POA) and mediobasal hypothalamus (MBH). We observed a significant decrease and increase, respectively, in the number of GABAergic synapses onto POA and MBH GnRH neurons in prenatal T-treated ewes; additionally, there was a significant increase in the number of GABAergic inputs onto KNDy neurons. To determine the actions of GABA on GnRH and KNDy neurons, we examined colocalization with the chloride transporters NKCC1 and KCC2, which indicate stimulatory or inhibitory activation of neurons by GABA, respectively. Most GnRH neurons in both POA and MBH colocalized NKCC1 cotransporter whereas none contained the KCC2 cotransporter. Most KNDy neurons colocalized either NKCC1 or KCC2, and 28% of the KNDy population contained NKCC1 alone. Therefore, we suggest that, as in the mouse, GABA in the sheep is stimulatory to GnRH neurons, as well as to a subset of KNDy neurons. Increased numbers of stimulatory GABAergic inputs to both MBH GnRH and KNDy neurons in prenatal T-treated animals may contribute to alterations in steroid feedback control and increased GnRH/LH pulse frequency seen in this animal model of PCOS.
Collapse
Affiliation(s)
- Danielle T Porter
- Graduate Program in Neuroscience, Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | - Aleisha M Moore
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Jade A Cobern
- Graduate Program in Neuroscience, Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | | | - Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - Lique M Coolen
- Graduate Program in Neuroscience, Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Michael N Lehman
- Graduate Program in Neuroscience, Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| |
Collapse
|
16
|
Progestogen profiling in plasma during the estrous cycle in cattle using an LC-MS based approach. Theriogenology 2019; 142:376-383. [PMID: 31708192 DOI: 10.1016/j.theriogenology.2019.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 10/02/2019] [Accepted: 10/08/2019] [Indexed: 11/23/2022]
Abstract
In many mammalian species, corpus luteum derived progesterone (P4) is the main functional gestagen during the estrous cycle and pregnancy. P4 can be metabolized into various metabolites, of which some are biologically active. While some metabolites target the classical nuclear progesterone receptor (PR), neurosteroids bind the receptors of type A γ-aminobutyric acid (GABAA-r) in the brain. According to the position of reduction within the molecule, metabolites of P4 can be characterized into C20-reduced progestogens (20α-dihydroprogesterone (20α-DHP) and 20β-dihydroprogesterone (20β-DHP)), C3-reduced progestogens (3α-dihydroprogesterone (3α-DHP) and 3β-dihydroprogesterone (3β-DHP)), 5α-reduced progestogens (5α-dihydroprogesterone (5α-DHP), allopregnanolone and isopregnanolone) and 5β-reduced progestogens (5β-dihydroprogesterone (5β-DHP), pregnanolone and epipregnanolone). We questioned whether the reduced progestogens are present in bovine plasma during the estrous cycle and whether their profiles differed from the profile of the common precursor P4 around the time of luteolysis. The analytes were monitored in plasma samples using liquid chromatography mass spectrometry (LC-MS). While progestogens lagged behind the drop of P4 at luteolysis, they followed the profile of P4 during the estrous cycle. The abundance of P4 was predominant followed by allopregnanolone, pregnanolone, epipregnanolone and 20β-DHP. Further studies will need to focus particularly on the period around luteolysis.
Collapse
|
17
|
Ruddenklau A, Campbell RE. Neuroendocrine Impairments of Polycystic Ovary Syndrome. Endocrinology 2019; 160:2230-2242. [PMID: 31265059 DOI: 10.1210/en.2019-00428] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 06/25/2019] [Indexed: 12/12/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a prevalent and distressing disorder of largely unknown etiology. Although PCOS defined by ovarian dysfunction, accumulating evidence supports a critical role for the brain in the ontogeny and pathophysiology of PCOS. A critical pathological feature of PCOS is impaired gonadal steroid hormone negative feedback to the GnRH neuronal network in the brain that regulates fertility. This impairment is associated with androgen excess, a cardinal feature of PCOS. Impaired steroid hormone feedback to GnRH neurons is thought to drive hyperactivity of the neuroendocrine axis controlling fertility, leading to a vicious cycle of androgen excess and reproductive dysfunction. Decades of clinical research have been unable to uncover the mechanisms underlying this impairment, because of the extreme difficulty in studying the brain in humans. It is only recently, with the development of preclinical models of PCOS, that we have begun to unravel the role of the brain in the development and progression of PCOS. Here, we provide a succinct overview of what is known about alterations in the steroid hormone-sensitive GnRH neuronal network that may underlie the neuroendocrine defects in clinical PCOS, with a particular focus on those that may contribute to impaired progesterone negative feedback, and the likely role of androgens in driving this impairment.
Collapse
Affiliation(s)
- Amy Ruddenklau
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| |
Collapse
|
18
|
Cintron-Colon R, Shankar K, Sanchez-Alavez M, Conti B. Gonadal hormones influence core body temperature during calorie restriction. Temperature (Austin) 2019; 6:158-168. [PMID: 31286026 DOI: 10.1080/23328940.2019.1607653] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/03/2019] [Accepted: 04/08/2019] [Indexed: 12/29/2022] Open
Abstract
During calorie restriction (CR), endotherms adjust several physiological processes including the decrease of core body temperature (Tb) and reduction of energy expenditure. We recently found that CR-induced hypothermia is regulated in a sex-dependent manner in mice with lowered central insulin-like growth factor receptor signaling. Here, we describe the contribution of sex hormones to CR-induced hypothermia in wild type C57BL6 mice by measuring Tb of female and male mice following bilateral gonadectomy and hormonal replacement. Specifically, we evaluated the effects of progesterone (P4), 17-ß estradiol (E2), a combination of both (P4 + E2) in females and of 5-α dihydrotestosterone (5-α DHT) in males. Gonadectomy resulted in an earlier and stronger CR-induced hypothermia in both sexes. These effects were fully antagonized in females by E2 replacement, but not by P4, which had only minor and partial effects when used alone and did not prevent the action of E2 during CR when both hormones were given in combination. 5-α-DHT had only minor and transient effects on preventing the reduction of Tb during CR on gonadectomized male mice. These findings indicate that gonadal hormones contribute to sex-specific regulation of Tb and energy expenditure when nutrient availability is scarce. Abbreviations: AL: ad libitum; ANOVA: analysis of variance; CR: calorie restriction; E2: 17-ß estradiol; GNX: gonadectomy or gonadectomized; IGF-1R: insulin-like growth factor 1 receptor; POA: preoptic area; P4: progesterone; RM: repeated measures; SD: standard deviation; SEM: standard error of mean; Tb: core body temperature; WT: wildtype; 5-α DHT: 5-α dihydrotestosterone.
Collapse
Affiliation(s)
- Rigo Cintron-Colon
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Kokila Shankar
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Manuel Sanchez-Alavez
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Facultad de Medicina y Psicología, Universidad Autónoma de Baja California, Tijuana, México
| | - Bruno Conti
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| |
Collapse
|
19
|
Glucocorticoids stimulate hypothalamic dynorphin expression accounting for stress-induced impairment of GnRH secretion during preovulatory period. Psychoneuroendocrinology 2019; 99:47-56. [PMID: 30176377 DOI: 10.1016/j.psyneuen.2018.08.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/03/2018] [Accepted: 08/27/2018] [Indexed: 11/24/2022]
Abstract
Stress-induced reproductive dysfunction is frequently associated with increased glucocorticoid (GC) levels responsible for suppressed GnRH/LH secretion and impaired ovulation. Besides the major role of the hypothalamic kisspeptin system, other key regulators may be involved in such regulatory mechanisms. Herein, we identify dynorphin as a novel transcriptional target of GC. We demonstrate that only priming with high estrogen (E2) concentrations prevailing during the late prooestrus phase enables stress-like GC concentrations to specifically stimulate Pdyn (prodynorphin) expression both in vitro (GT1-7 mouse hypothalamic cell line) and ex vivo (ovariectomized E2-supplemented mouse brains). Our results indicate that stress-induced GC levels up-regulate dynorphin expression within a specific kisspeptin neuron-containing hypothalamic region (antero-ventral periventricular nucleus), thus lowering kisspeptin secretion and preventing preovulatory GnRH/LH surge at the end of the prooestrus phase. To further characterize the molecular mechanisms of E2 and GC crosstalk, chromatin immunoprecipitation experiments and luciferase reporter gene assays driven by the proximal promoter of Pdyn show that glucocorticoid receptors bind specific response elements located within the Pdyn promoter, exclusively in presence of E2. Altogether, our work provides novel understanding on how stress affects hypothalamic-pituitary-gonadal axis and underscores the role of dynorphin in mediating GC inhibitory actions on the preovulatory GnRH/LH surge to block ovulation.
Collapse
|
20
|
Prepubertal Development of GABAergic Transmission to Gonadotropin-Releasing Hormone (GnRH) Neurons and Postsynaptic Response Are Altered by Prenatal Androgenization. J Neurosci 2018; 38:2283-2293. [PMID: 29374136 DOI: 10.1523/jneurosci.2304-17.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/29/2017] [Accepted: 01/20/2018] [Indexed: 11/21/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons regulate reproduction through pulsatile GnRH release. Women with polycystic ovary syndrome (PCOS) have persistently elevated luteinizing hormone release frequency, reflecting GnRH release; this exacerbates hyperandrogenemia and disrupted reproductive cycles that are characteristic of this disorder. Clinical evidence suggests that neuroendocrine features of PCOS may manifest peripubertally. Adult mice prenatally exposed to androgens (PNA) mimic several reproductive features of PCOS. GnRH neurons from these mice have increased firing activity and receive increased GABAergic transmission, which is excitatory. When changes emerge during development is unknown. To study the typical postnatal development of GABAergic transmission and the effects of PNA treatment and sex, whole-cell voltage-clamp recordings were made of GABAergic postsynaptic currents (PSCs) in GnRH neurons in brain slices from prepubertal through adult control and PNA female and male mice. GABAergic transmission was present by 1 week of age in females and males and increased in frequency, reaching adult levels at 3 and 4 weeks, respectively. GABAergic PSC frequency was elevated in 3-week-old PNA versus control females. PSC frequency in both controls and PNA mice was activity independent, suggesting that PNA induces changes in synapse organization. PNA also alters the functional response of GnRH neurons to GABA. GABA induced firing in fewer neurons from 3-week-old PNA than control females; membrane potential depolarization induced by GABA was also reduced in cells from PNA mice at this age. PNA thus induces changes during development in the presynaptic organization of the GABAergic network afferent to GnRH neurons as well as the postsynaptic GnRH neuron response, both of which may contribute to adult reproductive dysfunction.SIGNIFICANCE STATEMENT The central neuronal network that regulates reproduction is overactive in polycystic ovary syndrome (PCOS), a leading cause of infertility. Recent evidence of neuroendocrine dysfunction in midpubertal girls suggests that the pathophysiological mechanisms underlying PCOS may arise before pubertal maturation. Prenatal exposure to androgens (PNA) in mice mimics several neuroendocrine features of PCOS. GABAergic transmission to gonadotropin-releasing hormone (GnRH) neurons is important for reproduction and is increased in adult PNA mice. The typical development of this network and when changes with PNA and sex arise relative to puberty are unknown. These studies provide evidence that PNA alters prepubertal development of the GABAergic network afferent to GnRH neurons, including both the presynaptic organization and postsynaptic response. These changes may contribute to reproductive dysfunction in adults.
Collapse
|
21
|
Walters KA, Edwards MC, Tesic D, Caldwell ASL, Jimenez M, Smith JT, Handelsman DJ. The Role of Central Androgen Receptor Actions in Regulating the Hypothalamic-Pituitary-Ovarian Axis. Neuroendocrinology 2018; 106:389-400. [PMID: 29635226 DOI: 10.1159/000487762] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/16/2018] [Indexed: 12/20/2022]
Abstract
The androgen receptor (AR) is expressed throughout the hypothalamic-pituitary-gonadal (HPG) axis, and findings from female global AR knockout mice confirm that AR-mediated androgen actions play important roles in regulating female reproductive function. We generated neuron-specific AR knockout mice (NeurARKO) to investigate the functional role of neuronal AR-mediated androgen action in regulating the female HPG axis and fertility. Relative to control females, NeurARKO females exhibited elevated luteinizing hormone (LH) levels at diestrus (p < 0.05) and a compromised serum LH response to ovariectomy and E2 priming (p < 0.01). Furthermore, NeurARKO females displayed reduced Kiss1 mRNA expression in the anteroventral periventricular nucleus at diestrus (p < 0.05) and proestrus (p < 0.05), but elevated Kiss1 (p < 0.05) and neurokinin B (Tac2, p < 0.05) mRNA expression in the arcuate nucleus at proestrus compared to WT controls. Ovarian follicle dynamics were also altered in NeurARKO ovaries at 3 months of age, with a significant reduction in large antral follicle numbers at the proestrus stage compared to control WT ovaries (p < 0.05). Increased follicular atresia was evident in NeurARKO ovaries with a 4-fold increase in unhealthy large preantral follicles (p < 0.01). Despite the findings of aberrant neuroendocrine and ovarian characteristics in the NeurARKO females, estrous cyclicity and overall fertility were comparable between NeurARKO and WT females. In conclusion, our findings revealed that selective loss of neuronal AR actions impacts the kisspeptin/GnRH/LH cascade leading to compromised ovarian follicle dynamics.
Collapse
Affiliation(s)
- Kirsty A Walters
- School of Women's & Children's Health, University of New South Wales, Sydney, New South Wales, Australia
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Melissa C Edwards
- School of Women's & Children's Health, University of New South Wales, Sydney, New South Wales, Australia
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Dijana Tesic
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Washington, Australia
| | - Aimee S L Caldwell
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Mark Jimenez
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Jeremy T Smith
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Washington, Australia
| | - David J Handelsman
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
22
|
Siel D, Loaiza A, Vidal S, Caruffo M, Paredes R, Ramirez G, Lapierre L, Briceño C, Pérez O, Sáenz L. The immune profile induced is crucial to determine the effects of immunocastration over gonadal function, fertility, and GnRH-I expression. Am J Reprod Immunol 2017; 79. [PMID: 29048721 DOI: 10.1111/aji.12772] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/18/2017] [Indexed: 01/29/2023] Open
Abstract
PROBLEM Immunocastration or vaccination against the GnRH-I hormone is a promising alternative to reproductive control in different animal species. Given the low immunogenicity of this hormone, the use of adjuvants becomes necessary. METHOD OF STUDY This study evaluated the effects of three adjuvants that induce different immune response profiles over gonadal function, fertility, and expression of GnRH-I. Female mice (n = 6) were vaccinated at days 1 and 30 with a recombinant antigen for immunocastration and different adjuvants that induced preferentially Th1/Th2, Th2, and Th1 immune profiles. RESULTS Th1/Th2 response is the most efficient to block reproductive activity in vaccinated animals, reducing the number of luteal bodies and pre-ovulatory follicles. Th2 and Th1/Th2 responses induced an increase in GnRH-I at the hypothalamus. CONCLUSION The immune profile induced by different adjuvants is essential on the effects over fertility, gonadal function, and hypothalamic GnRH-I expression in immunocastrated animals.
Collapse
Affiliation(s)
- Daniela Siel
- Laboratory of Veterinary Vaccines, Department of Animal Biology, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Alexandra Loaiza
- Laboratory of Veterinary Vaccines, Department of Animal Biology, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Sonia Vidal
- Laboratory of Veterinary Vaccines, Department of Animal Biology, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Mario Caruffo
- Laboratory of Veterinary Vaccines, Department of Animal Biology, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Rodolfo Paredes
- Escuela de Medicina Veterinaria, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Santiago, Chile
| | - Galia Ramirez
- Department of Preventive Medicine, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Lisette Lapierre
- Department of Preventive Medicine, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Cristóbal Briceño
- Department of Preventive Medicine, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| | - Oliver Pérez
- Immunology Department, Instituto de Ciencias Básicas y Preclínicas "Victoria de Girón", Universidad de Ciencias Médicas de La Habana, La Habana, Cuba
| | - Leonardo Sáenz
- Laboratory of Veterinary Vaccines, Department of Animal Biology, Faculty of Veterinary and Animal Science, Universidad de Chile, Santiago, Chile
| |
Collapse
|
23
|
McCosh RB, Szeligo BM, Bedenbaugh MN, Lopez JA, Hardy SL, Hileman SM, Lehman MN, Goodman RL. Evidence That Endogenous Somatostatin Inhibits Episodic, but Not Surge, Secretion of LH in Female Sheep. Endocrinology 2017; 158:1827-1837. [PMID: 28379327 PMCID: PMC5460938 DOI: 10.1210/en.2017-00075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/28/2017] [Indexed: 11/19/2022]
Abstract
Two modes of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion are necessary for female fertility: surge and episodic secretion. However, the neural systems that regulate these GnRH secretion patterns are still under investigation. The neuropeptide somatostatin (SST) inhibits episodic LH secretion in humans and sheep, and several lines of evidence suggest SST may regulate secretion during the LH surge. In this study, we examined whether SST alters the LH surge in ewes by administering a SST receptor (SSTR) 2 agonist (octreotide) or antagonist [CYN154806 (CYN)] into the third ventricle during an estrogen-induced LH surge and whether endogenous SST alters episodic LH secretion. Neither octreotide nor CYN altered the amplitude or timing of the LH surge. Administration of CYN to intact ewes during the breeding season or anestrus increased LH secretion and increased c-Fos in a subset GnRH and kisspeptin cells during anestrus. To determine if these stimulatory effects are steroid dependent or independent, we administered CYN to ovariectomized ewes. This SSTR2 antagonist increased LH pulse frequency in ovariectomized ewes during anestrus but not during the breeding season. This study provides evidence that endogenous SST contributes to the control of LH secretion. The results demonstrate that SST, acting through SSTR2, inhibits episodic LH secretion, likely acting in the mediobasal hypothalamus, but action at this receptor does not alter surge secretion. Additionally, these data provide evidence that SST contributes to the steroid-independent suppression of LH pulse frequency during anestrus.
Collapse
Affiliation(s)
- Richard B McCosh
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Brett M Szeligo
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Michelle N Bedenbaugh
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Justin A Lopez
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Steven L Hardy
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Stanley M Hileman
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| | - Michael N Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi 39216
| | - Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506-9229
| |
Collapse
|
24
|
Tanco VM, Whitlock BK, Jones MA, Wilborn RR, Brandebourg TD, Foradori CD. Distribution and regulation of gonadotropin-releasing hormone, kisspeptin, RF-amide related peptide-3, and dynorphin in the bovine hypothalamus. PeerJ 2016; 4:e1833. [PMID: 27014517 PMCID: PMC4806599 DOI: 10.7717/peerj.1833] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/01/2016] [Indexed: 01/06/2023] Open
Abstract
Recent work has led to the hypothesis that kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the arcuate nucleus (ARC) play a key role in gonadotropin-releasing hormone (GnRH) pulse generation and gonadal steroid feedback, with kisspeptin driving GnRH release and neurokinin B and dynorphin acting as pulse start and stop signals, respectively. A separate cell group, expressing RFamide-related peptide-3 (RFRP-3) has been shown to be a primary inhibitor of GnRH release. Very little is known regarding these cell groups in the bovine. In this study, we examined the relative immunoreactivity of kisspeptin, dynorphin, and RFRP-3 and their possible connectivity to GnRH neurons in the hypothalami of periestrus and diestrus bovine. While GnRH and RFRP-3 immunoreactivity were unchanged, kisspeptin and dynorphin immunoreactivity levels varied in relation to plasma progesterone concentrations and estrous status. Animals with higher plasma progesterone concentrations in diestrus had lower kisspeptin and increased dynorphin immunoreactivity in the ARC. The percentage of GnRH cells with kisspeptin or RFRP-3 fibers in close apposition did not differ between estrous stages. However, the proportions of GnRH cells with kisspeptin or RFRP-3 contacts (∼49.8% and ∼31.3%, respectively) suggest direct communication between kisspeptin and RFRP-3 cells to GnRH cells in the bovine. The data produced in this work support roles for kisspeptin and dynorphin, within the KNDy neural network, in controlling GnRH release over the ovarian cycle and conveying progesterone-negative feedback onto GnRH neurons in the bovine.
Collapse
Affiliation(s)
- Valeria M Tanco
- Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee-Knoxville , Knoxville, TN , United States
| | - Brian K Whitlock
- Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee-Knoxville , Knoxville, TN , United States
| | - Melaney A Jones
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University , Auburn, AL , United States
| | - Robyn R Wilborn
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University , Auburn, AL , United States
| | - Terry D Brandebourg
- Department of Animal Sciences, College of Agriculture, Auburn University , Auburn, AL , United States
| | - Chad D Foradori
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University , Auburn, AL , United States
| |
Collapse
|
25
|
Cui P, Yang C, Zhang K, Gao X, Luo L, Tian Y, Song M, Liu Y, Zhang Y, Li Y, Zhang X, Su S, Fang F, Ding J. Effect of estrogen on the expression of GnRH and kisspeptin in the hypothalamus of rats during puberty. Theriogenology 2015; 84:1556-64. [DOI: 10.1016/j.theriogenology.2015.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 07/22/2015] [Accepted: 08/06/2015] [Indexed: 12/22/2022]
|
26
|
Ahn T, Fergani C, Coolen LM, Padmanabhan V, Lehman MN. Prenatal testosterone excess decreases neurokinin 3 receptor immunoreactivity within the arcuate nucleus KNDy cell population. J Neuroendocrinol 2015; 27:100-10. [PMID: 25496429 PMCID: PMC4412353 DOI: 10.1111/jne.12244] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/11/2014] [Accepted: 12/05/2014] [Indexed: 11/29/2022]
Abstract
Prenatal exposure of the female ovine foetus to excess testosterone leads to neuroendocrine disruptions in adulthood, as demonstrated by defects in responsiveness with respect to the ability of gonadal steroids to regulate gonadotrophin-releasing hormone (GnRH) secretion. In the ewe, neurones of the arcuate nucleus (ARC), which co-expresses kisspeptin, neurokinin B (NKB) and dynorphin (termed KNDy cells), play a key role in steroid feedback control of GnRH and show altered peptide expression after prenatal testosterone treatment. KNDy cells also co-localise NKB receptors (NK3R), and it has been proposed that NKB may act as an autoregulatory transmitter in KNDy cells where it participates in the mechanisms underlying steroid negative-feedback. In addition, recent evidence suggests that NKB/NK3R signalling may be involved in the positive-feedback actions of oestradiol leading to the GnRH/luteinising hormone (LH) surge in the ewe. Thus, we hypothesise that decreased expression of NK3R in KNDy cells may be present in the brains of prenatal testosterone-treated animals, potentially contributing to reproductive defects. Using single- and dual-label immunohistochemistry we found NK3R-positive cells in diverse areas of the hypothalamus; however, after prenatal testosterone treatment, decreased numbers of NK3R immunoreactive (-IR) cells were seen only in the ARC. Moreover, dual-label confocal analyses revealed a significant decrease in the percentage of KNDy cells (using kisspeptin as a marker) that co-localised NK3R. To investigate how NKB ultimately affects GnRH secretion in the ewe, we examined GnRH neurones in the preoptic area (POA) and mediobasal hypothalamus (MBH) for the presence of NK3R. Although, consistent with earlier findings, we found no instances of NK3R co-localisation in GnRH neurones in either the POA or MBH; in addition, > 70% GnRH neurones in both areas were contacted by NK3R-IR presynaptic terminals suggesting that, in addition to its role at KNDy cell bodies, NKB may regulate GnRH neurones by presynaptic actions. In summary, the finding of decreased NK3R within KNDy cells in prenatal testosterone-treated sheep complements previous observations of decreased NKB and dynorphin in the same population, and may contribute to deficits in the feedback control of GnRH/LH secretion in this animal model.
Collapse
Affiliation(s)
- T Ahn
- Department of Anatomy & Cell Biology, The University of Western Ontario, London, Canada; Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Canada
| | | | | | | | | |
Collapse
|
27
|
Sinchak K, Dalhousay L, Sanathara N. Orphanin FQ-ORL-1 regulation of reproduction and reproductive behavior in the female. VITAMINS AND HORMONES 2015; 97:187-221. [PMID: 25677773 DOI: 10.1016/bs.vh.2014.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Orphanin FQ (OFQ/N) and its receptor, opioid receptor-like receptor-1 (ORL-1), are expressed throughout steroid-responsive limbic and hypothalamic circuits that regulate female ovarian hormone feedback and reproductive behavior circuits. The arcuate nucleus of the hypothalamus (ARH) is a brain region that expresses OFQ/N and ORL-1 important for both sexual behavior and modulating estradiol feedback loops. Within the ARH, the activation of the OFQ/N-ORL-1 system facilitates sexual receptivity (lordosis) through the inhibition of β-endorphin neuronal activity. Estradiol initially activates ARH β-endorphin neurons to inhibit lordosis. Simultaneously, estradiol upregulates coexpression of OFQ/N and progesterone receptors and ORL-1 in ARH β-endorphin neurons. Ovarian hormones regulate pre- and postsynaptic coupling of ORL-1 to its G protein-coupled signaling pathways. When the steroid-primed rat is nonreceptive, estradiol acts pre- and postsynaptically to decrease the ability of the OFQ/N-ORL-1 system to inhibit ARH β-endorphin neurotransmission. Conversely, when sexually receptive, ORL-1 signaling is restored to inhibit β-endorphin neurotransmission. Although steroid signaling that facilitates lordosis converges to deactivate ARH β-endorphin neurons, estradiol-only facilitation of lordosis requires the activation of ORL-1, but estradiol+progesterone does not, indicating that multiple circuits mediate ovarian hormone signaling to deactivate ARH β-endorphin neurons. Research on the role of OFQ/N-ORL-1 in ovarian hormone feedback loops is just beginning. In the rat, OFQ/N may act to terminate gonadotropin-releasing hormone and luteinizing hormone release under positive and negative feedbacks. In the ewe, it appears to directly inhibit gonadotropin-releasing hormone release to mediate progesterone-negative feedback. As a whole, the localization and actions of OFQ/N-ORL-1 system indicate that it may mediate the actions of estradiol and progesterone to synchronize reproductive behavior and ovarian hormone feedback loops.
Collapse
Affiliation(s)
- Kevin Sinchak
- Department of Biological Sciences, California State University, Long Beach, California, USA.
| | - Lauren Dalhousay
- Department of Biological Sciences, California State University, Long Beach, California, USA
| | - Nayna Sanathara
- Department of Pharmacological Sciences, University of California, Irvine, California, USA
| |
Collapse
|
28
|
Li Q, Millar RP, Clarke IJ, Smith JT. Evidence that Neurokinin B Controls Basal Gonadotropin-Releasing Hormone Secretion but Is Not Critical for Estrogen-Positive Feedback in Sheep. Neuroendocrinology 2015; 101:161-74. [PMID: 25677216 DOI: 10.1159/000377702] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/04/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Loss-of-function mutations in genes encoding kisspeptin or neurokinin B (NKB) or their receptors cause infertility. NKB is coproduced in kisspeptin neurons in the arcuate nucleus (ARC), and these neurons also produce the NKB receptor (NK3R), allowing autosynaptic function. We tested the hypothesis that NKB action in ARC kisspeptin neurons is aligned with increased pulsatile secretion of luteinizing hormone (LH) and/or activation of the estrogen-induced LH surge in ewes. METHODS Using in situ hybridization and immunohistochemistry, we examined NKB expression in kisspeptin neurons during the ovine estrous cycle. We infused kisspeptin, senktide (an NK3R agonist), or dynorphin into the lateral ventricle during the luteal phase of the estrous cycle to determine effects on pulsatile LH secretion. Finally, we examined the effect of an NK3R antagonist (MRK-08) in ovariectomized ewes. RESULTS NKB (Tac3) mRNA expression in mid-ARC kisspeptin neurons was elevated during the mid-to-late follicular phase of the estrous cycle. The number of NKB-immunoreactive cells and NKB/kisspeptin terminals in the median eminence was similar during the estrous cycle. Kisspeptin and senktide increased LH pulse frequency and mean LH levels. Central MRK-08 infusion eliminated the LH pulses but did not prevent an estrogen-positive feedback on LH secretion. CONCLUSIONS NKB expression in ARC kisspeptin neurons is upregulated during the late follicular phase of the estrous cycle, when the pulsatile secretion of gonadotropin-releasing hormone (GnRH)/LH is maximal. When GnRH/LH secretion is minimal, central senktide infusion induces LH secretion, similar to the response to kisspeptin. Although the increase in LH in response to senktide appeared surge-like, we did not observe any change in the surge following NK3R antagonist treatment. We conclude that NKB plays a role in increasing basal GnRH/LH pulsatility in the follicular phase of the cycle but is not essential for estrogen-induced positive feedback.
Collapse
Affiliation(s)
- Qun Li
- Department of Physiology, Monash University, Clayton, Vic., Australia
| | | | | | | |
Collapse
|
29
|
Hua W, Luo L, Tian Y, Song M, Liu Y, Cui P, Song S, Jiang S, Li F, Fang F. Analysis of the serum concentrations of kisspeptin and neurokinin B in the geese during reproductive cycle and their localisation in the ovary. Anim Reprod Sci 2014; 151:78-84. [DOI: 10.1016/j.anireprosci.2014.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 09/02/2014] [Accepted: 09/12/2014] [Indexed: 11/27/2022]
|
30
|
Fergani C, Routly J, Jones D, Pickavance L, Smith R, Dobson H. Co-expression of c-Fos with oestradiol receptor α or somatostatin in the arcuate nucleus, ventromedial nucleus and medial preoptic area in the follicular phase of intact ewes: alteration after insulin-induced hypoglycaemia. Reprod Domest Anim 2014; 50:68-75. [PMID: 25399917 DOI: 10.1111/rda.12450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/07/2014] [Indexed: 11/29/2022]
Abstract
The aim of this study was to investigate how acute insulin-induced hypoglycaemia (IIH) alters the activity of cells containing oestradiol receptor α (ERα) or somatostatin (SST) in the arcuate nucleus (ARC) and ventromedial nucleus (VMN), and ERα cells in the medial preoptic area (mPOA) of intact ewes. Follicular phases were synchronized with progesterone vaginal pessaries. Control animals were killed at 0 h or 31 h (n = 5 and 6, respectively) after progesterone withdrawal (PW; time zero). At 28 h, five other animals received insulin (INS; 4 iu/kg) and were subsequently killed at 31 h. Hypothalamic sections were immunostained for ERα or SST each with c-Fos, a marker of neuronal transcriptional activation. Insulin did not alter the percentage of activated ERα cells in the ARC; however, it appeared visually that two insulin-treated animals (INS responders, with no LH surge) had an increase in the VMN (from 32 to 78%) and a decrease in the mPOA (from 40 to 12%) compared to no increase in the two INS non-responders (with an LH surge). The percentage of activated SST cells in the ARC was greater in all four insulin-treated animals (from 10 to 60%), whereas it was visually estimated that activated SST cells in the VMN increased only in the two insulin responders (from 10 to 70%). From these results, we suggest that IIH stimulates SST activation in the ARC as part of the glucose-sensing mechanism but ERα activation is unaffected in this region. We present evidence to support a hypothesis that disruption of the GnRH/LH surge may occur in insulin responders via a mechanism that involves, at least in part, SST cell activation in the VMN along with decreased ERα cell activation in the mPOA.
Collapse
Affiliation(s)
- C Fergani
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, UK
| | | | | | | | | | | |
Collapse
|
31
|
Porter KL, Hileman SM, Hardy SL, Nestor CC, Lehman MN, Goodman RL. Neurokinin-3 receptor activation in the retrochiasmatic area is essential for the full pre-ovulatory luteinising hormone surge in ewes. J Neuroendocrinol 2014; 26:776-84. [PMID: 25040132 PMCID: PMC4201879 DOI: 10.1111/jne.12180] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/18/2014] [Accepted: 07/14/2014] [Indexed: 11/30/2022]
Abstract
Neurokinin B (NKB) is essential for human reproduction and has been shown to stimulate luteinising hormone (LH) secretion in several species, including sheep. Ewes express the neurokinin-3 receptor (NK3R) in the retrochiasmatic area (RCh) and there is one report that placement of senktide, an NK3R agonist, therein stimulates LH secretion that resembles an LH surge in ewes. In the present study, we first confirmed that local administration of senktide to the RCh produced a surge-like increase in LH secretion, and then tested the effects of this agonist in two other areas implicated in the control of LH secretion and where NK3R is found in high abundance: the preoptic area (POA) and arcuate nucleus (ARC). Bilateral microimplants containing senktide induced a dramatic surge-like increase in LH when given in the POA similar to that seen with RCh treatment. By contrast, senktide treatment in the ARC resulted in a much smaller but significant increase in LH concentrations suggestive of an effect on tonic secretion. The possible role of POA and RCh NK3R activation in the LH surge was next tested by treating ewes with SB222200, an NK3R antagonist, in each area during an oestradiol-induced LH surge. SB222200 in the RCh, but not in the POA, reduced the LH surge amplitude by approximately 40% compared to controls, indicating that NK3R activation in the former region is essential for full expression of the pre-ovulatory LH surge. Based on these data, we propose that the actions of NKB in the RCh are an important component of the pre-ovulatory LH surge in ewes.
Collapse
Affiliation(s)
- K L Porter
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | | | | | | | | | | |
Collapse
|
32
|
Fergani C, Routly JE, Jones DN, Pickavance LC, Smith RF, Dobson H. Activation of cells containing estrogen receptor alpha or somatostatin in the medial preoptic area, arcuate nucleus, and ventromedial nucleus of intact ewes during the follicular phase, and alteration after lipopolysaccharide. Biol Reprod 2014; 91:141. [PMID: 25320149 DOI: 10.1095/biolreprod.114.122408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Cells in the medial preoptic area (mPOA), arcuate nucleus (ARC), and ventromedial nucleus (VMN) that possess estrogen receptor alpha (ER alpha) mediate estradiol feedback to regulate endocrine and behavioral events during the estrous cycle. A percentage of ER alpha cells located in the ARC and VMN express somatostatin (SST) and are activated in response to estradiol. The aims of the present study were to investigate the location of c-Fos, a marker for activation, in cells containing ER alpha or SST at various times during the follicular phase and to determine whether lipopolysaccharide (LPS) administration, which leads to disruption of the luteinizing hormone (LH) surge, is accompanied by altered ER alpha and/or SST activation patterns. Follicular phases were synchronized with progesterone vaginal pessaries, and control animals were killed at 0, 16, 31, and 40 h (n = 4-6/group) after progesterone withdrawal (PW [time 0]). At 28 h, other animals received LPS (100 ng/kg) and were subsequently killed at 31 h or 40 h (n = 5/group). Hypothalamic sections were immunostained for c-Fos and ER alpha or SST. LH surges occurred only in control ewes with onset at 36.7 ± 1.3 h after PW; these animals had a marked increase in the percentage of ER alpha cells that colocalized c-Fos (%ER alpha/c-Fos) in the ARC and mPOA from 31 h after PW and throughout the LH surge. In the VMN, %ER alpha/c-Fos was higher in animals that expressed sexual behavior than in those that did not. SST cell activation in the ARC and VMN was greater during the LH surge than in other stages in the follicular phase. At 31 or 40 h after PW (i.e., 3 or 12 h after treatment, respectively), LPS decreased %ER alpha/c-Fos in the ARC and the mPOA, but there was no change in the VMN compared to that in controls. The %SST/c-Fos increased in the VMN at 31 h after PW (i.e., 3 h after LPS) with no change in the ARC compared to controls. These results indicate that there is a distinct temporal pattern of ER alpha cell activation in the hypothalamus during the follicular phase, which begins in the ARC and mPOA at least 6-7 h before the LH surge onset and extends to the VMN after the onset of sexual behavior and LH surge. Furthermore, during the surge, some of these ER alpha-activated cells may be SST-secreting cells. This pattern is markedly altered by LPS administered during the late follicular phase, indicating that the disruptive effects of this stressor are mediated by suppressing ER alpha cell activation at the level of the mPOA and ARC and enhancing SST cell activation in the VMN, leading to the attenuation of the LH surge.
Collapse
Affiliation(s)
- Chrysanthi Fergani
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| | - Jean E Routly
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| | - David N Jones
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| | - Lucy C Pickavance
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| | - Robert F Smith
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| | - Hilary Dobson
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, United Kingdom
| |
Collapse
|
33
|
Dorfman VB, Saucedo L, Di Giorgio NP, Inserra PIF, Fraunhoffer N, Leopardo NP, Halperín J, Lux-Lantos V, Vitullo AD. Variation in Progesterone Receptors and GnRH Expression in the Hypothalamus of the Pregnant South American Plains Vizcacha, Lagostomus maximus (Mammalia, Rodentia)1. Biol Reprod 2013; 89:115. [DOI: 10.1095/biolreprod.113.107995] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
|
34
|
Nestor CC, Coolen LM, Nesselrod GL, Valent M, Connors JM, Hileman SM, Cheng G, Lehman MN, Goodman RL. Evidence that orphanin FQ mediates progesterone negative feedback in the ewe. Endocrinology 2013; 154:4249-58. [PMID: 23928375 PMCID: PMC3800756 DOI: 10.1210/en.2013-1274] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 07/30/2013] [Indexed: 11/19/2022]
Abstract
Orphanin FQ (OFQ), a member of the opioid family, is found in many areas of the hypothalamus and, when given centrally OFQ inhibits episodic LH secretion in rodents and sheep. Because GnRH neurons are devoid of the appropriate receptors to mediate steroid negative feedback directly, neurons that release OFQ may be involved. Using immunocytochemistry, we first determined that most OFQ neurons in the arcuate nucleus (ARC) and other hypothalamic regions of luteal phase ewes contained both estrogen receptor α and progesterone (P) receptor. Given a similar high degree of steroid receptor colocalization in other ARC subpopulations, we examined whether OFQ neurons of the ARC contained those other neuropeptides and neurotransmitters. OFQ did not colocalize with kisspeptin, tyrosine hydroxylase, or agouti-related peptide, but all ARC OFQ neurons coexpressed proopiomelanocortin. To test for a role for endogenous OFQ, we examined the effects of an OFQ receptor antagonist, [Nphe1,Arg14,Lys15]Nociceptin-NH2 (UFP-101) (30 nmol intracerebroventricular/h), on LH secretion in steroid-treated ewes in the breeding season and ovary-intact ewes in anestrus. Ovariectomized ewes with luteal phase concentrations of P and estradiol showed a significant increase in LH pulse frequency during infusion of UFP-101 (4.5 ± 0.5 pulses/6 h) compared with saline infusion (2.6 ± 0.4 pulses/6 h), whereas ewes implanted with only estradiol did not. Ovary-intact anestrous ewes displayed no significant differences in LH pulse amplitude or frequency during infusion of UFP-101. Therefore, we conclude that OFQ mediates, at least in part, the negative feedback action of P on GnRH/LH pulse frequency in sheep.
Collapse
Affiliation(s)
- Casey C Nestor
- Department of Physiology and Pharmacology, PO Box 9229, West Virginia University, Morgantown, West Virginia 26506.
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Petersen SL, Intlekofer KA, Moura-Conlon PJ, Brewer DN, Del Pino Sans J, Lopez JA. Nonclassical progesterone signalling molecules in the nervous system. J Neuroendocrinol 2013; 25:991-1001. [PMID: 23763432 DOI: 10.1111/jne.12060] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/30/2013] [Accepted: 06/09/2013] [Indexed: 11/26/2022]
Abstract
Progesterone (P4) regulates a wide range of cognitive, neuroendocrine, neuroimmune and neuroprotective functions. Therefore, it is not surprising that this ovarian hormone acts through multiple receptors. Ever since the 1980s, studies investigating the neural effects of P4 have focused mainly on genomic and nongenomic actions of the classical progestin receptor (PGR). More recently, two groups of nonclassical P4 signalling molecules have been identified: (i) the class II progestin and adipoQ receptor (PAQR) family, which includes PAQR 5, 6, 7, 8 and 9, also called membrane progestin receptor α (mPRα; PAQR7), mPRβ (PAQR8), mPRγ (PAQR5), mPRδ (PAQR6) and mPRε (PAQR9), and (ii) the b5-like haeme/steroid-binding protein family, which includes progesterone receptor membrane component 1 (Pgrmc1), Pgrmc2, neudesin and neuferricin. In this review, we describe the structures, neuroanatomical localisation and signalling mechanisms of these molecules. We also discuss gonadotrophin-releasing hormone regulation as an example of a physiological function regulated by multiple progesterone receptors but through different mechanisms.
Collapse
Affiliation(s)
- S L Petersen
- Veterinary and Animal Sciences Department, University of Massachusetts Amherst, Amherst, MA, USA
| | | | | | | | | | | |
Collapse
|
36
|
Foradori CD, Zimmerman AD, Hinds LR, Zuloaga KL, Breckenridge CB, Handa RJ. Atrazine inhibits pulsatile gonadotropin-releasing hormone (GnRH) release without altering GnRH messenger RNA or protein levels in the female rat. Biol Reprod 2013. [PMID: 23197165 DOI: 10.1095/biolreprod.112.102277] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Atrazine (ATR) is a commonly used pre-emergence/early postemergence herbicide. Previous work has shown that exposure to high doses of ATR in rats results in blunting of the hormone-induced luteinizing hormone (LH) surge and inhibition of pulsatile LH release without significantly reducing pituitary sensitivity to a gonadotropin-releasing hormone (GnRH) agonist. Accompanying the reduction in the LH surge was an attenuation of GnRH neuronal activation. These findings suggest that ATR exposure may be acting to inhibit GnRH release. In this study, we examined GnRH directly to determine the effect of high doses of ATR on GnRH pulsatile release, gene expression, and peptide levels in the female rat. Ovariectomized adult female Wistar rats were treated with ATR (200 mg/kg) or vehicle for 4 days via gavage. Following the final treatment, GnRH release was measured from ex vivo hypothalamic explants for 3 h. In another experiment, animals were administered either vehicle or ATR (50, 100, or 200 mg/kg) daily for 4 days. Following treatment, in situ hybridization was performed to examine total GnRH mRNA and the primary GnRH heterogeneous nuclear RNA transcript. Finally, GnRH immunoreactivity and total peptide levels were measured in hypothalamic tissue of treated animals. ATR treatment resulted in no changes to GnRH gene expression, peptide levels, or immunoreactivity but a reduction in GnRH pulse frequency and an increased pulse amplitude. These findings suggest that ATR acts to inhibit the secretory dynamics of GnRH pulses without interfering with GnRH mRNA and protein synthesis.
Collapse
Affiliation(s)
- Chad D Foradori
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
| | | | | | | | | | | |
Collapse
|
37
|
Bashour NM, Wray S. Progesterone directly and rapidly inhibits GnRH neuronal activity via progesterone receptor membrane component 1. Endocrinology 2012; 153:4457-69. [PMID: 22822163 PMCID: PMC3423625 DOI: 10.1210/en.2012-1122] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 07/03/2012] [Indexed: 01/03/2023]
Abstract
GnRH neurons are essential for reproduction, being an integral component of the hypothalamic-pituitary-gonadal axis. Progesterone (P4), a steroid hormone, modulates reproductive behavior and is associated with rapid changes in GnRH secretion. However, a direct action of P4 on GnRH neurons has not been previously described. Receptors in the progestin/adipoQ receptor family (PAQR), as well as progesterone receptor membrane component 1 (PgRMC1) and its partner serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1) mRNA binding protein 1 (SERBP1), have been shown to mediate rapid progestin actions in various tissues, including the brain. This study shows that PgRMC1 and SERBP1, but not PAQR, are expressed in prenatal GnRH neurons. Expression of PgRMC1 and SERBP1 was verified in adult mouse GnRH neurons. To investigate the effect of P4 on GnRH neuronal activity, calcium imaging was used on primary GnRH neurons maintained in explants. Application of P4 significantly decreased the activity of GnRH neurons, independent of secretion of gamma-aminobutyric acidergic and glutamatergic input, suggesting a direct action of P4 on GnRH neurons. Inhibition was not blocked by RU486, an antagonist of the classic nuclear P4 receptor. Inhibition was also maintained after uncoupling of the inhibitory regulative G protein (G(i/o)), the signal transduction pathway used by PAQR. However, AG-205, a PgRMC1 ligand and inhibitor, blocked the rapid P4-mediated inhibition, and inhibition of protein kinase G, thought to be activated downstream of PgRMC1, also blocked the inhibitory activity of P4. These data show for the first time that P4 can act directly on GnRH neurons through PgRMC1 to inhibit neuronal activity.
Collapse
Affiliation(s)
- Nicholas Michael Bashour
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892, USA
| | | |
Collapse
|
38
|
Foradori CD, Hinds LR, Quihuis AM, Lacagnina AF, Breckenridge CB, Handa RJ. The Differential Effect of Atrazine on Luteinizing Hormone Release in Adrenalectomized Adult Female Wistar Rats1. Biol Reprod 2011; 85:684-9. [DOI: 10.1095/biolreprod.111.092452] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
|
39
|
Goodman RL, Holaskova I, Nestor CC, Connors JM, Billings HJ, Valent M, Lehman MN, Hileman SM. Evidence that the arcuate nucleus is an important site of progesterone negative feedback in the ewe. Endocrinology 2011; 152:3451-60. [PMID: 21693677 PMCID: PMC3159787 DOI: 10.1210/en.2011-0195] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
There is now considerable evidence that dynorphin neurons mediate the negative feedback actions of progesterone to inhibit GnRH and LH pulse frequency, but the specific neurons have yet to be identified. In ewes, dynorphin neurons in the arcuate nucleus (ARC) and preoptic area (POA) are likely candidates based on colocalization with progesterone receptors. These studies tested the hypothesis that progesterone negative feedback occurs in either the ARC or POA by determining whether microimplants of progesterone into either site would inhibit LH pulse frequency (study 1) and whether microimplants of the progesterone receptor antagonist, RU486, would disrupt the inhibitory effects of peripheral progesterone (study 2). Both studies were done in ovariectomized (OVX) and estradiol-treated OVX ewes. In study 1, no inhibitory effects of progesterone were observed during treatment in either area. In study 2, microimplants of RU486 into the ARC disrupted the negative-feedback actions of peripheral progesterone treatments on LH pulse frequency in both OVX and OVX+estradiol ewes. In contrast, microimplants of RU486 into the POA had no effect on the ability of systemic progesterone to inhibit LH pulse frequency. We thus conclude that the ARC is one important site of progesterone-negative feedback in the ewe. These data, which are the first evidence on the neural sites in which progesterone inhibits GnRH pulse frequency in any species, are consistent with the hypothesis that ARC dynorphin neurons mediate this action of progesterone.
Collapse
Affiliation(s)
- Robert L Goodman
- Department of Physiology and Pharmacology, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia 26506, USA.
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Ryu BJ, Kim HR, Jeong JK, Lee BJ. Regulation of the female rat estrous cycle by a neural cell-specific epidermal growth factor-like repeat domain containing protein, NELL2. Mol Cells 2011; 32:203-7. [PMID: 21643849 PMCID: PMC3887675 DOI: 10.1007/s10059-011-0086-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 10/18/2022] Open
Abstract
NELL2, a protein containing epidermal growth factor-like repeat domains, is predominantly expressed in the nervous system. In the mammalian brain, NELL2 expression is mostly neuronal. Previously we found that NELL2 is involved in the onset of female puberty by regulating the release of gonadotropin-releasing hormone (GnRH), and in normal male sexual behavior by controlling the development of the sexually dimorphic nucleus of the preoptic area (POA). In this study we investigated the effect of NELL2 on the female rat estrous cycle. NELL2 expression in the POA was highest during the proestrous phase. NELL2 mRNA levels in the POA were increased by estrogen treatment in ovariectomized female rats. Blocking NELL2 synthesis in the female rat hypothalamus decreased the expression of kisspeptin 1, an important regulator of the GnRH neuronal apparatus, and resulted in disruption of the estrous cycle at the diestrous phase. These results indicate that NELL2 is involved in the maintenance of the normal female reproductive cycle in mammals.
Collapse
Affiliation(s)
| | | | | | - Byung Ju Lee
- Department of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea
| |
Collapse
|
41
|
Sun J, Moenter SM. Progesterone treatment inhibits and dihydrotestosterone (DHT) treatment potentiates voltage-gated calcium currents in gonadotropin-releasing hormone (GnRH) neurons. Endocrinology 2010; 151:5349-58. [PMID: 20739401 PMCID: PMC2954728 DOI: 10.1210/en.2010-0385] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
GnRH neurons are central regulators of fertility, and their activity is modulated by steroid feedback. In normal females, GnRH secretion is regulated by estradiol and progesterone (P). Excess androgens present in hyperandrogenemic fertility disorders may disrupt communication of negative feedback signals from P and/or independently stimulate GnRH release. Voltage-gated calcium channels (VGCCs) are important in regulating excitability and hormone release. Estradiol alters VGCCs in a time-of-day-dependent manner. To further elucidate ovarian steroid modulation of GnRH neuron VGCCs, we studied the effects of dihydrotestosterone (DHT) and P. Adult mice were ovariectomized (OVX) or OVX and treated with implants containing DHT (OVXD), estradiol (OVXE), estradiol and DHT (OVXED), estradiol and P (OVXEP), or estradiol, DHT, and P (OVXEDP). Macroscopic calcium current (I(Ca)) was recorded in the morning or afternoon 8-12 d after surgery using whole-cell voltage-clamp. I(Ca) was increased in afternoon vs. morning in GnRH neurons from OVXE mice but this increase was abolished in cells from OVXEP mice. I(Ca) in cells from OVXD mice was increased regardless of time of day; there was no additional effect in OVXED mice. P reduced N-type and DHT potentiated N- and R-type VGCCs; P blocked the DHT potentiation of N-type-mediated current. These data suggest P and DHT have opposing actions on VGCCs in GnRH neurons, but in the presence of both steroids, P dominates. VGCCs are targets of ovarian steroid feedback modulation of GnRH neuron activity and, more specifically, a potential mechanism whereby androgens could activate GnRH neuronal function.
Collapse
Affiliation(s)
- Jianli Sun
- Department of Medicine, University of Virginia, Charlottesville, Virginia 22908, USA
| | | |
Collapse
|
42
|
Eghlidi DH, Haley GE, Noriega NC, Kohama SG, Urbanski HF. Influence of age and 17beta-estradiol on kisspeptin, neurokinin B, and prodynorphin gene expression in the arcuate-median eminence of female rhesus macaques. Endocrinology 2010; 151:3783-94. [PMID: 20519367 PMCID: PMC2940528 DOI: 10.1210/en.2010-0198] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 05/06/2010] [Indexed: 11/19/2022]
Abstract
The neuropeptides kisspeptin, neurokinin B, and dynorphin A (collectively abbreviated as KNDy) are, respectively, encoded by KiSS-1, NKB, and PDYN and are coexpressed by neurons of the hypothalamic arcuate nucleus (ARC). Here, using quantitative real-time PCR, we examined age-related changes in the expression of genes encoding KNDy and associated receptors G protein-coupled receptor 54 (encoded by GPR54), neurokinin 3 receptor (encoded by NK3), and kappa-opioid receptor (encoded by KOR), in the female rhesus macaque ARC-median eminence (ARC-ME). Expression of KiSS-1 and NKB was highly elevated in old perimenopausal compared with young or middle-aged premenopausal animals. To test whether these age-related changes could be attributed to perimenopausal loss of sex steroids, we then examined KNDy, GPR54, NK3, and KOR expression changes in response to ovariectomy (OVX) and exposure to 17beta-estradiol (E(2)). Short-term (7 months) OVX (with or without 1 month of estrogen replacement) failed to modulate the expression of any of the KNDy-related genes. In contrast, long-term ( approximately 4 yr) OVX significantly increased KiSS-1 and NKB expression, and this was reversed by E(2) administration. Finally, we examined the expression of KNDy-related genes in young adult females during the early follicular, late follicular, or midluteal phases of their menstrual cycle but found no difference. Together, the results suggest that short-term alterations in circulating E(2) levels, such as those occurring during the menstrual cycle, may have little effect on the ARC-ME expression of KNDy and associated receptors. Nevertheless, they clearly demonstrate that loss of ovarian steroid negative feedback that occurs during perimenopause plays a major role in modulating the activity of KNDy circuits of the aging primate ARC-ME.
Collapse
Affiliation(s)
- Dominique H Eghlidi
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
| | | | | | | | | |
Collapse
|
43
|
Christian CA, Moenter SM. The neurobiology of preovulatory and estradiol-induced gonadotropin-releasing hormone surges. Endocr Rev 2010; 31:544-77. [PMID: 20237240 PMCID: PMC3365847 DOI: 10.1210/er.2009-0023] [Citation(s) in RCA: 199] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 02/18/2010] [Indexed: 12/14/2022]
Abstract
Ovarian steroids normally exert homeostatic negative feedback on GnRH release. During sustained exposure to elevated estradiol in the late follicular phase of the reproductive cycle, however, the feedback action of estradiol switches to positive, inducing a surge of GnRH release from the brain, which signals the pituitary LH surge that triggers ovulation. In rodents, this switch appears dependent on a circadian signal that times the surge to a specific time of day (e.g., late afternoon in nocturnal species). Although the precise nature of this daily signal and the mechanism of the switch from negative to positive feedback have remained elusive, work in the past decade has provided much insight into the role of circadian/diurnal and estradiol-dependent signals in GnRH/LH surge regulation and timing. Here we review the current knowledge of the neurobiology of the GnRH surge, in particular the actions of estradiol on GnRH neurons and their synaptic afferents, the regulation of GnRH neurons by fast synaptic transmission mediated by the neurotransmitters gamma-aminobutyric acid and glutamate, and the host of excitatory and inhibitory neuromodulators including kisspeptin, vasoactive intestinal polypeptide, catecholamines, neurokinin B, and RFamide-related peptides, that appear essential for GnRH surge regulation, and ultimately ovulation and fertility.
Collapse
Affiliation(s)
- Catherine A Christian
- Departments of Medicine and Cell Biology, University of Virginia, Charlottesville, 22908, USA.
| | | |
Collapse
|
44
|
Bliss SP, Navratil AM, Xie J, Roberson MS. GnRH signaling, the gonadotrope and endocrine control of fertility. Front Neuroendocrinol 2010; 31:322-40. [PMID: 20451543 PMCID: PMC2923852 DOI: 10.1016/j.yfrne.2010.04.002] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2010] [Revised: 04/26/2010] [Accepted: 04/30/2010] [Indexed: 11/28/2022]
Abstract
Mammalian reproductive cycles are controlled by an intricate interplay between the hypothalamus, pituitary and gonads. Central to the function of this axis is the ability of the pituitary gonadotrope to appropriately respond to stimulation by gonadotropin-releasing hormone (GnRH). This review focuses on the role of cell signaling and in particular, mitogen-activated protein kinase (MAPK) activities regulated by GnRH that are necessary for normal fertility. Recently, new mouse models making use of conditional gene deletion have shed new light on the relationships between GnRH signaling and fertility in both male and female mice. Within the reproductive axis, GnRH signaling is initiated through discrete membrane compartments in which the receptor resides leading to the activation of the extracellular signal-regulated kinases (ERKs 1/2). As defined by gonadotrope-derived cellular models, the ERKs appear to play a central role in the regulation of a cohort of immediate early genes that regulate the expression of late genes that, in part, define the differentiated character of the gonadotrope. Recent data would suggest that in vivo, conditional, pituitary-specific disruption of ERK signaling by GnRH leads to a gender-specific perturbation of fertility. Double ERK knockout in the anterior pituitary leads to female infertility due to LH biosynthesis deficiency and a failure in ovulation. In contrast, male mice are modestly LH deficient; however, this does not have an appreciable impact on fertility.
Collapse
Affiliation(s)
- Stuart P Bliss
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States
| | | | | | | |
Collapse
|
45
|
Smith JT, Shahab M, Pereira A, Pau KYF, Clarke IJ. Hypothalamic expression of KISS1 and gonadotropin inhibitory hormone genes during the menstrual cycle of a non-human primate. Biol Reprod 2010; 83:568-77. [PMID: 20574054 DOI: 10.1095/biolreprod.110.085407] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Kisspeptin, the product of the KISS1 gene, stimulates gonadotropin-releasing hormone (GnRH) secretion; gonadotropin inhibitory hormone (GnIH), encoded by the RF-amide-related peptide (RFRP) or NPVF gene, inhibits the reproductive axis. In sheep, kisspeptin neurons are found in the lateral preoptic area (POA) and the arcuate nucleus (ARC) and may be important for initiating the preovulatory GnRH/luteinizing hormone (LH) surge. GnIH cells are located in the ovine dorsomedial hypothalamic nucleus (DMN) and paraventricular nucleus (PVN), with similar distribution in the primate. KISS1 cells are found in the primate POA and ARC, but the function that kisspeptin and GnIH play in primates has not been elucidated. We examined KISS1 and NPVF mRNA throughout the menstrual cycle of a female primate, rhesus macaque (Macaca mulatta), using in situ hybridization. KISS1-expressing cells were found in the POA and ARC, and NPVF-expressing cells were located in the PVN/DMN. KISS1 expression in the caudal ARC and POA was higher in the late follicular phase of the cycle (just before the GnRH/LH surge) than in the luteal phase. NPVF expression was also higher in the late follicular phase. We ascertained whether kisspeptin and/or GnIH cells project to GnRH neurons in the primate. Close appositions of kisspeptin and GnIH fibers were found on GnRH neurons, with no change across the menstrual cycle. These data suggest a role for kisspeptin in the stimulation of GnRH cells before the preovulatory GnRH/LH surge in non-human primates. The role of GnIH is less clear, with paradoxical up-regulation of gene expression in the late follicular phase of the menstrual cycle.
Collapse
Affiliation(s)
- Jeremy T Smith
- Department of Physiology, Monash University, Clayton, Victoria, Australia.
| | | | | | | | | |
Collapse
|
46
|
Cheng G, Coolen LM, Padmanabhan V, Goodman RL, Lehman MN. The kisspeptin/neurokinin B/dynorphin (KNDy) cell population of the arcuate nucleus: sex differences and effects of prenatal testosterone in sheep. Endocrinology 2010; 151:301-11. [PMID: 19880810 PMCID: PMC2803147 DOI: 10.1210/en.2009-0541] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent work in sheep has identified a neuronal subpopulation in the arcuate nucleus that coexpresses kisspeptin, neurokinin B, and dynorphin (referred to here as KNDy cells) and that mediate the negative feedback influence of progesterone on GnRH secretion. We hypothesized that sex differences in progesterone negative feedback are due to sexual dimorphism of KNDy cells and compared neuropeptide and progesterone receptor immunoreactivity in this subpopulation between male and female sheep. In addition, because sex differences in progesterone negative feedback and neurokinin B are due to the influence of testosterone (T) during fetal life, we determined whether prenatal T exposure would mimic sex differences in KNDy cells. Adult rams had nearly half the number of kisspeptin, neurokinin B, dynorphin, and progesterone receptor-positive cells in the arcuate nucleus as did females, but the percentage of KNDy cells colocalizing progesterone receptors remained high in both sexes. Prenatal T treatment also reduced the number of dynorphin, neurokinin B, and progesterone receptor-positive cells in the female arcuate nucleus; however, the number of kisspeptin cells remained high and at levels comparable to control females. Thus, sex differences in kisspeptin in the arcuate nucleus, unlike that of dynorphin and neurokinin B, are not due solely to exposure to prenatal T, suggesting the existence of different critical periods for multiple peptides coexpressed within the same neuron. In addition, the imbalance between inhibitory (dynorphin) and stimulatory (kisspeptin) neuropeptides in this subpopulation provides a potential explanation for the decreased ability of progesterone to inhibit GnRH neurons in prenatal T-treated ewes.
Collapse
Affiliation(s)
- Guanliang Cheng
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | | | | | | | | |
Collapse
|
47
|
Amstalden M, Coolen LM, Hemmerle AM, Billings HJ, Connors JM, Goodman RL, Lehman MN. Neurokinin 3 receptor immunoreactivity in the septal region, preoptic area and hypothalamus of the female sheep: colocalisation in neurokinin B cells of the arcuate nucleus but not in gonadotrophin-releasing hormone neurones. J Neuroendocrinol 2010; 22:1-12. [PMID: 19912479 PMCID: PMC2821793 DOI: 10.1111/j.1365-2826.2009.01930.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent evidence has implicated neurokinin B (NKB) in the complex neuronal network mediating the effects of gonadal steroids on the regulation of gonadotrophin-releasing hormone (GnRH) secretion. Because the neurokinin 3 receptor (NK3R) is considered to mediate the effects of NKB at the cellular level, we determined the distribution of immunoreactive NK3R in the septal region, preoptic area (POA) and hypothalamus of the ewe. NK3R cells and/or fibres were found in areas including the bed nucleus of the stria terminalis, POA, anterior hypothalamic and perifornical areas, dopaminergic A15 region, dorsomedial and lateral hypothalamus, arcuate nucleus (ARC) and the ventral premammillary nucleus. We also used dual-label immunocytochemistry to determine whether a neuroanatomical basis for direct modulation of GnRH neurones by NKB was evident. No GnRH neurones at any rostral-caudal level were observed to contain NK3R immunoreactivity, although GnRH neurones and fibres were in proximity to NK3R-containing fibres. Because NKB fibres formed close contacts with NKB neurones in the ARC, we determined whether these NKB neurones also contained immunoreactive NK3R. In luteal-phase ewes, 64% +/- 11 of NKB neurones colocalised NK3R. In summary, NK3R is distributed in areas of the sheep POA and hypothalamus known to be involved in the control of reproductive neuroendocrine function. Colocalisation of NK3R in NKB neurones of the ARC suggests a potential mechanism for the autoregulation of this subpopulation; however, the lack of NK3R in GnRH neurones suggests that the actions of NKB on GnRH neurosecretory activity in the ewe are mediated indirectly via other neurones and/or neuropeptides.
Collapse
Affiliation(s)
- M. Amstalden
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH USA 45267-0521
- Department of Animal Science, Texas A&M University, College Station, TX USA 77843-2471
| | - L. M. Coolen
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH USA 45267-0521
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada
| | - A. M. Hemmerle
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH USA
| | - Heather J. Billings
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH USA 45267-0521
- Department of Neurobiology and Anatomy, West Virginia University Health Sciences Center, Morgantown, WV USA 26506-9128
| | - John M. Connors
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, WV USA 26506-9229
| | - Robert L. Goodman
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, WV USA 26506-9229
| | - Michael N. Lehman
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH USA 45267-0521
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada
| |
Collapse
|
48
|
Oakley AE, Breen KM, Tilbrook AJ, Wagenmaker ER, Karsch FJ. Role of estradiol in cortisol-induced reduction of luteinizing hormone pulse frequency. Endocrinology 2009; 150:2775-82. [PMID: 19179435 PMCID: PMC2689807 DOI: 10.1210/en.2008-1754] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Precise control of pulsatile GnRH and LH release is imperative to ovarian cyclicity but is vulnerable to environmental perturbations, like stress. In sheep, a sustained (29 h) increase in plasma cortisol to a level observed during stress profoundly reduces GnRH pulse frequency in ovariectomized ewes treated with ovarian steroids, whereas shorter infusion (6 h) is ineffective in the absence of ovarian hormones. This study first determined whether the ovarian steroid milieu or duration of exposure is the relevant factor in determining whether cortisol reduces LH pulse frequency. Prolonged (29 h) cortisol infusion did not lower LH pulse frequency in ovariectomized ewes deprived of ovarian hormones, but it did so in ovariectomized ewes treated with estradiol and progesterone to create an artificial estrous cycle, implicating ovarian steroids as the critical factor. Importantly, this effect of cortisol was more pronounced after the simulated preovulatory estradiol rise of the artificial follicular phase. The second experiment examined which component of the ovarian steroid milieu enables cortisol to reduce LH pulse frequency in the artificial follicular phase: prior exposure to progesterone in the luteal phase, low early follicular phase estradiol levels, or the preovulatory estradiol rise. Basal estradiol enabled cortisol to decrease LH pulse frequency, but the response was potentiated by the estradiol rise. These findings lead to the conclusion that ovarian steroids, particularly estradiol, enable cortisol to inhibit LH pulse frequency. Moreover, the results provide new insight into the means by which gonadal steroids, and possibly reproductive status, modulate neuroendocrine responses to stress.
Collapse
Affiliation(s)
- Amy E Oakley
- Department of Molecular and Integrative Physiology and Reproductive Sciences Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | |
Collapse
|
49
|
Dahl SK, Amstalden M, Coolen L, Fitzgerald M, Lehman M. Dynorphin immunoreactive fibers contact GnRH neurons in the human hypothalamus. Reprod Sci 2009; 16:781-7. [PMID: 19474285 DOI: 10.1177/1933719109336619] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dynorphin, an endogenous opioid peptide, mediates progesterone-negative feedback on gonadotropin-releasing hormone (GnRH) neurons in other species. The role of dynorphin in humans is unclear. The objective of this study was to determine if dynorphin fibers have close contacts with GnRH neurons in humans. Dual-label immunocytochemistry was performed on postmortem human hypothalamic tissue. The majority of GnRH neurons, 87.5%, had close contacts with dynorphin fibers and multiple close contacts were common, 62.5%. There were no regional differences between the hypothalamus and preoptic area in the distribution of close contacts. More close contacts were identified on the GnRH dendrites compared to the cell bodies (P < .001), but this difference was not significant when corrected for length. In conclusion, dynorphin fibers form close contacts with GnRH neurons in humans. This neuroanatomical evidence may suggest that dynorphin has effects on GnRH regulation in humans as seen in other species.
Collapse
Affiliation(s)
- Stephanie K Dahl
- Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
| | | | | | | | | |
Collapse
|
50
|
Albertson AJ, Talbott H, Wang Q, Jensen D, Skinner DC. The gonadotropin-releasing hormone type I receptor is expressed in the mouse cerebellum. THE CEREBELLUM 2009; 7:379-84. [PMID: 18592335 DOI: 10.1007/s12311-008-0038-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) is a decapeptide hypothalamic hormone that was named according to its first discovered function--at the head of the neuroendocrine reproductive axis. Numerous other organ systems express GnRH and/or its receptor, although a specific physiological role for GnRH outside of the reproductive axis has yet to be established. Several studies in lower vertebrates have reported GnRH and/or its receptor in the cerebellum. Here, we describe the presence of immunoreactive GnRH receptors in the Purkinje cells of the mammalian cerebellum for the first time. This study provides compelling anatomical evidence for a common link between the cerebellum and the hypothalamo-pituitary axis. Dysfunction of this link occurs in the rare genetic ataxia disorders--Gordon Holmes syndrome and Boucher-Neuhauser syndrome.
Collapse
Affiliation(s)
- Asher J Albertson
- Department of Zoology and Physiology & Neurobiology Program, University of Wyoming, Dept 3166, 1000 E University Avenue, Laramie, WY 82071, USA
| | | | | | | | | |
Collapse
|