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VanderLaan DP, Skorska MN, Peragine DE, Coome LA. Carving the Biodevelopment of Same-Sex Sexual Orientation at Its Joints. ARCHIVES OF SEXUAL BEHAVIOR 2023; 52:2939-2962. [PMID: 35960401 DOI: 10.1007/s10508-022-02360-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/30/2022] [Accepted: 06/04/2022] [Indexed: 06/15/2023]
Abstract
Sexual orientation is a core aspect of human experience and understanding its development is fundamental to psychology as a scientific discipline. Biological perspectives have played an important role in uncovering the processes that contribute to sexual orientation development. Research in this field has relied on a variety of populations, including community, clinical, and cross-cultural samples, and has commonly focused on female gynephilia (i.e., female sexual attraction to adult females) and male androphilia (i.e., male sexual attraction to adult males). Genetic, hormonal, and immunological processes all appear to influence sexual orientation. Consistent with biological perspectives, there are sexual orientation differences in brain development and evidence indicates that similar biological influences apply across cultures. An outstanding question in the field is whether the hypothesized biological influences are all part of the same process or represent different developmental pathways leading to same-sex sexual orientation. Some studies indicate that same-sex sexually oriented people can be divided into subgroups who likely experienced different biological influences. Consideration of gender expression in addition to sexual orientation might help delineate such subgroups. Thus, future research on the possible existence of such subgroups could prove to be valuable for uncovering the biological development of sexual orientation. Recommendations for such future research are discussed.
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Affiliation(s)
- Doug P VanderLaan
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada.
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | - Malvina N Skorska
- Child and Youth Psychiatry, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Diana E Peragine
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada
| | - Lindsay A Coome
- Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada
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2
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Cīrulis A. Sexual orientation as an important factor in personalized medicine. Eur Neuropsychopharmacol 2023; 66:62-63. [PMID: 36384055 DOI: 10.1016/j.euroneuro.2022.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/15/2022]
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3
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Nicholson AA, Siegel M, Wolf J, Narikuzhy S, Roth SL, Hatchard T, Lanius RA, Schneider M, Lloyd CS, McKinnon MC, Heber A, Smith P, Lueger-Schuster B. A systematic review of the neural correlates of sexual minority stress: towards an intersectional minority mosaic framework with implications for a future research agenda. Eur J Psychotraumatol 2022; 13:2002572. [PMID: 35251527 PMCID: PMC8890555 DOI: 10.1080/20008198.2021.2002572] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Systemic oppression, particularly towards sexual minorities, continues to be deeply rooted in the bedrock of many societies globally. Experiences with minority stressors (e.g. discrimination, hate-crimes, internalized homonegativity, rejection sensitivity, and microaggressions or everyday indignities) have been consistently linked to adverse mental health outcomes. Elucidating the neural adaptations associated with minority stress exposure will be critical for furthering our understanding of how sexual minorities become disproportionately affected by mental health burdens. UNLABELLED Following PRISMA-guidelines, we systematically reviewed published neuroimaging studies that compared neural dynamics among sexual minority and heterosexual populations, aggregating information pertaining to any measurement of minority stress and relevant clinical phenomena. RESULTS Only 1 of 13 studies eligible for inclusion examined minority stress directly, where all other studies focused on investigating the neurobiological basis of sexual orientation. In our narrative synthesis, we highlight important themes that suggest minority stress exposure may be associated with decreased activation and functional connectivity within the default-mode network (related to the sense-of-self and social cognition), and summarize preliminary evidence related to aberrant neural dynamics within the salience network (involved in threat detection and fear processing) and the central executive network (involved in executive functioning and emotion regulation). Importantly, this parallels neural adaptations commonly observed among individuals with posttraumatic stress disorder (PTSD) in the aftermath of trauma and supports the inclusion of insidious forms of trauma related to minority stress within models of PTSD. CONCLUSIONS Taken together, minority stress may have several shared neuropsychological pathways with PTSD and stress-related disorders. Here, we outline a detailed research agenda that provides an overview of literature linking sexual minority stress to PTSD and insidious trauma, moral affect (including shame and guilt), and mental health risk/resiliency, in addition to racial, ethnic, and gender related minority stress. Finally, we propose a novel minority mosaic framework designed to inform future directions of minority stress neuroimaging research from an intersectional lens.
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Affiliation(s)
- Andrew A Nicholson
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada.,Department of Cognition, Emotion, and Methods in Psychology, University of Vienna, Vienna, Austria.,Department of Medical Biophysics, Western University, London, Canada.,Homewood Research Institute, Guelph, Canada
| | - Magdalena Siegel
- Department of Developmental and Educational Psychology, University of Vienna, Vienna, Austria.,Department of Public Health, Institute of Tropical Medicine Antwerp, Antwerp, Belgium
| | - Jakub Wolf
- Department of Cognition, Emotion, and Methods in Psychology, University of Vienna, Vienna, Austria
| | - Sandhya Narikuzhy
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada
| | - Sophia L Roth
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada
| | - Taylor Hatchard
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada
| | - Ruth A Lanius
- Department of Psychiatry, Western University, London, Canada
| | - Maiko Schneider
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada
| | | | - Margaret C McKinnon
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada.,Homewood Research Institute, Guelph, Canada
| | | | - Patrick Smith
- The Centre of Excellence for PTSD, Royal Ottawa Hospital, Ottawa, Canada
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4
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Li H, Fernández-Guasti A, Xu Y, Swaab D. Retracted: Sexual orientation, neuropsychiatric disorders and the neurotransmitters involved. Neurosci Biobehav Rev 2021; 131:479-488. [PMID: 34597715 DOI: 10.1016/j.neubiorev.2021.09.048] [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: 03/01/2021] [Revised: 08/17/2021] [Accepted: 09/26/2021] [Indexed: 11/26/2022]
Abstract
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor in Chief of Neuroscience and Biobehavioral Reviews after concerns were raised with respect to the phrasing of comparisons drawn between humans and animal models. These comparisons were deemed unsupportable, and thus in the best interests of publication standards the Editor has concluded it is necessary to retract the paper. The authors disagree with the reason for the retraction.
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Affiliation(s)
- Haimei Li
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, PR China; Department of Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, Amsterdam, 1105 BA, the Netherlands
| | | | - Yi Xu
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, PR China; The Key Laboratory of Mental Disorder Management in Zhejiang Province, Hangzhou, 310003, PR China; Zhejiang Engineering Center for Mathematical Mental Health, Hangzhou, 310003, PR China; Brain Research Institute of Zhejiang University, Hangzhou, 31003, PR China.
| | - Dick Swaab
- Department of Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, Amsterdam, 1105 BA, the Netherlands.
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5
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Frigerio A, Ballerini L, Valdés Hernández M. Structural, Functional, and Metabolic Brain Differences as a Function of Gender Identity or Sexual Orientation: A Systematic Review of the Human Neuroimaging Literature. ARCHIVES OF SEXUAL BEHAVIOR 2021; 50:3329-3352. [PMID: 33956296 PMCID: PMC8604863 DOI: 10.1007/s10508-021-02005-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 05/05/2023]
Abstract
This review systematically explored structural, functional, and metabolic features of the cisgender brain compared with the transgender brain before hormonal treatment and the heterosexual brain compared to the homosexual brain from the analysis of the neuroimaging literature up to 2018, and identified and discussed subsequent studies published up to March 2021. Our main aim was to help identifying neuroradiological brain features that have been related to human sexuality to contribute to the understanding of the biological elements involved in gender identity and sexual orientation. We analyzed 39 studies on gender identity and 24 on sexual orientation. Our results suggest that some neuroanatomical, neurophysiological, and neurometabolic features in transgender individuals resemble those of their experienced gender despite the majority resembling those from their natal sex. In homosexual individuals the majority resemble those of their same-sex heterosexual population rather than their opposite-sex heterosexual population. However, it is always difficult to interpret findings with noninvasive neuroimaging. Given the gross nature of these measures, it is possible that more differences too subtle to measure with available tools yet contributing to gender identity and sexual orientation could be found. Conflicting results contributed to the difficulty of identifying specific brain features which consistently differ between cisgender and transgender or between heterosexual and homosexual groups. The small number of studies, the small-to-moderate sample size of each study, and the heterogeneity of the investigations made it impossible to meta-analyze all the data extracted. Further studies are necessary to increase the understanding of the neurological substrates of human sexuality.
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Affiliation(s)
- Alberto Frigerio
- Division of Health Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Lucia Ballerini
- Division of Health Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
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Amezcua-Gutiérrez C, Hernández-González M, Guasti AF, Aguilar MAC, Guevara MA. Observing Erotic Videos with Heterosexual Content Induces Different Cerebral Responses in Homosexual and Heterosexual Men. JOURNAL OF HOMOSEXUALITY 2021; 68:138-156. [PMID: 31430230 DOI: 10.1080/00918369.2019.1648079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To determine the cerebral functionality associated with the perception and processing of erotic stimuli in men with different sexual orientation, this work evaluated the electroencephalographic activity (EEG) from several cortical areas, as well as subjective arousal in homosexual and heterosexual men during observation of an erotic film with heterosexual content. The heterosexual men rated the erotic video with higher general and sexual arousal than the homosexual participants. During observation of the neutral and erotic videos, both groups showed a decreased amplitude of the alpha band in prefrontal and parietal cortices, indicating increased attention. When watching the erotic video, the homosexual men showed an increased amplitude of the theta and fast bands only in the prefrontal cortex, which could be related to the cognitive processing of the erotic stimulus. These EEG results should broaden our knowledge of the cortical mechanisms related to the different perception and processing of erotic stimuli in men with different sexual orientations.
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Affiliation(s)
| | | | | | - Manuel Alejandro Cruz Aguilar
- National Institute of Psychiatry, "Ramón de la Fuente Muñiz", Neuroscience Research Direction, Chronobiology and Sleep Laboratory , Mexico, México
| | - Miguel Angel Guevara
- Institute of Neuroscience, CUCBA, University of Guadalajara , Guadalajara, Jalisco, México
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7
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Swaab DF, Wolff SEC, Bao AM. Sexual differentiation of the human hypothalamus: Relationship to gender identity and sexual orientation. HANDBOOK OF CLINICAL NEUROLOGY 2021; 181:427-443. [PMID: 34238476 DOI: 10.1016/b978-0-12-820683-6.00031-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gender identity (an individual's perception of being male or female) and sexual orientation (heterosexuality, homosexuality, or bisexuality) are programmed into our brain during early development. During the intrauterine period in the second half of pregnancy, a testosterone surge masculinizes the fetal male brain. If such a testosterone surge does not occur, this will result in a feminine brain. As sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals, these two processes can be influenced independently of each other and can result in gender dysphoria. Nature produces a great variability for all aspects of sexual differentiation of the brain. Mechanisms involved in sexual differentiation of the brain include hormones, genetics, epigenetics, endocrine disruptors, immune response, and self-organization. Furthermore, structural and functional differences in the hypothalamus relating to gender dysphoria and sexual orientation are described in this review. All the genetic, postmortem, and in vivo scanning observations support the neurobiological theory about the origin of gender dysphoria, i.e., it is the sizes of brain structures, the neuron numbers, the molecular composition, functions, and connectivity of brain structures that determine our gender identity or sexual orientation. There is no evidence that one's postnatal social environment plays a crucial role in the development of gender identity or sexual orientation.
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Affiliation(s)
- Dick F Swaab
- Department Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Samantha E C Wolff
- Department Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Ai-Min Bao
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.
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8
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Wang Z, Hu JB, Ji GJ, Xu DR, Wang DD, Xi CX, Hu CC, Lu J, Du YL, Lu QQ, Huang TT, Lai JB, Chen JK, Zhou WH, Wei N, Xu Y, Wang K, Hu SH. Executive function and its relation to anatomical connectome in homosexual and heterosexual men. Quant Imaging Med Surg 2020; 10:1973-1983. [PMID: 33014729 DOI: 10.21037/qims-19-821b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Background Sexual orientation has been suggested to affect executive function, of which the neurobiological basis is still largely unknown. In this study, we explored the interrelationship between neuropsychological characteristics in homosexual and heterosexual men and their anatomical connectome by graph theoretical analysis. Methods Fifty-three homosexual and 47 heterosexual males underwent diffusion tensor magnetic resonance imaging (MRI) and neuropsychological assessments. Whole-brain anatomical networks were constructed using white matter tractography, performed on the diffusion tensor imaging data. Neuropsychological tests included the Wisconsin Card Sorting Test (WCST), the Continuous Performance Test (CPT) and the Trail-Making Test (TMT). Results The cognitive performance of homosexual men was significantly poorer than their heterosexual counterparts in terms of WCST total correct responses. Anatomical connectome analysis revealed a lower (P=0.001) anatomical connectivity between left PoCG and left SMG (P=0.003) in homosexual men as compared to heterosexual men. Linear regression analyses showed that the WCST total correct responses score was significantly linked with sexual orientation (P=0.001). The anatomical connectivity strength between left PoCG and left SMG was also shown to be significantly correlated with sexual orientation (P=0.039) and education (P=0.047). Conclusions Our study demonstrated the differences in the performance of WCST and anatomical connectome of large-scale brain networks between homosexual and heterosexual men, extending our understanding of the brain's circuitry and the characteristics of executive function in men of different sexual orientation.
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Affiliation(s)
- Zheng Wang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jian Bo Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Gong Jun Ji
- Laboratory of Cognitive Neuropsychology, Department of Medical Psychology, Anhui Medical University, Hefei, China
| | - Dong Rong Xu
- Epidemiology Division & MRI Unit, Department of Psychiatry, Columbia University & New York State Psychiatric Institute, New York, NY, USA
| | - Dan Dan Wang
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Cai Xi Xi
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Chan Chan Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jing Lu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Yan Li Du
- Zhejiang University School of Medicine, Hangzhou, China
| | - Qiao Qiao Lu
- Zhejiang University School of Medicine, Hangzhou, China
| | | | - Jian Bo Lai
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Jing Kai Chen
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Wei Hua Zhou
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Ning Wei
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Yi Xu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
| | - Kai Wang
- Laboratory of Cognitive Neuropsychology, Department of Medical Psychology, Anhui Medical University, Hefei, China
| | - Shao Hua Hu
- Department of Psychiatry, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,The Key Laboratory of Mental Disorder's Management of Zhejiang Province, Hangzhou, China
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9
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Amezcua-Gutiérrez C, Marisela HG, Fernández Guasti A, Aguilar MAC, Guevara MA. Observing Erotic Videos With Heterosexual Content Induces Different Cerebral Responses in Homosexual and Heterosexual Men. JOURNAL OF HOMOSEXUALITY 2018; 67:639-657. [PMID: 30526443 DOI: 10.1080/00918369.2018.1550331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To determine the cerebral functionality associated with the perception and processing of erotic stimuli in men with different sexual orientation, this work evaluated the electroencephalographic activity (EEG) from several cortical areas, as well as subjective arousal in homosexual and heterosexual men during observation of an erotic film with heterosexual content. The heterosexual men rated the erotic video with higher general and sexual arousal than the homosexual participants. During observation of the neutral and erotic videos, both groups showed a decreased amplitude of the alpha band in prefrontal and parietal cortices, indicating increased attention. When watching the erotic video, the homosexual men showed an increased amplitude of the theta and fast bands only in the prefrontal cortex, which could be related to the cognitive processing of the erotic stimulus. These EEG results should broaden our knowledge of the cortical mechanisms related to the different perception and processing of erotic stimuli in men with different sexual orientations.
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Affiliation(s)
| | | | | | - Manuel Alejandro Cruz Aguilar
- Dirección de Investigaciones en Neurociencias, Laboratorio de Cronobiología y Sueño, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", México City, México
| | - Miguel Angel Guevara
- Institute of Neuroscience, CUCBA, University of Guadalajara, Guadalajara, Jalisco, México
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10
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Evaluation of drug effects on cerebral blood flow and glucose uptake in un-anesthetized and un-stimulated rats: application of free-moving apparatus enabling to keep rats free during PET/SPECT tracer injection and uptake. Nucl Med Commun 2018; 39:753-760. [PMID: 29771718 PMCID: PMC6075887 DOI: 10.1097/mnm.0000000000000863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Objectives The purpose of this study is the development of novel fluorine-18-fluorodeoxyglucose (18F-FDG)-PET and 99mTc-hexamethylpropylene amine oxime (HMPAO) SPECT methods with free-moving apparatus on conscious rats to investigate brain activity without the effects of anesthesia and tactual stimulation. We also assessed the sensitivity of the experimental system by an intervention study using fluoxetine as a reference drug. Materials and methods A catheter was inserted into the femoral vein and connected to a free-moving cannula system. After fluoxetine administration, the rats were given an injection of 18F-FDG or 99mTc-HMPAO via the intravenous cannula and released into a free-moving cage. After the tracer was trapped in the brain, the rats were anesthetized and scanned with PET or SPECT scanners. Then a volume of interest analysis and statistical parametric mapping were performed. Results We could inject the tracer without touching the rats, while keeping them conscious until the tracers were distributed and trapped in the brain using the developed system. The effects of fluoxetine on glucose uptake and cerebral blood flow were perceptively detected by volume of interest and statistical parametric mapping analysis. Conclusion We successfully developed free-moving 18F-FDG-PET and 99mTc-HMPAO-SPECT imaging systems and detected detailed glucose uptake and cerebral blood flow changes in the conscious rat brain with fluoxetine administration. This system is expected to be useful to assess brain activity without the effects of anesthesia and tactual stimulation to evaluate drug effect or animal brain function.
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11
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Male rats with same-sex preference show higher immobility in the forced swim test, but similar effects of fluoxetine and desipramine than males that prefer females. Pharmacol Biochem Behav 2018; 171:39-45. [PMID: 29807066 DOI: 10.1016/j.pbb.2018.05.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 12/13/2022]
Abstract
Sex preference in male rats is partly determined by the organizational action of estradiol. Thus, several paradigms have used aromatase inhibitors to manipulate sex preference. We recently showed that a subpopulation of male rats prenatally treated with letrozole (0.56 μg/kg, G10-G22), a non-steroidal third generation aromatase inhibitor, had same-sex preference, female sexual behavior (including lordosis and proceptivity) and penile erections when exposed to other males. These males, in addition, displayed high levels of experimental anxiety in the plus maze test and were insensitive to the anxiogenic-like acute effect of FLX (10 mg/kg). The two main purposes of the present work were: a) to study the behavioral profile of males displaying same-sex preference in the forced swim test (FST), and b) to analyze if the antidepressant-like effect of the subchronic treatment with FLX (10 mg/kg, 3 times) or desipramine (DMI, 10 mg/kg, 3 times) vary according to sex preference. Males treated prenatally with letrozole with same-sex preference showed more immobility and less active behaviors (swimming and climbing) in the FST than males with female preference. Subchronic treatment with FLX and DMI reduced immobility when compared to saline controls, while FLX increased swimming and DMI increased climbing behavior. Treatments were equally effective in males with preference for other males and those that preferred females. These results indicate that an association exists between prenatal letrozole treatment, same-sex preference and immobility in the FST.
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12
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The art of matching brain tissue from patients and controls for postmortem research. HANDBOOK OF CLINICAL NEUROLOGY 2018; 150:197-217. [PMID: 29496142 DOI: 10.1016/b978-0-444-63639-3.00015-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The quality of postmortem research depends strongly on a thorough clinical investigation and documentation of the patient's disorder and therapies. In addition, a systematic and professional neuropathologic investigation of both cases and controls is absolutely crucial. In the experience of the Netherlands Brain Bank (NBB), about 20% of clinical neurologic diagnoses, despite being made in first-rate clinics, have to be revised or require an extra diagnosis after a complete and thorough review by the NBB. The neuropathology examination may reveal for instance that the "controls" already have preclinical neurodegenerative alterations. In postmortem studies the patient and control groups must be matched for as many of the known confounding factors as possible. This is necessary to make the groups as similar as possible, except for the topic being investigated. Confounding factors are present before, during, and after death. They are respectively: (1) genetic background, systemic diseases, duration and gravity of illness, medicines and addictive compounds used, age, sex, gender identity, sexual orientation, circadian and seasonal fluctuations, lateralization; (2) agonal state, stress of dying; and (3) postmortem delay, freezing procedures, fixation and storage time. Consequently, a brain bank should have a large number of controls at its disposal for appropriate matching. If matching fails for some confounders, then their influence may be determined by statistical methods such as analysis of variance or regression models.
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García-Cárdenas N, Olvera-Hernández S, Gómez-Quintanar BN, Fernández-Guasti A. Male rats with same sex preference show high experimental anxiety and lack of anxiogenic-like effect of fluoxetine in the plus maze test. Pharmacol Biochem Behav 2015; 135:128-35. [DOI: 10.1016/j.pbb.2015.05.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/22/2015] [Accepted: 05/28/2015] [Indexed: 01/04/2023]
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14
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Olvera-Hernández S, Fernández-Guasti A. Perinatal administration of aromatase inhibitors in rodents as animal models of human male homosexuality: similarities and differences. ADVANCES IN NEUROBIOLOGY 2015; 10:381-406. [PMID: 25287550 DOI: 10.1007/978-1-4939-1372-5_18] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this chapter we briefly review the evidence supporting the existence of biological influences on sexual orientation. We focus on basic research studies that have affected the estrogen synthesis during the critical periods of brain sexual differentiation in male rat offspring with the use of aromatase inhibitors, such as 1,4,6-androstatriene-3,17 (ATD) and letrozole. The results after prenatal and/or postnatal treatment with ATD reveal that these animals, when adults, show female sexual responses, such as lordosis or proceptive behaviors, but retain their ability to display male sexual activity with a receptive female. Interestingly, the preference and sexual behavior of these rats vary depending upon the circadian rhythm.Recently, we have established that the treatment with low doses of letrozole during the second half of pregnancy produces male rat offspring, that when adults spend more time in the company of a sexually active male than with a receptive female in a preference test. In addition, they display female sexual behavior when forced to interact with a sexually experienced male and some typical male sexual behavior when faced with a sexually receptive female. Interestingly, these males displayed both sexual behavior patterns spontaneously, i.e., in absence of exogenous steroid hormone treatment. Most of these features correspond with those found in human male homosexuals; however, the "bisexual" behavior shown by the letrozole-treated rats may be related to a particular human population. All these data, taken together, permit to propose letrozole prenatal treatment as a suitable animal model to study human male homosexuality and reinforce the hypothesis that human sexual orientation is underlied by changes in the endocrine milieu during early development.
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Affiliation(s)
- Sandra Olvera-Hernández
- Department of Pharmacobiology, Center for Research and Advanced Studies (CINVESTAV), Calzada de los Tenorios 235 Colonia Granjas Coapa, 14330, México, D.F., Mexico,
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Bao AM, Swaab DF. Sexual differentiation of the human brain: relation to gender identity, sexual orientation and neuropsychiatric disorders. Front Neuroendocrinol 2011; 32:214-26. [PMID: 21334362 DOI: 10.1016/j.yfrne.2011.02.007] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Revised: 02/04/2011] [Accepted: 02/14/2011] [Indexed: 11/28/2022]
Abstract
During the intrauterine period a testosterone surge masculinizes the fetal brain, whereas the absence of such a surge results in a feminine brain. As sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals, these two processes can be influenced independently of each other. Sex differences in cognition, gender identity (an individual's perception of their own sexual identity), sexual orientation (heterosexuality, homosexuality or bisexuality), and the risks of developing neuropsychiatric disorders are programmed into our brain during early development. There is no evidence that one's postnatal social environment plays a crucial role in gender identity or sexual orientation. We discuss the relationships between structural and functional sex differences of various brain areas and the way they change along with any changes in the supply of sex hormones on the one hand and sex differences in behavior in health and disease on the other.
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Affiliation(s)
- Ai-Min Bao
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.
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Molecular regulation of sexual preference revealed by genetic studies of 5-HT in the brains of male mice. Nature 2011; 472:95-9. [PMID: 21441904 DOI: 10.1038/nature09822] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 01/14/2011] [Indexed: 11/08/2022]
Abstract
Although the question of to whom a male directs his mating attempts is a critical one in social interactions, little is known about the molecular and cellular mechanisms controlling mammalian sexual preference. Here we report that the neurotransmitter 5-hydroxytryptamine (5-HT) is required for male sexual preference. Wild-type male mice preferred females over males, but males lacking central serotonergic neurons lost sexual preference although they were not generally defective in olfaction or in pheromone sensing. A role for 5-HT was demonstrated by the phenotype of mice lacking tryptophan hydroxylase 2 (Tph2), which is required for the first step of 5-HT synthesis in the brain. Thirty-five minutes after the injection of the intermediate 5-hydroxytryptophan (5-HTP), which circumvented Tph2 to restore 5-HT to the wild-type level, adult Tph2 knockout mice also preferred females over males. These results indicate that 5-HT and serotonergic neurons in the adult brain regulate mammalian sexual preference.
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Salu Y. The roots of sexual arousal and sexual orientation. Med Hypotheses 2011; 76:384-7. [DOI: 10.1016/j.mehy.2010.10.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 10/29/2010] [Indexed: 10/18/2022]
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Bao AM, Swaab DF. Sex differences in the brain, behavior, and neuropsychiatric disorders. Neuroscientist 2011; 16:550-65. [PMID: 20889965 DOI: 10.1177/1073858410377005] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sex differences in the brain are reflected in behavior and in the risk for neuropsychiatric disorders. The fetal brain develops in the male direction due to a direct effect of testosterone on the developing neurons, or in the female direction due to the absence of such a testosterone surge. Because sexual differentiation of the genitals takes place earlier in intrauterine life than sexual differentiation of the brain, these two processes can be influenced independently of each other. Gender identity (the conviction of belonging to the male or female gender), sexual orientation (heterosexuality, homosexuality, or bisexuality), pedophilia, sex differences in cognition, and the risks for neuropsychiatric disorders are programmed into our brains during early development. There is no proof that postnatal social environment has any crucial effect on gender identity or sexual orientation. Structural and functional sex differences in brain areas, together with changes in sex hormone levels and their receptors in development and adulthood, are closely related to sex differences in behavior and neuropsychiatric disorders. Knowing that such a relationship exists may help bring about sex-specific therapeutic strategies.
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Affiliation(s)
- Ai-Min Bao
- Department of Neurobiology, Institute of Neuroscience, Zhejiang University School of Medicine, Hangzhou, China.
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Savic I, Garcia-Falgueras A, Swaab DF. Sexual differentiation of the human brain in relation to gender identity and sexual orientation. PROGRESS IN BRAIN RESEARCH 2010; 186:41-62. [DOI: 10.1016/b978-0-444-53630-3.00004-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Hu SH, Wei N, Wang QD, Yan LQ, Wei EQ, Zhang MM, Hu JB, Huang ML, Zhou WH, Xu Y. Patterns of brain activation during visually evoked sexual arousal differ between homosexual and heterosexual men. AJNR Am J Neuroradiol 2008; 29:1890-6. [PMID: 18768725 DOI: 10.3174/ajnr.a1260] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Nowadays the mechanism of homosexuality is little known. Few studies have been carried out to explore the brain functional changes of homosexual men during sexual arousal. We used functional MR imaging (fMRI) to determine whether the patterns of brain activation in homosexual and heterosexual men differed during visually evoked sexual arousal. MATERIALS AND METHODS To all the subjects (10 homosexual and 10 heterosexual), real-time visual stimulation was provided by 3-minute exposure to 3 types of erotic film: heterosexual couples (F-M), male homosexual couples (M-M), and female homosexual couples (F-F) engaged in sexual activity, during which time fMRI was used to determine the patterns of brain activation. Self-reports of level of sexual arousal were collected immediately afterward. RESULTS Statistical parametric mapping showed that viewing erotic film excerpts that induced sexual arousal was associated, in both groups, with activation of the middle prefrontal gyrus, bilateral temporal lobe and postcentral gyrus, thalamus, insula, vermis, left precuneus, occipital cortex, parietal cortex, and cerebellum. In homosexual men, the left angular gyrus, left caudate nucleus, and right pallidum were activated; in contrast, heterosexual men showed no activation in these regions. However, heterosexual men showed activation in the bilateral lingual gyrus, right hippocampus, and right parahippocampal gyrus, areas not activated in homosexual men. In both groups, region-of-interest analysis revealed no correlation between the magnitude of amygdala or thalamus activation and the reported level of sexual arousal. CONCLUSION Our findings indicate that different neural circuits are active during sexual arousal in homosexual and heterosexual men and may contribute to a better understanding of the neural basis of male sexual orientation.
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Affiliation(s)
- S-H Hu
- Department of Mental Health, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Sexual orientation and its basis in brain structure and function. Proc Natl Acad Sci U S A 2008; 105:10273-4. [PMID: 18653758 DOI: 10.1073/pnas.0805542105] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
During the intrauterine period the human brain develops in the male direction via direct action of a boy's testosterone, and in the female direction through the absence of this hormone in a girl. During this time, gender identity (the feeling of being a man or a woman), sexual orientation, and other behaviors are programmed. As sexual differentiation of the genitals takes places in the first 2 months of pregnancy, and sexual differentiation of the brain starts during the second half of pregnancy, these two processes may be influenced independently of each other, resulting in transsexuality. This also means that in the case of an ambiguous gender at birth, the degree of masculinization of the genitals may not reflect the same degree of masculinization of the brain. Differences in brain structures and brain functions have been found that are related to sexual orientation and gender.
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Affiliation(s)
- Dick F Swaab
- Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam ZO, The Netherlands.
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