Changes in spermatozoal chromatin packaging and susceptibility to oxidative challenge during aging

Abstract

Objective: Our goal was to test the hypothesis that spermatozoal chromatin packaging changes with age and that aging affects the susceptibility of spermatozoal DNA to oxidative damage. Design: Laboratory study. Setting: Academic facility. Patient(s): Young (4 months) and old (21 months) Brown Norway rats. Intervention(s): Spermatozoa were collected from the cauda epididymidis and were incubated in saline or H 2 O 2 . Main Outcome Measurement(s): Thiols levels, chromatin condensation, DNA susceptibility to acid-induced DNA denaturation, and DNA damage were evaluated using monobromobimane, chromomycin A3 (CMA3), acridine orange, and polymerase chain reaction, respectively. Result(s): Spermatozoa from old rats had 25% fewer disulfides but similar levels of free thiols as compared with young. The CMA3 staining was decreased by 13% with age. Levels of chromatin denaturation and DNA damage were similar in control groups. After exposure to oxidant, free thiols became oxidized by about 20% irrespective of age, but CMA3 staining changed little. The acridine orange assay, however, showed a trend for greater chromatin denaturation in spermatozoa from old rats after oxidant treatment. Furthermore, the DNA from spermatozoa of old rats was significantly more susceptible to developing DNA breaks and modification after oxidative challenge.

The effects of age on DNA fragmentation, chromatin packaging and conventional semen parameters in spermatozoa of oligoasthenoteratozoospermic patients

“…Additionally, a number of studies have demonstrated an age-related increase in sperm cells with double-stranded DNA breaks or poor chromatin packaging [1,4,[26][27][28]. In the current study, it was observed that DNA fragmentation and poor chromatin packaging was significantly higher in OAT patients ≥35 years compared to patients younger than 34 years old.…”

The three-dimensional image analysis of the chromocenter in motile and immotile human sperm

“…Reactive oxygen species (ROS) appear to affect the stability of human sperm DNA and sperm chromatin condensation, which eventually impact sperm function [Zubkova et al 2005]. Furthermore, it has been shown that higher lipid peroxide levels in semen correlates to lower sperm motility [Kao et al 2008].…”

A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation

“…Our study suggests that the DNA of mice is extremely well protected against oxidative stress and DNA-breaking molecules. Interestingly, rat spermatozoa treated with 2.5 mM H 2 O 2 experienced a high increase in DNA damage compared with control treatments [66]. Further studies on other rodent species could elucidate why the sperm DNA of different rodent species may differ in their resistance to oxidative stress.…”