Spermatozoa Have Decreased Antioxidant Enzymatic Capacity and Increased Reactive Oxygen Species Production During Aging in the Brown Norway Rat
Bibliographic record
Abstract
As the proportion of aged males attempting to reproduce continues to rise, so does the concern regarding the quality of spermatozoa from aged men. An imbalance between the generation of reactive oxygen species (ROS) and cellular antioxidant defenses, as occurs in aging, ultimately leads to decreased protein, lipid, and DNA quality. Spermatozoa are highly susceptible to oxidative damage, and thus an age-related shift in redox status may have serious implications for fertility. Therefore, we examined the effect of age on antioxidant enzymatic activity, ROS production, and extent of lipid peroxidation in both caput and cauda epididymal spermatozoa from young (4-month-old) and old (21-month-old) Brown Norway rats. Glutathione peroxidase (Gpx1, Gpx4) and superoxide dismutase (SOD) enzymes had decreased activity in aging spermatozoa. Immunofluorescence studies indicated that Gpx4 expression was decreased in both the head and midpiece regions of spermatozoa in aged animals. The decrease in nuclear Gpx4 points to a novel potential mechanism that may explain the previously noted decreased levels of protamine disulfide bonds in aged sperm nuclei. Further, hydrogen peroxide (H2O2) and superoxide (O2(.-)) production were increased significantly in aging spermatozoa. Finally, lipid peroxidation was found to be drastically increased in aged spermatozoa. Taken together, these results suggest a decreased capacity for aged spermatozoa to handle oxidative stress and provide a potential basis for understanding the underlying cause of decreased quality of spermatozoa during aging.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".