High glucose concentrations per se do not adversely affect human sperm function in vitro.
Diabetes mellitus (DM) represents one of the greatest concerns to global health and it is associated with diverse clinical complications, including reproductive dysfunction. Given the multifactorial nature of DM, the mechanisms that underlie reproductive dysfunction remain unclear. Considering that hyperglycemia has been described as a major effector of the disease pathophysiology, we used an in vitro approach to address the isolated effect of high glucose conditions on human sperm function, thus avoiding other in vivo confounding players. We performed a complete and integrated analysis by measuring a variety of important indicators of spermatozoa functionality (such as motility, viability, capacitation status, acrosomal integrity, mitochondrial superoxide production and membrane potential) in human sperm samples after incubation with d- and l-glucose (5, 25, or 50 mM) for 24 and 48 h. No direct effects promoted by 25 or 50 mM d-glucose were found for any of the parameters assessed (P>0.05), except for the acrosome reaction, which was potentiated after 48 h of exposure to 50 mM d-glucose (P<0.05). Interestingly, non-metabolizable l-glucose drastically increased superoxide production (P<0.05) and suppressed sperm motility (P<0.05) and capacitation (P<0.05) after 24 h of treatment, whereas mitochondrial membrane potential (P<0.05), acrosomal integrity (P<0.01) and viability (P<0.05) were later decreased. The overall results suggest that high glucose levels per se do not influence human sperm function in vitro, which stresses the importance of other factors involved in DM pathology. Nevertheless, the absence of metabolizable glucose contributes to a severe impairment of sperm function and thus compromises male fertility.
Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal.
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Portela
Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal.
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Tavares
Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal.
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Mota
Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal.
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Ramalho-Santos
Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal Biology of Reproduction and Stem Cell GroupCenter for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-517 Coimbra, PortugalDepartment of Life SciencesUniversity of Coimbra, 3001-401 Coimbra, PortugalInstitute for Interdisciplinary ResearchUniversity of Coimbra, 3004-517 Coimbra, Portugal scgamaral@gmail.com.
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Amaral
D000177:Acrosome / Q000187:drug effects; D020101:Acrosome Reaction / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D013075:Sperm Capacitation / Q000187:drug effects*; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
D013481:Superoxides; D005947:Glucose