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


METHODS
Laboratory study.


METHODS
Academic facility.


METHODS
Young (4 months) and old (21 months) Brown Norway rats.


METHODS
Spermatozoa were collected from the cauda epididymidis and were incubated in saline or H2O2.


METHODS
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.


RESULTS
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.


CONCLUSIONS
Spermatozoal chromatin packaging changes with aging and vulnerability to oxidative damage increases.
Zubkova
Ekaterina V
EV
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
Wade
Michael
M
Robaire
Bernard
B
D000375:Aging / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D002843:Chromatin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008297:Male; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D011914:Rats, Inbred BN; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*
D002843:Chromatin; D016877:Oxidants