The Necessity of Having a Proper Dose of (−)Deprenyl (D) to Prolong the Life Spans of Rats Explains Discrepancies among Different Studies in the Past
Bibliographic record
Abstract
(-)Deprenyl (D) has been shown to be effective in prolonging life span in experimental animals, although, there are some discrepancies in its effect on the life span the even within the same species (rats). The present study aims to clarify the reason for these discrepancies. Male F344/DuCrj rats began receiving subcutaneous (s.c.) injections of D at the age of 18 months. Doses used were 0.25, 0.50, and 1.0 mg/kg/injection (inj.), three times a week. Average life spans of animals were significantly longer in male rats given 0.25 and 0.5 mg/kg/inj.; however, rats given a 1.0 mg/kg dose began dying earlier than control rats, leading to an inverse U-shaped dose-efficacy relationship, a hormesis. Old (27-month-old) rats given different doses of D for 1 month showed a typical hormetic response for antioxidant enzyme activities, indicating a significant increase in superoxide dismutase (SOD) and catalase (CAT) activities in brain dopaminergic regions with four lower doses (0.25 to 2 mg/kg/inj., 3 times a week), but a significantly negative response with the highest dose (4 mg/kg/inj.). Our results clearly indicate that a proper dose of D within a certain dose range can significantly increase the life span of rats, but that a greater dose becomes less effective and may actually adversely affect the life span of rats. A similar hormetic response for its effect on antioxidant enzyme activities and the parallel between the two different effects of D suggest a possible causal relationship between these two effects of D. The presence of this effective dose range of D may explain previously reported discrepancies in the effect of D on the life span of animals.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".