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Prévot V, Duittoz A. A role for GnRH in olfaction and cognition: Implications for veterinary medicine. Reprod Domest Anim 2023; 58 Suppl 2:109-124. [PMID: 37329313 DOI: 10.1111/rda.14411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/05/2023] [Accepted: 06/14/2023] [Indexed: 06/19/2023]
Abstract
Pulsatile secretion of gonadotropin-releasing hormone (GnRH) is essential for the activation and maintenance of the function of the hypothalamic-pituitary-gonadal (HPG) axis, which controls the onset of puberty and fertility. Two provocative recent studies suggest that, in addition to control reproduction, the neurons in the brain that produce GnRH are also involved in the control postnatal brain maturation, odour discrimination and adult cognition. Long-acting GnRH antagonists and agonists are commonly used to control fertility and behaviour in veterinary medicine, primarily in males. This review puts into perspective the potential risks of these androgen deprivation therapies and immunization on olfactory and cognitive performances and well-aging in domestic animals, including pets. We will also discuss the results reporting beneficial effects of pharmacological interventions restoring physiological GnRH levels on olfactory and cognitive alterations in preclinical models of Alzheimer's disease, which shares many pathophysiological and behavioural hallmarks with canine cognitive dysfunction. These novel findings raise the intriguing possibility that pulsatile GnRH therapy holds therapeutic potential for the management of this behavioural syndrome affecting older dogs.
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Affiliation(s)
- Vincent Prévot
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR_S1172, Lille, France
| | - Anne Duittoz
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAE Val de Loire, IFCE, Université de Tours, Nouzilly, France
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2
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Qin X, Xiao Y, Ye C, Jia J, Liu X, Liang H, Zou G, Hu G. Pituitary Action of E2 in Prepubertal Grass Carp: Receptor Specificity and Signal Transduction for Luteinizing Hormone and Follicle-Stimulating Hormone Regulation. Front Endocrinol (Lausanne) 2018; 9:308. [PMID: 29937753 PMCID: PMC6002485 DOI: 10.3389/fendo.2018.00308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/23/2018] [Indexed: 12/29/2022] Open
Abstract
17β-estradiol (E2) is an important sex steroid produced by ovary and brain. In mammals, E2 plays an important role in hypothalamus-pituitary-gonad axis to regulate puberty onset, however, little is known about the functional role of E2 in teleost pituitary. Using prepubertal grass carp as model, three nuclear estrogen receptors (nERs: estrogen receptor alpha, estrogen receptor beta 1, and estrogen receptor beta 2) and two G protein-coupled estrogen receptors (GPER1: GPER1a and GPER1b) were isolated from grass carp pituitary. Tissue distribution analysis indicated that both nERs and GPERs were highly detected in grass carp pituitary, which suggested that E2 should play an important role in grass carp pituitary. Using primary cultured grass carp pituitary cells as model, high-throughput RNA-seq was used to examine the E2-induced differentially expressed genes (DEGs). Transcriptomic analysis showed that E2 could significantly upregulate the expression of 28 genes in grass carp pituitary cells, which were characterized into different functions including reproduction, gonad development, and central nervous system development. Further studies confirmed that E2 could induce luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion and mRNA expression in prepubertal grass carp pituitary in vivo and in vitro. In the pituitary, LH and FSH regulation by E2 were mediated by both ERβ and GPER1. Apparently, E2-induced LHβ and FSHβ mRNA expression were mediated by adenylyl cyclase/cAMP/protein kinase A, phospholipase C/inositol 1,4,5-triphosphate/protein kinase C, and Ca2+/calmodulin/CaM-dependent protein kinase II pathways. In addition to LH and FSH, E2 could also induce growth regulation by estrogen in breast cancer 1 (a novel regulator for pituitary development) mRNA expression in grass carp pituitary cells. These results, as a whole, suggested that E2 could play an important role in gonadotropin hormone release and pituitary development in prepubertal grass carp.
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Affiliation(s)
- Xiangfeng Qin
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Yaqian Xiao
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Cheng Ye
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Jingyi Jia
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Xiangjiang Liu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Hongwei Liang
- Key Laboratory of Freshwater Biodiversity Conservation Ministry of Agriculture, Yangtze River Fisheries Research Institute, The Chinese Academy of Fishery Sciences, Wuhan, China
| | - Guiwei Zou
- Key Laboratory of Freshwater Biodiversity Conservation Ministry of Agriculture, Yangtze River Fisheries Research Institute, The Chinese Academy of Fishery Sciences, Wuhan, China
| | - Guangfu Hu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- *Correspondence: Guangfu Hu,
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Chimento A, Sirianni R, Casaburi I, Pezzi V. Role of estrogen receptors and g protein-coupled estrogen receptor in regulation of hypothalamus-pituitary-testis axis and spermatogenesis. Front Endocrinol (Lausanne) 2014; 5:1. [PMID: 24474947 PMCID: PMC3893621 DOI: 10.3389/fendo.2014.00001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 01/03/2014] [Indexed: 11/13/2022] Open
Abstract
Male reproductive function is under the control of both gonadotropins and androgens through a negative feedback loop that involves the hypothalamus, pituitary, and testis known as hypothalamus-pituitary-gonadal axis (HPG). Indeed, estrogens also play an important role in regulating HPG axis but the study on relative contribution to the inhibition of gonadotropins secretion exerted by the amount of estrogens produced within the hypothalamus and/or the pituitary or by the amount of circulating estrogens is still ongoing. Moreover, it is known that the maintenance of spermatogenesis is controlled by gonadotropins and testosterone, the effects of which are modulated by a complex network of locally produced factors, including estrogens. Physiological effects of estrogens are mediated by the classical nuclear estrogen receptor alpha and estrogen receptor beta, which mediate both genomic and rapid signaling events. In addition, estrogens induce rapid non-genomic responses through a membrane-associated G protein-coupled estrogen receptor (GPER). Ours and other studies reported that, in the testis, GPER is expressed in both normal germ cells and somatic cells and it is involved in mediating the estrogen action in spermatogenesis controlling proliferative and/or apoptotic events. Interestingly, GPER expression has been revealed also in the hypothalamus and pituitary. However, its role in mediating estrogen rapid actions in this context is under investigation. Recent studies indicate that GPER is involved in modulating gonadotropin-releasing hormone (GnRH) release as well as gonadotropins secretion. In this review, we will summarize the current knowledge concerning the role of estrogen/estrogen receptors molecular pathways in regulating GnRH, follicle-stimulating hormone, and luteinizing hormone release at the hypothalamic and pituitary levels in males as well as in controlling specific testicular functions such as spermatogenesis, focusing our attention mainly on estrogen signaling mediated by GPER.
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Affiliation(s)
- Adele Chimento
- Laboratory of Applied Biology, Department of Pharmacy, Health and Nutrition Sciences, University of Calabria, Cosenza, Italy
| | - Rosa Sirianni
- Laboratory of Applied Biology, Department of Pharmacy, Health and Nutrition Sciences, University of Calabria, Cosenza, Italy
| | - Ivan Casaburi
- Laboratory of Applied Biology, Department of Pharmacy, Health and Nutrition Sciences, University of Calabria, Cosenza, Italy
| | - Vincenzo Pezzi
- Laboratory of Applied Biology, Department of Pharmacy, Health and Nutrition Sciences, University of Calabria, Cosenza, Italy
- *Correspondence: Vincenzo Pezzi, Laboratory of Applied Biology, Department of Pharmacy, Health and Nutrition Sciences, University of Calabria, Edificio Polifunzionale, Arcavacata di Rende, Cosenza 87036, Italy e-mail:
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4
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Cell-specific distributions of estrogen receptor alpha (ERα) and androgen receptor (AR) in anterior pituitary glands from adult cockerels as revealed by immunohistochemistry. Cell Tissue Res 2012; 348:551-8. [DOI: 10.1007/s00441-012-1399-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 03/05/2012] [Indexed: 02/03/2023]
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Robinson JE, Hastie PM, Shah A, Smith A, Evans NP. Developmental programming: prenatal androgen exposure alters the gonadotroph population of the ovine pituitary gland. J Neuroendocrinol 2012; 24:434-42. [PMID: 22129152 DOI: 10.1111/j.1365-2826.2011.02264.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In utero exposure of the female foetus to androgens during development disrupts the reproductive axis and results in hypersecretion of luteinising hormone (LH) (but not follicle-stimulating hormone) in postnatal life. Abnormalities in the neural circuits controlling hypothalamic gonadotrophin-releasing hormone have been documented; however, androgens could also programme abnormalities in the pituitary gland. Ovine foetuses were exposed to either testosterone propionate or the non-aromatisable androgen dihydro-testosterone from days 30-90 of gestation (term 147 days) and the effects on the functional morphology of the pituitary were determined. Exogenous testosterone propionate exposure resulted in pituitary glands in adult male and female sheep that were 40% heavier than controls. Because this effect was not observed in the dihydro-testosterone-exposed animals, these actions are mediated via the oestrogen receptor (ER). No significant differences were apparent in 90- or 140-day foetuses. There was no difference between control and androgen-exposed animals in the density of LHβ or ERα immunoreactive cells in the pituitary although the density of follicle-stimulating hormone-β immunoreactive cells was lower in the testosterone-treated animals. The percentage of cells co-localising LHβ and ERα was lower in the testosterone-treated ewes and this may, in part, explain a reduced ability to respond to steroid feedback. Thus, enlargement of the pituitary gland, coupled with a reduced sensitivity to oestrogen negative-feedback, may contribute to the hyper-secretion of LH observed in animals that have been exposed to excess androgens during foetal life.
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Affiliation(s)
- J E Robinson
- Institute of Biodiversity, Animal Health and Comparative Medicine and School of Veterinary Medicine, College of Medicine, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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Huang LB, Yuan XJ. Expression of androgen receptor and estrogen receptor-alpha in the developing pituitary gland of male sheep lamb. Anim Reprod Sci 2011; 127:164-8. [PMID: 21880440 DOI: 10.1016/j.anireprosci.2011.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 07/18/2011] [Accepted: 07/23/2011] [Indexed: 11/24/2022]
Abstract
To explore the expression of androgen receptor (AR) and estrogen receptor alpha (ERα) in the developing pituitary of male lamb, we detected AR and ERα expression in the anterior pituitary of lambs aged 2-7 months old by immunohistochemistry. The results showed that both AR immunoreactivity (AR-ir) and ERα immunoreactivity (ERα-ir) were localized in the nuclei of anterior pituitary cell. The percentage of the anterior pituitary cells expressing ERα fluctuated from 8.79±0.02% to 11.80±0.04% during the examined stages, but fell significantly to the lowest level at 6 months. While the proportion of AR-ir showed significant changes, it was in 11.52±1.26% at 2 months, it firstly increased to 19.86±1.03% at 3 months, and then significantly decreased to 8.18±1.17% at 6 months (P<0.05). The expression of both AR-ir and ERα-ir were the lowest level at 6 months old. By staining for PCNA, we observed that the changes in expression of AR and ERα at different lamb ages did not result from cell proliferation of anterior pituitary cells. These results indicate that both AR and ERα are important in regulation of secretary function of anterior pituitary in sheep lamb, although the related mechanism needs to be elucidated further.
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Affiliation(s)
- Li-Bo Huang
- College of Animal Medicine and Science Technology, Shandong Agricultural University, Taian 271018, People's Republic of China.
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Polkowska J, Wańkowska M, Riddestråle Y, Wójcik-Gładysz A, Madej A, Tillet Y. Prepubertal changes in the synthesis, storage and release of growth hormone and luteinising hormone and in the immunoreactivity of oestrogen receptor-alpha in lamb pituitary cells. A morphofunctional study. J Chem Neuroanat 2008; 35:257-67. [PMID: 18282688 DOI: 10.1016/j.jchemneu.2007.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 12/21/2007] [Accepted: 12/27/2007] [Indexed: 10/22/2022]
Abstract
The present study was designed to determine the changes in the synthesis, storage and release of luteinising hormone (LH) and growth hormone (GH) in the hypophyseal cells by investigating the presence of oestrogen receptor-alpha (ERalpha) in developing prepubertal female lambs. The experiment was carried out on 14 prepubertal (17-week-old) and 14 peripubertal (32-week-old) ovary-intact lambs. Morphofunctional changes in the cells of the adenohypophyseal population were assayed with immunohistochemistry (IH), in situ hybridisation (ISH), Real-time PCR and radioimmunoassay (RIA). Blood samples (n=14) were taken every 2 weeks from 17 to 32 weeks of age for estimation of GH and LH by RIA. Computer image analysis was used to determine the percent of cells exhibiting IH and/or ISH reaction. The percentage of cells stained for LHbeta and GH increased for both LH- and GH-producing cells and were higher (P<0.001) in the peripubertal than prepubertal group. The percentage of mRNA LHbeta-expressing cells decreased and were lower for the peripubertal (P<0.001) than prepubertal group. The GH mRNA in pituitaries of prepubertal lambs was higher in comparison to peripubertal ones (P<0.001). The percentage of ERalpha positive cells increased significantly (P<0.001) in peripubertal compared to prepubertal lambs and this increase was significant (P<0.001) in both LH- and GH-producing cells. Plasma LH concentrations increased from 27 weeks of age, while GH concentrations gradually decreased from 17 weeks of age (P<0.05). The histomorphological changes in the LH- and GH-producing cells reflect the increasing pattern of the regulation of secretory processes of these hormones and an escalating regulatory role of oestrogen in the physiology of these cells during the prepubertal period. These results support the involvement of both hormones in the events leading up to puberty.
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Affiliation(s)
- Jolanta Polkowska
- Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-11 Jabłonna, Poland.
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8
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Szarek E, Farrand K, McMillen IC, Young IR, Houghton D, Schwartz J. Hypothalamic input is required for development of normal numbers of thyrotrophs and gonadotrophs, but not other anterior pituitary cells in late gestation sheep. J Physiol 2007; 586:1185-94. [PMID: 18096603 DOI: 10.1113/jphysiol.2007.141523] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
To evaluate the hypothalamic contribution to the development of anterior pituitary (AP) cells we surgically disconnected the hypothalamus from the pituitary (hypothalamo-pituitary disconnection, HPD) in fetal sheep and collected pituitaries 31 days later. Pituitaries (n = 6 per group) were obtained from fetal sheep (term = 147 +/- 3 days) at 110 days (unoperated group) of gestation and at 141 days from animals that had undergone HPD or sham surgery at 110 days. Cells were identified by labelling pituitary sections with antisera against the six AP hormones. Additionally, we investigated the colocalization of glycoprotein hormones. The proportions of somatotrophs and corticotrophs were unchanged by age or HPD. Lactotrophs increased 80% over time, but the proportion was unaffected by HPD. Thyrotrophs, which were unaffected by age, increased 70% following HPD. Gonadotrophs increased with gestational age (LH+ cells 55%; FSH+ cells 19-fold), but this was severely attenuated by HPD. We investigated the possible existence of a reciprocal effect of HPD on multipotential glycoprotein-expressing cells. Co-expression of LH and TSH was extremely rare (< 1%) and unchanged over the last month of gestation or HPD. The increase of gonadotrophs expressing FSH only or LH and FSH was attenuated by HPD. Therefore, the proportions of somatotrophs, lactotrophs and corticotrophs are regulated independently of hypothalamic input in the late gestation fetal pituitary. In marked contrast, the determination of the thyrotroph and gonadotroph lineages over the same time period is subject to complex mechanisms involving hypothalamic factors, which inhibit differentiation and/or proliferation of thyrotrophs, but stimulate gonadotrophs down the FSH lineage. Development of a distinct population of gonadotrophs, expressing only LH, appears to be subject to alternative mechanisms.
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Affiliation(s)
- Eva Szarek
- Discipline of Physiology, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, Australia
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9
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Cui S, Liu JL, Shao YJ, Zhang JC. Parallel changes between the percentage of fetal pituitary cells immunoreactive to oestrogen receptor alpha and the concentration of 17beta-oestradiol in fetal and maternal plasma during gestation in sheep. Reprod Fertil Dev 2007; 16:611-6. [PMID: 15740683 DOI: 10.1071/rd02104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2002] [Accepted: 04/23/2004] [Indexed: 11/23/2022] Open
Abstract
The present study was designed to investigate the relationship between fetal sheep pituitary oestrogen receptor (ER) alpha expression and changes in fetal and maternal plasma 17beta-oestradiol (E2) concentrations during gestation. The results revealed that immunoreactivity for ER was located in the nuclei and distributed throughout the fetal pituitary gland during gestation. The percentage of ERalpha-positive cells was approximately 2% of the total cell population in female fetuses at Day 60 of gestation, increased to approximately 7% and 13% of the total cell population at Days 90 and 120 of gestation, respectively, and then declined to approximately 10% at birth. The fetal plasma E2 concentrations were approximately 19 and 71 pg mL(-1) at Days 90 and 120 of gestation, respectively, and decreased to 22 pg mL(-1) after birth. In male fetuses, plasma E2 concentrations and the percentage of ERalpha-positive cells were similar to values in female fetuses throughout gestation, except on Day 120 when the plasma E2 level in female fetuses was significantly higher than in male fetuses. These data demonstrate that changes in the percentage of fetal pituitary ERalpha-positive cells parallel fetal plasma E2 concentrations throughout gestation.
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Affiliation(s)
- Sheng Cui
- Department of Animal Physiology, College of Biological Sciences, China Agricultural University, Beijing, PR China
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10
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Yuan X, He Y, Liu J, Luo H, Zhang J, Cui S. Expression of androgen receptor and its co-localization with estrogen receptor-alpha in the developing pituitary gland of sheep fetus. Histochem Cell Biol 2007; 127:423-32. [PMID: 17205307 DOI: 10.1007/s00418-006-0262-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
No information is known concerning the expression of androgen receptor (AR) and its co-localization with estrogen receptor alpha (ERalpha) in the developing pituitary of sheep fetus. In the present study, we detected AR expression and its co-localization with ERalpha in the anterior pituitary of sheep fetus from day 60 of gestation to the postnatal by dual immunochemistry. The results showed that both AR immunoreactivity (AR-ir) and ERalpha immunoreactivity (ERalpha-ir) were predominantly localized in the nuclei of LH positive gonadotropes. The cell counting results showed that the percentage of the anterior pituitary cells expressing AR fluctuated from 13.51 +/- 0.92 to 17.05 +/- 1.83% during the examined stages, but there were no significant differences between sexes and among ages examined (P > 0.05). However, the proportion of AR-ir cells containing LH markedly increased from day 60 of gestation to the neonatal (P < 0.05). The percentage of AR-ir cells expressing ERalpha-ir significantly increased from day 60 of gestation to the neonatal, respectively (P < 0.05), but no significant differences were seen between genders at each stage examined. These results indicate that both AR and ERalpha are mainly expressed in the gonadotropes of anterior pituitary gland of sheep fetuses, whereas the functions and interaction of AR and ERalpha expressions in the developing pituitary gland are required to be elucidated further.
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Affiliation(s)
- XueJun Yuan
- Department of Animal Physiology, College of Biological Sciences, China Agricultural University, Beijing, 100094, People's Republic of China
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11
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Liu J, Liu Z, Yi S, Cui S. Islet-1 expression and its colocalization with luteinising hormone, thyroid-stimulating hormone and oestrogen receptor alpha in the developing pituitary gland of the sheep foetus. J Neuroendocrinol 2005; 17:773-80. [PMID: 16280024 DOI: 10.1111/j.1365-2826.2005.01364.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Islet-1 has been reported to be involved in pituitary development in the early stages of mouse embryogenesis. Oestrogen receptor (ER) and its expression may be involved in regulating pituitary development and its hormone-secreting function. Islet-1 expression and its correlations to ER in the developing pituitary gland are unknown. We therefore determined the pituitary cell specific expression of Islet-1 and its colocalization with ER alpha (ERalpha) in sheep foetus by immunohistochemistry. The results demonstrated that Islet-1-immunoreactive (ir) cells were distributed throughout the pituitary gland from day 60 of gestation until birth. The Islet-1-ir cell number was significant higher at day 90 and 120 of gestation compared to that at day 60 and at birth. All of the ERalpha-ir cells were colocalized with Islet-1 at day 60 of gestation, although a few ERalpha-ir cells were negative for Islet-1 in the later stage of gestation. The dominant cell type expressing Islet-1 is the gonadotroph, although small proportions of thyrotrophs and lactotrophs also express Islet-1. The proportion of luteinising hormone-ir gonadotrophs possessing Islet-1 kept rising from day 60 to day 120 of gestation and persisted until birth. The proportion of thyroid-stimulating hormone-ir cells expressing Islet-1 was at a high level from day 60-120 of the gestation and significantly declined at birth. The percentage of prolactin (PRL)-ir cells expressing Islet-1 was about 20% at day 60 of gestation. Very few PRL-ir cells contained Islet-1 in later stages of gestation. These data suggest that the development and functional establishment of pituitary gonadotrophs, thyrotrophs and lactotrophs might be regulated by the expressions of Islet-1 and ERalpha and by their interactions, although any mechanisms need to be elucidated further.
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Affiliation(s)
- J Liu
- College of Biological Sciences, China Agricultural University, Beijing 100094, P.R. China
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12
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Abstract
Advances in our understanding of the complexity of GnRH actions at the pituitary and the various mechanisms involved in mediating differential LH and FSH biosynthesis and secretion at the gonadotrope, are continually emerging. In this review, we summarise recent studies pertaining to GnRH and GnRH receptor phylogeny, the divergent signalling and trafficking pathways initiated and utilised by GnRH and its receptor, and the pathways that mediate gonadotropin secretion from the gonadotrope.
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Affiliation(s)
- Adam J Pawson
- Human Reproductive Sciences Unit, Medical Research Council, The University of Edinburgh Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
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Liu J, Cui S. Ontogeny of estrogen receptor (ER) alpha and its co-localization with pituitary hormones in the pituitary gland of chick embryos. Cell Tissue Res 2005; 320:235-42. [PMID: 15789219 DOI: 10.1007/s00441-004-1051-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Accepted: 11/10/2004] [Indexed: 10/25/2022]
Abstract
Estrogen is involved in regulating the development and hormone secretion of the anterior pituitary gland following its binding to estrogen receptors (ERs) expressed on pituitary cells. However, the pituitary is comprised of several cell types, and to date, there is no data about the specific cell types expressing ERs in embyonic chick pituitary. We therefore followed, by immunohistochemistry, the ontogeny of the pituitary ER alpha (ERalpha), and the cell types expressing ERalpha throughout chick embryo development. ERalpha immunoreacitivity was restricted to the nuclei of pituitary cells. ERalpha-immunopositive (ERalpha(+)) cells were first detected at embryonic day 6.5 (E6.5), after which ERalpha(+) cells were consistently detected throughout the anterior pituitary gland, although the density of ERalpha(+) cells in the caudal lobe of the pars distalis was higher than that in the cephalic lobe. The proportion of ERalpha(+) cells in the pituitary was about 6% at E8.5; expression increased to 22% by E18.5 of gestation, with no additional change until hatching. Double-labeling of ERalpha and pituitary hormones showed that the dominant cell types expressing ERalpha were gonadotrophs immunopositive for luteinizing hormone (LH); the proportion of ERalpha(+) cells expressing LH increased throughout gestation and reached approximately 57% at hatching. About 2%-6% of thyroid-stimulating-hormone-immunopositive and 1%-2% prolactin-immunopositive cells expressed ERalpha at later stages of embryonic development, but no growth-hormone-positive or adrenocorticotropic-hormone-positive cells expressed ERalpha during the embryonic period. Thus, gonadotrophs are the main cell population expressing ERalpha in the anterior pituitary gland of chick embryo, and ERalpha is involved in regulating the development of the pituitary gland and the maturation of the hormone-secreting function.
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Affiliation(s)
- Jiali Liu
- College of Biological Sciences, Faculty of Veterinary Medicine, China Agricultural University, Beijing
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14
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Tian X, Cui S, Liu J, Yi S. Expression of estrogen receptors in the efferent ductule of male sheep fetuses during gestation. Histochem Cell Biol 2004; 122:473-5. [PMID: 15480738 DOI: 10.1007/s00418-004-0706-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2004] [Indexed: 11/27/2022]
Abstract
There is as yet no report about the developmental changes of estrogen receptors (ERs) in the male reproductive system of the sheep fetus. In the present study, the testis, efferent ductule, and epididymis of sheep fetuses were collected at days 70, 90, and 120 of gestation and in the newborn lamb. ER alpha (ERalpha) and ER beta (ERbeta) were detected by immunohistochemistry. The results showed that ERbeta staining was negative in all of the examined tissues throughout gestation, whereas ERalpha immunoreactivity was only located in the nuclei of the efferent ductule epithelium. In addition, both ERalpha staining intensity and the number of ERalpha-positive cells were higher at day 90 of gestation, compared with that at day 70 and at birth. These results suggest that estrogen may play important roles in efferent ductule development in sheep fetuses.
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Affiliation(s)
- Xinggui Tian
- Department of Animal Physiology, College of Biological Sciences, China Agricultural University, 100094 Beijing, People's Republic of China
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15
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Da Silva P, Aitken RP, Rhind SM, Racey PA, Wallace JM. Effect of maternal overnutrition during pregnancy on pituitary gonadotrophin gene expression and gonadal morphology in female and male foetal sheep at day 103 of gestation. Placenta 2003; 24:248-57. [PMID: 12566252 DOI: 10.1053/plac.2002.0897] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim was to determine whether nutritionally mediated restriction of placental growth alters foetal body growth, pituitary gonadotrophin gene expression and gonadal development at Day 103 of gestation. Embryos recovered from adult ewes inseminated by a single sire were transferred, singly, into the uteri of adolescent recipients. After transfer, adolescent ewes were offered a high (H, n=16) or moderate (M, n=12) level of a complete diet. Ewes were slaughtered at 103+/-0.2 days of gestation and foetal blood, brain, pituitary and gonads were collected. Mean placental weight was lower (P< 0.01) in H than in M groups but foetal weight and reproductive organ weights were similar. Maternal nutrition did not influence LHbeta or FSHbeta mRNA expression in either sex but FSHbeta mRNA expression was higher (P< 0.001) in female (n=11) than in male (n=17) foetal pituitaries. Mean foetal plasma gonadotrophin concentrations were not influenced by dietary intake in either sex. Plasma progesterone concentrations were lower (P=0.001) in foetuses derived from H compared with M intake dams. Compared with M foetuses (n=5), ovaries from H foetuses (n=6) had fewer primordial follicles (P< 0.05) and fewer follicles in total (P< 0.005). In contrast, maternal nutritional status did not influence either seminiferous cord or Sertoli cell numbers in male foetuses (H, n=10; M, n=7). It is concluded that high maternal nutrient intakes restricted placental growth and altered foetal ovarian follicular development prior to the end of the second third of gestation. The latter effect was independent of gonadotrophin secretion.Crown
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Affiliation(s)
- P Da Silva
- Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB, UK
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16
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Scanlan N, Skinner DC. Estradiol modulation of growth hormone secretion in the ewe: no growth hormone-releasing hormone neurons and few somatotropes express estradiol receptor alpha. Biol Reprod 2002; 66:1267-73. [PMID: 11967186 DOI: 10.1095/biolreprod66.5.1267] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Evidence suggests that estrogen modulates growth hormone (GH) release and that GH plays an important role in follicular and ovulatory processes. How estradiol affects GH secretion is unclear. Having verified that there is a coincident surge of GH at the time of the preovulatory LH surge, immunocytochemical studies incorporating high-temperature antigen retrieval were used to determine whether GH-releasing hormone (GHRH) neurons, somatotropes, or both, expressed estrogen receptor alpha (ER), in the ewe. Although GHRH neurons were surrounded by many ER cells, they did not express immunocytochemically detectable ERs. In contrast to gonadotropes, in which the majority expressed ERs, few somatotropes were estrogen receptive. These data suggest that estrogen does not act directly on GHRH neurons to influence GH secretion, and any direct effect on pituitary GH release, through the ERalpha, may be small.
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Affiliation(s)
- Niamh Scanlan
- Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, United Kingdom.
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Clarke IJ. Multifarious effects of estrogen on the pituitary gonadotrope with special emphasis on studies in the ovine species. Arch Physiol Biochem 2002; 110:62-73. [PMID: 11935402 DOI: 10.1076/apab.110.1.62.898] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The gonadotrope is a complex cell that expresses receptors for gonadotropin releasing hormone (GnRH) and estrogen. It has synthetic machinery for the production of 3 gonadotropin subunits which are assembled into two gonadotropins, luteinising hormone (LH) and follicle stimulating hormone (FSH). The production and secretion of LH and FSH are differentially regulated by GnRH and estrogen. Patterns of secretion of LH are dictated by the pulsatile release of GnRH from the median eminence as well as the feedback effects of estrogen. The means by which estrogen plays such an important role in the regulation of LH and FSH is reviewed in this chapter, with emphasis on work that has been done in the sheep. Estrogen regulates the second messenger systems in the gonadotrope as well as the number of GnRH receptors and the function of ion channels in the plasma membrane. Estrogen also regulates gene expression in these cells. Additionally, GnRH appears to regulate the level of estrogen receptor in the ovine gonadotrope, so there is substantial cross-talk between the signalling pathways for GnRH and estrogen. No clear picture has emerged as to how estrogen exerts a positive feedback effect on the gonadotrope and it is suggested that this might be forthcoming from more definitive studies on the way that estrogen regulates the second messenger systems and the trafficking of secretory vesicles.
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Affiliation(s)
- I J Clarke
- Prince Henry's Institute of Medical Research, Clayton, Australia.
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Tobin VA, Pompolo S, Clarke IJ. The percentage of pituitary gonadotropes with immunoreactive oestradiol receptors increases in the follicular phase of the ovine oestrous cycle. J Neuroendocrinol 2001; 13:846-54. [PMID: 11679053 DOI: 10.1046/j.1365-2826.2001.00701.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the oestrous cycle, there is an alteration in gonadotrope responsiveness to gonadotropin releasing hormone (GnRH). One cellular mechanism that may be involved in these changes at the pituitary level is the hormonal regulation of oestrogen receptor (ER) expression. Using double-label immunohistochemistry, we examined the proportion of gonadotropes, lactotropes and somatotropes with immunoreactive (ir) oestrogen receptor alpha (ERalpha) in pituitary sections from ewes at three stages of the ovine oestrous cycle (n = 8 per group). The percentage of ERalpha positive cells that also stained positive for luteinizing hormone (LH) increased in the transition from the luteal phase to the follicular phase (n = 8), with no further increase at the time of oestrus (n = 8). In the pituitaries from the luteal phase sheep, only a small number (15%) of lactotropes and 4% of somatotropes were found to contain ir-ERalpha and there were no alterations across the oestrous cycle. When we examined pituitaries from ovariectomized (OVX) ewes treated (i.m.) with either oestradiol benzoate (50 microg) or oil vehicle for 2, 4, 6 or 16 h (n = 4 per group), there was no effect of treatment. In fact, the percentage of gonadotropes that were ERalpha-positive in OVX ewes was similar to that observed in the pituitaries from the follicular phase ewes, both of which display a high frequency of pulsatile GnRH secretion. We conclude that the number of gonadotropes that contain ir-ERalpha increases in the follicular phase of the oestrous cycle and this may enhance the responsiveness of these cells to oestrogen and GnRH. We suggest that this may be due to increased pulsatile GnRH input rather than rising oestrogen levels.
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Affiliation(s)
- V A Tobin
- Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia
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19
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Abstract
Estrogen receptors (ER) are widely distributed in the central nervous system (CNS). Recent studies, to date in rat only, have shown that ER are also expressed in neurons of the dorsal root ganglia (DRG) where they appear to have functional roles. However, no data yet exists about estrogen receptors in the embryonic DRG. In the present study, immunocytochemical staining for ER in the DRG of chick embryos from day 6.5 to 18.5 (Hamburger and Hamilton St. 30-45) of incubation was performed. ER+ cells were first consistently observed at day 8.5 (St. 34), more concentrated in the ventral-lateral portion of the DRG. From day 8.5 to 12.5 (St. 38), the density of ER+ cells and the staining intensity increased, with no obvious changes from day (E) 12.5 to 18.5. Although ER is detected mainly in the cytoplasm of embryonic DRG neurones, ER+ cells with nuclear staining are sometimes observed and gradually increase in number during development. ER-immunoreactivity in the DRG at cervical, thoracic and lumbo-sacral levels is similar and no obvious differences in staining were observed between male and female embryos. ER+ neurons are also present in the sympathetic ganglia from E8.5 and some primary spinal motoneurons are ER+ beginning at E14.5. The results suggest that estrogen may play a role in the embryonic development of the DRG.
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Affiliation(s)
- S Cui
- China Agricultural University, College of Biology, 10094, Beijing, China
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