1
|
Derwand D, Zierau O, Thieme D, Keiler AM. Up to the maximum-testosterone dose-dependent effects on anabolic and androgen responsive tissues in orchiectomized rats. Andrology 2024; 12:231-240. [PMID: 37254653 DOI: 10.1111/andr.13466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 05/15/2023] [Accepted: 05/24/2023] [Indexed: 06/01/2023]
Abstract
BACKGROUND Despite the high number of synthetic androgenic-anabolic steroids, testosterone is still misused for doping in amateur and professional sports. However, only few studies investigated the dose-response effects of testosterone beyond its physiological concentrations and in over 90 years of research, no saturation dosage has been experimentally described for exogenous testosterone administration. OBJECTIVES We want to elucidate the physiological and pathophysiological effects of supra-physiological testosterone application and close this gap in testosterone dose-response data. MATERIALS AND METHODS Male orchiectomized rats were treated with different testosterone doses ranging from 0.1 to 50 mg/kg body weight for 3 weeks. Several physiological endpoints (e.g., body weight, organ and muscle weight, muscle strength, muscle fiber size) were examined during and after the termination of the treatment with an adjusted Hershberger assay, open-field-test, and (immuno-)histologic. RESULTS The wet weights of androgen responsive organs (penis, prostate, seminal vesicle) showed a significant increase in a dose-dependent manner. Histological evaluation of the prostate showed a significant higher percentage of KI67 positive prostate nuclei in the highest dosage group and an increasing hyperplasia with increasing testosterone administered. A significant anabolic effect was only observed in Levator ani wet weight, and to minor degree for the cardiac muscle. Regarding other skeletal muscles (Musculus soleus and Musculus gastrognemicus), no significant testosterone effects were observed. We showed a significant increasing dosage-response effect for testosterone in androgen responsive organs with saturation at the two highest concentration of 10 and 50 mg/kg body weight. DISCUSSION AND CONCLUSION The dose-dependent androgenic effects of testosterone were well observable and the anabolic effects on muscle tissue were visible although to a lesser degree, without the support of aerobic exercise and a protein rich diet. Future studies should investigate a combinatorial effect of testosterone and training. Nevertheless, with the chosen range of applied testosterone, we showed a saturation of testosterone effects in prostate, seminal vesicle, penis, and Levator ani.
Collapse
Affiliation(s)
- Daniel Derwand
- Institute of Doping Analysis and Sports Biochemistry Dresden, Kreischa, Germany
- Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Oliver Zierau
- Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Detlef Thieme
- Institute of Doping Analysis and Sports Biochemistry Dresden, Kreischa, Germany
| | - Annekathrin Martina Keiler
- Institute of Doping Analysis and Sports Biochemistry Dresden, Kreischa, Germany
- Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| |
Collapse
|
2
|
Şenyuva İ, Acar DB, Demirel HH, Tunç E. Effects of testosterone treatment on anal sphincter damage repair in ovariectomized rats. Turk J Med Sci 2023; 53:475-485. [PMID: 37476872 PMCID: PMC10388087 DOI: 10.55730/1300-0144.5607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 11/20/2022] [Indexed: 07/22/2023] Open
Abstract
BACKGROUND Fecal incontinence (FI) generally occurs with anal sphincter damage caused by vaginal delivery in women, obvious FI can develop in the postmenopausal stage. This pelvic floor dysfunction has no rational medical therapeutic options. We investigated the effect of testosterone treatment on the anal sphincter structure, serum thiol/disulfide levels, uterine tissue, and body composition in female rats in an experimental menopause-FI model. METHODS The animal experiments were performed between September and November 2020 at Experimental Animal Application and Research Center, Afyon Kocatepe University, Afyonkarahisar, Turkey. Thirty-two female rats were divided into four groups: sham, saline, 10 mg/kg testosterone undecanoate, 100 mg/kg testosterone undecanoate. Except for the sham group, all the other groups underwent ovariectomy (OVE) to create a menopause model. Two weeks after this procedure, the FI model was created under general anesthesia in all rat groups. At the end of the experiment, the rats were placed under general anesthesia, weighed, and euthanized after recording the data. The anal sphincter region and uterine tissue samples were collected for histopathological examinations, and blood samples were collected for total testosterone and thiol/disulfide homeostasis analyses. RESULTS An increase in anal sphincter muscles and connective tissue thickness was observed in the testosterone-administered groups (p = 0.001). No difference was detected between the groups in the total thiol, native thiol, and disulfide balance (p = 0.087, p = 0.604, p = 0.092). The testosterone-treated groups did not have severe uterine epithelial degradation, hyperemia, or increased endometrial thickness (p = 0.186, p = 0.222, p = 0.630). The body weight of all rats increased (p < 0.05), but the omental weight did not increase (p = 0.061). DISCUSSION Testosterone treatment increased the anal sphincter muscle and connective tissue thickness without causing any oxidative stress and did not result in a pathological change in the uterine tissue and body fat composition.
Collapse
Affiliation(s)
- İrem Şenyuva
- Department of Obstetrics and Gynecology, Faculty of Medicine, Uşak University, Uşak, Turkey
| | - Duygu Baki Acar
- Department of Obstetrics and Gynecology, Veterinary Faculty, Afyon Kocatepe University, Afyon, Turkey
| | | | - Ece Tunç
- Department of Obstetrics and Gynecology, Veterinary Faculty, Afyon Kocatepe University, Afyon, Turkey
| |
Collapse
|
3
|
Ipulan-Colet LA. Sexual dimorphism through androgen signaling; from external genitalia to muscles. Front Endocrinol (Lausanne) 2022; 13:940229. [PMID: 35983512 PMCID: PMC9379613 DOI: 10.3389/fendo.2022.940229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Sexual dimorphisms can be seen in many organisms with some exhibiting subtle differences while some can be very evident. The difference between male and female can be seen on the morphological level such as discrepancies in body mass, presence of body hair in distinct places, or through the presence of specific reproductive structures. It is known that the development of the reproductive structures is governed by hormone signaling, most commonly explained through the actions of androgen signaling. The developmental program of the male and female external genitalia involves a common anlage, the genital tubercle or GT, that later on develop into a penis and clitoris, respectively. Androgen signaling involvement can be seen in the different tissues in the GT that express Androgen receptor and the different genes that are regulated by androgen in the mesenchyme and endoderm component of the GT. Muscles are also known to be responsive to androgen signaling with male and female muscles exhibiting different capabilities. However, the occurrence of sexual dimorphism in muscle development is unclear. In this minireview, a summary on the role of androgen in the sexually dimorphic development of the genital tubercle was provided. This was used as a framework on analyzing the different mechanism employed by androgen signaling to regulate the sexual dimorphism in muscle development.
Collapse
|
4
|
Seo JY, Kim JH, Kong YY. Unraveling the Paradoxical Action of Androgens on Muscle Stem Cells. Mol Cells 2019; 42:97-103. [PMID: 30759971 PMCID: PMC6399011 DOI: 10.14348/molcells.2019.0004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 12/25/2022] Open
Abstract
Androgens act in almost all tissues throughout the lifetime and have important roles in skeletal muscles. The levels of androgens increase during puberty and remain sustained at high levels in adulthood. Because androgens have an anabolic effect on skeletal muscles and muscle stem cells, these increased levels of androgens after puberty should lead to spontaneous muscle hypertrophy and hyperplasia in adulthood. However, the maintenance of muscle volume, myonuclei number per myofiber, and quiescent state of satellite cells in adulthood despite the high levels of androgens produces paradoxical outcomes. Our recent study revealed that the physiological increase of androgens at puberty initiates the transition of muscle stem cells from proliferation to quiescence by the androgen-Mindbomb1-Notch signaling axis. This newly discovered androgen action on skeletal muscles underscores the physiological importance of androgens on muscle homeostasis throughout life. This review will provide an overview of the new androgen action on skeletal muscles and discuss the paradoxical effects of androgens suggested in previous studies.
Collapse
Affiliation(s)
- Ji-Yun Seo
- School of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| | - Ji-Hoon Kim
- School of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| | - Young-Yun Kong
- School of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| |
Collapse
|
5
|
Rana K, Chiu MWS, Russell PK, Skinner JP, Lee NKL, Fam BC, Zajac JD, MacLean HE. Muscle-specific androgen receptor deletion shows limited actions in myoblasts but not in myofibers in different muscles in vivo. J Mol Endocrinol 2016; 57:125-38. [PMID: 27402875 DOI: 10.1530/jme-15-0320] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 07/04/2016] [Indexed: 11/08/2022]
Abstract
The aim of this study was to investigate the direct muscle cell-mediated actions of androgens by comparing two different mouse lines. The cre-loxP system was used to delete the DNA-binding activity of the androgen receptor (AR) in mature myofibers (MCK mAR(ΔZF2)) in one model and the DNA-binding activity of the AR in both proliferating myoblasts and myofibers (α-actin mAR(ΔZF2)) in another model. We found that hind-limb muscle mass was normal in MCK mAR(ΔZF2) mice and that relative mass of only some hind-limb muscles was reduced in α-actin mAR(ΔZF2) mice. This suggests that myoblasts and myofibers are not the major cellular targets mediating the anabolic actions of androgens on male muscle during growth and development. Levator ani muscle mass was decreased in both mouse lines, demonstrating that there is a myofiber-specific effect in this unique androgen-dependent muscle. We found that the pattern of expression of genes including c-myc, Fzd4 and Igf2 is associated with androgen-dependent changes in muscle mass; therefore, these genes are likely to be mediators of anabolic actions of androgens. Further research is required to identify the major targets of androgen actions in muscle, which are likely to include indirect actions via other tissues.
Collapse
Affiliation(s)
- Kesha Rana
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Maria W S Chiu
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Patricia K Russell
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Jarrod P Skinner
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Nicole K L Lee
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Barbara C Fam
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Jeffrey D Zajac
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Helen E MacLean
- Department of MedicineUniversity of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| |
Collapse
|
6
|
Dalbo VJ, Roberts MD, Mobley CB, Ballmann C, Kephart WC, Fox CD, Santucci VA, Conover CF, Beggs LA, Balaez A, Hoerr FJ, Yarrow JF, Borst SE, Beck DT. Testosterone and trenbolone enanthate increase mature myostatin protein expression despite increasing skeletal muscle hypertrophy and satellite cell number in rodent muscle. Andrologia 2016; 49. [PMID: 27246614 DOI: 10.1111/and.12622] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2016] [Indexed: 01/03/2023] Open
Abstract
The androgen-induced alterations in adult rodent skeletal muscle fibre cross-sectional area (fCSA), satellite cell content and myostatin (Mstn) were examined in 10-month-old Fisher 344 rats (n = 41) assigned to Sham surgery, orchiectomy (ORX), ORX + testosterone (TEST; 7.0 mg week-1 ) or ORX + trenbolone (TREN; 1.0 mg week-1 ). After 29 days, animals were euthanised and the levator ani/bulbocavernosus (LABC) muscle complex was harvested for analyses. LABC muscle fCSA was 102% and 94% higher in ORX + TEST and ORX + TREN compared to ORX (p < .001). ORX + TEST and ORX + TREN increased satellite cell numbers by 181% and 178% compared to ORX, respectively (p < .01), with no differences between conditions for myonuclear number per muscle fibre (p = .948). Mstn protein was increased 159% and 169% in the ORX + TEST and ORX + TREN compared to ORX (p < .01). pan-SMAD2/3 protein was ~30-50% greater in ORX compared to SHAM (p = .006), ORX + TEST (p = .037) and ORX + TREN (p = .043), although there were no between-treatment effects regarding phosphorylated SMAD2/3. Mstn, ActrIIb and Mighty mRNAs were lower in ORX, ORX + TEST and ORX + TREN compared to SHAM (p < .05). Testosterone and trenbolone administration increased muscle fCSA and satellite cell number without increasing myonuclei number, and increased Mstn protein levels. Several genes and signalling proteins related to myostatin signalling were differentially regulated by ORX or androgen therapy.
Collapse
Affiliation(s)
- V J Dalbo
- Medical and Applied Sciences, Central Queensland University, Rockhampton, Qld, Australia
| | - M D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - C B Mobley
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - C Ballmann
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - W C Kephart
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - C D Fox
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - V A Santucci
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - C F Conover
- Malcom Randall Veterans Affairs Medical Center, Geriatric Research Education and Clinical Center, Gainesville, FL, USA
| | - L A Beggs
- Malcom Randall Veterans Affairs Medical Center, Geriatric Research Education and Clinical Center, Gainesville, FL, USA.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - A Balaez
- Malcom Randall Veterans Affairs Medical Center, Geriatric Research Education and Clinical Center, Gainesville, FL, USA.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - F J Hoerr
- Veterinary Diagnostic Pathology LLC, Auburn, AL, USA
| | - J F Yarrow
- Malcom Randall Veterans Affairs Medical Center, Geriatric Research Education and Clinical Center, Gainesville, FL, USA.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - S E Borst
- Malcom Randall Veterans Affairs Medical Center, Geriatric Research Education and Clinical Center, Gainesville, FL, USA.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - D T Beck
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL, USA
| |
Collapse
|
7
|
Abstract
Testosterone is a key hormone in the pathology of metabolic diseases such as obesity. Low testosterone levels are associated with increased fat mass (particularly central adiposity) and reduced lean mass in males. These morphological features are linked to metabolic dysfunction, and testosterone deficiency is associated with energy imbalance, impaired glucose control, reduced insulin sensitivity and dyslipidaemia. A bidirectional relationship between testosterone and obesity underpins this association indicated by the hypogonadal-obesity cycle and evidence weight loss can lead to increased testosterone levels. Androgenic effects on enzymatic pathways of fatty acid metabolism, glucose control and energy utilization are apparent and often tissue specific with differential effects noted in different regional fat depots, muscle and liver to potentially explain the mechanisms of testosterone action. Testosterone replacement therapy demonstrates beneficial effects on measures of obesity that are partially explained by both direct metabolic actions on adipose and muscle and also potentially by increasing motivation, vigour and energy allowing obese individuals to engage in more active lifestyles. The degree of these beneficial effects may be dependent on the treatment modality with longer term administration often achieving greater improvements. Testosterone replacement may therefore potentially be an effective adjunctive treatment for weight management in obese men with concomitant hypogonadism.
Collapse
Affiliation(s)
- D M Kelly
- Department of Human Metabolism, Medical School, The University of Sheffield, Sheffield, UK
| | - T H Jones
- Department of Human Metabolism, Medical School, The University of Sheffield, Sheffield, UK.,Centre for Diabetes and Endocrinology, Barnsley Hospital NHS Foundation Trust, Barnsley, UK
| |
Collapse
|
8
|
Parr MK, Zhao P, Haupt O, Ngueu ST, Hengevoss J, Fritzemeier KH, Piechotta M, Schlörer N, Muhn P, Zheng WY, Xie MY, Diel P. Estrogen receptor beta is involved in skeletal muscle hypertrophy induced by the phytoecdysteroid ecdysterone. Mol Nutr Food Res 2014; 58:1861-72. [DOI: 10.1002/mnfr.201300806] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 04/28/2014] [Accepted: 04/30/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Maria Kristina Parr
- Center for Preventive Doping Research; German Sport University; Cologne Germany
- Institute of Pharmacy; Freie Universität Berlin; Germany
| | - Piwen Zhao
- School of Preclinical Medicine; Beijing University of Chinese Medicine; Bejing P. R. China
| | - Oliver Haupt
- Center for Preventive Doping Research; German Sport University; Cologne Germany
- Central Institute of the Bundeswehr Medical Service; Garching-Hochbrück Germany
| | | | - Jonas Hengevoss
- Center for Preventive Doping Research; German Sport University; Cologne Germany
| | | | - Marion Piechotta
- Clinic for Cattle, Endocrinology Laboratory; University of Veterinary Medicine Hannover; Hannover Germany
| | - Nils Schlörer
- Institute of Organic Chemistry; University of Cologne; Germany
| | | | - Wen-Ya Zheng
- Center for Preventive Doping Research; German Sport University; Cologne Germany
- State Key Laboratory of Food Science and Technology; Nanchang University; Nanchang P. R. China
| | - Ming-Yong Xie
- State Key Laboratory of Food Science and Technology; Nanchang University; Nanchang P. R. China
| | - Patrick Diel
- Center for Preventive Doping Research; German Sport University; Cologne Germany
| |
Collapse
|
9
|
Swift-Gallant A, Monks DA. Androgen receptor expression in satellite cells of the neonatal levator ani of the rat. Dev Neurobiol 2013; 73:448-54. [PMID: 23239638 DOI: 10.1002/dneu.22066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/24/2012] [Accepted: 12/06/2012] [Indexed: 12/23/2022]
Abstract
Androgens are thought to mediate sexual differentiation of spinal nucleus of the bulbocavernosus (SNB) motoneurons via actions on androgen receptors (ARs) within their target muscles bulbocavernosus and levator ani (LA). However, the cells within these muscles which mediate masculinization of the SNB remain undefined. Until recently, myocytes were thought to be the most likely candidate cell type. However, genetic tests of AR function in myocytes have failed to support a sufficient role for these cells in producing masculine SNB morphology, suggesting the involvement of other cell types. To identify other candidate cell types in the LA, we evaluated whether satellite cells or fibroblasts express AR. Fluorescent immunohistochemistry and confocal microscopy were used to evaluate whether satellite cells and fibroblasts express AR in neonatal male and female rats in the LA and an adjacent sexually monomorphic control muscle (CM). We found that a small proportion of satellite cells in the LA express AR and that this proportion is significantly greater in the LA compared to the CM. No sex differences were found between the proportions of satellite cells expressing AR in either muscle. Less colocalization of satellite cells and AR was seen in postnatal day 3 muscle than in postnatal day 1 muscle. In contrast, only negligible amounts of fibroblasts labeled with S100A4 express AR in either the LA or the CM. Together, findings support satellite cells, but not fibroblasts, as a candidate cell type involved in the sexual differentiation of the SNB neuromuscular system.
Collapse
Affiliation(s)
- Ashlyn Swift-Gallant
- Department of Psychology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
| | | |
Collapse
|
10
|
Silva MA, Villaseñor RMV, Márquez SR, González MH, Jaime HB, García XG, Montiel JLC. Testosterone Levels and Development of the Penile Spines and Testicular Tissue during the Postnatal Growth in Wistar Rats. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/asm.2013.33a001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
11
|
Turning sex inside-out: Peripheral contributions to sexual differentiation of the central nervous system. Biol Sex Differ 2012; 3:12. [PMID: 22640590 PMCID: PMC3464926 DOI: 10.1186/2042-6410-3-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 05/28/2012] [Indexed: 02/04/2023] Open
Abstract
Sexual differentiation of the nervous system occurs via the interplay of genetics, endocrinology and social experience through development. Much of the research into mechanisms of sexual differentiation has been driven by an implicit theoretical framework in which these causal factors act primarily and directly on sexually dimorphic neural populations within the central nervous system. This review will examine an alternative explanation by describing what is known about the role of peripheral structures and mechanisms (both neural and non-neural) in producing sex differences in the central nervous system. The focus of the review will be on experimental evidence obtained from studies of androgenic masculinization of the spinal nucleus of the bulbocavernosus, but other systems will also be considered.
Collapse
|
12
|
Dubois V, Laurent M, Boonen S, Vanderschueren D, Claessens F. Androgens and skeletal muscle: cellular and molecular action mechanisms underlying the anabolic actions. Cell Mol Life Sci 2012; 69:1651-67. [PMID: 22101547 PMCID: PMC11115174 DOI: 10.1007/s00018-011-0883-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/27/2011] [Accepted: 11/07/2011] [Indexed: 12/14/2022]
Abstract
Androgens increase both the size and strength of skeletal muscle via diverse mechanisms. The aim of this review is to discuss the different cellular targets of androgens in skeletal muscle as well as the respective androgen actions in these cells leading to changes in proliferation, myogenic differentiation, and protein metabolism. Androgens bind and activate a specific nuclear receptor which will directly affect the transcription of target genes. These genes encode muscle-specific transcription factors, enzymes, structural proteins, as well as microRNAs. In addition, anabolic action of androgens is partly established through crosstalk with other signaling molecules such as Akt, myostatin, IGF-I, and Notch. Finally, androgens may also exert non-genomic effects in muscle by increasing Ca(2+) uptake and modulating kinase activities. In conclusion, the anabolic effect of androgens on skeletal muscle is not only explained by activation of the myocyte androgen receptor but is also the combined result of many genomic and non-genomic actions.
Collapse
Affiliation(s)
- Vanessa Dubois
- Molecular Endocrinology Laboratory, Department of Molecular Cell Biology, K.U. Leuven, Campus Gasthuisberg, O&N1, Herestraat 49, Leuven, Belgium
| | | | | | | | | |
Collapse
|
13
|
Fu R, Liu J, Fan J, Li R, Li D, Yin J, Cui S. Novel evidence that testosterone promotes cell proliferation and differentiation via G protein-coupled receptors in the rat L6 skeletal muscle myoblast cell line. J Cell Physiol 2011; 227:98-107. [DOI: 10.1002/jcp.22710] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
14
|
Pradidarcheep W, Wallner C, Dabhoiwala NF, Lamers WH. Anatomy and histology of the lower urinary tract. Handb Exp Pharmacol 2011:117-148. [PMID: 21290225 DOI: 10.1007/978-3-642-16499-6_7] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The function of the lower urinary tract is basically storage of urine in the bladder and the at-will periodic evacuation of the stored urine. Urinary incontinence is one of the most common lower urinary tract disorders in adults, but especially in the elderly female. The urethra, its sphincters, and the pelvic floor are key structures in the achievement of continence, but their basic anatomy is little known and, to some extent, still incompletely understood. Because questions with respect to continence arise from human morbidity, but are often investigated in rodent animal models, we present findings in human and rodent anatomy and histology. Differences between males and females in the role that the pelvic floor plays in the maintenance of continence are described. Furthermore, we briefly describe the embryologic origin of ureters, bladder, and urethra, because the developmental origin of structures such as the vesicoureteral junction, the bladder trigone, and the penile urethra are often invoked to explain (clinical) observations. As the human pelvic floor has acquired features in evolution that are typical for a species with bipedal movement, we also compare the pelvic floor of humans with that of rodents to better understand the rodent (or any other quadruped, for that matter) as an experimental model species. The general conclusion is that the "Bauplan" is well conserved, even though its common features are sometimes difficult to discern.
Collapse
Affiliation(s)
- Wisuit Pradidarcheep
- AMC Liver Center, Academic Medical Center, University of Amsterdam, Meibergdreef 69-71, 1105 BK, Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
15
|
Serra C, Bhasin S, Tangherlini F, Barton ER, Ganno M, Zhang A, Shansky J, Vandenburgh HH, Travison TG, Jasuja R, Morris C. The role of GH and IGF-I in mediating anabolic effects of testosterone on androgen-responsive muscle. Endocrinology 2011; 152:193-206. [PMID: 21084444 PMCID: PMC3033058 DOI: 10.1210/en.2010-0802] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Testosterone (T) supplementation increases skeletal muscle mass, circulating GH, IGF-I, and im IGF-I expression, but the role of GH and IGF-I in mediating T's effects on the skeletal muscle remains poorly understood. Here, we show that T administration increased body weight and the mass of the androgen-dependent levator ani muscle in hypophysectomized as well as castrated plus hypophysectomized adult male rats. T stimulated the proliferation of primary human skeletal muscle cells (hSKMCs) in vitro, an effect blocked by transfecting hSKMCs with small interference RNA targeting human IGF-I receptor (IGF-IR). In differentiation conditions, T promoted the fusion of hSKMCs into larger myotubes, an effect attenuated by small interference RNA targeting human IGF-IR. Notably, MKR mice, which express a dominant negative form of the IGF-IR in skeletal muscle fibers, treated with a GnRH antagonist (acyline) to suppress endogenous T, responded to T administration by an attenuated increase in the levator ani muscle mass. In conclusion, circulating GH and IGF-I are not essential for mediating T's effects on an androgen-responsive skeletal muscle. IGF-I signaling plays an important role in mediating T's effects on skeletal muscle progenitor cell growth and differentiation in vitro. However, IGF-IR signaling in skeletal muscle fibers does not appear to be obligatory for mediating the anabolic effects of T on the mass of androgen-responsive skeletal muscles in mice.
Collapse
Affiliation(s)
- Carlo Serra
- Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center, 670 Albany Street, Boston, Massachusetts 02118, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Jacob DA, Ray T, Bengston CL, Lindsten T, Wu J, Thompson CB, Forger NG. The role of cell death in sexually dimorphic muscle development: male-specific muscles are retained in female bax/bak knockout mice. Dev Neurobiol 2009; 68:1303-14. [PMID: 18563702 DOI: 10.1002/dneu.20658] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The bulbocavernosus (BC) and levator ani (LA) muscles are present in males but absent or severely reduced in females, and the fate of these muscles controls the survival of motoneurons in the sexually dimorphic spinal nucleus of the bulbocavernosus. However, the mechanism underlying the sex difference in BC and LA development has been controversial. We examined the role of cell death in sexual differentiation of the bulbocavernosus BC/LA muscles in mice. Muscle development was mapped from embryonic day 16 (E16) to postnatal day 5 (P5). A sex difference (male>female) first arose on E17 (BC) or E18 (LA), and increased in magnitude postnatally. TUNEL labeling revealed dying cells in the BC and LA muscles of both sexes perinatally. However, females had a significantly higher density of TUNEL-positive cells than did males. A role for the proapoptotic factors, Bax and Bak, in BC/LA development was tested by examining mice lacking one or both of these proteins. In females lacking either Bax or Bak, the BC was absent and the LA rudimentary. Deletion of both bax and bak genes, however, rescued the BC, increased LA size approximately 20-fold relative to controls, and virtually eliminated TUNEL-positive cells in both muscles. We conclude that cell death plays an essential role in sexual differentiation of the BC/LA muscles. The presence of either Bax or Bak is sufficient for cell death in the BC/LA, whereas the absence of both prevents sexually dimorphic muscle cell death.
Collapse
Affiliation(s)
- Dena A Jacob
- Department of Psychology, Center for Neuroendocrine Studies, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Rhoads RP, Fernyhough ME, Liu X, McFarland DC, Velleman SG, Hausman GJ, Dodson MV. Extrinsic regulation of domestic animal-derived myogenic satellite cells II. Domest Anim Endocrinol 2009; 36:111-26. [PMID: 19261429 DOI: 10.1016/j.domaniend.2008.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/18/2008] [Accepted: 12/19/2008] [Indexed: 12/12/2022]
Abstract
The existence of myogenic satellite cells was reported some 47 years ago, and, since that time, satellite cell research has flourished. So much new information is generated (daily) on these cells that it can be difficult for individuals to keep abreast of important issues related to their activation and proliferation, the modulation of the activity of other cell types, the differentiation of the cells to facilitate normal skeletal muscle growth and development, or to the repair of damaged myofibers. The intent of this review is to summarize new information about the extrinsic regulation of myogenic satellite cells and to provide specific mechanisms involved in altering satellite cell physiology. Where possible, examples from agriculturally important animals are used for illustrative purposes.
Collapse
Affiliation(s)
- R P Rhoads
- Department of Animal Sciences, University of Arizona, Tucson, AZ 85719, USA
| | | | | | | | | | | | | |
Collapse
|
18
|
Muscle fibre characteristics of two contrasting sheep breeds: Scottish Blackface and Texel. Meat Sci 2009; 81:372-81. [DOI: 10.1016/j.meatsci.2008.08.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Revised: 08/26/2008] [Accepted: 08/31/2008] [Indexed: 11/21/2022]
|
19
|
Chen Y, Lee NKL, Zajac JD, MacLean HE. Generation and analysis of an androgen-responsive myoblast cell line indicates that androgens regulate myotube protein accretion. J Endocrinol Invest 2008; 31:910-8. [PMID: 19092298 DOI: 10.1007/bf03346441] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Androgens have anabolic actions in skeletal muscle and could potentially act to: (a) increase proliferation of myoblasts; (b) delay differentiation to myotubes; and (c) induce protein accretion in post-proliferative myofibers. To identify the site of androgens action, we investigated the proliferative response of the C2C12 mouse myoblast cell line to testosterone and dihydrotestosterone (DHT) treatment. Neither androgens affected cell proliferation after up to 7 days treatment, nor was there a synergistic effect of androgens on the proliferative response of C2C12 cells to IGF-I treatment. However, proliferating C2C12 cells expressed 0.1% of the level of androgen receptor (AR) mRNA found in adult mouse gastrocnemius muscle (p<0.01). Therefore, we generated mouse C2C12 myoblast cell lines stably transfected with the mouse AR cDNA driven by the SV40 promoter (C2C12-AR). C2C12-AR cell proliferation, differentiation, and protein content were analyzed in response to androgen treatment. Our data demonstrated that androgen treatment does not alter either proliferation rate or differentiation rate of C2C12-AR cells. However, treatment of differentiated C2C12-AR myotubes with 100 nM DHT for 3 days caused a 20% increase in total protein content vs vehicle treatment (p<0.05). This effect was not observed in control C2C12 cells transfected with empty vector. These data suggest that androgens act via the AR to upregulate myotube protein content. This model cell line will be useful to further investigate the molecular mechanisms via which androgens regulate protein accretion.
Collapse
Affiliation(s)
- Y Chen
- Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Australia
| | | | | | | |
Collapse
|
20
|
Ting HJ, Chang C. Actin associated proteins function as androgen receptor coregulators: an implication of androgen receptor's roles in skeletal muscle. J Steroid Biochem Mol Biol 2008; 111:157-63. [PMID: 18590822 DOI: 10.1016/j.jsbmb.2008.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 06/05/2008] [Indexed: 11/28/2022]
Abstract
This review of androgen receptor (AR) coregulators, which also function as actin-binding proteins, intends to establish the connection between actin cytoskeletal components and androgen signaling, especially in skeletal muscle. In cellular and animal models, androgen activated AR modulates myoblasts proliferation, promotes sexual dimorphic muscle development, and alters muscle fiber type. In the clinical setting, administration of anabolic androgens can decrease cachexia and speed wound healing. During myogenesis and regeneration of skeletal muscle in embryo and adult, the membrane of myoblasts fuse and the actin cytoskeleton is rearranged to form an alignment with myosin to form myotubes then ultimately the myofibrils. Contraction of skeletal muscle promotes the growth of myocytes by coordinating signals from the neuromuscular junction to intra-myofibrils through costameres, the functional structure comprised of signal proteins closely associated with actin filaments and involved in muscular dystrophy. Therefore, the discovery of actin-binding proteins functioning as AR coregulators implies that androgen signaling is tightly regulated during the process of the development and regeneration of skeletal muscle. The search for selective androgen receptor modulators (SARM) that act precisely in skeletal muscle instead of other tissues could target the engineering of a SARM-AR complex that selectively recruits these coregulators.
Collapse
Affiliation(s)
- Huei-Ju Ting
- Department of Pathology and Urology, The Cancer Center, University of Rochester Medical Center, Rochester, NY 14642, USA
| | | |
Collapse
|
21
|
MacLean HE, Chiu WSM, Notini AJ, Axell AM, Davey RA, McManus JF, Ma C, Plant DR, Lynch GS, Zajac JD. Impaired skeletal muscle development and function in male, but not female, genomic
androgen receptor
knockout mice. FASEB J 2008; 22:2676-89. [DOI: 10.1096/fj.08-105726] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Helen E. MacLean
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - W. S. Maria Chiu
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - Amanda J. Notini
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - Anna-Maree Axell
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - Rachel A. Davey
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - Julie F. McManus
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - Cathy Ma
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| | - David R. Plant
- Department of PhysiologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Gordon S. Lynch
- Department of PhysiologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Jeffrey D. Zajac
- Department of MedicineUniversity of Melbourne, Austin HealthHeidelbergVictoriaAustralia
| |
Collapse
|
22
|
Androgen-promoted physiological traits and criminality: A test of the evolutionary neuroandrogenic theory. PERSONALITY AND INDIVIDUAL DIFFERENCES 2008. [DOI: 10.1016/j.paid.2007.10.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
23
|
Mendler L, Baka Z, Kovács-Simon A, Dux L. Androgens negatively regulate myostatin expression in an androgen-dependent skeletal muscle. Biochem Biophys Res Commun 2007; 361:237-42. [PMID: 17658471 DOI: 10.1016/j.bbrc.2007.07.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 07/08/2007] [Indexed: 11/21/2022]
Abstract
Myostatin is an important negative regulator of skeletal muscle growth, while androgens are strong positive effectors. In order to investigate the possible interaction between myostatin and androgen pathways, we followed myostatin expression in the androgen-dependent levator ani (LA) muscle of the rat as a function of androgen status. By testosterone deprivation (castration), we induced LA growth arrest in young male rats, whilst atrophy in adult ones, however, both processes could be reversed by testosterone supplementation. After castration, a significant up-regulation of active myostatin protein (and its propeptide) was found, whereas the subsequent testosterone treatment reduced myostatin protein levels to normal values in both young and adult rats. Similarly, a testosterone-induced suppression of myostatin mRNA levels was observed in castrated adult but not in young animals. Altogether, androgens seem to have strong negative impact on myostatin expression, which might be a key factor in the weight regulation of LA muscle.
Collapse
Affiliation(s)
- Luca Mendler
- Institute of Biochemistry, Faculty of General Medicine, University of Szeged, Dóm tér 9., 6720 Szeged, Hungary.
| | | | | | | |
Collapse
|
24
|
Taylor EN, Denardo DF. Sexual size dimorphism and growth plasticity in snakes: an experiment on the Western Diamond-backed Rattlesnake (Crotalus atrox). ACTA ACUST UNITED AC 2005; 303:598-607. [PMID: 15945080 DOI: 10.1002/jez.a.189] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We conducted an experiment to examine the effects of sex and food intake on growth, mass gain, and attainment of sexual maturity in Western Diamond-backed Rattlesnakes (Crotalus atrox). We also measured testosterone levels to determine whether testosterone might be involved in the male-biased sexual size dimorphism observed in this species. We collected neonate rattlesnakes and raised them in the laboratory for 2 years on either a high-intake diet (fed one mouse per week) or a low-intake diet (fed one mouse every 3 weeks). High-intake snakes grew and gained mass more rapidly than low-intake snakes, but males did not grow or gain mass more rapidly than females in either treatment group. High-intake snakes attained reproductive maturity earlier than low-intake snakes, indicating that size, not age, is the critical determinant of reproductive maturity. Males had higher levels of testosterone than females but did not grow more quickly, suggesting that testosterone may not affect growth in this species and may therefore not be the proximate determinant of sexual size dimorphism.
Collapse
Affiliation(s)
- Emily N Taylor
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA.
| | | |
Collapse
|
25
|
Johansen JA, Jordan CL, Breedlove SM. Steroid hormone masculinization of neural structure in rats: a tale of two nuclei. Physiol Behav 2005; 83:271-7. [PMID: 15488544 DOI: 10.1016/j.physbeh.2004.08.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We review the mechanisms by which steroid hormones masculinize two different regions of the central nervous system (CNS) in rats. Although in both cases, androgens induce a male phenotype, the detailed mechanisms are remarkably different in the two models. In the spinal nucleus of the bulbocavernosus (SNB), testosterone must be present during the perinatal period to spare motoneurons and their target muscles from cell death. This masculinization of the SNB system is through activation of androgen receptors, because XY rats with a defective gene for the androgen receptor fail to develop a masculine SNB system. Interestingly, the motoneurons are spared by androgen, even though they themselves do not possess androgen receptors during the critical period for their survival. Thus, steroids can act on one part of the body to secondarily masculinize the CNS. In the posterodorsal aspect of the medial amygdala (MePD), testosterone can induce masculine development even in adulthood, indicating that there is no critical period for steroids to affect sexual differentiation of this system. In the case of the MePD, both estrogen receptors and androgen receptors appear to mediate testosterone's masculinizing influence on neural structure. The extended neural plasticity of the MePD may reflect annual "reorganization" of the brain in the seasonally breeding ancestors of laboratory rats.
Collapse
Affiliation(s)
- Jamie A Johansen
- Neuroscience Program, Michigan State University, East Lansing, MI 48824-1101, USA
| | | | | |
Collapse
|
26
|
Hebbeler SL, Sengelaub DR. Development of a sexually dimorphic neuromuscular system in male rats after spinal transection: morphologic changes and implications for estrogen sites of action. J Comp Neurol 2004; 467:80-96. [PMID: 14574681 DOI: 10.1002/cne.10911] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The lumbar spinal cord of rats contains the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB). In male rats, SNB motoneurons exhibit a biphasic pattern of dendritic growth, having an initial period of exuberant growth followed by a period of retraction to mature lengths by 7 weeks of age. This growth is steroid dependent: dendrites fail to grow after castration, but growth is supported in castrates treated with estradiol. In this experiment, we examined whether supraspinal afferent input by means of descending spinal tracts to the SNB was involved in the normal postnatal development of SNB motoneurons, and whether the effect of estradiol on SNB dendritic growth could be explained by an indirect action of estradiol on supraspinal afferents. Motoneuron morphology was assessed in normal males, early- or late-postnatally transected males, castrated males left untreated or treated with estradiol, and transected castrates treated with estradiol. SNB motoneurons were retrogradely labeled with cholera toxin-horseradish peroxidase during both the growth and retraction phases of dendritic development and reconstructed in three dimensions. The removal of supraspinal afferents resulted in extremely local effects within the developing SNB arbor, as well as transient alterations in somal growth. Furthermore, spinal transection did not block the trophic effect of estradiol on supporting SNB dendritic growth, indicating that estrogens do not act by means of supraspinal input to support SNB motoneuron development.
Collapse
Affiliation(s)
- Sara L Hebbeler
- Department of Psychology, Indiana University, Bloomington, Indiana 47405, USA
| | | |
Collapse
|
27
|
Siegford JM, Ulibarri C. Increase in motoneurons in the spinal nucleus of the bulbocavernosus of prepubertally castrated male Mongolian gerbils following delayed treatment with testosterone. J Comp Neurol 2004; 473:485-95. [PMID: 15116385 DOI: 10.1002/cne.20083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sexual dimorphism in the spinal nucleus of the bulbocavernosus (SNB) of the Mongolian gerbil is achieved by two periods of postnatal increase, one in the first month after birth and one at puberty. The pubertal increase in motoneuron number is of particular interest because it occurs in a nearly adult animal. The purpose of this research was threefold. The first was to determine the response of the SNB in prepubertally castrated male gerbils receiving delayed hormone replacement as adults. Testosterone propionate (TP) treatment resulted in numbers of SNB motoneurons comparable to those seen in intact males, whereas androgen metabolites were less effective. The second purpose was to determine the latency of motoneurons to appear in response to TP. New SNB motoneurons appeared within 2 days of delayed TP replacement in prepubertally castrated males, and 16 days of treatment did not further increase SNB motoneuron numbers. The response of the motoneurons to TP appeared more rapid than the response of the bulbocavernosus (BC) muscle, scent gland, and seminal vesicles. The third purpose was to determine whether the new cells were connected to a target muscle. After 16 days of TP treatment, more motoneurons were labeled in the SNB following injection of a retrograde tract tracer into the BC muscle compared with the number seen in control animals. Thus, new motoneurons appeared in the SNB of prepubertally castrated male Mongolian gerbils within 2 days of the start of delayed TP treatment and were connected to a target within 16 days of TP treatment.
Collapse
Affiliation(s)
- Janice Marie Siegford
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-6520, USA.
| | | |
Collapse
|
28
|
Siegford JM, Hadi Mansouri S, Ulibarri C. Normal ontogeny of perineal muscles and testosterone levels in Mongolian gerbils; Response to testosterone in developing females. ACTA ACUST UNITED AC 2003; 275:997-1008. [PMID: 14533174 DOI: 10.1002/ar.a.10118] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The spinal nucleus of the bulbocavernosus (SNB) of Mongolian gerbils (Meriones unguiculatus) becomes sexually dimorphic during postnatal life, rather than prenatally as in rats. We therefore examined the early postnatal ontogeny of Mongolian gerbils, focusing on growth, serum testosterone (T) levels, and the sexually dimorphic perineal musculature innervated by the SNB. Serum T levels were higher in males than in females from birth through adulthood, with several early postnatal peaks and a large increase in T occurring during puberty in males. The SNB target muscles-the bulbocavernosus (BC) and levator ani (LA)-were present in both sexes on postnatal day 1 (PND1). Cross-sectional areas of BC fibers in males increased with age, and concurrently the myofibers of the BC became more fully developed and organized. In PND10 female pups, the BC muscle was virtually absent, while the LA muscle remained (although it was reduced in size). Postnatal treatment of female gerbils with androgen caused the BC muscle to remain and the LA muscle to become larger by PND10. Sexual dimorphism of the SNB develops differently in gerbils compared to other species, although its target muscles appear to respond to androgen in a manner similar to that in rats.
Collapse
Affiliation(s)
- Janice M Siegford
- Department of Veterinary, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.
| | | | | |
Collapse
|
29
|
Sinha-Hikim I, Roth SM, Lee MI, Bhasin S. Testosterone-induced muscle hypertrophy is associated with an increase in satellite cell number in healthy, young men. Am J Physiol Endocrinol Metab 2003; 285:E197-205. [PMID: 12670837 DOI: 10.1152/ajpendo.00370.2002] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Testosterone (T) supplementation in men induces muscle fiber hypertrophy. We hypothesized that T-induced increase in muscle fiber size is associated with a dose-dependent increase in satellite cell number. We quantitated satellite cell and myonuclear number by using direct counting and spatial orientation methods in biopsies of vastus lateralis obtained at baseline and after 20 wk of treatment with a gonadotropin-releasing hormone agonist and a 125-, 300-, or 600-mg weekly dose of T enanthate. T administration was associated with a significant increase in myonuclear number in men receiving 300- and 600-mg doses. The posttreatment percent satellite cell number, obtained by direct counting, differed significantly among the three groups (ANCOVA P < 0.000001); the mean posttreatment values (5.0 and 15.0%) in men treated with 300- and 600-mg doses were greater than baseline (2.5 and 2.5%, respectively, P < 0.05 vs. baseline). The absolute satellite cell number measured by spatial orientation at 20 wk (1.5 and 4.0/mm) was significantly greater than baseline (0.3 and 0.6/mm) in men receiving the 300- and 600-mg doses (P < 0.05). The change in percent satellite cell number correlated with changes in total (r = 0.548) and free T concentrations (r = 0.468). Satellite cell and mitochondrial areas were significantly higher and the nuclear-to-cytoplasmic ratio lower after treatment with 300- and 600-mg doses. We conclude that T-induced muscle fiber hypertrophy is associated with an increase in satellite cell number, a proportionate increase in myonuclear number, and changes in satellite cell ultrastructure.
Collapse
Affiliation(s)
- Indrani Sinha-Hikim
- Division of Endocrinology, Metabolism, and Molecular Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, California 90059, USA
| | | | | | | |
Collapse
|
30
|
Romeo RD, Richardson HN, Sisk CL. Puberty and the maturation of the male brain and sexual behavior: recasting a behavioral potential. Neurosci Biobehav Rev 2002; 26:381-91. [PMID: 12034137 DOI: 10.1016/s0149-7634(02)00009-x] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The pubertal transition from the juvenile to adult state requires significant changes in behavior to meet the demands for success and survival in adulthood. These behavioral changes during puberty must be mediated by changes in the structure and/or function of the central nervous system. Despite the profound consequences of puberty on an animal's behavioral repertoire, the mechanisms underlying pubertal maturation of the nervous system remain largely unknown. In this review, we provide a synthesis of neural development during puberty as it relates to maturation of male reproductive behavior. We first outline neuroendocrine events associated with puberty and review work from our laboratory that identifies pubertal changes in the neural substrate controlling male reproduction by comparing the neural responses of prepubertal and adult males to steroids and female chemosensory cues. We then raise the question of whether puberty is a sensitive period in which gonadal hormones influence the structural and functional organization of neural circuits underlying male reproductive behavior. The central thesis of this review is that the development of the nervous system during puberty alters the way in which the male responds to social stimuli, involving the restructuring of neural circuits that integrate steroidal and sensory information and ultimately mediate steroid-dependent social behaviors in adulthood.
Collapse
Affiliation(s)
- Russell D Romeo
- Department of Psychology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | | | | |
Collapse
|
31
|
YIOU RENÉ, DELMAS VINCENT, CARMELIET PETER, GHERARDI ROMAINK, BARLOVATZ-MEIMON GEORGIA, CHOPIN DOMINIQUEK, ABBOU CLÉMENTCLAUDE, LEFAUCHEUR JEANPASCAL. The pathophysiology of pelvic floor disorders: evidence from a histomorphologic study of the perineum and a mouse model of rectal prolapse. J Anat 2001; 199:599-607. [PMID: 11760891 PMCID: PMC1468371 DOI: 10.1046/j.1469-7580.2001.19950599.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The muscle changes related to pelvic floor disorders are poorly understood. We conducted an anatomical and histological study of the perineum of the normal mouse and of a transgenic mouse strain deficient in urokinase-type plasminogen activator (uPA-/-) that was previously reported to develop a high incidence of rectal prolapse. We could clearly identify the iliococcygeus (ILC) and pubococcygeus (PC) muscles and anal (SPA) and urethral (SPU) sphincters in male and female mice. The bulbocavernosus (BC), ischiocavernosus (ISC) and levator ani (LA) muscles could be found only in male mice. Histochemical analysis of the pelvic floor muscles revealed a majority of type IIA fibres. Rectal prolapses were observed only in male uPA-/- mice. The most obvious finding was an irreducible evagination of the rectal mucosa and a swelling of the entire perineal region corresponding to an irreducible hernia of the seminal vesicles through the pelvic outlet. The hernia caused stretching and thinning of the ISC, BC and LA. Myopathic damage, with degenerated and centronucleated myofibres, were observed in these muscles. The PC, ILC, SPA and SPU were not affected. This study provides an original description of a model of pelvic floor disorder and illustrates the differences existing between the perineum of humans and that of a quadruped species. In spite of these differences, the histopathologic changes observed in the pelvic floor muscles of uPA-/- mice with rectal prolapse suggest that prolonged muscular stretching causes a primary myopathic injury. This should be taken into account in the evaluation of pelvic floor disorders.
Collapse
Affiliation(s)
- RENÉ YIOU
- Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France
- Service d'Urologie, Faculté des Saints-Pères, Paris, France
| | - VINCENT DELMAS
- Laboratoire d'Anatomie, Faculté des Saints-Pères, Paris, France
| | - PETER CARMELIET
- Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, University of Leuven, Belgium
| | | | | | | | | | - JEAN-PASCAL LEFAUCHEUR
- Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France
- Service de Physiologie, CHU Henri Mondor, Créteil, Faculté des Saints-Pères, Paris, France
- Correspondence to Dr Jean-Pascal Lefaucheur, Service de Physiologie – Explorations Fonctionnelles, CHU Henri Mondor, 51 avenue de Lattre de Tassigny, 94000 Créteil, France. Tel.: 01 49 81 26 94; fax: 01 49 81 46 60; e-mail:
| |
Collapse
|
32
|
Hebbeler SL, Verhovshek T, Sengelaub DR. Ovariectomy attenuates dendritic growth in hormone-sensitive spinal motoneurons. JOURNAL OF NEUROBIOLOGY 2001; 48:301-14. [PMID: 11500843 DOI: 10.1002/neu.1059] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The lumbar spinal cord of rats contains the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB). Dendritic development of SNB motoneurons in male rats is biphasic, initially showing exuberant growth through 4 weeks of age followed by a retraction to mature lengths by 7 weeks of age. The initial growth is steroid dependent, attenuated by castration or aromatase inhibition, and supported by hormone replacement. Dendritic retraction is also steroid sensitive and can be prevented by testosterone treatment, but is unaffected by aromatase inhibition. Together, these results suggest a role for estrogens during the initial growth phase of SNB development. In this study, we tested whether ovarian hormones could support SNB somal and dendritic development. Motoneuron morphology was assessed in normal males and in females perinatally masculinized with dihydrotestosterone and then either ovariectomized or left intact. SNB motoneurons were retrogradely labeled with cholera toxin-HRP at 4 or 7 weeks of age and reconstructed in three dimensions. Initial growth of SNB dendrites was reduced after ovariectomy in masculinized females. However, no differences in dendritic length were seen at 7 weeks of age between intact and ovariectomized masculinized females, and lengths in both groups were significantly lower than those of normal males. Together with previous findings, these results suggest that estrogens are involved in the early growth of SNB dendrites, but not in their subsequent retraction.
Collapse
Affiliation(s)
- S L Hebbeler
- Department of Psychology, Indiana University, Bloomington 47405, USA
| | | | | |
Collapse
|
33
|
Nnodim JO. Testosterone mediates satellite cell activation in denervated rat levator ani muscle. THE ANATOMICAL RECORD 2001; 263:19-24. [PMID: 11331967 DOI: 10.1002/ar.1072] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Denervation stimulates quiescent satellite cells in skeletal muscle to reenter the cell cycle. In the androgen-sensitive rat levator ani muscle (LA), this mitotic response to loss of neural input fails to occur in castrated animals. To elucidate the role of androgens in denervation-induced satellite cell proliferation, the denervated LA of castrated rats (Group A) was compared with that of animals infixed with testosterone implants after castration (Group B). Mean myofiber cross-sectional areas (Group A: 362.95 microm(2) +/- 27.74; Group B: 403.13 microm(2) +/- 53.87) and linear nuclear densities (Group A: 74.07 mm(-1) +/- 17.58; Group B: 104.13 mm(-1) +/- 4.06) were similar (P > 0.05) in both groups. The androgen-deprived myofibers of Group A, however, had a significantly lower nuclear content (271.0 +/- 74.91 vs. 1,285.80 +/- 81.74 in Group B; P < 0.05) on account of their considerably shorter mean length (3.44 mm +/- 0.29 vs. 12.31 mm +/- 0.92 in Group B; P < 0.05). The proportional representation of satellite cells in hormone-replaced, denervated muscle was more than twice that in the untreated group (Group B: 5.15 +/- 0.83% vs. Group A: 2.28 +/- 0.23%; P < 0.05). In absolute terms, the satellite cell number in Group B was approximately an order of magnitude greater than in Group A (408.4 x 10(3) vs. 38.08 x 10(3)). The results confirm the absence of testosterone as the factor responsible for the inability of satellite cells in the LA of castrated rats to respond mitotically to the withdrawal of neural input after denervation.
Collapse
Affiliation(s)
- J O Nnodim
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109-2007, USA
| |
Collapse
|
34
|
Abstract
Skeletal muscle is an extremely heterogeneous tissue composed of a variety of fast and slow fiber types and subtypes. Moreover, muscle fibers are versatile entities capable of adjusting their phenotypic properties in response to altered functional demands. Major differences between muscle fiber types relate to their myosin complement, i.e., isoforms of myosin light and heavy chains. Myosin heavy chain (MHC) isoforms appear to represent the most appropriate markers for fiber type delineation. On this basis, pure fiber types are characterized by the expression of a single MHC isoform, whereas hybrid fiber type express two or more MHC isoforms. Hybrid fibers bridge the gap between the pure fiber types. The fiber population of skeletal muscles, thus, encompasses a continuum of pure and hybrid fiber types. Under certain conditions, changes can be induced in MHC isoform expression heading in the direction of either fast-to-slow or slow-to-fast. Increased neuromuscular activity, mechanical loading, and hypothyroidism are conditions that induce fast-to-slow transitions, whereas reduced neuromuscular activity, mechanical unloading, and hyperthyroidism cause transitions in the slow-to-fast direction.
Collapse
Affiliation(s)
- D Pette
- Department of Biology, University of Konstanz, D-78547 Konstanz, Germany
| | | |
Collapse
|
35
|
Emerson SB. Vertebrate Secondary Sexual Characteristics-Physiological Mechanisms and Evolutionary Patterns. Am Nat 2000; 156:84-91. [PMID: 10824023 DOI: 10.1086/303370] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/1999] [Accepted: 02/03/2000] [Indexed: 11/04/2022]
Abstract
As most commonly presented, the organization-activation theory of sexual differentiation emphasizes the importance of the relative age of the organism for understanding steroid hormone effects. However, considering the actual physiological mechanisms of tissue enlargement (hyperplasia/hypertrophy) provides an additional perspective for interpreting patterns of evolutionary change in sexual dimorphism. Using that focus, it is possible to suggest mechanistic explanations for patterns of allometry and the size of some secondary sexual characteristics produced by "runaway" selection. It can also lead to the formulation of testable hypotheses regarding the type of sexually dimorphic characters that might evolve through "good genes" models; the relationship between intrasexual competition, polygyny, and the development and size of male weapons; and the control and type of secondary sexual characteristics that will be present in males with associated and disassociated reproductive patterns.
Collapse
|
36
|
Nnodim JO. Quantitative study of the effects of denervation and castration on the levator ani muscle of the rat. THE ANATOMICAL RECORD 1999; 255:324-33. [PMID: 10411399 DOI: 10.1002/(sici)1097-0185(19990701)255:3<324::aid-ar8>3.0.co;2-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The levator ani muscle (LA) of the rat is highly androgen-sensitive and, like all skeletal muscles, deteriorates structurally and functionally when denervated. In order to elucidate the interplay of neural and endocrine influences, the separate and combined effects of denervation and castration on myofiber cross-sectional area and nuclear populations were quantitatively studied. In one group of 4-month-old male rats (A), the LA was denervated. Another group (B) was surgically castrated and a third group (C) was both denervated and castrated. The control rats (D) remained both gonad- and nerve-intact. After two months, the LA was obtained for myofiber and nuclear enumeration, cross-sectional area and satellite cell frequency determination. In the denervated muscle of gonad-intact rats (Group A), myofiber cross-sectional area was markedly diminished (265.84+/-11.38 microm2; compared with controls [Group D]: 1519.98+/-79.41 microm2; P < 0.05). Satellite cell nuclei, as a percentage of total sublaminar nuclei (i.e., satellite cell ratio), increased significantly (4.26%, from a control value of 1.91%). Castration alone (Group B) resulted in pronounced myofiber atrophy (mean cross-sectional area: 754.03+/-89.63 microm2) but had no significant effect on satellite cell ratio (2.36%). The combination of castration and denervation (Group C) elicited the same degree of myofiber atrophy as denervation alone (Group A) but had no significant impact on satellite cell ratio. Instead, the nuclear count per myofiber declined to about a third of the control level (300.5+/-38.49 compared with 861.7+/-24.8; P < 0.05). The results indicate that the atrophic effects of denervation and castration on the LA are non-synergistic and mechanistically similar. They also show that the inability of satellite cells to respond mitotically to the withdrawal of neural input under disandrogenized conditions is a factor in the myonuclear depletion of the denervated muscle of castrated rats.
Collapse
Affiliation(s)
- J O Nnodim
- Department of Anatomy and Cell Biology, University of Michigan Medical School, Ann Arbor 48109, USA.
| |
Collapse
|
37
|
Hegstrom CD, Breedlove SM. Short day lengths delay development of the SNB neuromuscular system in the Siberian hamster,Phodopus sungorus. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1097-4695(19980615)35:4<355::aid-neu2>3.0.co;2-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
38
|
Abstract
The role of androgens in vertebrate females has been overlooked until recently. We examine the functional significance of androgens in females by reviewing studies that document relatively high levels of circulating plasma androgens, androgen receptors, or androgen-metabolizing enzymes in females. Among the mechanisms of androgenic action identified are enhanced neuron survival, stimulation of muscle satellite cell proliferation, alteration of ion current kinetics, and release of somatostatin. These mechanisms are not sex specific and thus we hypothesize that androgens play a significant role in normal female development. We encourage study in this nontraditional research area.
Collapse
Affiliation(s)
- N L Staub
- Biology Department, Gonzaga University, Spokane, Washington, 99258, USA.
| | | |
Collapse
|
39
|
Dodson MV, McFarland DC, Grant AL, Doumit ME, Velleman SG. Extrinsic regulation of domestic animal-derived satellite cells. Domest Anim Endocrinol 1996; 13:107-26. [PMID: 8665800 DOI: 10.1016/0739-7240(95)00062-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Satellite cells are the postnatal myogenic cells, as they provide myonuclei to support skeletal muscle hypertrophy and are principal cells responsible for myofiber repair and regeneration. Even though research with satellite cells from meat animals is new, considerable data exist to suggest that these cells are regulated through both intrinsic and extrinsic mechanisms. This review covers the present status of the extrinsic factors known or postulated to modulate meat animal satellite cell growth and development.
Collapse
Affiliation(s)
- M V Dodson
- Department of Animal Science, Washington State University, Pullman 99164-6320, USA
| | | | | | | | | |
Collapse
|