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An Update on Semen Physiology, Technologies, and Selection Techniques for the Advancement of In Vitro Equine Embryo Production: Section I. Animals (Basel) 2021; 11:ani11113248. [PMID: 34827983 PMCID: PMC8614440 DOI: 10.3390/ani11113248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/09/2021] [Accepted: 11/11/2021] [Indexed: 12/05/2022] Open
Abstract
Simple Summary Male fertility is often estimated by simple sperm assessment, and therefore, it is crucial to establish species-specific baselines for normal sperm parameters. In this paper, sperm physiology, function, and common abnormalities in stallions will be reviewed. Abstract As the use of assisted reproductive technologies (ART) and in vitro embryo production (IVP) expand in the equine industry, it has become necessary to further our understanding of semen physiology as it applies to overall fertility. This segment of our two-section review will focus on normal sperm parameters, beginning with development and extending through the basic morphology of mature spermatozoa, as well as common issues with male factor infertility in IVP. Ultimately, the relevance of sperm parameters to overall male factor fertility in equine IVP will be assessed.
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Pintus E, Ros-Santaella JL. Impact of Oxidative Stress on Male Reproduction in Domestic and Wild Animals. Antioxidants (Basel) 2021; 10:antiox10071154. [PMID: 34356386 PMCID: PMC8301082 DOI: 10.3390/antiox10071154] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/27/2021] [Accepted: 07/16/2021] [Indexed: 01/02/2023] Open
Abstract
Oxidative stress occurs when the levels of reactive oxygen species (ROS) overcome the antioxidant defenses of the organism, jeopardizing several biological functions, including reproduction. In the male reproductive system, oxidative stress not only impairs sperm fertility but also compromises offspring health and survival, inducing oxidative damage to lipids, proteins and nucleic acids. Although a clear link between oxidative stress and male fertility disorders has been demonstrated in humans and laboratory rodents, little information is available about the implications of impaired redox homeostasis in the male fertility of domestic and wild animals. Therefore, this review aims to provide an update regarding the intrinsic and extrinsic factors that are associated with oxidative stress in the male reproductive system and their impact on the reproductive performance of domestic and wild animals. The most recent strategies for palliating the detrimental effects of oxidative stress on male fertility are reviewed together with their potential economic and ecological implications in the livestock industry and biodiversity conservation.
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Keshtgar S, Ebrahimi B, Shid-Moosavi SM, Erfani N. NADPH oxidase 5 activation; a novel approach to human sperm cryoinjury. Cell Tissue Bank 2020; 21:675-684. [PMID: 32607683 DOI: 10.1007/s10561-020-09845-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 06/23/2020] [Indexed: 12/19/2022]
Abstract
Sperm cryopreservation leads to various structural and functional damages, some of which induce by oxidative stress. The reactive oxygen species (ROS) generates by mitochondria and membrane NADPH oxidases (NOXs). Among the NOXs, only NOX5 has been identified in the cell membrane of human sperm. This study was designed to clarify the possible role of NOX5 on sperm cryoinjury. Forty human semen samples were washed and randomly divided into fresh and cryopreserved groups. Each group was divided into 4 subgroups containing Ham's F10 (control), 0.1% DMSO (vehicle), 100 nM of PMA (phorbol 12-myristate 13-acetate) and 1 µM of DPI (diphenyleneiodonium), as NOX5 activator and inhibitor. The samples of cryopreserved groups were preserved in liquid nitrogen for 1 month. The sperm kinematics, membrane integrity, ROS production, apoptosis rate, mitochondrial membrane potential (MMP), intracellular ATP and calcium concentration [Ca2+]i were evaluated. The percent of sperm with intact membrane and motile sperm reduced significantly after thawing (p ≤ 0.01). The ROS production (p ≤ 0.01) and the apoptotic rate increased, MMP dissipated, and the percentage of live cells with high [Ca2+]i decreased significantly in the cryopreserved control group relative to the fresh control group. DPI, in contrast to PMA, improved sperm progressive motility (p ≤ 0.01), membrane integrity in fresh and cryopreserved groups and reduced the ROS amount in cryopreserved group (p ≤ 0.01). Apoptotic rate, [Ca2+]i, ATP, and MMP did not change with DPI and PMA in cryopreserved groups. We conclude that NOX5 activity in fresh sperm is low, and it increases during cryopreservation. NOX5 inhibition improves the cryopreserved sperm quality.
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Affiliation(s)
- Sara Keshtgar
- Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Zand Blvd, 71348-45794, Shiraz, Iran
| | - Bahareh Ebrahimi
- Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Zand Blvd, 71348-45794, Shiraz, Iran.
| | - Seyed Mostafa Shid-Moosavi
- Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Zand Blvd, 71348-45794, Shiraz, Iran
| | - Nasrollah Erfani
- Department of Immunology and Institute for Cancer Research, School of Medicine, Shiraz University of Medical Sciences, 71345-1798, Shiraz, Iran
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Abstract
Information on donkey sperm bioenergetics, kinetics and oxidative status is scarce even though crucial for development of reproductive technologies and germplasm conservation. For these reasons, it is interesting to monitor sperm kinetics, bioenergetics, and oxidative status during sperm storage at +4°C and with several sperm extenders and concentrations. Donkey semen was collected from three jackasses, three times each. It was diluted with four extenders (Kenney, Equiplus, INRA96 or Hippex), set at three sperm concentrations (30, 50 or 70 × 106 spermatozoa/ml) and evaluated for its functionality after 0, 3, 24, 48 and 72 h storage at +4°C. Sperm kinetics was analyzed by Sperm Computer Analysis; sperm bioenergetics was assessed by mitochondrial membrane potential (MMP); sperm oxidative status was evaluated by lipid peroxidation (LPO), anti-LPO potential and nitroblue tetrazolium (NBT) assays. Incubation produced a progressive (P < 0.01) decline in sperm kinetics and MMP, whereas parameters related to oxidative status either increased (LPO, NBT) or decreased (anti-LPO). The anti-LPO potential was the index better related to sperm motility and kinetics. Extenders proved to be differently (P < 0.01) effective in preserving sperm kinetics, MMP, and oxidative status. The concentration of 30 × 106 spermatozoa/ml provided an optimum preservation of sperm functions. Significant correlations emerged between most parameters examined. This study identified reference criteria for storing donkey spermatozoa at +4°C. A low sperm concentration together with a proper extender are crucial requirements for optimum sperm cryopreservation efficiency. Field trials are, however, required to validate these findings, making them operational in practice.
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Mostek A, Slowinska M, Judycka S, Karol H, Ciereszko A, Dietrich MA. Identification of oxidatively modified proteins due to cryopreservation of carp semen. J Anim Sci 2018. [PMID: 29534196 DOI: 10.1093/jas/sky063] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
During semen cryopreservation, spermatozoa are exposed to physical and chemical stressors that result in their functional and structural damage. Growing evidence suggests that most cryoinjuries result from oxidative stress accompanying sperm cryopreservation. Elevated amounts of reactive oxygen species (ROS) generated during cryopreservation can react with sperm macromolecules, including proteins. The goal of this study was to investigate the oxidative modifications (measured as carbonylation level changes) of carp spermatozoa proteins triggered by the cryopreservation process. Flow cytometry and computer-assisted sperm analysis were used to evaluate changes in viability, ROS level, and motility of spermatozoa. The spermatozoa proteins that were specifically carbonylated were identified and quantified by Western blotting, in conjunction with 2-dimensional electrophoresis (2D-oxyblot) and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Cryopreservation decreased spermatozoa motility (P < 0.01) and viability (P < 0.0001) and significantly increased (P < 0.0001) the number of ROS-positive cells. We identified 25 protein spots, corresponding to 19 proteins, with increases (P < 0.05) in carbonylation level due to freezing/thawing. The identified proteins are involved in motility, metabolism, calcium-ion binding, signal transduction, protein folding, and intracellular transport. The results suggest that carbonylation of flagellar proteins can result in motility disorders and may contribute to the reduced percentage of motile spermatozoa and disturbances in movement trajectory after sperm cryopreservation. Moreover, cryopreservation may contribute to impaired cellular respiration, ATP regeneration, disturbances of Ca2+ turnover, unfolding of cytoplasmic or histone proteins, disturbances of cell signaling and intracellular transport, and reduced membrane stability. Our results contribute to the knowledge concerning cryoinjury and to further development of a modified cryopreservation procedure aimed at minimizing oxidative damage of carp sperm proteins.
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Affiliation(s)
- Agnieszka Mostek
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
| | - Mariola Slowinska
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
| | - Sylwia Judycka
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
| | - Halina Karol
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
| | - Andrzej Ciereszko
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
| | - Mariola A Dietrich
- Department of Gamete and Embryo Biology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences in Olsztyn, Tuwima, Olsztyn, Poland
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Moraes CR, Meyers S. The sperm mitochondrion: Organelle of many functions. Anim Reprod Sci 2018; 194:71-80. [DOI: 10.1016/j.anireprosci.2018.03.024] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 12/31/2022]
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Addition of Antioxidants Myoinositol, Ferulic Acid, and Melatonin and Their Effects on Sperm Motility, Membrane Integrity, and Reactive Oxygen Species Production in Cooled Equine Semen. J Equine Vet Sci 2017. [DOI: 10.1016/j.jevs.2017.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Laforenza U, Pellavio G, Marchetti AL, Omes C, Todaro F, Gastaldi G. Aquaporin-Mediated Water and Hydrogen Peroxide Transport Is Involved in Normal Human Spermatozoa Functioning. Int J Mol Sci 2016; 18:ijms18010066. [PMID: 28042826 PMCID: PMC5297701 DOI: 10.3390/ijms18010066] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/16/2016] [Accepted: 12/24/2016] [Indexed: 12/31/2022] Open
Abstract
Different aquaporins (AQPs) are expressed in human sperm cells and with a different localization. Their function has been related to cell volume control in response to the osmotic changes encountered passing from the epididymal fluid to the cervical mucus or involved in the end stage of cytoplasm removal during sperm maturation. Recently, AQPs have also shown hydrogen peroxide (H₂O₂) permeability properties. Here, we investigate the expression, localization and functioning of AQPs in human sperm cells with particular attention to their role as peroxiporins in reactive oxygen species (ROS) scavenging in both normospermic and sub-fertile human subjects. Western blotting and immunocytochemistry were used to confirm and clarify the AQPs expression and localization. Water and H₂O₂ permeability was tested by stopped flow light scattering method and by the CM-H2DCFDA (5-(and-6)-chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate, acetyl ester) H₂O₂ fluorescence probe, respectively. AQP3, -7, -8, and -11 proteins were found in human sperm cells and localized in the head (AQP7), in the middle piece (AQP8) and in the tail (AQP3 and -11) in both the plasma membrane and in intracellular structures. Sperm cells showed water and H₂O₂ permeability which was reversibly inhibited by H₂O₂, heat stress and the AQP inhibitor HgCl₂. Reduced functionality was observed in patients with compromised basal semen parameters. Present findings suggest that AQPs are involved in both volume regulation and ROS elimination. The relationship between sperm number and motility and AQP functioning was also demonstrated.
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Affiliation(s)
- Umberto Laforenza
- Department of Molecular Medicine, University of Pavia, I-27100 Pavia, Italy.
| | - Giorgia Pellavio
- Department of Molecular Medicine, University of Pavia, I-27100 Pavia, Italy.
| | - Anna Lisa Marchetti
- Scientific Direction, Fondazione IRCCS Policlinico San Matteo, I-27100 Pavia, Italy.
| | - Claudia Omes
- Center for Reproductive Medicine, Obstetrics and Ginecology Unit, Fondazione IRCCS Policlinico San Matteo, I-27100 Pavia, Italy.
| | - Federica Todaro
- Center for Reproductive Medicine, Obstetrics and Ginecology Unit, Fondazione IRCCS Policlinico San Matteo, I-27100 Pavia, Italy.
| | - Giulia Gastaldi
- Department of Molecular Medicine, University of Pavia, I-27100 Pavia, Italy.
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Darr CR, Cortopassi GA, Datta S, Varner DD, Meyers SA. Mitochondrial oxygen consumption is a unique indicator of stallion spermatozoal health and varies with cryopreservation media. Theriogenology 2016; 86:1382-92. [DOI: 10.1016/j.theriogenology.2016.04.082] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/26/2016] [Accepted: 04/26/2016] [Indexed: 12/31/2022]
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New flow cytometry approaches in equine andrology. Theriogenology 2016; 86:366-72. [PMID: 27160445 DOI: 10.1016/j.theriogenology.2016.04.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 01/20/2016] [Accepted: 03/14/2016] [Indexed: 01/07/2023]
Abstract
Flow cytometry is currently recognized as a robust tool for the evaluation of sperm quality and function. However, within equine reproduction, this technique has not reached the sophistication of other areas of biology and medicine. In recent years, more sophisticated flow cytometers have been introduced in andrology laboratories, and the number of tests that can be potentially used in the evaluation of sperm physiology has increased accordingly. In this review, recent advances in the evaluation of stallion spermatozoa will be discussed. These new techniques in flow cytometry are able to simultaneously measure damage to different sperm regions and/or changes in functionality.
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Balao da Silva CM, Ortega-Ferrusola C, Morrell JM, Rodriguez Martínez H, Peña FJ. Flow Cytometric Chromosomal Sex Sorting of Stallion Spermatozoa Induces Oxidative Stress on Mitochondria and Genomic DNA. Reprod Domest Anim 2015; 51:18-25. [DOI: 10.1111/rda.12640] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/11/2015] [Indexed: 01/29/2023]
Affiliation(s)
- CM Balao da Silva
- Laboratory of Equine Reproduction and Equine Spermatology; Veterinary Teaching Hospital; Caceres Spain
| | - C Ortega-Ferrusola
- Laboratory of Equine Reproduction and Equine Spermatology; Veterinary Teaching Hospital; Caceres Spain
| | - JM Morrell
- Division of Reproduction; Faculty of Veterinary Medicine and Animal Sciences; Swedish University of Agricultural Sciences; Uppsala Sweden
| | - H Rodriguez Martínez
- Department of Clinical and Experimental Medicine; Faculty of Health Sciences; Linköping University; Linköping Sweden
| | - FJ Peña
- Laboratory of Equine Reproduction and Equine Spermatology; Veterinary Teaching Hospital; Caceres Spain
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The β-SiC nanowires (~100 nm) induce apoptosis via oxidative stress in mouse osteoblastic cell line MC3T3-E1. BIOMED RESEARCH INTERNATIONAL 2014; 2014:312901. [PMID: 24967352 PMCID: PMC4055168 DOI: 10.1155/2014/312901] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/26/2013] [Accepted: 11/28/2013] [Indexed: 11/17/2022]
Abstract
Silicon carbide (SiC), a compound of silicon and carbon, with chemical formula SiC, the beta modification ( β-SiC), with a zinc blende crystal structure (similar to diamond), is formed at temperature below 1700°C. β-SiC will be the most suitable ceramic material for the future hard tissue replacement, such as bone and tooth. The in vitro cytotoxicity of β-SiC nanowires was investigated for the first time. Our results indicated that 100 nm long SiC nanowires could significantly induce the apoptosis in MC3T3-E1 cells, compared with 100 μm long SiC nanowires. And 100 nm long SiC nanowires increased oxidative stress in MC3T3-E1 cells, as determined by the concentrations of MDA (as a marker of lipid peroxidation) and 8-OHdG (indicator of oxidative DNA damage). Moreover, transmission electron microscopy (TEM) was performed to evaluate the morphological changes of MC3T3-E1 cells. After treatment with 100 nm long SiC nanowires, the mitochondria were swelled and disintegrated, and the production of ATP and the total oxygen uptake were also decreased significantly. Therefore, β-SiC nanowires may have limitations as medical material.
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Aitken RJ, Lambourne S, Gibb Z. The John Hughes Memorial Lecture: Aspects of Sperm Physiology—Oxidative Stress and the Functionality of Stallion Spermatozoa. J Equine Vet Sci 2014. [DOI: 10.1016/j.jevs.2013.10.120] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Aitken RJ, De Iuliis GN, Gibb Z, Baker MA. The Simmet Lecture: New Horizons on an Old Landscape - Oxidative Stress, DNA Damage and Apoptosis in the Male Germ Line. Reprod Domest Anim 2012; 47 Suppl 4:7-14. [DOI: 10.1111/j.1439-0531.2012.02049.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Urban-Chmiel R, Hola P, Lisiecka U, Wernicki A, Puchalski A, Dec M, Wysocka M. An evaluation of the effects of α-tocopherol and ascorbic acid in bovine respiratory disease complex occurring in feedlot calves after transport. Livest Sci 2011. [DOI: 10.1016/j.livsci.2011.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rodriguez PC, Valdez LB, Zaobornyj T, Boveris A, Beconi MT. Nitric Oxide and Superoxide Anion Production During Heparin-Induced Capacitation in Cryopreserved Bovine Spermatozoa. Reprod Domest Anim 2011; 46:74-81. [DOI: 10.1111/j.1439-0531.2010.01583.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Burnaugh L, Ball B, Sabeur K, Thomas A, Meyers S. Osmotic stress stimulates generation of superoxide anion by spermatozoa in horses. Anim Reprod Sci 2010; 117:249-60. [DOI: 10.1016/j.anireprosci.2009.05.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 05/08/2009] [Accepted: 05/18/2009] [Indexed: 10/20/2022]
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Oxidative stress, osmotic stress and apoptosis: Impacts on sperm function and preservation in the horse. Anim Reprod Sci 2008; 107:257-67. [DOI: 10.1016/j.anireprosci.2008.04.014] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Reactive oxygen species (ROS) play an important role in normal sperm function, and spermatozoa possess specific mechanisms for ROS generation via an NAD(P)H-dependent oxidase. The aim of this study was to identify the presence of an NADPH oxidase 5 (NOX5) in equine testis and spermatozoa. The mRNA of NOX5 was expressed in equine testis as detected by northern blot probed with human NOX5 cDNA and by RT-PCR. Immunoblotting with affinity purified alpha-NOX5 revealed one major protein in equine testis and other tissues. Immunolocalization of NOX5 showed labeling over the rostral sperm head with some labeling in the equatorial and post-acrosomal regions. In the testis, there was abundant staining in the adluminal region of the seminiferous tubules associated with round and elongating spermatids. The RT-PCR and sequence analysis revealed a high homology with human NOX5. This study demonstrates that NOX5 is present in equine spermatozoa and testes and therefore represents a potential mechanism for ROS generation in equine spermatozoa.
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Affiliation(s)
- K Sabeur
- Department of Population Health and Reproduction, University of California, Davis, California 95616, USA
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Burnaugh L, Sabeur K, Ball BA. Generation of superoxide anion by equine spermatozoa as detected by dihydroethidium. Theriogenology 2006; 67:580-9. [PMID: 17045638 DOI: 10.1016/j.theriogenology.2006.07.021] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Accepted: 07/27/2006] [Indexed: 11/29/2022]
Abstract
Low-level production of the superoxide anion (O2*-) is an important signal transduction event in sperm function including capacitation; however, excessive production of O2*- can be detrimental to sperm function. The objective of this study was to assess dihydroethidium (DHE) as a probe for O2*- in equine spermatozoa. Ejaculated spermatozoa were separated by centrifugation over a Percoll gradient (40:80), and loaded with DHE (2.0 microM) as well as with calcein-acetoxymethylester (CAM, 7.8 nM) to determine cell viability. In Experiment 1, cells were incubated with the xanthine-xanthine oxidase (X, 0.1 mM; XO, 0.01 U/mL) generating system for the production of O2*-, with or without the addition of superoxide dismutase (SOD, 150 U/mL) or the SOD mimetic, Tiron (0.1, 1.0 or 5.0 mM) for 1h. Changes in fluorescence of DHE were determined for the live cell population (calcein-positive cells) by flow cytometry. The DHE fluorescence increased with the X-XO incubation; this increase was inhibited by SOD or Tiron, indicating that DHE is specific for O2*- detection. In Experiment 2, spermatozoa were loaded with DHE/CAM, treated with calcium ionophore A23187 (0, 0.8, or 8.0 microM), and incubated for 15 min. Cell fluorescence was again determined by flow cytometry. Calcium ionophore A23187 increased O2*- production in a dose-dependent manner. In Experiment 3, cells were loaded with DHE/CAM, treated with NADPH (0.0, 0.25, 0.5, or 1 mM) with or without 0.5% Triton X-100, and incubated for 15 min prior to flow cytometry. Cells treated with NADPH with or without 0.5% Triton X-100 did not have O2*- levels that were significantly different from the control. In Experiment 4, spermatozoa loaded with DHE/CAM were incubated under capacitating conditions (1.2 mM dibutryl-cAMP+1.0 mM caffeine) or in control media for 3h. Although O2*- generation increased over time in control and capacitated treatments, spermatozoa incubated under capacitating conditions had higher O2*- production than those incubated in control media. Therefore, DHE was a useful probe for the detection of O2*- in equine spermatozoa and elevation in intracellular calcium as well as capacitation in vitro were associated with increased generation of O2*-.
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Affiliation(s)
- L Burnaugh
- Department of Population Health and Reproduction, 1114 Tupper Hall, University of California, Davis, CA 95616, USA
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