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Kuwahara N, Nicholson K, Isaacs L, MacLusky NJ. Androgen Effects on Neural Plasticity. ANDROGENS: CLINICAL RESEARCH AND THERAPEUTICS 2021; 2:216-230. [PMID: 35024693 PMCID: PMC8744448 DOI: 10.1089/andro.2021.0022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 10/24/2021] [Indexed: 12/20/2022]
Abstract
Androgens are synthesized in the brain, gonads, and adrenal glands, in both sexes, exerting physiologically important effects on the structure and function of the central nervous system. These effects may contribute to the incidence and progression of neurological disorders such as autism spectrum disorder, schizophrenia, and Alzheimer's disease, which occur at different rates in males and females. This review briefly summarizes the current state of knowledge with respect to the neuroplastic effects of androgens, with particular emphasis on the hippocampus, which has been the focus of much of the research in this field.
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Affiliation(s)
- Nariko Kuwahara
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Kate Nicholson
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Lauren Isaacs
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Neil J. MacLusky
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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2
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Shevchouk OT, Ghorbanpoor S, Ball GF, Cornil CA, Balthazart J. Testosterone-induced neuroendocrine changes in the medial preoptic area precede song activation and plasticity in song control nuclei of female canaries. Eur J Neurosci 2017; 45:886-900. [DOI: 10.1111/ejn.13530] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/26/2016] [Accepted: 01/24/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Olesya T. Shevchouk
- GIGA Neurosciences; University of Liege; 15 avenue Hippocrate B-4000 Liège Belgium
| | - Samar Ghorbanpoor
- GIGA Neurosciences; University of Liege; 15 avenue Hippocrate B-4000 Liège Belgium
| | - Gregory F. Ball
- Department of Psychology; University of Maryland; College Park MD USA
| | - Charlotte A. Cornil
- GIGA Neurosciences; University of Liege; 15 avenue Hippocrate B-4000 Liège Belgium
| | - Jacques Balthazart
- GIGA Neurosciences; University of Liege; 15 avenue Hippocrate B-4000 Liège Belgium
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3
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Paulson AF, Prasad MS, Thuringer AH, Manzerra P. Regulation of cadherin expression in nervous system development. Cell Adh Migr 2013; 8:19-28. [PMID: 24526207 DOI: 10.4161/cam.27839] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
This review addresses our current understanding of the regulatory mechanisms for classical cadherin expression during development of the vertebrate nervous system. The complexity of the spatial and temporal expression patterns is linked to morphogenic and functional roles in the developing nervous system. While the regulatory networks controlling cadherin expression are not well understood, it is likely that the multiple signaling pathways active in the development of particular domains also regulate the specific cadherins expressed at that time and location. With the growing understanding of the broader roles of cadherins in cell-cell adhesion and non-adhesion processes, it is important to understand both the upstream regulation of cadherin expression and the downstream effects of specific cadherins within their cellular context.
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Affiliation(s)
- Alicia F Paulson
- Division of Basic Biomedical Sciences; Sanford School of Medicine of The University of South Dakota; Vermillion, SD USA
| | - Maneeshi S Prasad
- Department of Molecular Biosciences; Northwestern University; Evanston, IL USA
| | | | - Pasquale Manzerra
- Division of Basic Biomedical Sciences; Sanford School of Medicine of The University of South Dakota; Vermillion, SD USA
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4
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Verhovshek T, Sengelaub DR. Trophic effects of brain-derived neurotrophic factor blockade in an androgen-sensitive neuromuscular system. Endocrinology 2010; 151:5337-48. [PMID: 20861229 PMCID: PMC2954719 DOI: 10.1210/en.2010-0799] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In adult male rats, androgens are necessary for the maintenance of the motoneurons and their target muscles of the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB) neuromuscular system, regulating motoneuron and muscle morphology, function, and expression of trophic factors. Castration of males results in somal, dendritic, and muscle atrophy as well as increases in brain-derived neurotrophic factor (BDNF) in the target musculature. Because BDNF can have either facilitative or inhibitory effects in other systems, we examined SNB neuromuscular morphology after BDNF blockade using a fusion protein (tyrosine kinase receptor type B IgG). Blockade of BDNF in gonadally intact males resulted in hypertrophy of SNB motoneuron dendrites and target musculature, suggesting that normal levels of BDNF are inhibitory in SNB neuromuscular system. BDNF blockade in castrated males prevented SNB motoneuron atrophy and attenuated target muscle weight loss. This is the first demonstration that the highly androgen-sensitive SNB motoneuron dendrites and target muscles can be maintained in the absence of gonadal hormones and, furthermore, that blocking BDNF can have trophic effects on skeletal muscle. These results suggest that whereas BDNF is involved in the signaling cascade mediating the androgenic support of SNB neuromuscular morphology, its action can be inhibitory. Furthermore, the elevations in BDNF after castration may be responsible for the castration-induced atrophy in SNB motoneurons and target muscles, and the trophic effects of androgens may be mediated in part through a suppression of BDNF. These results may have relevance to therapeutic approaches to the treatment of neurodegenerative disease or myopathies.
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Affiliation(s)
- Tom Verhovshek
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana 47405, USA
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Fernando SM, Rao P, Niel L, Chatterjee D, Stagljar M, Monks DA. Myocyte androgen receptors increase metabolic rate and improve body composition by reducing fat mass. Endocrinology 2010; 151:3125-32. [PMID: 20427479 PMCID: PMC2903941 DOI: 10.1210/en.2010-0018] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Testosterone and other androgens are thought to increase lean body mass and reduce fat body mass in men by activating the androgen receptor. However, the clinical potential of androgens for improving body composition is hampered by our limited understanding of the tissues and cells that promote such changes. Here we show that selective overexpression of androgen receptor in muscle cells (myocytes) of transgenic male rats both increases lean mass percentage and reduces fat mass. Similar changes in body composition are observed in human skeletal actin promoter driving expression of androgen receptor (HSA-AR) transgenic mice and result from acute testosterone treatment of transgenic female HSA-AR rats. These shifts in body composition in HSA-AR transgenic male rats are associated with hypertrophy of type IIb myofibers and decreased size of adipocytes. Metabolic analyses of transgenic males show higher activity of mitochondrial enzymes in skeletal muscle and increased O(2) consumption by the rats. These results indicate that androgen signaling in myocytes not only increases muscle mass but also reduces fat body mass, likely via increases in oxidative metabolism.
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Affiliation(s)
- Shannon M Fernando
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada M5S 3G3
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6
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Verhovshek T, Buckley KE, Sergent MA, Sengelaub DR. Testosterone metabolites differentially maintain adult morphology in a sexually dimorphic neuromuscular system. Dev Neurobiol 2010; 70:206-21. [PMID: 20024940 PMCID: PMC2905164 DOI: 10.1002/dneu.20780] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The lumbar spinal cord of rats contains the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB). Androgens are necessary for the development of the SNB neuromuscular system, and in adulthood, continue to influence the morphology and function of the motoneurons and their target musculature. However, estrogens are also involved in the development of the SNB system, and are capable of maintaining function in adulthood. In this experiment, we assessed the ability of testosterone metabolites, estrogens and nonaromatizable androgens, to maintain neuromuscular morphology in adulthood. Motoneuron and muscle morphology was assessed in adult normal males, sham-castrated males, castrated males treated with testosterone, dihydrotestosterone, estradiol, or left untreated, and gonadally intact males treated with the 5alpha-reductase inhibitor finasteride or the aromatase inhibitor fadrozole. After 6 weeks of treatment, SNB motoneurons were retrogradely labeled with cholera toxin-HRP and reconstructed in three dimensions. Castration resulted in reductions in SNB target muscle size, soma size, and dendritic morphology. Testosterone treatment after castration maintained SNB soma size, dendritic morphology, and elevated target muscle size; dihydrotestosterone treatment also maintained SNB dendritic length, but was less effective than testosterone in maintaining both SNB soma size and target muscle weight. Treatment of intact males with finasteride or fadrozole did not alter the morphology of SNB motoneurons or their target muscles. In contrast, estradiol treatment was completely ineffective in preventing castration-induced atrophy of the SNB neuromuscular system. Together, these results suggest that the maintenance of adult motoneuron or muscle morphology is strictly mediated by androgens.
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Affiliation(s)
- Tom Verhovshek
- Department of Psychological and Brain Sciences and Program in Neuroscience Indiana University, Bloomington, Indiana 47405
| | - Katherine E. Buckley
- Department of Psychological and Brain Sciences and Program in Neuroscience Indiana University, Bloomington, Indiana 47405
| | - Melissa A. Sergent
- Department of Psychological and Brain Sciences and Program in Neuroscience Indiana University, Bloomington, Indiana 47405
| | - Dale R. Sengelaub
- Department of Psychological and Brain Sciences and Program in Neuroscience Indiana University, Bloomington, Indiana 47405
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7
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Neuroprotective actions of androgens on motoneurons. Front Neuroendocrinol 2009; 30:130-41. [PMID: 19393684 PMCID: PMC2726741 DOI: 10.1016/j.yfrne.2009.04.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 04/03/2009] [Accepted: 04/14/2009] [Indexed: 01/30/2023]
Abstract
Androgens have a variety of protective and therapeutic effects in both the central and peripheral nervous systems. Here we review these effects as they related specifically to spinal and cranial motoneurons. Early in development, androgens are critical for the formation of important neuromuscular sex differences, decreasing the magnitude of normally occurring cell death in select motoneuron populations. Throughout the lifespan, androgens also protect against motoneuron death caused by axonal injury. Surviving motoneurons also display regressive changes to their neurites as a result of both direct axonal injury and loss of neighboring motoneurons. Androgen treatment enhances the ability of motoneurons to recover from these regressive changes and regenerate both axons and dendrites, restoring normal neuromuscular function. Androgens exert these protective effects by acting through a variety of molecular pathways. Recent work has begun to examine how androgen treatment can interact with other treatment strategies in promoting recovery from motoneuron injury.
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Monks DA, Rao P, Mo K, Johansen JA, Lewis G, Kemp MQ. Androgen receptor and Kennedy disease/spinal bulbar muscular atrophy. Horm Behav 2008; 53:729-40. [PMID: 18321505 PMCID: PMC2883265 DOI: 10.1016/j.yhbeh.2007.12.009] [Citation(s) in RCA: 18] [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: 07/24/2007] [Revised: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 02/06/2023]
Abstract
Kennedy Disease/Spinal Bulbar Muscular Atrophy (KD/SBMA) is a progressive neurodegenerative disease caused by genetic polyglutamine expansion of the androgen receptor. We have recently found that overexpression of wildtype androgen receptor in skeletal muscle of transgenic mice results in a KD/SBMA phenotype. This surprising result challenges the orthodox view that KD/SBMA requires expression of polyglutamine expanded androgen receptor within motoneurons. Theories relating to the etiology of this disease drawn from studies of human patients, cellular and mouse models are considered with a special emphasis on potential myogenic contributions to as well as the molecular etiology of KD/SBMA.
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Affiliation(s)
- Douglas Ashley Monks
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6.
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9
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Sengelaub DR, Forger NG. The spinal nucleus of the bulbocavernosus: firsts in androgen-dependent neural sex differences. Horm Behav 2008; 53:596-612. [PMID: 18191128 PMCID: PMC2423220 DOI: 10.1016/j.yhbeh.2007.11.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 11/01/2007] [Accepted: 11/05/2007] [Indexed: 11/30/2022]
Abstract
Cell number in the spinal nucleus of the bulbocavernosus (SNB) of rats was the first neural sex difference shown to differentiate under the control of androgens, acting via classical intracellular androgen receptors. SNB motoneurons reside in the lumbar spinal cord and innervate striated muscles involved in copulation, including the bulbocavernosus (BC) and levator ani (LA). SNB cells are much larger and more numerous in males than in females, and the BC/LA target muscles are reduced or absent in females. The relative simplicity of this neuromuscular system has allowed for considerable progress in pinpointing sites of hormone action, and identifying the cellular bases for androgenic effects. It is now clear that androgens act at virtually every level of the SNB system, in development and throughout adult life. In this review we focus on effects of androgens on developmental cell death of SNB motoneurons and BC/LA muscles; the establishment and maintenance of SNB motoneuron soma size and dendritic length; BC/LA muscle morphology and physiology; and behaviors controlled by the SNB system. We also describe new data on neurotherapeutic effects of androgens on SNB motoneurons after injury in adulthood.
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Affiliation(s)
- Dale R Sengelaub
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.
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10
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Fargo KN, Sengelaub DR. Androgenic, but not estrogenic, protection of motoneurons from somal and dendritic atrophy induced by the death of neighboring motoneurons. Dev Neurobiol 2007; 67:1094-106. [PMID: 17565709 PMCID: PMC2747260 DOI: 10.1002/dneu.20454] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Motoneuron loss is a significant medical problem, capable of causing severe movement disorders or even death. We have been investigating the effects of motoneuron loss on surviving motoneurons in a lumbar motor nucleus, the spinal nucleus of the bulbocavernosus (SNB). SNB motoneurons undergo marked dendritic and somal atrophy following the experimentally induced death of other nearby SNB motoneurons. However, treatment with testosterone at the time of lesioning attenuates this atrophy. Because testosterone can be metabolized into the estrogen estradiol (as well as other physiologically active steroid hormones), it was unknown whether the protective effect of testosterone was an androgen effect, an estrogen effect, or both. In the present experiment, we used a retrogradely transported neurotoxin to kill the majority of SNB motoneurons on one side of the spinal cord only in adult male rats. Some animals were also treated with either testosterone, the androgen dihydrotestosterone (which cannot be converted into estradiol), or the estrogen estradiol. As seen previously, partial motoneuron loss led to reductions in soma area and in dendritic length and extent in surviving motoneurons. Testosterone and dihydrotestosterone attenuated these reductions, but estradiol had no protective effect. These results indicate that the neuroprotective effect of testosterone on the morphology of SNB motoneurons following partial motoneuron depletion is an androgen effect rather than an estrogen effect.
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Affiliation(s)
- Keith N Fargo
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana 47405, USA
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11
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Abstract
This review focuses on the effect of gonadal steroid hormones, androgen and estrogen, on dendrites in the adult rat central nervous system (CNS). Four hormone-responsive nuclei are considered: The spinal nucleus of the bulbocavernosus (SNB), the medial nucleus of the amygdala (MeA), the ventromedial nucleus of the hypothalamus (VMN), and the CA1 region of the dorsal hippocampus. Particular emphasis is placed on the mode of hormone action in each nucleus. In the SNB, VMN, and hippocampus, hormones appear to mediate their effects indirectly, via cells other than those that display morphological plasticity. In the MeA, estrogen and/or androgen appears to act primarily on those cells whose dendrites are modulated by the hormone. Importantly, increasing levels of gonadal hormones do not simply result in increases in dendritic parameters. In the VMN, high levels of estrogen associated with proestrus increase dendritic spine density in one subset of cells and reduce spine density in another subset. The pyramidal cells of dorsal CA1 also undergo phasic changes in dendritic spine and synapse density across the estrous cycle. The estrogen-induced excitatory synapses connect with preexisting axonal boutons that also form synapses with other CA1 cells, thereby increasing the divergence of excitatory afferents to dorsal CA1. These findings indicate that gonadal steroids have a profound impact on the morphology of dendrites and patterns of synaptic connectivity. Consequently, the experimental manipulation of hormone levels is a powerful tool to study structure-function relationships in the mammalian brain.
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Affiliation(s)
- Bradley M Cooke
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA.
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12
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Fargo KN, Sengelaub DR. Exogenous testosterone prevents motoneuron atrophy induced by contralateral motoneuron depletion. ACTA ACUST UNITED AC 2004; 60:348-59. [PMID: 15281072 DOI: 10.1002/neu.20027] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Gonadal steroids exhibit neuroprotective and neurotherapeutic effects. The lumbar spinal cord of male rats contains a highly androgen-sensitive population of motoneurons, the spinal nucleus of the bulbocavernosus (SNB), whose morphology and function are dependent on testosterone in adulthood. Unilateral SNB motoneuron depletion induces dendritic atrophy in contralateral SNB motoneurons, but this atrophy is reversed in previously castrated males treated with testosterone. In the present experiment we test the hypothesis that the morphology of SNB motoneurons is protected from atrophy after contralateral motoneuron depletion by exogenous testosterone alone (i.e., with no delay between castration and testosterone replacement). We unilaterally depleted SNB motoneurons by intramuscular injection of cholera toxin conjugated saporin. Simultaneously, some saporin-injected rats were castrated and immediately given replacement testosterone. Four weeks later, contralateral SNB motoneurons were labeled with cholera toxin conjugated HRP, soma sizes were measured, and dendritic arbors were reconstructed. Contralateral SNB motoneuron depletion induced somal atrophy and dendritic retraction, but testosterone treatment prevented both of these effects. Thus, the presence of high-normal levels of testosterone prevents motoneuron atrophy induced by contralateral motoneuron depletion. These data support a therapeutic role for testosterone in preventing atrophy induced by motoneuron injury.
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Affiliation(s)
- Keith N Fargo
- Psychology Department and Program in Neural Science, Indiana University, Bloomington, Indiana 47405, USA
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Fargo KN, Sengelaub DR. Testosterone manipulation protects motoneurons from dendritic atrophy after contralateral motoneuron depletion. J Comp Neurol 2004; 469:96-106. [PMID: 14689475 DOI: 10.1002/cne.10991] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Dendritic morphology is reactive to many kinds of injuries, including axotomy and deafferentation. In this study, we examined the response of motoneurons in the spinal nucleus of the bulbocavernosus (SNB), an androgen-dependent population of motoneurons in the lumbar spinal cord of the rat, to partial motoneuron depletion. We depleted SNB motoneurons on one side only of the spinal cord by unilateral intramuscular injection of a retrogradely transported form of saporin, and examined the morphology of contralateral SNB motoneurons. Motoneuron morphology was assessed in normal control males, gonadally intact saporin-treated males, and saporin-treated males who had been castrated 6 weeks previously and given testosterone replacement beginning at the time of saporin injection. Untreated castrated males served as an additional control group. Four weeks after saporin treatment, SNB motoneurons contralateral to the saporin injection were retrogradely labeled with horseradish peroxidase conjugated to the cholera toxin B subunit and reconstructed in three dimensions. In gonadally intact males, unilateral motoneuron depletion caused regressive changes in contralateral SNB motoneurons: Soma size and dendritic length were both decreased. However, testosterone manipulation (i.e., castration followed by testosterone replacement) completely prevented the dendritic retraction. These data suggest a therapeutic role for testosterone in preventing, or accelerating recovery from, dendritic atrophy induced by motoneuron injury.
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Affiliation(s)
- Keith Nolan Fargo
- Department of Psychology and Program in Neural Science, Indiana University, Bloomington, Indiana 47405, USA
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Fargo KN, Foster AM, Harty MW, Sengelaub DR. Estrogen alters excitability but not morphology of a sexually dimorphic neuromuscular system in adult rats. JOURNAL OF NEUROBIOLOGY 2003; 56:66-77. [PMID: 12767033 DOI: 10.1002/neu.10224] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In rats, motoneurons of the spinal nucleus of the bulbocavernosus (SNB) innervate the bulbocavernosus (BC) muscle, which surrounds the base of the penis. The SNB/BC is a sexually dimorphic, steroid-sensitive neuromuscular system, which is critically important in male reproductive behavior. Androgens are necessary for the development, morphology, and function of the SNB/BC system. However, estradiol (E) is also necessary for the development of the SNB/BC system, and E is capable of maintaining BC EMG activity in adulthood. In this study, we used electrophysiological and anatomical methods to examine estrogenic effects on BC EMG activity. We used a modified H-reflex testing method to investigate polysynaptic reflex characteristics in intact males, castrates, and castrates treated short term with estradiol benzoate (EB). Measures of EMG activity, response latency, and spike count were altered in castrates, but maintained in EB-treated castrates to the levels of intact males. Furthermore, estrogenic effects were found in EMG activity that could be isolated to the periphery of the SNB/BC system. BC NMJ size and muscle fiber area have been demonstrated to be hormone sensitive, and we examined these for possible correlates of E's effects on BC EMG activity. BC muscles of intact males, castrates, and short-term EB-treated castrates were fixed and stained with zinc iodide and osmium tetroxide. NMJ size and muscle fiber area did not differ between groups. Together, these data suggest that E treatment results in changes in the neuromuscular periphery that maintain BC EMG activity, but this effect cannot be accounted for by changes in NMJ size or muscle fiber area.
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Affiliation(s)
- Keith N Fargo
- Psychology Department, Indiana University, Bloomington, Indiana 47405, USA
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15
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Zup SL, Forger NG. Testosterone regulates BCL-2 immunoreactivity in a sexually dimorphic motor pool of adult rats. Brain Res 2002; 950:312-6. [PMID: 12231259 DOI: 10.1016/s0006-8993(02)03190-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bcl-2 and Bax immunoreactivity were examined in the spinal nucleus of the bulbocavernosus (SNB), an androgen-sensitive motor pool of adult rats. Castration reduced Bcl-2 immunoreactivity and testosterone treatment of castrates prevented this decline. Hormone manipulations did not affect Bcl-2 or Bax staining in the retrodorsolateral nucleus (RDLN), a relatively androgen-insensitive nucleus at the same spinal level. Changes in Bcl-2 expression may underlie the hormonal control of cell death and/or neural plasticity in SNB motoneurons.
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Affiliation(s)
- Susan L Zup
- Center for Neuroendocrine Studies, Neuroscience and Behavior Program, University of Massachusetts, Amherst, MA 01003, USA.
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16
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Monks DA, Watson NV. N-cadherin expression in motoneurons is directly regulated by androgens: a genetic mosaic analysis in rats. Brain Res 2001; 895:73-9. [PMID: 11259762 DOI: 10.1016/s0006-8993(01)02031-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have recently reported that systemic androgens regulate adult N-cadherin (N-cad) expression in spinal motoneurons. However, the mechanism through which androgen mediates this effect remains undetermined. Androgen may act directly on motoneurons to regulate N-cad expression, or indirectly, via effects on androgen-sensitive afferent or efferent structures. Here, we describe a genetic mosaic investigation of this site-of-action indeterminacy. Following developmental random X chromosome inactivation, androgenized female rats heterozygous for the tfm androgen receptor mutation (X(WT)X(tfm)) are phenotypic mosaics of androgen-sensitive wild-type (WT) and androgen-insensitive (tfm) motoneurons. We compared steroid effects on WT and tfm cells in two sexually-dimorphic motoneuron pools, the spinal nucleus of the bulbocavernosus (SNB) and the dorsolateral nucleus (DLN), as well as a less steroid responsive motoneuron pool, the sexually monomorphic retrodorsolateral nucleus (RDLN). Independent of steroid treatment, a greater proportion of wild-type cells were N-cad immunoreactive (IR) in the DLN and RDLN. Following testosterone treatment, increased N-cad expression was observed in both cell types in the DLN, but in the SNB only the androgen-competent WT cells increased N-cad expression. Testosterone treatment did not significantly alter N-cad expression in the mosaic RDLN. The results indicate both cell autonomous and cell non-autonomous androgenic regulation of N-cad expression in spinal motoneurons.
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Affiliation(s)
- D A Monks
- Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada, V5A 1S6
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