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Cioffi L, Grassi D, Diviccaro S, Caruso D, Pinto-Benito D, Arevalo MA, Garcia-Segura LM, Melcangi RC, Giatti S. Sex chromosome complement interacts with gonadal hormones in determining regional-specific neuroactive steroid levels in plasma, hippocampus, and hypothalamus. A study using the four core genotype mouse model. J Steroid Biochem Mol Biol 2024; 241:106514. [PMID: 38554982 DOI: 10.1016/j.jsbmb.2024.106514] [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: 02/02/2024] [Revised: 03/18/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024]
Abstract
An important aspect of the neuromodulatory and neuroprotective actions exerted by neuroactive steroids is that they are sex-specific, as determined by the sexually dimorphic levels of these molecules in plasma and the nervous tissue. Thus, the identification of the factors that generate the sex-dimorphic levels of neuroactive steroids may be crucial from a neuroprotectant perspective. The main driver for sex determination in mammals is the SRY gene and the subsequent presence of a specific gonad: testes for males and ovaries for females, thus producing hormonal compounds, primarily androgens and estrogens, respectively. Nowadays, it is well established that despite the relevance of gonads, other factors control sexual features, and, among them, sex chromosome complement is highly relevant. In this study, neuroactive steroids were evaluated by liquid chromatography-tandem mass spectrometry in the hypothalamus, the hippocampus, and plasma of the four core genotype mouse model, to determine the relative contribution of sex chromosome complement and gonads in determining their sex dimorphic levels. The data obtained reveal that although gonads are the main contributing factor for sex differences in neuroactive steroid levels, the levels of some neuroactive steroids, including testosterone, are also influenced in brain and plasma by tissue-specific actions of sex chromosomes. The data presented here adds a new piece to the puzzle of steroid level regulation, which may be useful in designing sex-specific neuroprotective approaches to pathological conditions affecting the nervous system.
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Affiliation(s)
- Lucia Cioffi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Milano 20133, Itlay
| | - Daniela Grassi
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Autonoma University of Madrid, Calle Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Silvia Diviccaro
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Milano 20133, Itlay
| | - Donatella Caruso
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Milano 20133, Itlay
| | - Daniel Pinto-Benito
- Cajal Institute, CSIC, Avenida Doctor Arce 37, 28002 Madrid, Spain and Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid 28029, Spain
| | - Maria-Angeles Arevalo
- Cajal Institute, CSIC, Avenida Doctor Arce 37, 28002 Madrid, Spain and Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid 28029, Spain
| | - Luis Miguel Garcia-Segura
- Cajal Institute, CSIC, Avenida Doctor Arce 37, 28002 Madrid, Spain and Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid 28029, Spain
| | - Roberto Cosimo Melcangi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Milano 20133, Itlay
| | - Silvia Giatti
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Milano 20133, Itlay
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Grissom NM, Glewwe N, Chen C, Giglio E. Sex mechanisms as nonbinary influences on cognitive diversity. Horm Behav 2024; 162:105544. [PMID: 38643533 DOI: 10.1016/j.yhbeh.2024.105544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/23/2024]
Abstract
Essentially all neuropsychiatric diagnoses show some degree of sex and/or gender differences in their etiology, diagnosis, or prognosis. As a result, the roles of sex-related variables in behavior and cognition are of strong interest to many, with several lines of research showing effects on executive functions and value-based decision making in particular. These findings are often framed within a sex binary, with behavior of females described as less optimal than male "defaults"-- a framing that pits males and females against each other and deemphasizes the enormous overlap in fundamental neural mechanisms across sexes. Here, we propose an alternative framework in which sex-related factors encompass just one subset of many sources of valuable diversity in cognition. First, we review literature establishing multidimensional, nonbinary impacts of factors related to sex chromosomes and endocrine mechanisms on cognition, focusing on value- based decision-making tasks. Next, we present two suggestions for nonbinary interpretations and analyses of sex-related data that can be implemented by behavioral neuroscientists without devoting laboratory resources to delving into mechanisms underlying sex differences. We recommend (1) shifting interpretations of behavior away from performance metrics and towards strategy assessments to avoid the fallacy that the performance of one sex is worse than another; and (2) asking how much variance sex explains in measures and whether any differences are mosaic rather than binary, to avoid assuming that sex differences in separate measures are inextricably correlated. Nonbinary frameworks in research on cognition will allow neuroscience to represent the full spectrum of brains and behaviors.
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Affiliation(s)
- Nicola M Grissom
- Department of Psychology, University of Minnesota, United States of America.
| | - Nic Glewwe
- Department of Psychology, University of Minnesota, United States of America
| | - Cathy Chen
- Department of Psychiatry and Behavioral Sciences, University of Minnesota, United States of America
| | - Erin Giglio
- Department of Psychology, University of Minnesota, United States of America
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3
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Laine MA, Greiner EM, Shansky RM. Sex differences in the rodent medial prefrontal cortex - What Do and Don't we know? Neuropharmacology 2024; 248:109867. [PMID: 38387553 DOI: 10.1016/j.neuropharm.2024.109867] [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: 11/30/2023] [Revised: 01/22/2024] [Accepted: 02/08/2024] [Indexed: 02/24/2024]
Abstract
The prefrontal cortex, particularly its medial subregions (mPFC), mediates critical functions such as executive control, behavioral inhibition, and memory formation, with relevance for everyday functioning and psychopathology. Despite broad characterization of the mPFC in multiple model organisms, the extent to which mPFC structure and function vary according to an individual's sex is unclear - a knowledge gap that can be attributed to a historical bias for male subjects in neuroscience research. Recent efforts to consider sex as a biological variable in basic science highlight the great need to close this gap. Here we review the knowns and unknowns about how rodents categorized as male or female compare in mPFC neuroanatomy, pharmacology, as well as in aversive, appetitive, and goal- or habit-directed behaviors that recruit the mPFC. We propose that long-standing dogmatic concepts of mPFC structure and function may not remain supported when we move beyond male-only studies, and that empirical challenges to these dogmas are warranted. Additionally, we note some common pitfalls in this work. Most preclinical studies operationalize sex as a binary categorization, and while this approach has furthered the inclusion of non-male rodents it is not as such generalizable to what we know of sex as a multidimensional, dynamic variable. Exploration of sex variability may uncover both sex differences and sex similarities, but care must be taken in their interpretation. Including females in preclinical research needs to go beyond the investigation of sex differences, improving our knowledge of how this brain region and its subregions mediate behavior and health. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".
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Affiliation(s)
- M A Laine
- Department of Psychology, Northeastern University, Boston, MA, USA
| | - E M Greiner
- Department of Psychology, Northeastern University, Boston, MA, USA.
| | - R M Shansky
- Department of Psychology, Northeastern University, Boston, MA, USA
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4
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Garcia-Segura LM, Méndez P, Arevalo MA, Azcoitia I. Neuroestradiol and neuronal development: Not an exclusive male tale anymore. Front Neuroendocrinol 2023; 71:101102. [PMID: 37689249 DOI: 10.1016/j.yfrne.2023.101102] [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: 07/26/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023]
Abstract
The brain synthesizes a variety of neurosteroids, including neuroestradiol. Inhibition of neuroestradiol synthesis results in alterations in basic neurodevelopmental processes, such as neurogenesis, neuroblast migration, neuritogenesis and synaptogenesis. Although the neurodevelopmental actions of neuroestradiol are exerted in both sexes, some of them are sex-specific, such as the well characterized effects of neuroestradiol derived from the metabolism of testicular testosterone during critical periods of male brain development. In addition, recent findings have shown sex-specific actions of neuroestradiol on neuroblast migration, neuritic growth and synaptogenesis in females. Among other factors, the epigenetic regulation exerted by X linked genes, such as Kdm6a/Utx, may determine sex-specific actions of neuroestradiol in the female brain. This review evidences the impact of neuroestradiol on brain formation in both sexes and highlights the interaction of neural steriodogenesis, hormones and sex chromosomes in sex-specific brain development.
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Affiliation(s)
- Luis M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain.
| | - Pablo Méndez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| | - M Angeles Arevalo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain.
| | - Iñigo Azcoitia
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain; Department of Cell Biology, Universidad Complutense de Madrid, C José Antonio Nováis 12, 28040 Madrid, Spain
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5
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Le AL, Lynch WJ, Rissman EF. Sex Chromosome Complement and Estradiol Modify Cocaine Self-Administration Behaviors in Male Mice. Neuroendocrinology 2023; 113:1177-1188. [PMID: 37348474 DOI: 10.1159/000531648] [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: 04/11/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023]
Abstract
INTRODUCTION Women are more vulnerable to cocaine's reinforcing effects and have a more rapid course to addiction after initial cocaine use as compared to men. Studies in rodents similarly indicate an enhanced sensitivity to the reinforcing effects of cocaine in females versus males. Levels of estradiol (E2) are correlated with vulnerability to the rewarding actions of cocaine. Here, we asked if sex chromosome complement (SCC) influences vulnerability to cocaine use. METHODS We used the four-core genotype mouse that produces gonadal males and females with either XX or XY SCC. Mice were gonadectomized and implanted with either an estradiol (E2) or cholesterol-filled pellet. This allowed us to determine the effects of SCC in the absence (cholesterol-treated) and presence of tonic high physiological hormone levels (estradiol). Acquisition of cocaine self-administration was determined over a 12-day period using an escalated dose procedure (0.3 mg/kg/infusion, sessions 1-6; 0.6 mg/kg/infusion, sessions 6-12). RESULTS Without estradiol treatment, a greater percentage of castrated XY mice acquired cocaine self-administration and did so at a faster rate than XX castrates and ovariectomized XY females. These same XY males acquired sooner, infused more cocaine, and directed more nose pokes to the rewarded nose-poke hole than XX castrates and XY males receiving E2. CONCLUSION Our results suggest that in gonadal male mice, SCC and estradiol can modulate the reinforcing effects of cocaine which may influence the likelihood of cocaine use.
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Affiliation(s)
- Aaron L Le
- Department of Biological Sciences, Center for Human Health and the Environment, NCSU, Raleigh, North Carolina, USA
| | - Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Emilie F Rissman
- Department of Biological Sciences, Center for Human Health and the Environment, NCSU, Raleigh, North Carolina, USA
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6
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Cabrera Zapata LE, Garcia-Segura LM, Cambiasso MJ, Arevalo MA. Genetics and Epigenetics of the X and Y Chromosomes in the Sexual Differentiation of the Brain. Int J Mol Sci 2022; 23:ijms232012288. [PMID: 36293143 PMCID: PMC9603441 DOI: 10.3390/ijms232012288] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/10/2022] [Accepted: 10/11/2022] [Indexed: 11/27/2022] Open
Abstract
For many decades to date, neuroendocrinologists have delved into the key contribution of gonadal hormones to the generation of sex differences in the developing brain and the expression of sex-specific physiological and behavioral phenotypes in adulthood. However, it was not until recent years that the role of sex chromosomes in the matter started to be seriously explored and unveiled beyond gonadal determination. Now we know that the divergent evolutionary process suffered by X and Y chromosomes has determined that they now encode mostly dissimilar genetic information and are subject to different epigenetic regulations, characteristics that together contribute to generate sex differences between XX and XY cells/individuals from the zygote throughout life. Here we will review and discuss relevant data showing how particular X- and Y-linked genes and epigenetic mechanisms controlling their expression and inheritance are involved, along with or independently of gonadal hormones, in the generation of sex differences in the brain.
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Affiliation(s)
- Lucas E. Cabrera Zapata
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Instituto Cajal (IC), Consejo Superior de Investigaciones Científicas (CSIC), 28002 Madrid, Spain
| | | | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Cátedra de Biología Celular, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
- Correspondence: (M.J.C.); (M.A.A.)
| | - Maria Angeles Arevalo
- Instituto Cajal (IC), Consejo Superior de Investigaciones Científicas (CSIC), 28002 Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: (M.J.C.); (M.A.A.)
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7
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Cabrera Zapata LE, Cambiasso MJ, Arevalo MA. Epigenetic modifier Kdm6a/Utx controls the specification of hypothalamic neuronal subtypes in a sex-dependent manner. Front Cell Dev Biol 2022; 10:937875. [PMID: 36268511 PMCID: PMC9577230 DOI: 10.3389/fcell.2022.937875] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/07/2022] [Indexed: 11/23/2022] Open
Abstract
Kdm6a is an X-chromosome-linked H3K27me2/3 demethylase that promotes chromatin accessibility and gene transcription and is critical for tissue/cell-specific differentiation. Previous results showed higher Kdm6a levels in XX than in XY hypothalamic neurons and a female-specific requirement for Kdm6a in mediating increased axogenesis before brain masculinization. Here, we explored the sex-specific role of Kdm6a in the specification of neuronal subtypes in the developing hypothalamus. Hypothalamic neuronal cultures were established from sex-segregated E14 mouse embryos and transfected with siRNAs to knockdown Kdm6a expression (Kdm6a-KD). We evaluated the effect of Kdm6a-KD on Ngn3 expression, a bHLH transcription factor regulating neuronal sub-specification in hypothalamus. Kdm6a-KD decreased Ngn3 expression in females but not in males, abolishing basal sex differences. Then, we analyzed Kdm6a-KD effect on Ascl1, Pomc, Npy, Sf1, Gad1, and Th expression by RT-qPCR. While Kdm6a-KD downregulated Ascl1 in both sexes equally, we found sex-specific effects for Pomc, Npy, and Th. Pomc and Th expressed higher in female than in male neurons, and Kdm6a-KD reduced their levels only in females, while Npy expressed higher in male than in female neurons, and Kdm6a-KD upregulated its expression only in females. Identical results were found by immunofluorescence for Pomc and Npy neuropeptides. Finally, using ChIP-qPCR, we found higher H3K27me3 levels at Ngn3, Pomc, and Npy promoters in male neurons, in line with Kdm6a higher expression and demethylase activity in females. At all three promoters, Kdm6a-KD induced an enrichment of H3K27me3 only in females. These results indicate that Kdm6a plays a sex-specific role in controlling the expression of transcription factors and neuropeptides critical for the differentiation of hypothalamic neuronal populations regulating food intake and energy homeostasis.
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Affiliation(s)
| | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
- Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
- *Correspondence: María Julia Cambiasso, , Maria Angeles Arevalo,
| | - Maria Angeles Arevalo
- Instituto Cajal (IC), CSIC, Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- *Correspondence: María Julia Cambiasso, , Maria Angeles Arevalo,
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8
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Pallier PN, Ferrara M, Romagnolo F, Ferretti MT, Soreq H, Cerase A. Chromosomal and environmental contributions to sex differences in the vulnerability to neurological and neuropsychiatric disorders: Implications for therapeutic interventions. Prog Neurobiol 2022; 219:102353. [PMID: 36100191 DOI: 10.1016/j.pneurobio.2022.102353] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 08/22/2022] [Accepted: 09/06/2022] [Indexed: 10/14/2022]
Abstract
Neurological and neuropsychiatric disorders affect men and women differently. Multiple sclerosis, Alzheimer's disease, anxiety disorders, depression, meningiomas and late-onset schizophrenia affect women more frequently than men. By contrast, Parkinson's disease, autism spectrum condition, attention-deficit hyperactivity disorder, Tourette's syndrome, amyotrophic lateral sclerosis and early-onset schizophrenia are more prevalent in men. Women have been historically under-recruited or excluded from clinical trials, and most basic research uses male rodent cells or animals as disease models, rarely studying both sexes and factoring sex as a potential source of variation, resulting in a poor understanding of the underlying biological reasons for sex and gender differences in the development of such diseases. Putative pathophysiological contributors include hormones and epigenetics regulators but additional biological and non-biological influences may be at play. We review here the evidence for the underpinning role of the sex chromosome complement, X chromosome inactivation, and environmental and epigenetic regulators in sex differences in the vulnerability to brain disease. We conclude that there is a pressing need for a better understanding of the genetic, epigenetic and environmental mechanisms sustaining sex differences in such diseases, which is critical for developing a precision medicine approach based on sex-tailored prevention and treatment.
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Affiliation(s)
- Patrick N Pallier
- Blizard Institute, Centre for Neuroscience, Surgery and Trauma, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
| | - Maria Ferrara
- Institute of Psychiatry, Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy; Department of Psychiatry, Yale University, School of Medicine, New Haven, CT, United States; Women's Brain Project (WBP), Switzerland
| | - Francesca Romagnolo
- Institute of Psychiatry, Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
| | | | - Hermona Soreq
- The Edmond and Lily Safra Center of Brain Science, The Hebrew University of Jerusalem, 9190401, Israel
| | - Andrea Cerase
- EMBL-Rome, Via Ramarini 32, 00015 Monterotondo, RM, Italy; Blizard Institute, Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK; Department of Biology, University of Pisa, SS12 Abetone e Brennero 4, 56127 Pisa, Italy.
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9
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Stockman SL, Kight KE, Bowers JM, McCarthy MM. Neurogenesis in the neonatal rat hippocampus is regulated by sexually dimorphic epigenetic modifiers. Biol Sex Differ 2022; 13:9. [PMID: 35255959 PMCID: PMC8900308 DOI: 10.1186/s13293-022-00418-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/25/2022] [Indexed: 12/04/2022] Open
Abstract
Background Neurogenesis in the hippocampus endures across the lifespan but is particularly prolific during the first postnatal week in the developing rodent brain. The majority of new born neurons are in the dentate gyrus (DG). The number of new neurons born during the first postnatal week in the DG of male rat pups is about double the number in females. In other systems, the rate of cell proliferation is controlled by epigenetic modifications in stem cells. We, therefore, explored the potential impact of DNA methylation and histone acetylation on cell genesis in the developing DG of male and female rats.
Methods Cell genesis was assessed by quantification of BrdU + cells in the DG of neonatal rats following injections on multiple days. Methylation and acetylation were manipulated pharmacologically by injection of well vetted drugs. DNA methylation, histone acetylation and associated enzyme activity were measured using commercially available colorimetric assays. mRNA was quantified by PCR. Multiple group comparisons were made by one- or two-way ANOVA followed by post-hoc tests controlling for multiple comparisons. Two groups were compared by t test. Results We found higher levels of DNA methylation in male DG and treatment with the DNA methylating enzyme inhibitor zebularine reduced the methylation and correspondingly reduced cell genesis. The same treatment had no impact on either measure in females. By contrast, treatment with a histone deacetylase inhibitor, trichostatin-A, increased histone acetylation in the DG of both sexes but increased cell genesis only in females. Females had higher baseline histone deacetylase activity and greater inhibition in response to trichostatin-A treatment. The mRNA levels of the proproliferative gene brain-derived neurotrophic factor were greater in males and reduced by inhibiting both DNA methylation and histone deacetylation only in males.
Conclusions These data reveal a sexually dimorphic epigenetically based regulation of neurogenesis in the DG but the mechanisms establishing the distinct regulation involving DNA methylation in males and histone acetylation in females is unknown. Neurogenesis in the dentate gyrus peaks in the early postnatal period and in the laboratory rat is significantly greater in males than females. Here we report divergent regulation of cell genesis in the neonatal dentate gyrus. DNA methylation is a critical regulator of the higher rates of proliferation in males. Conversely, histone acetylation is essential for cell genesis in females.
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Affiliation(s)
- S L Stockman
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA
| | - K E Kight
- Department of Pharmacology, University of Maryland School of Medicine, 685 W. Baltimore Street, Baltimore, MD, 21201, USA
| | - J M Bowers
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
| | - M M McCarthy
- Department of Pharmacology, University of Maryland School of Medicine, 685 W. Baltimore Street, Baltimore, MD, 21201, USA. .,University of Maryland Baltimore, Program in Neuroscience, Baltimore, MD, 21201, USA.
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10
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Rossetti MF, Varayoud J, Ramos JG. Steroidogenic enzymes in the hippocampus: Transcriptional regulation aspects. VITAMINS AND HORMONES 2022; 118:171-198. [PMID: 35180926 DOI: 10.1016/bs.vh.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Neurosteroids are steroids synthesized de novo from cholesterol in brain regions, and regulate processes associated with the development and functioning of the nervous system. Enzymes and proteins involved in the synthesis of these steroids have been detected in several brain regions, including hippocampus, hypothalamus, and cerebral cortex. Hippocampus has long been associated with learning and memory functions, while the loss of its functionality has been linked to neurodegenerative pathologies. In this sense, neurosteroids are critical for the maintenance of hippocampal functions and neuroprotective effects. Moreover, several factors have been shown to deregulate expression of steroidogenic enzymes in the rodent brain, including aging, enrichment experiences, diet habits, drug/alcohol consumption, hormone fluctuations, neurodegenerative processes and other diseases. These transcriptional deregulations are mediated mainly by transcription factors and epigenetic mechanisms. An epigenetic modification of chromatin involves changes in bases and associated proteins in the absence of changes in the DNA sequence. One of the most well-studied mechanisms related to gene silencing is DNA methylation, which involves a reversible addition of methyl groups in a cytosine base. Importantly, these epigenetic marks could be maintained over time and could be transmitted transgenerationally. The aim of this chapter is to present the most relevant steroidogenic enzymes described in rodent hippocampus; to discuss about their transcriptional regulation under different conditions; to show the main gene control regions and to propose DNA methylation as an epigenetic mechanism through which the expression of these enzymes could be controlled.
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Affiliation(s)
- María Florencia Rossetti
- Departamento de Bioquímica Clínica y Cuantitativa, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina; Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral-CONICET, Santa Fe, Argentina
| | - Jorgelina Varayoud
- Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral-CONICET, Santa Fe, Argentina; Cátedra de Fisiología Humana, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Jorge Guillermo Ramos
- Departamento de Bioquímica Clínica y Cuantitativa, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina; Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral-CONICET, Santa Fe, Argentina.
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11
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Brann DW, Lu Y, Wang J, Zhang Q, Thakkar R, Sareddy GR, Pratap UP, Tekmal RR, Vadlamudi RK. Brain-derived estrogen and neural function. Neurosci Biobehav Rev 2021; 132:793-817. [PMID: 34823913 PMCID: PMC8816863 DOI: 10.1016/j.neubiorev.2021.11.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/26/2021] [Accepted: 11/12/2021] [Indexed: 01/02/2023]
Abstract
Although classically known as an endocrine signal produced by the ovary, 17β-estradiol (E2) is also a neurosteroid produced in neurons and astrocytes in the brain of many different species. In this review, we provide a comprehensive overview of the localization, regulation, sex differences, and physiological/pathological roles of brain-derived E2 (BDE2). Much of what we know regarding the functional roles of BDE2 has come from studies using specific inhibitors of the E2 synthesis enzyme, aromatase, as well as the recent development of conditional forebrain neuron-specific and astrocyte-specific aromatase knockout mouse models. The evidence from these studies support a critical role for neuron-derived E2 (NDE2) in the regulation of synaptic plasticity, memory, socio-sexual behavior, sexual differentiation, reproduction, injury-induced reactive gliosis, and neuroprotection. Furthermore, we review evidence that astrocyte-derived E2 (ADE2) is induced following brain injury/ischemia, and plays a key role in reactive gliosis, neuroprotection, and cognitive preservation. Finally, we conclude by discussing the key controversies and challenges in this area, as well as potential future directions for the field.
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Affiliation(s)
- Darrell W Brann
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| | - Yujiao Lu
- Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Jing Wang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Quanguang Zhang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Roshni Thakkar
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA
| | - Gangadhara R Sareddy
- Department of Obstetrics and Gynecology, University of Texas Health, San Antoio TX, 78229, USA
| | - Uday P Pratap
- Department of Obstetrics and Gynecology, University of Texas Health, San Antoio TX, 78229, USA
| | - Rajeshwar R Tekmal
- Department of Obstetrics and Gynecology, University of Texas Health, San Antoio TX, 78229, USA
| | - Ratna K Vadlamudi
- Department of Obstetrics and Gynecology, University of Texas Health, San Antoio TX, 78229, USA; Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX, 78229, USA.
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12
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Gata-Garcia A, Porat A, Brimberg L, Volpe BT, Huerta PT, Diamond B. Contributions of Sex Chromosomes and Gonadal Hormones to the Male Bias in a Maternal Antibody-Induced Model of Autism Spectrum Disorder. Front Neurol 2021; 12:721108. [PMID: 34721260 PMCID: PMC8548617 DOI: 10.3389/fneur.2021.721108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 09/14/2021] [Indexed: 11/29/2022] Open
Abstract
Autism Spectrum Disorder (ASD) is a group of neurodevelopmental conditions that is four times more commonly diagnosed in males than females. While susceptibility genes located in the sex chromosomes have been identified in ASD, it is unclear whether they are sufficient to explain the male bias or whether gonadal hormones also play a key role. We evaluated the sex chromosomal and hormonal influences on the male bias in a murine model of ASD, in which mice are exposed in utero to a maternal antibody reactive to contactin-associated protein-like 2 (Caspr2), which was originally cloned from a mother of a child with ASD (termed C6 mice henceforth). In this model, only male mice are affected. We used the four-core-genotypes (FCG) model in which the Sry gene is deleted from the Y chromosome (Y−) and inserted into autosome 3 (TgSry). Thus, by combining the C6 and FCG models, we were able to differentiate the contributions of sex chromosomes and gonadal hormones to the development of fetal brain and adult behavioral phenotypes. We show that the presence of the Y chromosome, or lack of two X chromosomes, irrespective of gonadal sex, increased the susceptibility to C6-induced phenotypes including the abnormal growth of the developing fetal cerebral cortex, as well as a behavioral pattern of decreased open-field exploration in adult mice. Our results indicate that sex chromosomes are the main determinant of the male bias in the maternal C6-induced model of ASD. The less dominant hormonal effect may be due to modulation by sex chromosome genes of factors involved in gonadal hormone pathways in the brain.
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Affiliation(s)
- Adriana Gata-Garcia
- Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States.,Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States
| | - Amit Porat
- Elmezzi Graduate School of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Lior Brimberg
- Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Bruce T Volpe
- Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Patricio T Huerta
- Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States.,Laboratory of Immune and Neural Networks, Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Betty Diamond
- Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Northwell Health, Manhasset, NY, United States.,Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States
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13
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X-linked histone H3K27 demethylase Kdm6a regulates sexually dimorphic differentiation of hypothalamic neurons. Cell Mol Life Sci 2021; 78:7043-7060. [PMID: 34633482 PMCID: PMC8558156 DOI: 10.1007/s00018-021-03945-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/26/2021] [Accepted: 09/17/2021] [Indexed: 12/26/2022]
Abstract
Several X-linked genes are involved in neuronal differentiation and may contribute to the generation of sex dimorphisms in the brain. Previous results showed that XX hypothalamic neurons grow faster, have longer axons, and exhibit higher expression of the neuritogenic gene neurogenin 3 (Ngn3) than XY before perinatal masculinization. Here we evaluated the participation of candidate X-linked genes in the development of these sex differences, focusing mainly on Kdm6a, a gene encoding for an H3K27 demethylase with functions controlling gene expression genome-wide. We established hypothalamic neuronal cultures from wild-type or transgenic Four Core Genotypes mice, a model that allows evaluating the effect of sex chromosomes independently of gonadal type. X-linked genes Kdm6a, Eif2s3x and Ddx3x showed higher expression in XX compared to XY neurons, regardless of gonadal sex. Moreover, Kdm6a expression pattern with higher mRNA levels in XX than XY did not change with age at E14, P0, and P60 in hypothalamus or under 17β-estradiol treatment in culture. Kdm6a pharmacological blockade by GSK-J4 reduced axonal length only in female neurons and decreased the expression of neuritogenic genes Neurod1, Neurod2 and Cdk5r1 in both sexes equally, while a sex-specific effect was observed in Ngn3. Finally, Kdm6a downregulation using siRNA reduced axonal length and Ngn3 expression only in female neurons, abolishing the sex differences observed in control conditions. Altogether, these results point to Kdm6a as a key mediator of the higher axogenesis and Ngn3 expression observed in XX neurons before the critical period of brain masculinization.
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14
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Arnold ML, Saijo K. Estrogen Receptor β as a Candidate Regulator of Sex Differences in the Maternal Immune Activation Model of ASD. Front Mol Neurosci 2021; 14:717411. [PMID: 34531723 PMCID: PMC8438209 DOI: 10.3389/fnmol.2021.717411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 08/09/2021] [Indexed: 12/25/2022] Open
Abstract
Interestingly, more males are diagnosed with autism spectrum disorder (ASD) than females, yet the mechanism behind this difference is unclear. Genes on the sex chromosomes and differential regulation by sex steroid hormones and their receptors are both candidate mechanisms to explain this sex-dependent phenotype. Nuclear receptors (NRs) are a large family of transcription factors, including sex hormone receptors, that mediate ligand-dependent transcription and may play key roles in sex-specific regulation of immunity and brain development. Infection during pregnancy is known to increase the probability of developing ASD in humans, and a mouse model of maternal immune activation (MIA), which is induced by injecting innate immune stimulants into pregnant wild-type mice, is commonly used to study ASD. Since this model successfully recaptures the behavioral phenotypes and male bias observed in ASD, we will discuss the potential role of sex steroid hormones and their receptors, especially focusing on estrogen receptor (ER)β, in MIA and how this signaling may modulate transcription and subsequent inflammation in myeloid-lineage cells to contribute to the etiology of this neurodevelopmental disorder.
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Affiliation(s)
- Madeline L Arnold
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Kaoru Saijo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
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15
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Arnold AP. Four Core Genotypes and XY* mouse models: Update on impact on SABV research. Neurosci Biobehav Rev 2020; 119:1-8. [PMID: 32980399 PMCID: PMC7736196 DOI: 10.1016/j.neubiorev.2020.09.021] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 12/17/2022]
Abstract
The impact of two mouse models is reviewed, the Four Core Genotypes and XY* models. The models are useful for determining if the causes of sex differences in phenotypes are either hormonal or sex chromosomal, or both. Used together, the models also can distinguish between the effects of X or Y chromosome genes that contribute to sex differences in phenotypes. To date, the models have been used to uncover sex chromosome contributions to sex differences in a wide variety of phenotypes, including brain and behavior, autoimmunity and immunity, cardiovascular disease, metabolism, and Alzheimer's Disease. In some cases, use of the models has been a strategy leading to discovery of specific X or Y genes that protect from or exacerbate disease. Sex chromosome and hormonal factors interact, in some cases to reduce the effects of each other. Future progress will come from more extensive application of these models, and development of similar models in other species.
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Affiliation(s)
- Arthur P Arnold
- Department of Integrative Biology & Physiology, Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, UCLA, 610 Charles Young Drive South, Los Angeles, CA, 90095-7239, United States.
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16
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Harp SJ, Martini M, Lynch WJ, Rissman EF. Sexual Differentiation and Substance Use: A Mini-Review. Endocrinology 2020; 161:bqaa129. [PMID: 32761086 PMCID: PMC7438703 DOI: 10.1210/endocr/bqaa129] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/30/2020] [Indexed: 12/18/2022]
Abstract
The organizational/activational hypothesis suggests that gonadal steroid hormones like testosterone (T) and estradiol (E2) are important at 2 different times during the lifespan when they perform 2 different functions. First steroids "organize" brain structures early in life and during puberty, and in adults these same hormones "activate" sexually dimorphic behaviors. This hypothesis has been tested and proven valid for a large number of behaviors (learning, memory, social, and sexual behaviors). Sex differences in drug addiction are well established both for humans and animal models. Previous research in this field has focused primarily on cocaine self-administration by rats. Traditionally, observed sex differences have been explained by the sex-specific concentrations of gonadal hormones present at the time of the drug-related behavior. Studies with gonadectomized rodents establishes an activational role for E2 that facilitates vulnerability in females, and when E2 is combined with progesterone, addiction is attenuated. Literature on organizational actions of steroids is sparse but predicts that T, after it is aromatized to E2, changes aspects of the neural reward system. Here we summarize these data and propose that sex chromosome complement also plays a role in determining sex-specific drug-taking behavior. Future research is needed to disentangle the effects of hormones and sex chromosome complement, and we propose the four core genotype mouse model as an effective tool for answering these questions.
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Affiliation(s)
- Samuel J Harp
- Center for Human Health and the Environment and Program in Genetics, North Carolina State University, Raleigh, North Carolina
| | - Mariangela Martini
- Center for Human Health and the Environment and Program in Genetics, North Carolina State University, Raleigh, North Carolina
| | - Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Emilie F Rissman
- Center for Human Health and the Environment and Program in Genetics, North Carolina State University, Raleigh, North Carolina
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17
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Cisternas CD, Cabrera Zapata LE, Mir FR, Scerbo MJ, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Estradiol-dependent axogenesis and Ngn3 expression are determined by XY sex chromosome complement in hypothalamic neurons. Sci Rep 2020; 10:8223. [PMID: 32427857 PMCID: PMC7237695 DOI: 10.1038/s41598-020-65183-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/14/2020] [Indexed: 01/15/2023] Open
Abstract
Hypothalamic neurons show sex differences in neuritogenesis, female neurons have longer axons and higher levels of the neuritogenic factor neurogenin 3 (Ngn3) than male neurons in vitro. Moreover, the effect of 17-β-estradiol (E2) on axonal growth and Ngn3 expression is only found in male-derived neurons. To investigate whether sex chromosomes regulate these early sex differences in neuritogenesis by regulating the E2 effect on Ngn3, we evaluated the growth and differentiation of hypothalamic neurons derived from the “four core genotypes” mouse model, in which the factors of “gonadal sex” and “sex chromosome complement” are dissociated. We showed that sex differences in neurite outgrowth are determined by sex chromosome complement (XX > XY). Moreover, E2 increased the mRNA expression of Ngn3 and axonal length only in XY neurons. ERα/β expressions are regulated by sex chromosome complement; however, E2-effect on Ngn3 expression in XY neurons was only fully reproduced by PPT, a specific ligand of ERα, and prevented by MPP, a specific antagonist of ERα. Together our data indicate that sex chromosomes regulate early development of hypothalamic neurons by orchestrating not only sex differences in neuritogenesis, but also regulating the effect of E2 on Ngn3 expression through activation of ERα in hypothalamic neurons.
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Affiliation(s)
- Carla Daniela Cisternas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lucas Ezequiel Cabrera Zapata
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Franco Rafael Mir
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Julia Scerbo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Angeles Arevalo
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina. .,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina.
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18
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Arnold AP. Sexual differentiation of brain and other tissues: Five questions for the next 50 years. Horm Behav 2020; 120:104691. [PMID: 31991182 PMCID: PMC7440839 DOI: 10.1016/j.yhbeh.2020.104691] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/13/2020] [Accepted: 01/15/2020] [Indexed: 12/16/2022]
Abstract
This paper is part of the celebration of the 50th anniversary of founding of the journal Hormones and Behavior, the official journal of the Society for Behavioral Neuroendocrinology. All sex differences in phenotypic development stem from the sexual imbalance in X and Y chromosomes, which are the only known differences in XX and XY zygotes. The sex chromosome genes act within cells to cause differences in phenotypes of XX and XY cells throughout the body. In the gonad, they determine the type of gonad, leading to differences in secretion of testicular vs. ovarian hormones, which cause further sex differences in tissue function. These current ideas of sexual differentiation are briefly contrasted with a hormones-only view of sexual differentiation of the last century. The multiple, independent action of diverse sex-biasing agents means that sex-biased factors can be synergistic, increasing sex differences, or compensatory, making the two sexes more equal. Several animal models have been fruitful in demonstrating sex chromosome effects, and interactions with gonadal hormones. MRI studies of human brains demonstrate variation in brain structure associated with both differences in gonadal hormones, and in the number of X and Y chromosomes. Five unanswered questions are posed as a challenge to future investigators to improve understanding of sexual differentiation throughout the body.
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Affiliation(s)
- Arthur P Arnold
- Department Integrative Biology and Physiology, University of California, Los Angeles, United States of America.
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19
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Giatti S, Diviccaro S, Serafini MM, Caruso D, Garcia-Segura LM, Viviani B, Melcangi RC. Sex differences in steroid levels and steroidogenesis in the nervous system: Physiopathological role. Front Neuroendocrinol 2020; 56:100804. [PMID: 31689419 DOI: 10.1016/j.yfrne.2019.100804] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/10/2019] [Accepted: 10/30/2019] [Indexed: 12/13/2022]
Abstract
The nervous system, in addition to be a target for steroid hormones, is the source of a variety of neuroactive steroids, which are synthesized and metabolized by neurons and glial cells. Recent evidence indicates that the expression of neurosteroidogenic proteins and enzymes and the levels of neuroactive steroids are different in the nervous system of males and females. We here summarized the state of the art of neuroactive steroids, particularly taking in consideration sex differences occurring in the synthesis and levels of these molecules. In addition, we discuss the consequences of sex differences in neurosteroidogenesis for the function of the nervous system under healthy and pathological conditions and the implications of neuroactive steroids and neurosteroidogenesis for the development of sex-specific therapeutic interventions.
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Affiliation(s)
- Silvia Giatti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Silvia Diviccaro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Melania Maria Serafini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Barbara Viviani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Roberto C Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
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20
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Azcoitia I, Barreto GE, Garcia-Segura LM. Molecular mechanisms and cellular events involved in the neuroprotective actions of estradiol. Analysis of sex differences. Front Neuroendocrinol 2019; 55:100787. [PMID: 31513774 DOI: 10.1016/j.yfrne.2019.100787] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/27/2019] [Accepted: 09/07/2019] [Indexed: 12/12/2022]
Abstract
Estradiol, either from peripheral or central origin, activates multiple molecular neuroprotective and neuroreparative responses that, being mediated by estrogen receptors or by estrogen receptor independent mechanisms, are initiated at the membrane, the cytoplasm or the cell nucleus of neural cells. Estrogen-dependent signaling regulates a variety of cellular events, such as intracellular Ca2+ levels, mitochondrial respiratory capacity, ATP production, mitochondrial membrane potential, autophagy and apoptosis. In turn, these molecular and cellular actions of estradiol are integrated by neurons and non-neuronal cells to generate different tissue protective responses, decreasing blood-brain barrier permeability, oxidative stress, neuroinflammation and excitotoxicity and promoting synaptic plasticity, axonal growth, neurogenesis, remyelination and neuroregeneration. Recent findings indicate that the neuroprotective and neuroreparative actions of estradiol are different in males and females and further research is necessary to fully elucidate the causes for this sex difference.
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Affiliation(s)
- Iñigo Azcoitia
- Department of Cell Biology, Faculty of Biology, Universidad Complutense de Madrid, 28040 Madrid, Spain; Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludables (CIBERFES), Instituto de Salud Carlos III, Avenida Monforte de Lemos, 3-5, 28029 Madrid, Spain.
| | - George E Barreto
- Department of Biological Sciences, School of Natural Sciences, University of Limerick, Limerick, Ireland.
| | - Luis M Garcia-Segura
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludables (CIBERFES), Instituto de Salud Carlos III, Avenida Monforte de Lemos, 3-5, 28029 Madrid, Spain; Instituto Cajal, CSIC, Avenida Doctor Arce 37, 28002 Madrid, Spain.
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21
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Cisternas CD, Cortes LR, Bruggeman EC, Yao B, Forger NG. Developmental changes and sex differences in DNA methylation and demethylation in hypothalamic regions of the mouse brain. Epigenetics 2019; 15:72-84. [PMID: 31378140 DOI: 10.1080/15592294.2019.1649528] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
DNA methylation is dynamically modulated during postnatal brain development, and plays a key role in neuronal lineage commitment. This epigenetic mark has also recently been implicated in the development of neural sex differences, many of which are found in the hypothalamus. The level of DNA methylation depends on a balance between the placement of methyl marks by DNA methyltransferases (Dnmts) and their removal, which is catalyzed by ten-eleven translocation (Tet) methylcytosine dioxygenases. Here, we examined developmental changes and sex differences in the expression of Tet and Dnmt enzymes from birth to adulthood in two hypothalamic regions (the preoptic area and ventromedial nucleus) and the hippocampus of mice. We found highest expression of all Tet enzymes (Tet1, Tet2, Tet3) and Dnmts (Dnmt1, Dnmt3a, Dnmt3b) in newborns, despite the fact that global methylation and hydroxymethylation were at their lowest levels at birth. Expression of the Dnmt co-activator, Dnmt3l, followed a pattern opposite to that of the canonical Dnmts (i.e., was very low in newborns and increased with age). Tet enzyme activity was much higher at birth than at weaning in both the hypothalamus and hippocampus, mirroring developmental changes in gene expression. Sex differences in Tet enzyme expression were seen in all brain regions examined during the first week of life, whereas Dnmt expression was more balanced between the sexes. Neonatal testosterone treatment of females only partially masculinized enzyme expression. Thus, Tet expression and activity are elevated during neonatal brain development, and may play important roles in sexual differentiation of the brain.
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Affiliation(s)
- Carla D Cisternas
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, USA
| | - Laura R Cortes
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, USA
| | - Emily C Bruggeman
- Department of Human Genetics, Emory School of Medicine, Atlanta, GA, USA
| | - Bing Yao
- Department of Human Genetics, Emory School of Medicine, Atlanta, GA, USA
| | - Nancy G Forger
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, USA
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22
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Abstract
Evolution of genetic mechanisms of sex determination led to two processes causing sex differences in somatic phenotypes: gonadal differentiation and sex chromosome dosage inequality. In species with heteromorphic sex chromosomes, the sex of the individual is established at the time of formation of the zygote, leading to inherent sex differences in expression of sex chromosome genes beginning as soon as the embryonic transcriptome is activated. The inequality of sex chromosome gene expression causes sexual differentiation of the gonads and of non-gonadal tissues. The difference in gonad type in turn causes lifelong differences in gonadal hormones, which interact with unequal effects of X and Y genes acting within cells. Separating the effects of gonadal hormones and sex chromosomes has been possible using mouse models in which gonadal determination is separated from the sex chromosomes, allowing comparison of XX and XY mice with the same type of gonad. Sex differences caused by gonadal hormones and sex chromosomes affect basic physiology and disease mechanisms in most or all tissues.
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23
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Abstract
Sex differences exist in the regulation of energy homeostasis. Better understanding of the underlying mechanisms for sexual dimorphism in energy balance may facilitate development of gender-specific therapies for human diseases, e.g. obesity. Multiple organs, including the brain, liver, fat and muscle, play important roles in the regulations of feeding behavior, energy expenditure and physical activity, which therefore contribute to the maintenance of energy balance. It has been increasingly appreciated that this multi-organ system is under different regulations in male vs. female animals. Much of effort has been focused on roles of sex hormones (including androgens, estrogens and progesterone) and sex chromosomes in this sex-specific regulation of energy balance. Emerging evidence also indicates that other factors (not sex hormones/receptors and not encoded by the sex chromosomes) exist to regulate energy homeostasis differentially in males vs. females. In this review, we summarize factors and signals that have been shown to regulate energy homeostasis in a sexually dimorphic fashion and propose a framework where these factors and signals may be integrated to mediate sex differences in energy homeostasis.
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Affiliation(s)
- Chunmei Wang
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030
| | - Yong Xu
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030
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24
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Brocca ME, Garcia-Segura LM. Non-reproductive Functions of Aromatase in the Central Nervous System Under Physiological and Pathological Conditions. Cell Mol Neurobiol 2018; 39:473-481. [PMID: 30084008 DOI: 10.1007/s10571-018-0607-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 07/25/2018] [Indexed: 02/07/2023]
Abstract
The modulation of brain function and behavior by steroid hormones was classically associated with their secretion by peripheral endocrine glands. The discovery that the brain expresses the enzyme aromatase, which produces estradiol from testosterone, expanded this traditional concept. One of the best-studied roles of brain estradiol synthesis is the control of reproductive behavior. In addition, there is increasing evidence that estradiol from neural origin is also involved in a variety of non-reproductive functions. These include the regulation of neurogenesis, neuronal development, synaptic transmission, and plasticity in brain regions not directly related with the control of reproduction. Central aromatase is also involved in the modulation of cognition, mood, and non-reproductive behaviors. Furthermore, under pathological conditions aromatase is upregulated in the central nervous system. This upregulation represents a neuroprotective and likely also a reparative response by increasing local estradiol levels in order to maintain the homeostasis of the neural tissue. In this paper, we review the non-reproductive functions of neural aromatase and neural-derived estradiol under physiological and pathological conditions. We also consider the existence of sex differences in the role of the enzyme in both contexts.
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Affiliation(s)
- Maria Elvira Brocca
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
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25
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Giatti S, Garcia-Segura LM, Barreto GE, Melcangi RC. Neuroactive steroids, neurosteroidogenesis and sex. Prog Neurobiol 2018; 176:1-17. [PMID: 29981391 DOI: 10.1016/j.pneurobio.2018.06.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 05/25/2018] [Accepted: 06/30/2018] [Indexed: 12/12/2022]
Abstract
The nervous system is a target and a source of steroids. Neuroactive steroids are steroids that target neurons and glial cells. They include hormonal steroids originated in the peripheral glands, steroids locally synthesized by the neurons and glial cells (neurosteroids) and synthetic steroids, some of them used in clinical practice. Here we review the mechanisms of synthesis, metabolism and action of neuroactive steroids, including the role of epigenetic modifications and the mitochondria in their sex specific actions. We examine sex differences in neuroactive steroid levels under physiological conditions and their role in the establishment of sex dimorphic structures in the nervous system and sex differences in its function. In addition, particular attention is paid to neuroactive steroids under pathological conditions, analyzing how pathology alters their levels and their role as neuroprotective factors, considering the influence of sex in both cases.
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Affiliation(s)
- Silvia Giatti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Luis M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Roberto C Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
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26
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Cisternas CD, Garcia-Segura LM, Cambiasso MJ. Hormonal and genetic factors interact to control aromatase expression in the developing brain. J Neuroendocrinol 2018; 30. [PMID: 28891264 DOI: 10.1111/jne.12535] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/05/2017] [Accepted: 09/05/2017] [Indexed: 02/03/2023]
Abstract
Brain expression of the enzyme P450-aromatase has been studied extensively. Subsequent to the aromatisation hypothesis having established brain aromatase as a key factor to convert gonadal testosterone to oestradiol, several studies have investigated the regulation of aromatase during the critical period of brain sexual differentiation. We review previous and recent findings concerning regulation of aromatase. The role of gonadal hormones, sex chromosome genes and neurosteroids is analysed in terms of their contribution to aromatase expression, as well as implications for the organisational effect of steroids during development.
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Affiliation(s)
- C D Cisternas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - L M Garcia-Segura
- Instituto Cajal, CSIC, Madrid, Spain
- Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - M J Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
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27
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Rosenfeld CS, Shay DA, Vieira-Potter VJ. Cognitive Effects of Aromatase and Possible Role in Memory Disorders. Front Endocrinol (Lausanne) 2018; 9:610. [PMID: 30386297 PMCID: PMC6199361 DOI: 10.3389/fendo.2018.00610] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 09/26/2018] [Indexed: 12/14/2022] Open
Abstract
Diverse cognitive functions in many vertebrate species are influenced by local conversion of androgens to 17β-estradiol (E2) by aromatase. This enzyme is highly expressed in various brain regions across species, with some inter-species variation in terms of regional brain expression. Since women with breast cancer and men and women with other disorders are often treated with aromatase inhibitors (AI), these populations might be especially vulnerable to cognitive deficits due to low neuroE2 synthesis, i.e., synthesis of E2 directly within the brain. Animal models have been useful in deciphering aromatase effects on cognitive functions. Consequences of AI administration at various life cycle stages have been assessed on auditory, song processing, and spatial memory in birds and various aspects of cognition in rodent models. Additionally, cognitive deficits have been described in aromatase knockout (ArKO) mice that systemically lack this gene throughout their lifespan. This review will consider evidence to date that AI treatment in male and female rodent models, birds, and humans results in cognitive impairments. How brain aromatase regulates cognitive function throughout the lifespan, and gaps in current knowledge will be considered, along with future directions to better define how aromatase might guide learning and memory from early development through the geriatric period. Better understanding the importance of E2 synthesis on neurobehavioral responses at various ages will likely aid in the discovery of therapeutic strategies to prevent potential cognitive deficits, including Alzheimer's Disease, in individuals treated with AI or those possessing CYP19 gene polymorphisms, as well as cognitive effects of normal aging that may be related to changes in brain aromatase activity.
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Affiliation(s)
- Cheryl S. Rosenfeld
- Bond Life Sciences Center, University of Missouri, Columbia, MO, United States
- Thompson Center for Autism and Neurobehavioral Disorders, University of Missouri, Columbia, MO, United States
- Biomedical Sciences, University of Missouri, Columbia, MO, United States
- *Correspondence: Cheryl S. Rosenfeld
| | - Dusti A. Shay
- Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, United States
| | - Victoria J. Vieira-Potter
- Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, United States
- Victoria J. Vieira-Potter
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28
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Rosenfeld CS. Brain Sexual Differentiation and Requirement of SRY: Why or Why Not? Front Neurosci 2017; 11:632. [PMID: 29200993 PMCID: PMC5696354 DOI: 10.3389/fnins.2017.00632] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/30/2017] [Indexed: 12/22/2022] Open
Abstract
Brain sexual differentiation is orchestrated by precise coordination of sex steroid hormones. In some species, programming of select male brain regions is dependent upon aromatization of testosterone to estrogen. In mammals, these hormones surge during the organizational and activational periods that occur during perinatal development and adulthood, respectively. In various fish and reptiles, incubation temperature during a critical embryonic period results in male or female sexual differentiation, but this can be overridden in males by early exposure to estrogenic chemicals. Testes development in mammals requires a Y chromosome and testis determining gene SRY (in humans)/Sry (all other therian mammals), although there are notable exceptions. Two species of spiny rats: Amami spiny rat (Tokudaia osimensis) and Tokunoshima spiny rat (Tokudaia tokunoshimensis) and two species of mole voles (Ellobius lutescens and Ellobius tancrei), lack a Y chromosome/Sry and possess an XO chromosome system in both sexes. Such rodent species, prototherians (monotremes, who also lack Sry), and fish and reptile species that demonstrate temperature sex determination (TSD) seemingly call into question the requirement of Sry for brain sexual differentiation. This review will consider brain regions expressing SRY/Sry in humans and rodents, respectively, and potential roles of SRY/Sry in the brain will be discussed. The evidence from various taxa disputing the requirement of Sry for brain sexual differentiation in mammals (therians and prototherians) and certain fish and reptilian species will be examined. A comparative approach to address this question may elucidate other genes, pathways, and epigenetic modifications stimulating brain sexual differentiation in vertebrate species, including humans.
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Affiliation(s)
- Cheryl S Rosenfeld
- Bond Life Sciences Center, University of Missouri, Columbia, MO, United States.,Biomedical Sciences, University of Missouri, Columbia, MO, United States.,Thompson Center for Autism and Neurobehavioral Disorders, University of Missouri, Columbia, MO, United States.,Genetics Area Program, University of Missouri, Columbia, MO, United States
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29
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Cisternas CD, Cabrera Zapata LE, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Regulation of aromatase expression in the anterior amygdala of the developing mouse brain depends on ERβ and sex chromosome complement. Sci Rep 2017; 7:5320. [PMID: 28706210 PMCID: PMC5509695 DOI: 10.1038/s41598-017-05658-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/01/2017] [Indexed: 12/11/2022] Open
Abstract
During development sex differences in aromatase expression in limbic regions of mouse brain depend on sex chromosome factors. Genes on the sex chromosomes may affect the hormonal regulation of aromatase expression and this study was undertaken to explore that possibility. Male E15 anterior amygdala neuronal cultures expressed higher levels of aromatase (mRNA and protein) than female cultures. Furthermore, treatment with oestradiol (E2) or dihydrotestosterone (DHT) increased Cyp19a1 expression and aromatase protein levels only in female neuronal cultures. The effect of E2 on aromatase expression was not imitated by oestrogen receptor (ER) α agonist PPT or the GPER agonist G1, but it was fully reproduced by DPN, a specific ligand of ERβ. By contrast, the effect of DHT on aromatase expression was not blocked by the anti-androgen flutamide, but completely abrogated by the ERβ antagonist PHTPP. Experiments using the four core genotype model showed a sex chromosome effect in ERβ expression (XY > XX) and regulation by E2 or DHT (only XX respond) in amygdala neurons. In conclusion, sex chromosome complement governs the hormonal regulation of aromatase expression through activation of ERβ in developing mouse brain.
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Affiliation(s)
- Carla Daniela Cisternas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lucas Ezequiel Cabrera Zapata
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Angeles Arevalo
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina. .,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina.
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30
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Panzica G, Melcangi RC. Structural and molecular brain sexual differences: A tool to understand sex differences in health and disease. Neurosci Biobehav Rev 2016; 67:2-8. [DOI: 10.1016/j.neubiorev.2016.04.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 02/07/2023]
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31
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Forger NG, Strahan JA, Castillo-Ruiz A. Cellular and molecular mechanisms of sexual differentiation in the mammalian nervous system. Front Neuroendocrinol 2016; 40:67-86. [PMID: 26790970 PMCID: PMC4897775 DOI: 10.1016/j.yfrne.2016.01.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 12/31/2015] [Accepted: 01/09/2016] [Indexed: 01/16/2023]
Abstract
Neuroscientists are likely to discover new sex differences in the coming years, spurred by the National Institutes of Health initiative to include both sexes in preclinical studies. This review summarizes the current state of knowledge of the cellular and molecular mechanisms underlying sex differences in the mammalian nervous system, based primarily on work in rodents. Cellular mechanisms examined include neurogenesis, migration, the differentiation of neurochemical and morphological cell phenotype, and cell death. At the molecular level we discuss evolving roles for epigenetics, sex chromosome complement, the immune system, and newly identified cell signaling pathways. We review recent findings on the role of the environment, as well as genome-wide studies with some surprising results, causing us to re-think often-used models of sexual differentiation. We end by pointing to future directions, including an increased awareness of the important contributions of tissues outside of the nervous system to sexual differentiation of the brain.
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Affiliation(s)
- Nancy G Forger
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States.
| | - J Alex Strahan
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States.
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