Seminal plasma selenium concentrations, sperm mtDNAcn, and semen
quality: association and mediation analyses among healthy Chinese men
Abstract
Objective: To investigate the associations of seminal plasma selenium
(Se) concentrations with semen quality and to explore the mediating role
of sperm mitochondrial DNA copy number (mtDNAcn). Design:
Cross-sectional study with repeated measurements. Setting: Hubei
Province Human Sperm Bank of China. Population: A total of 1159 healthy
men who repeatedly provided 5617 semen samples were included. Main
Outcome Measures: Seminal plasma Se concentration and sperm mtDNAcn of
healthy men screened as potential sperm donors were determined using
inductively coupled plasma mass spectrometry (ICP-MS) and real-time
fluorescent quantitative PCR (RT-qPCR), respectively. Methods: Linear
mixed-effects models and mediation analyses were performed. Result(s):
After adjusting for potential confounders, we observed positive
associations of seminal plasma Se concentrations with sperm
concentration and total count (both p-Values for trend <
0.001). Volunteers in the highest vs. lowest quartiles of seminal plasma
Se concentrations had 70.1% (95% CI: 53.3%, 88.9%) and 59.1% (95%
CI: 40.5%, 80.2%) higher sperm concentration and total count,
respectively. We also found inverse associations between within-subject
pooled seminal plasma Se concentrations and sperm mtDNAcn, and between
sperm mtDNAcn and sperm concentration, total count, total motility, and
progressive motility (all p-Values for trend < 0.05).
Mediation analyses showed that sperm mtDNAcn mediated 19.7% (95% CI:
15.9%, 25.3%) and 23.1% (95% CI: 17.4%, 33.4%) of the associations
between within-subject average seminal plasma Se concentrations and
sperm concentration and total count, respectively. Conclusions: Seminal
plasma Se concentrations were positively associated with sperm
concentration and total count, which was partly mediated by sperm
mtDNAcn.