Testosterone induces higher carotid body response to hypoxia in older adult male rats
Bibliographic record
Abstract
Excessive carotid body responsiveness to chemical stimuli contributes to respiratory instability and apneas during sleep. In hypogonadal men, testosterone supplementation increases the risk of sleep‐disordered breathing; however, the site of action is unknown. The present study tested the hypothesis that exposure to elevated levels of testosterone potentiates the carotid body’s response to hypoxia. Because testosterone levels decline with age, we also determined whether these effects are age‐dependent. To do so, carotid bodies were isolated ex vivo from young (70 days old) and aging (185 days old) male Sprague‐Dawley rats. Isolated organs were maintained in oxygenated Tyrode solution (95% O 2 ; 5% CO 2 ) in the presence of testosterone (5 nM) or vehicle (<0.001% DMSO) for 90–120 min. Preparations were then mounted in the recording chamber and a suction electrode was placed on the carotid sinus nerve to record activity (# of impulses/sec). Activity was recorded at rest and during exposure to hypoxia (0% O 2 , 5% CO 2 , 95% N 2 ; 15 min). Basal carotid body activity did not differ between age groups; however, the responses to both stimuli were greater in young rats. Testosterone exposure augmented the responses to hypoxia in aging rats only. In vivo experiments performed on anesthetised rats show that testosterone injection (2 mg/kg) 30 min prior hypoxic exposure (12%O 2 ; 20 min) potentiates the hypoxic ventilatory response in an age‐dependent fashion. We conclude that age‐dependent potentiation of the carotid body’s O 2 chemosensitivity by testosterone may lead to ventilatory adjustments that exceed the organism’s need. In aging animals, this may predispose to respiratory instability and apnea during sleep. Support or Funding Information Supported by a discovery grant from the Natural Sciences and Engineering Research Council of Canada (RK). Dr Janes was supported by a scholarship from the Réseau en Recherche Respiratoire du Québec.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".