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Iovino M, Messana T, Tortora A, Giusti C, Lisco G, Giagulli VA, Guastamacchia E, De Pergola G, Triggiani V. Oxytocin Signaling Pathway: From Cell Biology to Clinical Implications. Endocr Metab Immune Disord Drug Targets 2021; 21:91-110. [PMID: 32433011 DOI: 10.2174/1871530320666200520093730] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/04/2020] [Accepted: 04/16/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND In addition to the well-known role played in lactation and parturition, Oxytocin (OT) and OT receptor (OTR) are involved in many other aspects such as the control of maternal and social behavior, the regulation of the growth of the neocortex, the maintenance of blood supply to the cortex, the stimulation of limbic olfactory area to mother-infant recognition bond, and the modulation of the autonomic nervous system via the vagal pathway. Moreover, OT and OTR show antiinflammatory, anti-oxidant, anti-pain, anti-diabetic, anti-dyslipidemic and anti-atherogenic effects. OBJECTIVE The aim of this narrative review is to summarize the main data coming from the literature dealing with the role of OT and OTR in physiology and pathologic conditions focusing on the most relevant aspects. METHODS Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined. RESULTS We report the most significant and updated data on the role played by OT and OTR in physiology and different clinical contexts. CONCLUSION Emerging evidence indicates the involvement of OT system in several pathophysiological mechanisms influencing brain anatomy, cognition, language, sense of safety and trust and maternal behavior, with the possible use of exogenous administered OT in the treatment of specific neuropsychiatric conditions. Furthermore, it modulates pancreatic β-cell responsiveness and lipid metabolism leading to possible therapeutic use in diabetic and dyslipidemic patients and for limiting and even reversing atherosclerotic lesions.
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Affiliation(s)
- Michele Iovino
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Tullio Messana
- Infantile Neuropsychiatry, IRCCS - Institute of Neurological Sciences, Bologna, Italy
| | - Anna Tortora
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Consuelo Giusti
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giuseppe Lisco
- Hospital Unit of Endocrinology, Perrino Hospital, Brindisi, Italy
| | - Vito Angelo Giagulli
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Edoardo Guastamacchia
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giovanni De Pergola
- Clinical Nutrition Unit, Medical Oncology, Department of Internal Medicine and Clinical Oncology, University of Bari, School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Vincenzo Triggiani
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
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Vilhena-Franco T, Mecawi AS, Almeida-Pereira G, Lucio-Oliveira F, Elias LLK, Antunes-Rodrigues J. Oestradiol acts through its beta receptor to increase vasopressin neuronal activation and secretion induced by dehydration. J Neuroendocrinol 2019; 31:e12712. [PMID: 30887585 DOI: 10.1111/jne.12712] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 01/22/2023]
Abstract
Vasopressinergic neurones of the supraoptic (SON) and paraventricular (PVN) nuclei express oestrogen receptor (ER)β and receive afferent projections from osmosensitive neurones that express ERα. However, which subtype of these receptors mediates the effects of oestradiol on vasopressin (AVP) secretion induced by hydromineral challenge has not yet been demonstrated in vivo. Moreover, AVP secretion induced by hyperosmolality is known to involve activation of TRPV1 (transient receptor potential vanilloid, member 1) in magnocellular neurones, although whether oestradiol modulates expression of this receptor is unknown. Thus, the present study aimed to clarify the mechanisms involved in the modulation exerted by oestradiol on AVP secretion, specifically investigating the involvement of ERβ, ERα and TRPV1 receptors in response to water deprivation (WD). We observed that treatment with an ERβ agonist potentiated AVP secretion and vasopressinergic neuronal activation induced by WD. This increase in AVP secretion induced by WD was reversed by an ERβ antagonist. By contrast to ERβ, the ERα agonist did not alter plasma AVP concentrations or activation of AVP neurones in the SON and PVN. Additionally, Fos expression in the subfornical organ was not altered by the ERα agonist. TRPV1 mRNA expression was increased by WD in the SON, although this response was not altered by any treatment. The results of the present study suggest that ERβ mediates the effects of oestradiol on AVP secretion in response to WD, indicating that the effects of oestradiol occur directly in AVP neurones without affecting TRPV1.
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Affiliation(s)
- Tatiane Vilhena-Franco
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil
| | - André Souza Mecawi
- Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Gislaine Almeida-Pereira
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil
| | - Fabiana Lucio-Oliveira
- Federal Institute of Education, Science and Technology of Southern Minas Gerais, Muzambinho, Brazil
| | | | - José Antunes-Rodrigues
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil
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Santollo J, Daniels D. Control of fluid intake by estrogens in the female rat: role of the hypothalamus. Front Syst Neurosci 2015; 9:25. [PMID: 25788879 PMCID: PMC4349057 DOI: 10.3389/fnsys.2015.00025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 02/13/2015] [Indexed: 01/25/2023] Open
Abstract
Body fluid homeostasis is maintained by a complex network of central and peripheral systems that regulate blood pressure, fluid and electrolyte excretion, and fluid intake. The behavioral components, which include well regulated water and saline intake, are influenced by a number of hormones and neuropeptides. Since the early 1970s, it has been known that the ovarian estrogens play an important role in regulating fluid intake in females by decreasing water and saline intake under a variety of hypovolemic conditions. Behavioral, electrophysiological, gene and protein expression studies have identified nuclei in the hypothalamus, along with nearby forebrain structures such as the subfornical organ (SFO), as sites of action involved in mediating these effects of estrogens and, importantly, all of these brain areas are rich with estrogen receptors (ERs). This review will discuss the multiple ER subtypes, found both in the cell nucleus and associated with the plasma membrane, that provide diversity in the mechanism through which estrogens can induce behavioral changes in fluid intake. We then focus on the relevant brain structures, hypothesized circuits, and various peptides, such as angiotensin, oxytocin, and vasopressin, implicated in the anti-dipsogenic and anti-natriorexigenic actions of the estrogens.
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Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
| | - Derek Daniels
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
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Lucio-Oliveira F, Franci CR. Effect of the interaction between food state and the action of estrogen on oxytocinergic system activity. J Endocrinol 2012; 212:129-38. [PMID: 22083216 DOI: 10.1530/joe-11-0272] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Increased plasma osmolality by food intake evokes augmentation of plasma oxytocin (OT). Ovarian steroids may also influence the balance of body fluids by acting on OT neurones. Our aim was to determine if estrogen influences the activity of OT neurones in paraventricular nucleus (PVN) and supraoptic nucleus (SON) under different osmotic situations. Ovariectomized rats (OVX) were treated with either estradiol (E(2)) or vehicle and were divided into three groups: group I was fed ad libitum, group II underwent 48 h of fasting, and group III was refed after 48 h of fasting. On the day of the experiment, blood samples were collected to determine the plasma osmolality and OT. The animals were subsequently perfused, and OT/FOS immunofluorescence analysis was conducted on neurones in the PVN and the SON. When compared to animals which were fasted or fed ad libitum, the plasma osmolality of refed animals was higher, regardless of whether they were treated with vehicle or E(2). We observed neural activation of OT cells in vehicle- or E(2)-treated OVX rats refed after 48 h of fasting, but not in animals fed ad libitum or in animals that only underwent 48 h of fasting. Finally, the percentage of neurones that co-expressed OT and FOS was lower in both the PVN and the SON of animals treated with E(2) and refed, when compared to vehicle-treated animals. These results suggest that E(2) may have an inhibitory effect on OT neurones and may modulate the secretion of OT in response to the increase of osmolality induced by refeeding.
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Affiliation(s)
- F Lucio-Oliveira
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto - SP, Brazil
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Fong KSK, Cooper TB, Drumhiller WC, Somponpun SJ, Yang S, Ernst T, Chang L, Lozanoff S. Craniofacial features resembling frontonasal dysplasia with a tubulonodular interhemispheric lipoma in the adult 3H1 tuft mouse. ACTA ACUST UNITED AC 2012; 94:102-13. [PMID: 22246904 DOI: 10.1002/bdra.22878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Revised: 10/17/2011] [Accepted: 10/24/2011] [Indexed: 02/06/2023]
Abstract
Intracranial lipomas are rare, but 45% of them occur along the midline cisterns between the hemispheres and are often associated with corpus callosum hypoplasia and craniofacial defects. They are difficult to detect as they are generally asymptomatic and visible by MRI or by postmortem examination. The exact cause of these interhemispheric lipomas is not known, but they arise from a developmental defect resulting in the maldifferentiation of mesenchymal cells into mesodermal derivatives that are not normally present. We have identified a new mouse mutant called tuft, exhibiting a forebrain, intracranial lipoma with midline craniofacial defects resembling frontonasal dysplasia (FND) that arose spontaneously in our wild-type 3H1 colony. The tuft trait seems to be transmitted in recessive fashion, but approximately 80% less frequent than the expected Mendelian 25%, due to either incomplete penetrance or prenatal lethality. MRI and histologic analysis revealed that the intracranial lipoma occurred between the hemispheres and often protruded through the sagittal suture. We also observed a lesion at the lamina terminalis (LT) that may indicate improper closure of the anterior neuropore. We have mapped the tuft trait to within an 18 cM region on mouse chromosome 10 by microsatellite linkage analysis and identified several candidate genes involved with craniofacial development and cellular differentiation of adipose tissue. Tuft is the only known mouse model for midline craniofacial defects with an intracranial lipoma. Identifying the gene(s) and mutation(s) causing this early developmental defect will help us understand the pathogenesis of FND and related craniofacial disorders.
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Affiliation(s)
- Keith S K Fong
- Department of Anatomy, Biochemistry, and Physiology, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii 96813, USA.
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Spary EJ, Maqbool A, Batten TFC. Oestrogen receptors in the central nervous system and evidence for their role in the control of cardiovascular function. J Chem Neuroanat 2009; 38:185-96. [PMID: 19505570 DOI: 10.1016/j.jchemneu.2009.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 05/05/2009] [Accepted: 05/27/2009] [Indexed: 02/07/2023]
Abstract
Oestrogen is considered beneficial to cardiovascular health through protective effects not only on the heart and vasculature, but also on the autonomic nervous system via actions on oestrogen receptors. A plethora of evidence supports a role for the hormone within the central nervous system in modulating the pathways regulating cardiovascular function. A complex interaction of several brainstem, spinal and forebrain nuclei is required to receive, integrate and co-ordinate inputs that contribute appropriate autonomic reflex responses to changes in blood pressure and other cardiovascular parameters. Central effects of oestrogen and oestrogen receptors have already been demonstrated in many of these areas. In addition to the classical nuclear oestrogen receptors (ERalpha and ERbeta) a recently discovered G-protein coupled receptor, GPR30, has been shown to be a novel mediator of oestrogenic action. Many anatomical and molecular studies have described a considerable overlap in the regional expression of these receptors; however, the receptors do exhibit specific characteristics and subtype specific expression is found in many autonomic brain areas, for example ERbeta appears to predominate in the hypothalamic paraventricular nucleus, whilst ERalpha is important in the nucleus of the solitary tract. This review provides an overview of the available information on the localisation of oestrogen receptor subtypes and their multitude of possible modulatory actions in different groups of neurochemically and functionally defined neurones in autonomic-related areas of the brain.
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Affiliation(s)
- Emma J Spary
- Division of Cardiovascular and Neuronal Remodelling, Worsley Building, LIGHT Institute, University of Leeds, Leeds LS2 9JT, UK.
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Curtis KS. Estrogen and the central control of body fluid balance. Physiol Behav 2009; 97:180-92. [DOI: 10.1016/j.physbeh.2009.02.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/19/2009] [Accepted: 02/20/2009] [Indexed: 10/21/2022]
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Ryu V, Lee JH, Um JW, Yoo SB, Lee J, Chung KC, Jahng JW. Water-deprivation-induced expression of neuronal nitric oxide synthase in the hypothalamic paraventricular nucleus of rat. J Neurosci Res 2008; 86:1371-9. [PMID: 18092361 DOI: 10.1002/jnr.21598] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study was conducted to define the molecular mechanism by which dehydration induces expression of neuronal nitric oxide synthase (nNOS) in the hypothalamic paraventricular nucleus (PVN). Rats were deprived from water for 48 hr and then sacrificed immediately or 1 hr after ad libitum access to water. Another group of rats had free access to food and water and was included as euhydrate control group. The PVN sections fixed with 4% paraformaldehyde were processed for nNOS immunohistochemistry and NADPH-diaphorase (NADPH-d)/pCREB or NADPH-d/c-Fos double staining. nNOS-ir neurons significantly increased with water deprivation and decreased with rehydration, both in the posterior magnocellular (pM)- and the medial parvocellular (mP)-PVN. Most NADPH-d histostained neurons in the PVN appeared to exhibit pCREB-ir as well. Water deprivation markedly increased, and rehydration decreased, NADPH-d/pCREB neurons both in the pM- and in the mP-PVN. Gel shift assay demonstrated that dehydration may promote CREB binding to nNOS promoter in the PVN neurons. Significant amounts of NADPH-d-stained neurons in the PVN of water-deprived rats (67-68% in both the mP and the pM) exhibited c-Fos-ir. NADPH-d/c-Fos neurons in the pM-PVN were increased by water deprivation but not changed by rehydration. NADPH-d/c-Fos double-stained neurons in the mP-PVN did not significantly change depending on different water conditions. These results suggest that pCREB may play a role in dehydration-induced nNOS gene expression in the PVN neurons, and c-Fos might not be implicated in the regulatory pathway.
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Affiliation(s)
- Vitaly Ryu
- Department of Oral and Maxillofacial Surgery, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea
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Taylor AC, McCarthy JJ, Stocker SD. Mice lacking the transient receptor vanilloid potential 1 channel display normal thirst responses and central Fos activation to hypernatremia. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1285-93. [PMID: 18272658 DOI: 10.1152/ajpregu.00003.2008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neurons of the organum vasculosum of the lamina terminalis (OVLT) are necessary for thirst and vasopressin secretion during hypersmolality in rodents. Recent evidence suggests the osmosensitivity of these neurons is mediated by a gene product encoding the transient receptor potential vanilloid-1 (TRPV1) channel. The purpose of the present study was to determine whether mice lacking the TRPV1 channel had blunted thirst responses and central Fos activation to acute and chronic hyperosmotic stimuli. Surprisingly, TRPV1-/- vs. wild-type mice ingested similar amounts of water after injection (0.5 ml sc) of 0.5 M NaCl and 1.0 M NaCl. Chronic increases in plasma osmolality produced by overnight water deprivation or sole access to a 2% NaCl solution for 48 h produced similar increases in water intake between wild-type and TRPV1-/- mice. There were no differences in cumulative water intakes in response to hypovolemia or isoproterenol. In addition, the number of Fos-positive cells along the lamina terminalis, including the OVLT, as well as the supraoptic nucleus and hypothalamic paraventricular nucleus, was similar between wild-type and TRPV1-/- mice after both acute and chronic osmotic stimulation. These findings indicate that TRPV1 channels are not necessary for osmotically driven thirst or central Fos activation, and thereby suggest that TRPV1 channels are not the primary ion channels that permit the brain to detect changes in plasma sodium concentration or osmolality.
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Affiliation(s)
- A Caitlynn Taylor
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
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Estrogen receptors: their roles in regulation of vasopressin release for maintenance of fluid and electrolyte homeostasis. Front Neuroendocrinol 2008; 29:114-27. [PMID: 18022678 PMCID: PMC2274006 DOI: 10.1016/j.yfrne.2007.08.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 06/28/2007] [Accepted: 08/14/2007] [Indexed: 11/22/2022]
Abstract
Long standing interest in the impact of gonadal steroid hormones on fluid and electrolyte balance has led to a body of literature filled with conflicting reports about gender differences, the effects of gonadectomy, hormone replacement, and reproductive cycles on plasma vasopressin (VP), VP secretion, and VP gene expression. This reflects the complexity of gonadal steroid hormone actions in the body resulting from multiple sites of action that impact fluid and electrolyte balance (e.g. VP target organs, afferent pathways regulating the VP neurons, and the VP secreting neurons themselves). It also reflects involvement of multiple types of estrogen receptors (ER) in these diverse sites including ERs that act as transcription factors regulating gene expression (i.e. the classic ERalpha as well as the more recently discovered ERbeta) and potentially G-protein coupled, membrane localized ERs that mediate rapid non-genomic actions of estrogen. Furthermore, altered expression of these receptors in physiologically diverse conditions of fluid and electrolyte balance contributes to the difficulty of using simplistic approaches such as gender comparisons, gonadectomy, and hormone replacement to assess the role of gonadal steroids in regulation of VP secretion for maintenance of fluid and electrolyte homeostasis. This review catalogs these inconsistencies and provides a frame work for understanding them by describing: (1) the effect of gonadal steroids on target organ responsiveness to VP; (2) the expression of multiple types of estrogen receptors in the VP neurons and in brain regions monitoring feedback signals from the periphery; and (3) the impact of dehydration and hyponatremia on expression of these receptors.
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Somponpun SJ. Neuroendocrine regulation of fluid and electrolyte balance by ovarian steroids: contributions from central oestrogen receptors. J Neuroendocrinol 2007; 19:809-18. [PMID: 17850463 DOI: 10.1111/j.1365-2826.2007.01587.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Like other hormonally mediated mechanisms, maintenance of body fluid osmolality requires integrated responses from multiple signals at various tissue locales, a large number of which are open to modulation by circulating endocrine factors including the ovarian steroid, oestrogens (E(2)). However, the precise mechanism and the site of action of E(2) in regulating fluid osmolality are not properly understood. More importantly, the biological significance of this action is not clear and the physiological circumstances in which this modulation is engaged remain incomplete. The demonstration of oestrogen receptors (ER) in neural tissues that bear no direct relation to reproduction led us to examine and characterise the expression of ER in brain nuclei that are critical for the maintenance of fluid osmolality. In the rat, ERbeta is prominently expressed in the vasopressin magnocellular neuroendocrine cells of the hypothalamus, whereas ERalpha is localised extensively in the sensory circumventricular organ neurones in the basal forebrain. These nuclei are the primary brain sites that are engaged in defense of fluid perturbation, thus providing a neuroendocrine basis for oestrogenic influence on body fluid regulation. Plasticity in receptor expression that accompanies fluid disturbances at these central loci suggests the functional importance of the receptors and implicates E(2) as one of the fluid regulating hormones in water homeostasis.
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Affiliation(s)
- S J Somponpun
- Department of Clinical Investigation, Tripler Army Medical Center, Tripler AMC, HI 96859, USA.
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Weiser MJ, Foradori CD, Handa RJ. Estrogen receptor beta in the brain: from form to function. ACTA ACUST UNITED AC 2007; 57:309-20. [PMID: 17662459 PMCID: PMC2374745 DOI: 10.1016/j.brainresrev.2007.05.013] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/23/2007] [Accepted: 05/24/2007] [Indexed: 01/30/2023]
Abstract
Estrogens have numerous effects on the brain, both in adulthood and during development. These actions of estrogen are mediated by two distinct estrogen receptor (ER) systems, ER alpha (ERalpha) and ER beta (ERbeta). In brain, ERalpha plays a critical role in regulating reproductive neuroendocrine function and behavior, however, a definitive role for ERbeta in any neurobiological function has been slow in forthcoming. Clues to the function of ERbeta in the central nervous system can be gleaned from the neuroanatomical distribution of ERbeta and the phenotypes of neurons that express ERbeta. ERbeta immunoreactivity has been found in populations of GnRH, CRH, vasopressin, oxytocin and prolactin containing neurons in the hypothalamus. Utilizing subtype-selective estrogen receptor agonists can help determine the roles for ERbeta in non-reproductive behaviors in rat models. ERbeta-selective agonists exert potent anxiolytic activity when animals were tested in a number of behavioral paradigms. Consistent with this, ERbeta-selective agonists also inhibited the ACTH and corticosterone response to stress. In contrast, ERalpha selective agonists were found to be anxiogenic and correspondingly increased the hormonal stress response. Taken together, our studies implicate ERbeta as an important modulator of some non-reproductive neurobiological systems. The molecular and neuroanatomical targets of estrogen that are mediated by ERbeta remain to be determined. A number of splice variants of ERbeta mRNA have been reported in brain tissue. Imaging of eGFP labeled chimeric receptor proteins transfected into cell lines shows that ERbeta splice variation can alter trafficking patterns and function. The originally described ERbeta (herein termed ERbeta1) is characterized by possessing a high affinity for estradiol. Similar to ERalpha, it is localized in the nucleus and is trafficked to nuclear sites termed "hyperspeckles" following ligand binding. In contrast, ERbeta2 contains an 18 amino acid insert within the ligand-binding domain and as a result can be best described as a low affinity form of ERbeta. A delta3 (delta3) variant of ERbeta has a deletion of the 3rd exon (coding for the second half of the DNA-binding domain) and as a result does not bind an estrogen response element in DNA. delta3 variants are trafficked to a unique low abundance and larger nuclear site following ligand binding. A delta4 (delta4) variant lacks exon 4 and as a result is localized to the cytoplasm. The amount of individual splice variant mRNAs varies depending upon brain region. Examination of neuropeptide promoter regulation by ERbeta splice variants demonstrates that ERbeta functions as a constitutively active transcription factor. Moreover, it appears that splice variation of ERbeta alters its ability to regulate transcription in a promoter-dependent and ligand-dependent fashion.
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Affiliation(s)
- Michael J Weiser
- Department of Biomedical Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, CO 80523, USA
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Somponpun SJ, Johnson AK, Beltz T, Sladek CD. Estrogen receptor-α expression in osmosensitive elements of the lamina terminalis: regulation by hypertonicity. Am J Physiol Regul Integr Comp Physiol 2004; 287:R661-9. [PMID: 15142833 DOI: 10.1152/ajpregu.00136.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subfornical organ (SFO), median preoptic nucleus (MnPO), and organum vasculosum lamina terminalis (OVLT), which are associated with the lamina terminalis, are important in the control of body fluid balance. Neurons in these regions express estrogen receptor (ER)-α, but whether the ER-α neurons are activated by hypertonicity and whether hypertonicity regulates ER-α expression are not known. Using fluorescent, double-label immunocytochemistry, we examined the expression of ER-α-immunoreactivity (ir) and Fos-ir in control and water-deprived male rats. In control animals, numerous ER-α-positive neurons were expressed in the periphery of the SFO, in both the dorsal and ventral MnPO, and in the dorsal cap of the OVLT. Fos-positive neurons were sparse in euhydrated rats but were numerous in the SFO, MnPO, and the dorsal cap of the OVLT after 48-h water deprivation. Most ER-α-ir neurons in these areas were positive for Fos, indicating a significant degree of colocalization. To examine the effect of dehydration on ER-α expression, animals with and without lesions surrounding the anterior and ventral portion of the 3rd ventricle (AV3V) were water deprived for 48 h. Water deprivation resulted in a moderate increase in ER-α-ir in the SFO of sham-lesioned rats ( P = 0.03) and a dramatic elevation in AV3V-lesioned animals ( P < 0.05). This was probably induced by the significant increase in plasma osmolality in both dehydrated groups ( P < 0.001) rather than a decrease in blood volume, because hematocrit was significantly increased only in the dehydrated sham-lesioned animals. Thus these studies implicate the osmosensitive regions of the lamina terminalis as possible targets for sex steroid effects on body fluid homeostasis.
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Affiliation(s)
- Suwit J Somponpun
- Department of Physiology and Biophysics, University of Colorado Health Science Center, 4200 E. Ninth Ave. Box C240, Denver, CO 80262, USA
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Stocker SD, Cunningham JT, Toney GM. Water deprivation increases Fos immunoreactivity in PVN autonomic neurons with projections to the spinal cord and rostral ventrolateral medulla. Am J Physiol Regul Integr Comp Physiol 2004; 287:R1172-83. [PMID: 15271657 DOI: 10.1152/ajpregu.00394.2004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study sought to determine whether water deprivation increases Fos immunoreactivity, a neuronal marker related to synaptic activation, in sympathetic-regulatory neurons of the hypothalamic paraventricular nucleus (PVN). Fluorogold (4%, 50 nl) and cholera toxin subunit B (0.25%, 20-30 nl) were microinjected into the spinal cord (T1-T3) and rostral ventrolateral medulla (RVLM), respectively. Rats were then deprived of water but not food for 48 h. Water deprivation significantly increased the number of Fos-positive nuclei throughout the dorsal, ventrolateral, and lateral parvocellular divisions of the PVN (water deprived, 215 +/- 23 cells; control, 45 +/- 7 cells, P < 0.01). Moreover, a significantly greater number of Fos-positive nuclei were localized in spinally projecting (11 +/- 3 vs. 2 +/- 1 cells, P < 0.025) and RVLM-projecting (45 +/- 7 vs. 7 +/- 1 cells, P < 0.025) neurons of the PVN in water-deprived vs. control rats, respectively. The majority of these double-labeled neurons was found in the ventrolateral and lateral parvocellular divisions of the ipsilateral PVN. Interestingly, a significantly greater percentage of RVLM-projecting PVN neurons were Fos positive compared with spinally projecting PVN neurons in the ventrolateral (25.8 +/- 0.7 vs. 8.0 +/- 1.5%, respectively, P < 0.01) and lateral (23.4 +/- 2.1 vs. 5.0 +/- 0.9%, respectively, P > 0.01) parvocellular divisions. In addition, we analyzed spinally projecting neurons of the RVLM and found a significantly greater percentage were Fos positive in water-deprived rats than in control rats (26 +/- 3 vs. 3 +/- 1%, respectively; P < 0.001). Collectively, the present findings indicate that water deprivation evokes a distinct cellular response in sympathetic-regulatory neurons of the PVN and RVLM.
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Affiliation(s)
- Sean D Stocker
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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