Objective: To investigate the role of DNA damage induced by beta-nicotinamide adenine dinucleotide phosphate (NADPH) in human spermatozoa.
Design: Prospective controlled study.
Setting: Male infertility clinic at the Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
Patient(s): Twenty-eight men undergoing infertility screening.
Intervention(s): Chemiluminescence assay and terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling (TUNEL) assay coupled flow cytometry after incubating mature and immature sperm separated by density gradient with 5 mM NADPH for 0, 3, and 24 hours.
Main outcome measure(s): Reactive oxygen species (ROS) generation (10(6) counted photons per minute/10(6) sperm) and percentage of spermatozoa with fragmented DNA.
Result(s): Immature sperm from teratozoospermic semen samples were characterized by a statistically significant presence of cytoplasmic residues in the mid-piece when compared with mature normozoospermic samples. Increased ROS production was observed in spermatozoa rich in cytoplasmic residues that showed a statistically significant positive correlation with sperm DNA damage in a time-dependent manner.
Conclusion(s): Immature sperm contain high nicotinamide adenine dinucleotide phosphate (NADPH) in cytoplasmic droplets, but it has not yet been clear whether abnormal sperm morphology plays any role in sperm DNA damage induced by oxidative stress. Our data support the role of NAPDH in ROS-mediated sperm DNA damage and suggest that abnormal sperm morphology combined with elevated ROS production may serve as a useful indicator of potential damage to sperm DNA.