P-041 Impact of cigarette smoking on level of sperm reactive oxygen species in normozoospermic men
Authors: Ye L , Peng Y , Song M , Lai L , Xiao W , Wen W 
Published: July 2024

Abstract

Study question
Does cigarette smoking influence the levels of sperm reactive oxygen species (ROS) in men with normal semen routine parameters?

Summary answer
Cigarettes impact the sperm ROS of normozoospermic smokers, whose sperm ROS level is elevated when they smoke equal to or more than 10 cigarettes daily.

What is known already
Increasing evidence indicates that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated ROS levels in semen. Cigarette smoking leads to an imbalance between ROS and antioxidants in the semen of smokers, which may negatively affect semen quality and male fertility. However, few studies concern whether cigarette smoking would influence the sperm ROS levels in normozoospermic men.

Study design, size, duration
Data of semen analysis from January 2021 to December 2023 were involved. Men with normal semen routine parameters, including sperm concentration, total sperm number, sperm progressive motility, total motility and normal forms of sperm morphology, were included in the study. Sperm ROS levels of normozoospermic men were retrospectively analyzed. Men with varicocele and leucocytospermia were excluded.

Participants/materials, setting, methods
Sperm count and motility were analyzed by the computer-assisted sperm analysis (CASA) system, while sperm morphology was examined after the Diff-Quik rapid staining procedure. Sperm ROS was measured by flow cytometry using the probe DCFH-DA. Sperm ROS levels of smokers and non-smokers were compared by the Mann-Whitney U test. The Kruskal-Wallis H test was used for the comparison of sperm ROS levels among the control group and smoking subgroups.

Main results and the role of chance
A total of 2946 subjects were involved in the present study. The included subjects were divided into smokers (n = 730) and non-smokers (n = 2216) according to the clinical records. And the included smokers were subsequently divided into three subgroups according to the daily cigarettes taken, which were group A (1∼9 cigarettes/day, n = 184), group B (1∼19 cigarettes/day, n = 315), and group C (&gt;20 cigarettes/day, n = 231). No statistically significant differences in age or BMI were found between smokers and non-smokers with normozoospermia. The sperm ROS level of the smoker was higher than that of the non-smoker [14.53% (14.84%) vs. 13.07% (12.09%), p = 0.001]. Compared to the control group (non-smoker), the sperm ROS levels of group B [13.07% (12.09%) vs. 15.44% (14.28%), p = 0.002] and group C [13.07% (12.09%) vs. 14.80% (14.31%)., p = 0.042] were significantly elevated. ROS levels in the control group and group A were comparable [13.07% (12.09%) vs. 13.46% (15.74%)., p = 0.391].

Limitations, reasons for caution
It is a single-center study and the above results were from a retrospective analysis.

Wider implications of the findings
The above results indicate that cigarette smoking, although it would not deteriorate semen routine parameters, may increase the ROS level in sperm. Elevated ROS in sperm may lead to an imbalance of redox in sperm, which may contribute to male infertility.

Trial registration number
not applicable