Acute Neuroendocrine Response to Hyperbaric Stress in Experienced Male Divers Versus Non-Divers
Bibliographic record
Abstract
Adaptation through repeated exposure to a given absolute physical stress, such as exercise, will result in a lower relative strain and a reduced neuroendocrine stress response at any absolute intensity. It is unclear, however, whether such adaptation is evident following repeated exposure to hyperbaric stress. PURPOSE: The purpose of this study was to compare the effects of 3 different levels of hyperbaric stress on the neuroendocrine response in experienced divers (Ex) or naive (N) individuals. METHODS: Two male groups [N; (n=10) vs Ex divers; (n=12)] underwent 30-min hyperbaric exposures at 180 kPa (18 msw; low stress), 300 kPa (30 msw; moderate stress) and 450 kPa (45 msw; high stress) separated by at least 7 days. Venous blood samples were drawn pre-dive and at 20 and 60 min post-dive. Blood was centrifuged, separated, and serum/plasma stored frozen until analyzed for dopamine (DA), norepinephrine (NE), epinephrine (E), and serotonin (5-HT) using gas chromatography/mass spectrometry and cortisol (C), growth hormone (GH), adrenocorticotrophic hormone (ACTH), prolactin (PRL) and dehydroepiandrosterone (DHEA) using a chemiluminescent immunoassay (Immulite®). RESULTS: There was no difference between groups, across time or among levels of hyperbaric stress for E, NE, 5-HT, or DHEA. C and ACTH also were not different between groups but small decreases over time were noted independent of dive level reflecting diurnal effects. The changes in DA were not different between groups but increased later following the low versus the high hyperbaric stress. GH also was not different between groups but demonstrated a significant increase independent of stress level from 0.20 ± 0.3 mIU/L to 1.16 ± 2.02 mIU/L 20 min following exposure that returned to baseline levels at 60 min. In contrast, PRL increased significantly more for N from 7.8 ± 3.0 ug/L to 11.8 ± 5.3 ug/L 20 min following exposure compared with Ex divers (7.5 ± 2.2 ug/L to 8.6 ± 2.5 ug/L, respectively). CONCLUSION: Varying levels of hyperbaric stress produced a measurable neuroendocrine stress response within the hypothalamic-pituitary axis in both Ex and N individuals with the change in PRL being greater for the latter group. Research was funded by the Defence R&D Canada Technology Investment Fund and the US Office of Naval Research.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 teacher head, 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".