Influence Of Slow Versus Fast Increases In Core Temperature On Prolactin And TNF-alpha
Bibliographic record
Abstract
Prolactin (PRL), a pituitary hormone regulated by neurons in the hypothalamus, has been suggested as an indicator of fatigue during exercise-induced hyperthermia (EIH) given its strong relationship with body core temperature (Tco). However, the strength of this relationship during different rates of Tco increase and subsequent recovery are unknown. In addition, given the influence that systemic inflammatory cytokines, such as Tumor necrosis factor (TNF)-α, have on the pituitary gland; it would be of interest to determine the relationship between PRL and TNF-α during EIH. PURPOSE: To examine the PRL and TNF-α heat stress responses during low (slow heating) and moderate (fast heating) exercise intensities and subsequent resting or cold water immersion recovery. METHODS: Seven trained individuals (5 males, 2 females, mean ± SE: 27.0 ± 3.3 yrs, 57.9 ± 2.2 mL·kg-1nim·-1, 18.5 ± 2.4 % fat) underwent 4 EIH sessions (40°C, 30% R.H.) on a treadmill to a rectal temperature (Tre), measured continuously, of 39.5°C while wearing an impermeable rain suit followed by upright seated resting or 2°C ice-water immersion recovery. Venous blood was obtained at rest (PRE; prior to exercise), during exercise (Tre 38, 39, 39.5°C), the start of recovery (5 min post 39.5°C), and subsequent recovery (Tre 39, 38°C). PRL and TNF-α (high sensitivity) were measured by an ELISA and corrected for changes in plasma volume. RESULTS: PRL exhibited a strong relationship with Tre during exercise (r >0.75), where no differences were observed between the slow and fast trials at a given Tre. During recovery, PRL remained elevated at 39°C (46 ng·mL-1) and 38°C (37 ng·mL-1) during the cooling compared to resting (28 and 16 ng·mL-1, respectively). TNF-α was elevated throughout cooling compared to resting recovery (0.76-0.82 vs. 0.58-0.69 pg·mL-1), the fast but not the slow EIH. CONCLUSION: PRL remained elevated during the cooling compared to resting recovery, likely due to the shorter recovery and reduced clearance from a decrease in blood flow via cutaneous vasoconstriction. It appears that the influence of TNF-α on the pituitary gland does not interfere with the Tre, or stronger, stimulus for the secretion of PRL. Support: Natural Sciences and Research Council of Canada and Canada Foundation for Innovation (held by G.P. Kenny).
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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 | 0.000 | 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".