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Chung JY, Chen H, Zirkin B. Sirt1 and Nrf2: regulation of Leydig cell oxidant/antioxidant intracellular environment and steroid formation†. Biol Reprod 2021; 105:1307-1316. [PMID: 34363387 PMCID: PMC8598996 DOI: 10.1093/biolre/ioab150] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/16/2021] [Accepted: 08/05/2021] [Indexed: 12/29/2022] Open
Abstract
Previous studies reported that, with aging, Leydig cell intracellular antioxidants are reduced in concentration and intracellular ROS levels increase, suggesting that oxidant/antioxidant imbalance may contribute to the reduced testosterone production that characterizes the aging cells. As yet, little is known about how the Leydig cell oxidant/antioxidant environment is regulated. Sirt1, an enzyme that deacetylates transcription factors, and the transcription factor Nrf2, have been shown to be associated with cellular response to oxidative stress. We hypothesized that Sirt1 and/or Nrf2 might be involved in regulating the oxidant/antioxidant environment of Leydig cells, and therefore, the testosterone production. We found that Sirt1 and Nrf2 are present in the Leydig cells of Brown Norway rats, though reduced in aged cells. In MA-10 cells in which Sirt1 or Nrf2 were suppressed by nicotinamide (NAM) or ML385, respectively, or in which siRNAs were used for knockdown of Sirt1 or Nrf2, increased ROS levels and decreased progesterone production occurred. In rat Leydig cells, inhibition of Sirt1 by culturing the cells with NAM resulted in increased ROS and reduced testosterone production, and subsequent removal of NAM from the culture medium resulted in increased testosterone production. Activation of rat Leydig cells Sirt1 with honokiol or of Nrf2 with sulforaphane resulted in the maintenance of testosterone production despite the exposure of the cells to oxidizing agent. These results, taken together, suggest that Sirt1 and Nrf2 are involved in maintaining the Leydig cell oxidant/antioxidant environment, and thus in maintaining steroid production.
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Affiliation(s)
- Jin-Yong Chung
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
| | - Haolin Chen
- Department of Anesthesiology, the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Barry Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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Chen M, Yang W, Liu N, Zhang X, Dong W, Lan X, Pan C. Pig Hsd17b3: Alternative splice variants expression, insertion/deletion (indel) in promoter region and their associations with male reproductive traits. J Steroid Biochem Mol Biol 2019; 195:105483. [PMID: 31550505 DOI: 10.1016/j.jsbmb.2019.105483] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 02/05/2023]
Abstract
Hydroxysteroid 17-Beta Dehydrogenase 3 (Hsd17b3), primarily expressed in Leydig cells (LCs) of the mammalian testes, is essential for testosterone biosynthesis and male fertility. The aim of our study was to profile the expression, splice variants (SV) and novel insertion/deletion (indel) of Hsd17b3 in boars. Quantitative analysis showed that the expression level of Hsd17b3 in the testis was significantly highest. Among different testicular cell types, the Hsd17b3 mRNA expression level of LCs was significantly higher than that of SSCs (spermatogonial stem cells) and SCs (Sertoli cells). Furthermore, the SV was firstly identified in pigs and it was highly expressed in LCs comparing with SSCs and SCs. In addition, two mutations were identified in pig Hsd17b3 gene promotor and intron, respectively, which were associated with male reproductive traits (P < 0.05). In conclusion, both transcripts of Hsd17b3 gene were highly expressed in pig testes and LCs; the two novel indel variants of Hsd17b3 gene can be used as potential DNA makers for the marker-assisted selection in pigs. All these findings would enrich the study of Hsd17b3 gene in pig genetic breeding.
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Affiliation(s)
- Mingyue Chen
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Wenjing Yang
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Nuan Liu
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Xuelian Zhang
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Wuzi Dong
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Xianyong Lan
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Chuanying Pan
- College of Animal Science and Technology, Northwest A&F University, Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Yangling, 712100, Shaanxi, China.
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Kim K, Choe HK. Role of hypothalamus in aging and its underlying cellular mechanisms. Mech Ageing Dev 2018; 177:74-79. [PMID: 29729230 DOI: 10.1016/j.mad.2018.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/20/2018] [Accepted: 04/30/2018] [Indexed: 02/06/2023]
Abstract
Aging is characterized by a progressive loss of several physiological functions that can cause various age-related disorders. Several factors have been identified as causes of aging to elucidate the decline in functions. Various aspects of physiological deterioration are controlled by the hypothalamus, a critical brain region that connects the neuroendocrine system to physiological functions. In addition, functional alterations in a set of agouti-related peptide/neuropeptide Y (AgRP/NPY) and pro-opiomelanocortin (POMC) neurons, a set of growth hormone-releasing hormone (GHRH) and somatostatin (SST) neurons, a set of arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP) neurons, and a set of gonadotropin-releasing hormone (GnRH) and kisspeptin/neurokinin B/dynorphin (KNDy) neurons contribute to age-related physiological decline in energy metabolism, hormone regulation, circadian rhythm, and reproduction, respectively. The underlying cellular mechanism for the hypothalamus-mediated aging progression comprises dysregulation of nutrient sensing, altered intercellular communication, stem cell exhaustion, loss of proteostasis, and epigenetic alterations. Furthermore, mammalian target of rapamycin (mTOR), NF-kB, hypothalamic stem cell, autophagy, and SIRT1 have been recognized as critical factors or pathways mediating the mechanism. Perhaps, further dissection of these pathways or components could provide the potential for developing a therapeutic intervention for age-related diseases or the extension of healthy lifespan.
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Affiliation(s)
- Keetae Kim
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea.
| | - Han Kyoung Choe
- Department of Brain and Cognitive Sciences, DGIST, Daegu, 42988, Republic of Korea.
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Frenette E, Guilleminault C. NEUROHORMONES AND SLEEP. Continuum (Minneap Minn) 2009. [DOI: 10.1212/01.con.0000300027.22909.c4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Andersen ML, Tufik S. The effects of testosterone on sleep and sleep-disordered breathing in men: Its bidirectional interaction with erectile function. Sleep Med Rev 2008; 12:365-79. [DOI: 10.1016/j.smrv.2007.12.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Lacombe A, Lelievre V, Roselli CE, Salameh W, Lue YH, Lawson G, Muller JM, Waschek JA, Vilain E. Delayed testicular aging in pituitary adenylate cyclase-activating peptide (PACAP) null mice. Proc Natl Acad Sci U S A 2006; 103:3793-8. [PMID: 16505386 PMCID: PMC1450155 DOI: 10.1073/pnas.0505827103] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Age-related decline in male sex hormones is a direct consequence of testicular aging. These changes in the hormonal complement cause physiological disturbances affecting the quality of life for millions of aging men. To assess the influence on testicular aging of pituitary adenylate cyclase-activating peptide (PACAP), a polypeptide that regulates testicular steroidogenesis in vitro, we compared the testicular structure and function between C57BL/6 wild-type and PACAP-/- male mice, at 4 and 15 months of age. We show that, in 4-month-old PACAP-/- mice, steroidogenesis (evaluated by levels of testosterone, steroidogenic acute regulatory protein, 3beta-hydroxysteroid dehydrogenase, and P450c17) was impaired. However, the testicular structure of these animals was not affected. At 15 months of age, wild-type testis displayed typical signs of aging (patchy seminiferous tubules, germ cell depletion, and vacuolization), whereas testicular structure was remarkably well conserved in PACAP-/- animals. The depletion of germ cells found in wild-type animals was associated with a higher content of peroxynitrites, a marker of reactive oxygen species, and a higher number of apoptotic cells compared with PACAP-/- mice. Our results show that testicular aging is delayed in PACAP-/- animals. Because the expression levels of steroidogenic factors are low and constant over time in knockout animals, a proposed mechanism for the protection against testicular degeneration is that production of reactive oxygen species, a byproduct of steroidogenesis that induces apoptosis, is down-regulated in PACAP-/- animals.
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Affiliation(s)
- Arnaud Lacombe
- *Departments of Human Genetics, Pediatrics, and Urology, University of California, Gonda Center, 695 Charles Young Drive South, Los Angeles, CA 90095-7088
- Institut de Physiologie et Biologie Cellulaires, Centre National de la Recherche Scientifique–Unité Mixte de Recherche 6187 Pôle Biologie Santé, 40 Avenue du Recteur Pineau, 86022 Poitiers, France; and
| | - Vincent Lelievre
- Institut National de la Santé et de la Recherche Médicale U676, Hôpital Robert-Debré, 48 Boulevard Sérurier, F-75019 Paris, France
- Mental Retardation Research Center, University of California, Neurosciences Research Building, 655 Charles Young Drive South, Los Angeles, CA 90095-7088
| | - Charles E. Roselli
- Department of Physiology and Pharmacology L334, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97201-3098
| | - Wael Salameh
- Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, 1000 West Carson Street, Torrance, CA 90509
| | - Yan-he Lue
- Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, 1000 West Carson Street, Torrance, CA 90509
| | - Gregory Lawson
- **Division of Laboratory Animal Medicine, University of California, 924 Westwood Boulevard, Los Angeles, CA 90095-7336
| | - Jean-Marc Muller
- Institut de Physiologie et Biologie Cellulaires, Centre National de la Recherche Scientifique–Unité Mixte de Recherche 6187 Pôle Biologie Santé, 40 Avenue du Recteur Pineau, 86022 Poitiers, France; and
| | - James A. Waschek
- Mental Retardation Research Center, University of California, Neurosciences Research Building, 655 Charles Young Drive South, Los Angeles, CA 90095-7088
| | - Eric Vilain
- *Departments of Human Genetics, Pediatrics, and Urology, University of California, Gonda Center, 695 Charles Young Drive South, Los Angeles, CA 90095-7088
- To whom correspondence should be addressed at:
David Geffen School of Medicine, University of California, Gonda Center, Room 6357, 695 Charles Young Drive South, Los Angeles, CA 90095-7088. E-mail:
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Abstract
Serum testosterone levels decline in men with increasing age. Late-onset hypogonadism with its characteristic symptoms can occur in men as they age. Typical symptoms of late-onset hypogonadism are decreased libido and sexual function, osteoporosis, altered distribution of body fat, overall reduction in physical strength, and alterations in general mood. Late-onset hypogonadism can be treated with testosterone, and different forms of testosterone have become available for this indication. The aim of testosterone replacement therapy is to produce serum testosterone levels within the physiological range avoiding levels above and below this range. Although hormone replacement therapy has become accepted in aging males, careful consideration of the indications and therapy monitoring are still required since there are major concerns about the long-term outcome of this therapy and particularly its effects on the prostate gland.
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Affiliation(s)
- T Diemer
- Klinik und Poliklinik für Urologie und Kinderurologie, Universitätsklinikum Giessen und Marburg, Justus-Liebig-Universität, Giessen.
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Abstract
Aging is associated with a progressive decline in physical and cognitive functions. The impact of age-dependent endocrine changes regulated by the central nervous system on the dynamics of neuronal behavior, neurodegeneration, cognition, biological rhythms, sexual behavior, and metabolism are reviewed. We also briefly review how functional deficits associated with increases in glucocorticoids and cytokines and declining production of sex steroids, GH, and IGF are likely exacerbated by age-dependent molecular misreading and alterations in components of signal transduction pathways and transcription factors.
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Affiliation(s)
- Roy G Smith
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, M320, Houston, TX 77030, USA.
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Sader MA, McGrath KCY, Hill MD, Bradstock KF, Jimenez M, Handelsman DJ, Celermajer DS, Death AK. Androgen receptor gene expression in leucocytes is hormonally regulated: implications for gender differences in disease pathogenesis. Clin Endocrinol (Oxf) 2005; 62:56-63. [PMID: 15638871 DOI: 10.1111/j.1365-2265.2004.02173.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE There is evidence that male sex hormones influence the rate of progression of inflammatory and cardiovascular diseases. We have previously shown that human leucocytes and arterial cells isolated from male donors express more androgen receptor (AR) than those from female cells, with potentially pro-atherogenic effects. We now investigate whether the gender difference in AR expression is due to genetic or hormonal regulation. DESIGN AND PATIENTS The influence of hormones on AR expression were studied in hpg mice (a mouse model of androgen deficiency) treated with testosterone, oestradiol or dihydrotestosterone (DHT). Blood samples were obtained for leucocyte AR expression and hormone levels from 53 subjects, grouped into: 12 male [six young adult (27-45 years), six elderly (71-79 years)] and six female (young adult 25-45 years) healthy controls; six male-to-female transsexuals (M2F; 20-50 years) receiving stable pharmacological oral oestrogen treatment; six female-to-male transsexuals (F2M; 31-51 years) receiving stable androgen replacement therapy; five younger men (18-56 years) who had been receiving long-term androgen replacement therapy for hypogonadal disease; six elderly men (72-88 years) who had undergone medical castration for prostate cancer treatment; and 12 male bone marrow transplant recipients (BMT; 23-65 years) from either male or female donors. MEASUREMENTS Serum testosterone and oestradiol concentrations were measured by established immunoflurometric assays from unextracted human serum. AR mRNA levels were measured by RT-PCR and AR protein levels by western blot (cell culture) or immunohistochemistry (mouse arteries). RESULTS We found that AR mRNA levels were significantly down-regulated in the leucocytes of hpg mice that were treated with exogenous testosterone, oestradiol or DHT. AR protein levels were also lower in aortic tissue from the same mice. In humans, we found AR expression was significantly down-regulated by exogenous treatment with testosterone in F2M (31 +/- 13%, compared with control) or oestradiol in M2F (22 +/- 5%) but was significantly up-regulated by endogenous testosterone in BMT (128 +/- 17%). Low androgen levels measured in castrated older men were associated with markedly increased AR expression (207 +/- 26%, P < 0.05) compared with age-matched older male controls (100 +/- 2%). CONCLUSIONS Our results indicate a regulated ability of vascular cells to respond to sex hormones, with the effects of exogenous therapies differing markedly from those due to endogenous sex hormones. We conclude that the gender difference in AR expression in vascular cells is hormonally, rather than genetically, controlled.
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Affiliation(s)
- Mark A Sader
- Department of Cardiology, Royal Prince Alfred Hospital, NSW, Australia
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Chen H, Liu J, Luo L, Zirkin BR. Dibutyryl cyclic adenosine monophosphate restores the ability of aged Leydig cells to produce testosterone at the high levels characteristic of young cells. Endocrinology 2004; 145:4441-6. [PMID: 15231695 DOI: 10.1210/en.2004-0639] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The wealth of knowledge about the function and regulation of adult Leydig cells, the cells within the mammalian testis that produce testosterone, make these cells ideal for studying principles and mechanisms of aging. A hallmark of mammalian aging is decreased serum testosterone concentration. In the Brown Norway rat, this has been shown to be associated with the reduced ability of aged Leydig cells to produce testosterone in response to LH. Herein, we demonstrate that culturing the aged cells with dibutyryl cAMP, a membrane-permeable cAMP agonist that bypasses the LH receptor-adenlyly cyclase cascade, restores testosterone production to levels comparable to those of young cells and also restores steroidogenic acute regulatory protein and P450scc, the proteins involved in the rate-limiting steps of steroidogenesis. These results strongly suggest that signal transduction deficits are responsible for reduced steroidogenesis by aged Leydig cells and that bypassing signal transduction reverses the steroidogenic decline by the aged cells.
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Affiliation(s)
- Haolin Chen
- Department of Biochemistry and Molecular Biology, Division of Reproductive Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA.
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Chen H. Gene expression by the anterior pituitary gland: effects of age and caloric restriction. Mol Cell Endocrinol 2004; 222:21-31. [PMID: 15249122 DOI: 10.1016/j.mce.2004.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2003] [Revised: 05/14/2004] [Accepted: 05/19/2004] [Indexed: 10/26/2022]
Abstract
Biological aging is associated with functional deficits at the cellular, organ, and system levels. The pituitary gland, the central organ of the neuroendocrine system, has been shown to play an important role in the aging process. To gain a better understanding of its functional changes with aging, we compared the gene expression profiles of the anterior pituitary of young and old Brown Norway rats, focusing on the major pituitary hormone genes. We also explored the effects of caloric restriction, an intervention shown to delay or inhibit age-associated pathologic and biologic changes in a number of systems and organisms, on the expression of these genes. Of the total of 1176 genes arrayed on each of the six membranes per group that we used, 542 (46%) were detectable in the anterior pituitary of young and old rats. Significance analysis of microarrays (SAM) of these 542 detectable genes revealed 28 genes that changed significantly with age, among which 24 decreased and 4 increased. Among the five major hormone genes on the membrane, growth hormone (GH) and prolactin decreased with age, the glycoprotein hormone common alpha subunit gene increased, and follicle-stimulating hormone-beta subunit (FSH-beta) and thyrotropin-beta (TSH-beta) subunit did not change. Among these genes, the three found to change by array analysis were confirmed to do so by Northern blot analysis. For the two genes among the five that were not selected (i.e. did not change) by array analysis, TSH-beta also showed no significant change by Northern blot; but the other, FSH-beta, showed significant increase. Thus, of the five genes checked by Northern blot analysis, the results were consistent with the array data in four cases. Short-term caloric restriction (5 weeks) of young adult animals resulted in 19 genes being significantly down-regulated, while no significantly up-regulated genes were identified. Among the genes that were down-regulated were GH, gonadotropin releasing hormone receptor (GnRH-R), three cytochrome c oxidase subunits and two heat shock proteins. With long-term (21 month) caloric restriction, about 30% of the genes that changed with aging (8/28) were prevented from doing so, and none of the age-related changes was enhanced with long-term caloric restriction. The genes that showed most significant rescue were neuropeptide Y, GnRH-R, DNA-binding protein inhibitor Id-3, and nerve growth factor-induced protein I-B. These results indicate that long-term caloric restriction can partially prevent some of the age-related changes in gene expression in the anterior pituitary of Brown Norway rats, suggesting a benefit of this regimen to be the slowing of the aging process. The fact that fewer than 30% genes derived benefit also suggests that the effect of caloric restriction is rather limit, which is consistent with the thesis that caloric restriction may slow, but not prevent, the aging process.
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Affiliation(s)
- Haolin Chen
- Division of Reproductive Biology, Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA.
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Chen H, Cangello D, Benson S, Folmer J, Zhu H, Trush MA, Zirkin BR. Age-related increase in mitochondrial superoxide generation in the testosterone-producing cells of Brown Norway rat testes: relationship to reduced steroidogenic function? Exp Gerontol 2001; 36:1361-73. [PMID: 11602210 DOI: 10.1016/s0531-5565(01)00118-8] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Aging in Brown Norway rats is accompanied by the reduced production of testosterone by the Leydig cells, the testicular cells responsible for synthesizing and secreting this essential steroid. As yet, the mechanism by which Leydig cell steroidogenesis is reduced is unknown. Herein we assess the production of mitochondrial reactive oxygen species by intact Leydig cells isolated from the testes of young and old rats. To this end, Leydig cells were incubated with lucigenin (bis-N-methylacridinium nitrate), a probe that enters cells, localizes to mitochondria, and yields a significant chemiluminescent response following its reaction with intramitochondrial superoxide. Leydig cells from old rats elicited significantly greater lucigenin-derived chemiluminescence (LDCL) than those from young rats. Electron microscopic stereological analysis revealed that the absolute volume of mitochondria in the old cells was reduced from that in the young. These results, taken together, suggest that there are age-related changes in the production of reactive oxygen species by the mitochondria of Leydig cells, with those of old Leydig cells producing significantly greater levels than those of young Leydig cells. The results are consistent with the proposal that mitochondrial-derived reactive oxygen may play a role in the irreversible decline in the ability of old Leydig cells to produce testosterone.
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Affiliation(s)
- H Chen
- Department of Biochemistry and Molecular Biology, Division of Reproductive Biology, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
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Affiliation(s)
- I Huhtaniemi
- Department of Obstetrics and Gyneacology, University of Aberdeen, Scotland, United Kingdom
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