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Published on: February 5, 2018
The effects of male age on sperm DNA damage: an evaluation of 2,178 semen samples
Claudia G Petersen1,2, Ana L Mauri1,2, Laura D Vagnini2
1Center for Human Reproduction Prof. Franco Jr., Ribeirão Preto, SP, Brazil.
Objective:
This study aimed to evaluate the effects of male age on sperm DNA damage.
Methods:
This cross-sectional study included semen samples collected from 2,178 men seen at an infertility clinic. For DNA integrity analysis, the proportions of spermatozoa showing DNA fragmentation (TUNEL assay), abnormal chromatin packaging/underprotamination (chromomycin A3), abnormal mitochondrial membrane potential (MMP/MitoTracker Green), and apoptosis (annexin V) were recorded. For group comparisons, enrolled subjects were divided into three groups based on their ages: ≤35 years; 36-44 years; and ≥45 years. The associations between age and sperm parameters were assessed using Spearman's rank correlation coefficient.
Results:
Although aging did not affect sperm apoptosis (p>.05), sperm DNA fragmentation and MMP deteriorated significantly with age (p<.05). Chromatin packaging/protamination improved significantly with age (p<.05).
Conclusion:
Sperm DNA fragmentation worsened with age and was apparently associated with mitochondrial damage. The age-related increase in sperm DNA damage suggests that delaying childbearing, not only in women but also in men, might jeopardize a couple's reproductive capacity. The increase seen in chromatin packaging might represent a protective feature for DNA. However, additional studies must be performed to confirm the results concerning chromatin packaging/protamination.
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