Are oxidative stress markers associated with unexplained male infertility?

Male infertility can be responsible for up to 20% of the cases attending fertility consultation facilities; nonetheless, the underlying molecular mechanisms that could explain it are still elusive. Therefore, we aimed to evaluate conventional and functional parameters of semen samples from patients who presented with male infertility of unknown origin. Conventional semen parameters and functional parameters (i.e. intracellular reactive oxygen species production, mitochondrial membrane potential, sperm chromatin structure assay, sperm membrane lipid peroxidation and antioxidant capacity of seminal plasma) were evaluated on semen samples from 54 healthy donors, 23 patients with idiopathic infertility and 34 fertile controls. No significant differences were observed in the conventional seminal parameters between the fertile and infertile men. However, increased intracellular reactive oxygen species (ROS) production and DNA fragmentation were observed in the infertile patients compared to the fertile group. Alterations in intracellular ROS production and DNA fragmentation could be associated with male idiopathic infertility. These parameters could eventually distinguish both groups more accurately than the conventional parameters. Our current results are encouraging, and the efficacy of these parameters in the clinical settings needs to be further assessed to establish their predictive potential as a marker of unexplained male infertility.

Evaluación de los parámetros funcionales espermáticos en individuos infértiles normozooespérmicos / Evaluation of Sperm Functional Parameters in Normozoospermic Infertile Individuals

Objetivo: El presente estudio piloto evaluó la integridad de la cromatina, los niveles de especies reactivas del oxígeno (ROS), el potencial de membrana mitocondrial (PMM), el daño en el ADN y la lipoperoxidación de la membrana espermática en muestras de hombres clasificados como infértiles de causa desconocida. Método: Entre febrero de 2010 y julio de 2011 se evaluaron los parámetros seminales y pruebas funcionales en 10 individuos con fertilidad probada, 10 donantes pertenecientes a la población general y 8 con infertilidad idiopática. Adicional al espermiograma convencional se realizaron los siguientes análisis seminales no convencionales: evaluación de ROS, PMM, ensayo de la cromatina espermática (SCSA) por citometría de flujo, evaluación de la lipoperoxidación de la membrana espermática por espectrofotometría y el ensayo cometa mediante electroforesis alcalina. Resultados: Se observó un aumento significativo (p<0,05) en la producción de ROS y en la fragmentación o daño del ADN espermático en la población de hombres infértiles. No se encontraron diferencias estadísticamente significativas (p>0,05) en los análisis de integridad de membranas espermáticas entre los grupos. Adicionalmente, se observaron correlaciones significativas (p<0,05) entre SCSA y el ensayo cometa (r=0,86) y la producción de ROS intracelular (r=−0,588). Conclusión: Los espermatozoides de los individuos diagnosticados con infertilidad idiopática mostraron altos niveles de ROS intracelular y un aumento en los niveles de fragmentación del ADN espermático. Estos resultados sugieren que estos parámetros se encuentran relacionados con la infertilidad de origen desconocido, y por tanto tienen potencial importancia clínica como una posible herramienta diagnóstica y pronóstica en la evaluación de la infertilidad idiopática masculina (AU)

Objective: This study evaluated the integrity of the chromatin structure, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), DNA damage and lipid peroxidation of semen samples from infertile men classified as unexplained infertility. Methods: Between February 2010 and July 2011 semen parameters and functional tests were evaluated in 10 subjects with proven fertility, 10 that belong to general population and 8 with idiopathic infertility. In addition to the conventional semen analysis, the following unconventional seminal analysis were conducted: evaluation of ROS, MMP, sperm chromatin structure assay (SCSA) by flow cytometry, assessment of sperm membrane lipid peroxidation by spectrophotometry, and alkaline comet assay by electrophoresis. Results: We observed a significant increase (P<0.05) in the production of ROS and the fragmentation or sperm DNA damage in the population of infertile men. There were no statistically significant differences (P>0.05) in the analysis of sperm membrane integrity between the groups. Moreover, we observed significant correlations (P<0.05) between SCSA and comet assay (r=0.86) and the production of intracellular ROS (r=-0.588). Conclusion: The sperm from individuals with idiopathic infertility showed high levels of intracellular ROS and increased levels of DNA fragmentation in the sperm. These results suggest that these two parameters are related to unexplained infertility and therefore have clinical importance as a possible diagnostic and prognostic tool in the evaluation of idiopathic male infertility (AU)

[Evaluation of sperm functional parameters in normozoospermic infertile individuals]. / Evaluación de los parámetros funcionales espermáticos en individuos infértiles normozooespérmicos.

OBJECTIVE: This study evaluated the integrity of the chromatin structure, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), DNA damage and lipid peroxidation of semen samples from infertile men classified as unexplained infertility. METHODS: Between February 2010 and July 2011 semen parameters and functional tests were evaluated in 10 subjects with proven fertility, 10 that belong to general population and 8 with idiopathic infertility. In addition to the conventional semen analysis, the following unconventional seminal analysis were conducted: evaluation of ROS, MMP, sperm chromatin structure assay (SCSA) by flow cytometry, assessment of sperm membrane lipid peroxidation by spectrophotometry, and alkaline comet assay by electrophoresis. RESULTS: We observed a significant increase (P<.05) in the production of ROS and the fragmentation or sperm DNA damage in the population of infertile men. There were no statistically significant differences (P>.05) in the analysis of sperm membrane integrity between the groups. Moreover, we observed significant correlations (P<.05) between SCSA and comet assay (r=0.86) and the production of intracellular ROS (r=-0.588). CONCLUSION: The sperm from individuals with idiopathic infertility showed high levels of intracellular ROS and increased levels of DNA fragmentation in the sperm. These results suggest that these two parameters are related to unexplained infertility and therefore have clinical importance as a possible diagnostic and prognostic tool in the evaluation of idiopathic male infertility.