Aging is accompanied by an increase in reactive oxygen species (ROS). Spermatozoa are vulnerable to the effects of ROS; these result in damage to membranes and chromatin, the former affecting their motility and the latter impeding successful progeny outcome. The epididymis is important in protecting spermatozoa by removing ROS using glutathione and antioxidant enzymes. Therefore, our goals were to investigate how aging affects (i) the redox capacity of the epididymis, spermatozoal motility and spermatozoal chromatin packaging and integrity, as well as (ii) the susceptibility of these parameters to in vivo and in vitro oxidative challenge. Caput, corpus and cauda segments of the epididymides from young and old male Brown Norway rats were collected and glutathione and antioxidant enzyme activities were measured. Spermatozoa from the cauda epididymidis were analyzed for motility; chromatin packaging and integrity were evaluated in spermatozoa from both the caput and cauda epididymides. In vivo oxidative challenge was induced by 7-day systemic administration of L-buthionine-S,R-sulfoximine (BSO), which is an inhibitor of glutathione synthesis, and in vitro oxidative challenge was induced by incubating spermatozoa in H 2O2. We found that the redox capacity of the cauda epididymidis was altered with age, where the balance shifted towards conserving glutathione. Spermatozoal chromatin become more tightly packaged and less prone to dissociation and DNA quality decreased. Additionally, spermatozoa from old rats contained fewer overall thiols and disulfide bonds, which was due to the appearance of a low-thiol population. After BSO administration glutathione recycling increased and alternative pathways became upregulated throughout the epididymis; this response was greatest in the corpus region, whereas the cauda was affected in an age-dependent manner. Spermatozoal motility became compromised after BSO, where the effect was greater in spermatozoa from older rats. Exposure to BSO and H2O2 revealed that spermatozoa from the cauda epididymidis of older rats had a unique susceptibility to their combined effects. In summary, spermatozoal quality becomes altered in an age-dependent and epididymal segment-specific manner; it is proposed that this may be attributable to the effect of aging on the cauda epididymidis. Susceptibility to oxidative challenge also increases with age, both at the level of spermatozoal chromatin and motility.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.102774 |
| Date | January 2006 |
| Creators | Zubkova, Ekaterina V. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Pharmacology & Therapeutics.) |
| Rights | © Ekaterina V. Zubkova, 2006 |
| Relation | alephsysno: 002541585, proquestno: AAINR27862, Theses scanned by UMI/ProQuest. |
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