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Spool JA, Bergan JF, Remage-Healey L. A neural circuit perspective on brain aromatase. Front Neuroendocrinol 2022; 65:100973. [PMID: 34942232 PMCID: PMC9667830 DOI: 10.1016/j.yfrne.2021.100973] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 12/23/2022]
Abstract
This review explores the role of aromatase in the brain as illuminated by a set of conserved network-level connections identified in several vertebrate taxa. Aromatase-expressing neurons are neurochemically heterogeneous but the brain regions in which they are found are highly-conserved across the vertebrate lineage. During development, aromatase neurons have a prominent role in sexual differentiation of the brain and resultant sex differences in behavior and human brain diseases. Drawing on literature primarily from birds and rodents, we delineate brain regions that express aromatase and that are strongly interconnected, and suggest that, in many species, aromatase expression essentially defines the Social Behavior Network. Moreover, in several cases the inputs to and outputs from this core Social Behavior Network also express aromatase. Recent advances in molecular and genetic tools for neuroscience now enable in-depth and taxonomically diverse studies of the function of aromatase at the neural circuit level.
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Affiliation(s)
- Jeremy A Spool
- Center for Neuroendocrine Studies, Neuroscience and Behavior Graduate Program, University of Massachusetts, Amherst, MA 01003, United States
| | - Joseph F Bergan
- Center for Neuroendocrine Studies, Neuroscience and Behavior Graduate Program, University of Massachusetts, Amherst, MA 01003, United States
| | - Luke Remage-Healey
- Center for Neuroendocrine Studies, Neuroscience and Behavior Graduate Program, University of Massachusetts, Amherst, MA 01003, United States.
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2
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Wright KN, Johnson NL, Dossat AM, Wilson JT, Wesson DW. Reducing local synthesis of estrogen in the tubular striatum promotes attraction to same-sex odors in female mice. Horm Behav 2022; 140:105122. [PMID: 35101702 DOI: 10.1016/j.yhbeh.2022.105122] [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: 11/23/2021] [Revised: 01/14/2022] [Accepted: 01/19/2022] [Indexed: 11/17/2022]
Abstract
Brain-derived 17β-estradiol (E2) confers rapid effects on neural activity. The tubular striatum (TuS, also called the olfactory tubercle) is both capable of local E2 synthesis due to its abundant expression of aromatase and is a critical locus for odor-guided motivated behavior and odor hedonics. TuS neurons also contain mRNA for estrogen receptors α, β, and the G protein-coupled estrogen receptor. We demonstrate here that mRNA for estrogen receptors appears to be expressed upon TuS dopamine 1 receptor-expressing neurons, suggesting that E2 may play a neuromodulatory role in circuits which are important for motivated behavior. Therefore, we reasoned that E2 in the TuS may influence attraction to urinary odors which are highly attractive. Using whole-body plethysmography, we examined odor-evoked high-frequency sniffing as a measure of odor attaction. Bilateral infusion of the aromatase inhibitor letrozole into the TuS of gonadectomized female adult mice induced a resistance to habituation over successive trials in their investigatory sniffing for female mouse urinary odors, indicative of an enhanced attraction. All males displayed resistance to habituation for female urinary odors, indicative of enhanced attraction that is independent from E2 manipulation. Letrozole's effects were not due to group differences in basal respiration, nor changes in the ability to detect or discriminate between odors (both monomolecular odorants and urinary odors). Therefore, de novo E2 synthesis in the TuS impacts females' but not males' attraction to female urinary odors, suggesting a sex-specific influence of E2 in odor hedonics.
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Affiliation(s)
- Katherine N Wright
- University of Florida, Department of Pharmacology & Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, 1200 Newell Dr., Gainesville, FL 32610, USA.
| | - Natalie L Johnson
- University of Florida, Department of Pharmacology & Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, 1200 Newell Dr., Gainesville, FL 32610, USA
| | - Amanda M Dossat
- University of Florida, Department of Pharmacology & Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, 1200 Newell Dr., Gainesville, FL 32610, USA
| | - Jamie T Wilson
- University of Florida, Department of Pharmacology & Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, 1200 Newell Dr., Gainesville, FL 32610, USA
| | - Daniel W Wesson
- University of Florida, Department of Pharmacology & Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, 1200 Newell Dr., Gainesville, FL 32610, USA
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3
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Arroyo MAM, Santos PRDS, de Oliveira MF, de Assis AC. Prolonged use of letrozole causes morphological changes on gonads in Galea spixii. Anim Reprod 2021; 18:e20200029. [PMID: 34306212 PMCID: PMC8291776 DOI: 10.1590/1984-3143-ar2020-0029] [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: 10/20/2020] [Accepted: 06/01/2021] [Indexed: 11/22/2022] Open
Abstract
Letrozole is used as a therapeutic agent in reproductive disorders caused by high estrogen levels. Letrozole inhibits cytochrome P450 aromatase and reduces estrogen levels. However, the effects of long-term use on reproductive traits are unknown. The aim of this study was to evaluate the prolonged use of letrozole in the gonads of rodents (Spix's yellow-toothed cavy; Galea spixii). Forty-eight rodents (24 males and 24 females) were randomly divided into the treated and control groups. Letrozole administration started at 15 days of age and continued weekly until 30, 45, 90, and 120 days of age. The body, testis, and ovary weights were analyzed, as well as the morphological progression of spermatogenesis and folliculogenesis. Macroscopically, body weight gain and gonads weight were increased in the letrozole group. Microscopically, the ovaries of treated females showed stratified epithelium and a cellular disorder of the tunica albuginea. In the testes of treated males, the development of seminiferous tubules was delayed and sperm was absent. The collective findings indicate that the prolonged use of letrozole alters secondary sexual characteristics, and causes weight gain, reproductive changes, and male infertility.
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Affiliation(s)
- Maria Angelica Machado Arroyo
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Paulo Ramos da Silva Santos
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | - Antônio Chaves de Assis
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brasil
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4
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Hayashi K, Gonzales TK, Kapoor A, Ziegler TE, Meethal SV, Atwood CS. Development of Classification Models for the Prediction of Alzheimer's Disease Utilizing Circulating Sex Hormone Ratios. J Alzheimers Dis 2020; 76:1029-1046. [PMID: 32623397 DOI: 10.3233/jad-200418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND While sex hormones are essential for normal cognitive health, those individuals with greater endocrine dyscrasia around menopause and with andropause are more likely to develop cognitive loss and Alzheimer's disease (AD). OBJECTIVE To assess whether circulating sex hormones may provide an etiologically significant, surrogate biomarker, for cognitive decline. METHODS Plasma (n = 152) and serum (n = 107) samples from age- and gender-matched AD and control subjects from the Wisconsin Alzheimer's Disease Research Center (ADRC) were analyzed for 11 steroids and follicle-stimulating hormone. Logistic regression (LR), correlation analyses, and recursive partitioning (RP) were used to examine the interactions of hormones and hormone ratios and their association with AD. Models generated were then tested on an additional 43 ADRC samples. RESULTS The wide variation and substantial overlap in the concentrations of all circulating sex steroids across control and AD groups precluded their use for predicting AD. Classification tree analyses (RP) revealed interactions among single hormones and hormone ratios that associated with AD status, the most predictive including only the hormone ratios identified by LR. The strongest associations were observed between cortisol, cortisone, and androstenedione with AD, with contributions from progesterone and 17β-estradiol. Utilizing this model, we correctly predicted 81% of AD test cases and 64% of control test cases. CONCLUSION We have developed a diagnostic model for AD, the Wisconsin Hormone Algorithm Test for Cognition (WHAT-Cog), that utilizes classification tree analyses of hormone ratios. Further refinement of this technology could provide a quick and cheap diagnostic method for screening those with AD.
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Affiliation(s)
- Kentaro Hayashi
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Tina K Gonzales
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.,Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI, USA
| | - Amita Kapoor
- Assay Services Unit and Institute for Clinical and Translational Research Core Laboratory, National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Toni E Ziegler
- Assay Services Unit and Institute for Clinical and Translational Research Core Laboratory, National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Sivan Vadakkadath Meethal
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Craig S Atwood
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.,Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI, USA.,School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
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5
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Amodei R, Gribbin K, He W, Lindgren I, Corder KR, Jonker SS, Estill CT, Coolen LM, Lehman MN, Whitler W, Stormshak F, Roselli CE. Role for Kisspeptin and Neurokinin B in Regulation of Luteinizing Hormone and Testosterone Secretion in the Fetal Sheep. Endocrinology 2020; 161:bqaa013. [PMID: 32005991 PMCID: PMC7079722 DOI: 10.1210/endocr/bqaa013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 01/29/2020] [Indexed: 11/19/2022]
Abstract
Evidence suggests that the hypothalamic-pituitary-gonadal (HPG) axis is active during the critical period for sexual differentiation of the ovine sexually dimorphic nucleus, which occurs between gestational day (GD) 60 and 90. Two possible neuropeptides that could activate the fetal HPG axis are kisspeptin and neurokinin B (NKB). We used GD85 fetal lambs to determine whether intravenous administration of kisspeptin-10 (KP-10) or senktide (NKB agonist) could elicit luteinizing hormone (LH) release. Immunohistochemistry and fluorescent in situ hybridization (FISH) were employed to localize these peptides in brains of GD60 and GD85 lamb fetuses. In anesthetized fetuses, KP-10 elicited robust release of LH that was accompanied by a delayed rise in serum testosterone in males. Pretreatment with the GnRH receptor antagonist (acyline) abolished the LH response to KP-10, confirming a hypothalamic site of action. In unanesthetized fetuses, senktide, as well as KP-10, elicited LH release. The senktide response of females was greater than that of males, indicating a difference in NKB sensitivity between sexes. Gonadotropin-releasing hormone also induced a greater LH discharge in females than in males, indicating that testosterone negative feedback is mediated through pituitary gonadotrophs. Kisspeptin and NKB immunoreactive cells in the arcuate nucleus were more abundant in females than in males. Greater than 85% of arcuate kisspeptin cells costained for NKB. FISH revealed that the majority of these were kisspeptin/NKB/dynorphin (KNDy) neurons. These results support the hypothesis that kisspeptin-GnRH signaling regulates the reproductive axis of the ovine fetus during the prenatal critical period acting to maintain a stable androgen milieu necessary for brain masculinization.
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Affiliation(s)
- Rebecka Amodei
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon
| | - Kyle Gribbin
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon
| | - Wen He
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Isa Lindgren
- Center for Developmental Health, Oregon Health and Science University, Portland, Oregon
| | - Keely R Corder
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon
| | - Sonnet S Jonker
- Center for Developmental Health, Oregon Health and Science University, Portland, Oregon
| | - Charles T Estill
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon
- College of Veterinary Medicine, Oregon State University, Corvallis, Oregon
| | - Lique M Coolen
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Michael N Lehman
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - William Whitler
- College of Veterinary Medicine, Oregon State University, Corvallis, Oregon
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon
| | - Charles E Roselli
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon
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6
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Cansler HL, Wright KN, Stetzik LA, Wesson DW. Neurochemical organization of the ventral striatum's olfactory tubercle. J Neurochem 2020; 152:425-448. [PMID: 31755104 PMCID: PMC7042089 DOI: 10.1111/jnc.14919] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/08/2019] [Accepted: 11/17/2019] [Indexed: 12/11/2022]
Abstract
The ventral striatum is a collection of brain structures, including the nucleus accumbens, ventral pallidum and the olfactory tubercle (OT). While much attention has been devoted to the nucleus accumbens, a comprehensive understanding of the ventral striatum and its contributions to neurological diseases requires an appreciation for the complex neurochemical makeup of the ventral striatum's other components. This review summarizes the rich neurochemical composition of the OT, including the neurotransmitters, neuromodulators and hormones present. We also address the receptors and transporters involved in each system as well as their putative functional roles. Finally, we end with briefly reviewing select literature regarding neurochemical changes in the OT in the context of neurological disorders, specifically neurodegenerative disorders. By overviewing the vast literature on the neurochemical composition of the OT, this review will serve to aid future research into the neurobiology of the ventral striatum.
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Affiliation(s)
- Hillary L Cansler
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
| | - Katherine N Wright
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
| | - Lucas A Stetzik
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
| | - Daniel W Wesson
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
- Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, USA
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7
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Montelli S, Graïc JM, Ruiz JA, Stelletta C, Peruffo A. Neurochemical characterization of the hypothalamus of the early fetal and newborn alpaca Vicugna pacos. Anat Rec (Hoboken) 2019; 303:2865-2877. [PMID: 31854109 DOI: 10.1002/ar.24342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 11/05/2019] [Accepted: 11/14/2019] [Indexed: 11/08/2022]
Abstract
In this study we performed a neurochemical characterization of the hypothalamus in the developing alpaca (Vicugna pacos) with the aim of revealing the distributions of immunoreactive (-ir) cells containing parvalbumin (PV), calbindin (CB), calretinin (CR), the somatostatin (SOM), the enzyme aromatase P450 (P450Arom), the estrogen receptor α (ER-α), and estrogen receptor β (ER-β) in embryonal stages, early fetal age, and in the newborn. This analysis has been carried out on embryos at 20, 30, 45 days, fetuses at 90 days, and newborn alpaca. Our immunohistochemical results revealed no cells-ir throughout the embryonic hypothalami of 20, 30, and 45 days. On the fetal stage of 90 days, SOM-ir cells were observed in the lateral hypothalamus and the ventromedial nuclei of the tuberal region. We checked for the presence of P450Arom-ir cells in the periventricular area and dorsomedial hypothalamic nucleus of the tuberal region. In these fetal stages, no PV-ir, CB-ir, CR-ir or ERs-ir cells were identified. In the newborn, the PV-ir, CB-ir, CR-ir, and SOM-ir cells were detected in both the anterior and tuberal hypothalamic area. The P450Arom-ir cells the ER-α-ir and ER-β-ir cells were found in the anterior hypothalamus. Our results offer a contribution in the future purpose to obtain a time-expression pattern of the considered markers in alpaca during gestation and represents a foundation for future investigations on the alpaca brain to define the cross talk between PV, CB, CR, P450Arom, SOM, and ERs in the hypothalamus, the strategic region for the control of the reproductive behavior.
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Affiliation(s)
- Stefano Montelli
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy
| | - Jaime Antonio Ruiz
- Laboratorio de Biotecnologías Reproductivas, Facultad de Ciencias de Ingeniería, Universidad Nacional de Huancavelica, Huancavelica, Peru
| | - Calogero Stelletta
- Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Italy
| | - Antonella Peruffo
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy
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8
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Shay DA, Vieira-Potter VJ, Rosenfeld CS. Sexually Dimorphic Effects of Aromatase on Neurobehavioral Responses. Front Mol Neurosci 2018; 11:374. [PMID: 30374289 PMCID: PMC6196265 DOI: 10.3389/fnmol.2018.00374] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 09/21/2018] [Indexed: 01/16/2023] Open
Abstract
Aromatase is the enzyme responsible for converting testosterone to estradiol. In mammals, aromatase is expressed in the testes, ovaries, brain, and other tissues. While estrogen is traditionally associated with reproduction and sexual behavior in females, our current understanding broadens this perspective to include such biological functions as metabolism and cognition. It is now well-recognized that aromatase plays a vital lifetime role in brain development and neurobehavioral function in both sexes. Thus, ongoing investigations seek to highlight potentially vital sex differences in the role of aromatase, particularly regarding its centrally mediated effects. To characterize the role of aromatase in mediating such functions, effects of aromatase inhibitor (AI) treatments on humans and animal models have been determined. Aromatase knockout (ArKO) mice that systemically lack the enzyme have also been employed. Humans possessing mutations in the gene encoding aromatase, CYP19, have also provided critical insight into how aromatase affects brain function in a possible sex-dependent manner. A better understanding of how AIs, used to treat breast cancer and other clinical conditions, may detrimentally affect neurobehavioral responses will likely promote development of future therapies to combat these effects. Herein, we will provide a critical review of the current knowledge of sex differences in aromatase regulation of various neurobehavioral functions. Although many species have been used to better understand the functions of aromatase, this review focuses on rodent models and humans. Critical gaps in our present understanding of this area will be considered, and important future research directions will be discussed.
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Affiliation(s)
- Dusti A Shay
- Nutrition and Exercise Physiology, University of Missouri Columbia, MO, United States
| | | | - 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.,Department of Biomedical Sciences, University of Missouri Columbia, MO, United States
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9
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Construction of an MRI 3D high resolution sheep brain template. Magn Reson Imaging 2015; 33:1329-1337. [PMID: 26363468 DOI: 10.1016/j.mri.2015.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/16/2015] [Accepted: 09/02/2015] [Indexed: 01/05/2023]
Abstract
Sheep is a developing animal model used in the field of neurosciences for the study of many behavioral, physiological or pathophysiological mechanisms, including for example, the central control of social behavior, brain injury or neurodegenerative diseases. However, sheep remains an orphan species in the field of magnetic resonance imaging (MRI). Therefore, a mean image (template), resulting of registrations of multiple subject images is needed and currently does not exist. In this study, we: i) computed multimodal high resolution 3D in-vivo sheep brain templates of T1 weighted (T1W) and T2W images, ii) computed gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) prior probability maps using linear and optimized non-linear registrations iii) used prior probability maps to perform the segmentation of a single brain tissues. Computed multimodal sheep brain templates showed to preserve and underline all brain patterns of a single T1W or T2W image, and prior probability maps allowed to improve the segmentation of brain tissues. Finally, we demonstrated that these templates and prior probability maps were able to be portable in other publicly available imaging software and could be used as standardized spaces for multi-institution neuroimaging studies or other neuroscience methods.
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10
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Reddy RC, Amodei R, Estill CT, Stormshak F, Meaker M, Roselli CE. Effect of Testosterone on Neuronal Morphology and Neuritic Growth of Fetal Lamb Hypothalamus-Preoptic Area and Cerebral Cortex in Primary Culture. PLoS One 2015; 10:e0129521. [PMID: 26053052 PMCID: PMC4460015 DOI: 10.1371/journal.pone.0129521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/08/2015] [Indexed: 12/22/2022] Open
Abstract
Testosterone plays an essential role in sexual differentiation of the male sheep brain. The ovine sexually dimorphic nucleus (oSDN), is 2 to 3 times larger in males than in females, and this sex difference is under the control of testosterone. The effect of testosterone on oSDN volume may result from enhanced expansion of soma areas and/or dendritic fields. To test this hypothesis, cells derived from the hypothalamus-preoptic area (HPOA) and cerebral cortex (CTX) of lamb fetuses were grown in primary culture to examine the direct morphological effects of testosterone on these cellular components. We found that within two days of plating, neurons derived from both the HPOA and CTX extend neuritic processes and express androgen receptors and aromatase immunoreactivity. Both treated and control neurites continue to grow and branch with increasing time in culture. Treatment with testosterone (10 nM) for 3 days significantly (P < 0.05) increased both total neurite outgrowth (35%) and soma size (8%) in the HPOA and outgrowth (21%) and number of branch points (33%) in the CTX. These findings indicate that testosterone-induced somal enlargement and neurite outgrowth in fetal lamb neurons may contribute to the development of a fully masculine sheep brain.
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Affiliation(s)
- Radhika C. Reddy
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Rebecka Amodei
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Charles T. Estill
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, United States of America
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Mary Meaker
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Charles E. Roselli
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
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11
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Roselli CE, Reddy RC, Estill CT, Scheldrup M, Meaker M, Stormshak F, Montilla HJ. Prenatal influence of an androgen agonist and antagonist on the differentiation of the ovine sexually dimorphic nucleus in male and female lamb fetuses. Endocrinology 2014; 155:5000-10. [PMID: 25216387 PMCID: PMC4239424 DOI: 10.1210/en.2013-2176] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 09/05/2014] [Indexed: 01/09/2023]
Abstract
The ovine sexually dimorphic nucleus (oSDN) is 2 times larger in rams than in ewes. Sexual differentiation of the oSDN is produced by testosterone exposure during the critical period occurring between gestational day (GD)60 and GD90 (term, 147 d). We tested the hypothesis that testosterone acts through the androgen receptor to control development of the male-typical oSDN. In experiment 1, pregnant ewes received injections of vehicle, androgen receptor antagonist flutamide, or nonaromatizable androgen dihydrotestosterone (DHT) propionate during the critical period. Fetuses were delivered at GD135. Both antagonist and agonist treatments significantly reduced mean oSDN volume in males but had no effects in females. Experiment 2, we analyzed the effect of treatments on the fetal hypothalamic-pituitary-gonadal axis to determine whether compensatory changes in hormone secretion occurred that could explain the effect of DHT. Pregnant ewes were injected with vehicle, flutamide, or DHT propionate from GD60 to GD84, and fetuses were delivered on GD85. Flutamide significantly increased LH and testosterone in males, whereas DHT significantly decreased both hormones. In females, LH was unaffected by flutamide but significantly reduced by DHT exposure. DHT significantly decreased pituitary gonadotropin and hypothalamic kisspeptin mRNA expression in males and females. These results suggest that androgen receptor mediates the effect of testosterone on oSDN masculinization, because this process was blocked by the androgen receptor antagonist flutamide in eugonadal males. In contrast, the reduction of oSDN volume observed after DHT exposure appears to be mediated by a negative feedback mechanism exerted on the hypothalamus to reduce LH and testosterone secretion. The reduced androgen exposure most likely accounted for the decreased oSDN volume. We conclude that, during the critical period, the male reproductive axis in long gestation species, such as sheep, is sufficiently developed to react to perturbations in serum androgens and mitigate disruptions in brain masculinization.
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Affiliation(s)
- Charles E Roselli
- Department of Physiology and Pharmacology (C.E.R., R.C.R., M.S.), Oregon Health and Science University, Portland, Oregon 97239-3098; and Departments of Animal and Rangeland Sciences (C.T.E., M.M., F.S.) and Clinical Sciences (C.T.E., H.J.M.), College of Veterinary Medicine, Oregon State University, Corvallis, Oregon 97331-4501
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12
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Reddy R, Estill C, Meaker M, Stormshak F, Roselli CE. Sex differences in expression of oestrogen receptor α but not androgen receptor mRNAs in the foetal lamb brain. J Neuroendocrinol 2014; 26:321-8. [PMID: 24730418 PMCID: PMC4071168 DOI: 10.1111/jne.12152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/12/2014] [Accepted: 03/16/2014] [Indexed: 11/26/2022]
Abstract
Gonadal steroid hormones play important roles during critical periods of development to organise brain structures that control sexually dimorphic neuroendocrine responses and behaviours. Specific receptors for androgens and oestrogens must be expressed at appropriate times during development to mediate these processes. The present study was performed to test for sex differences in the relative expression of oestrogen receptor (ER)α and androgen receptor (AR) mRNA during the window of time in gestation that is critical for behavioural masculinisation and differentiation of the ovine sexually dimorphic nucleus (oSDN) in the sheep. In addition, we examined whether ERα and AR mRNA expression is localised within the nascent oSDN and could be involved in its development. Using the quantitative real-time polymerase chain reaction, we found that females expressed more ERα mRNA than males in medial preoptic area and medial basal hypothalamus during the mid-gestational critical period for brain sexual differentiation. No sex differences were found for AR mRNA in any tissue examined or for ERα in amygdala and frontal cortex. Using radioactive in situ hybridisation, we found that the distributions of ERα and AR mRNA overlapped with aromatase mRNA, which delineates the boundaries of the developing oSDN and identifies this nucleus as a target for both androgens and oestrogens. These data demonstrate that the transcriptional machinery for synthesising gonadal steroid receptors is functional in the foetal lamb brain during the critical period for sexual differentiation and suggest that possible mechanisms for establishing dimorphisms controlled by gonadal steroids may exist at the level of steroid hormone receptor expression.
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Affiliation(s)
- Radhika Reddy
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239-3098
| | - Charles Estill
- College of Veterinary Medicine Oregon State University, Corvallis, OR 97331-4501
| | - Mary Meaker
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
| | - Charles E. Roselli
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239-3098
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
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13
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Reddy RC, Scheldrup M, Meaker M, Stormshak F, Estill CT, Roselli CE. Cell death in the central division of the medial preoptic nucleus of male and female lamb fetuses. Brain Res 2014; 1554:21-8. [PMID: 24491631 DOI: 10.1016/j.brainres.2014.01.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/22/2014] [Accepted: 01/25/2014] [Indexed: 10/25/2022]
Abstract
The medial preoptic area of the adult sheep contains an ovine sexually dimorphic nucleus (oSDN) that is larger and has more neurons in males than in females. In the lamb fetus, the nascent oSDN occupies the central division of the medial preoptic nucleus (MPNc) and consists of a cluster of cells that is organized by the action of testosterone during gestational days 60-90 of a 147 day term pregnancy. The current study sought to determine whether programmed cell death contributes to the emergence of the oSDN. Male and female lamb fetuses were euthanized at different ages spanning the period during which the oSDN is organized. The expression of the pro- and anti-apoptotic genes bcl-2 and bax, respectively, was measured by quantitative RT-PCR to assess possible sex differences in neuron vulnerability to programmed cell death. The appearance of DNA-fragmentation was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and used to estimate the occurrence of apoptotic cell death. We found that bcl-2 and bax mRNA expression in the medial preoptic area of the developing lamb fetus decreased during the last half of the 147-day gestation. The ratio of bcl-2/bax gene expression was highest at gestational day 85 but was equivalent between males and females. TUNEL staining in the MPNc was very low and although it decreased significantly with age, it was not significantly different between sexes. These results using two different methods to assess cell death indicate that a sex difference in the incidence of cell death is not a primary mechanism leading to sexual differentiation of the oSDN.
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Affiliation(s)
- Radhika C Reddy
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA
| | - Melissa Scheldrup
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA
| | - Mary Meaker
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Charles T Estill
- College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Charles E Roselli
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA.
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14
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Stanić D, Dubois S, Chua HK, Tonge B, Rinehart N, Horne MK, Boon WC. Characterization of aromatase expression in the adult male and female mouse brain. I. Coexistence with oestrogen receptors α and β, and androgen receptors. PLoS One 2014; 9:e90451. [PMID: 24646567 PMCID: PMC3960106 DOI: 10.1371/journal.pone.0090451] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 01/30/2014] [Indexed: 01/13/2023] Open
Abstract
Aromatase catalyses the last step of oestrogen synthesis. There is growing evidence that local oestrogens influence many brain regions to modulate brain development and behaviour. We examined, by immunohistochemistry, the expression of aromatase in the adult male and female mouse brain, using mice in which enhanced green fluorescent protein (EGFP) is transcribed following the physiological activation of the Cyp19A1 gene. EGFP-immunoreactive processes were distributed in many brain regions, including the bed nucleus of the stria terminalis, olfactory tubercle, medial amygdaloid nucleus and medial preoptic area, with the densest distributions of EGFP-positive cell bodies in the bed nucleus and medial amygdala. Differences between male and female mice were apparent, with the density of EGFP-positive cell bodies and fibres being lower in some brain regions of female mice, including the bed nucleus and medial amygdala. EGFP-positive cell bodies in the bed nucleus, lateral septum, medial amygdala and hypothalamus co-expressed oestrogen receptor (ER) α and β, or the androgen receptor (AR), although single-labelled EGFP-positive cells were also identified. Additionally, single-labelled ERα-, ERβ- or AR-positive cell bodies often appeared to be surrounded by EGFP-immunoreactive nerve fibres/terminals. The widespread distribution of EGFP-positive cell bodies and fibres suggests that aromatase signalling is common in the mouse brain, and that locally synthesised brain oestrogens could mediate biological effects by activating pre- and post-synaptic oestrogen α and β receptors, and androgen receptors. The higher number of EGFP-positive cells in male mice may indicate that the autocrine and paracrine effects of oestrogens are more prominent in males than females.
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Affiliation(s)
- Davor Stanić
- Systems Neurophysiology, The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Department of Florey Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Sydney Dubois
- Neurodegeneration, The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Départment de Biologie, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Hui Kheng Chua
- Neurodegeneration, The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Bruce Tonge
- Centre for Developmental Psychiatry & Psychology, Monash University, Clayton, Victoria, Australia
| | - Nicole Rinehart
- Centre for Developmental Psychiatry & Psychology, Monash University, Clayton, Victoria, Australia
| | - Malcolm K. Horne
- Neurodegeneration, The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Department of Florey Neuroscience, University of Melbourne, Parkville, Victoria, Australia
- Neurology Department, St Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Wah Chin Boon
- Neurodegeneration, The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Department of Florey Neuroscience, University of Melbourne, Parkville, Victoria, Australia
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia
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