Examining the effects of housing temperature on mitochondrial adaptations to exercise and the browning of white adipose tissue
Bibliographic record
Abstract
The thermoneutral zone for small rodents is ~29–31°C and with decreases in ambient temperature below this there are consequent increases in metabolism to promote thermogenesis. Despite this, many studies report housing mice at room temperature for the convenience of the researchers studying them. As such, the conflicting reports between human and rodent models of exercise‐induced mitochondrial biogenesis in adipose tissue and the browning of white adipose tissue may be explained by the often‐overlooked variable, housing temperature. Male 8‐week‐old C57BL/6 mice were housed in cages with (VWR) or without (SED) running wheels ( n = 12/group/condition) for 5–6 weeks at room temperature (RT; 22°C) or at thermoneutrality (TN; ~29°C). Mice housed at TN ran a greater distance. VWR protected against weight gain independent of housing temperature however food intake was greater in both VWR and SED mice housed at RT compared to TN. Inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT) mass were reduced following VWR independent of housing temperature and there were main effects of both exercise and temperature to reduce brown adipose tissue (BAT) mass. There was no effect of housing temperature on circulating glucose or glycerol concentrations however NEFA, insulin, and the HOMA‐IR were increased at TN. In eWAT there was a main effect of exercise to increase cytochrome c oxidoreductase core I subunit (CORE1), cytochrome c oxidase, and peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α) protein content with a main effect of housing temperature for PGC‐1α as well. There was a strong trend for an exercise‐induced increase in pyruvate dehydrogenase (PDH). In iWAT, there was a main effect of exercise and temperature on mitochondrial proteins with VWR leading to the expected increases in PDH, CORE1, COX IV, and PGC‐1α, but reduced markers of mitochondrial content at TN. Most notably protein content of the thermogenic uncoupling protein‐1 (UCP‐1) was undetectable in iWAT at TN. Qualitative histological analysis revealed patches of multilocular adipocytes in iWAT with VWR at RT but not at TN. Together our findings provide novel evidence that while housing mice at TN reduces markers of mitochondrial content in adipose tissue under sedentary conditions, the ability of exercise to increase mitochondrial protein content remains largely intact. Support or Funding Information Ontario Graduate Scholarship Canada Research Chairs Program This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".