Effects of Different Oxygen Concentrations on Human Differentiated Preadipocytes Lipogenic and Lipolytic functions
Bibliographic record
Abstract
Context Fat stored in white adipose tissue is the human body's largest energy reservoir. Adipocytes, the predominant cell population in white adipose tissue, play a central role in the clearance of circulating triglyceride (TG) and the delivery of fatty acids for use by peripheral tissues. Impaired regulation of adipose tissue functions is thought to stimulate lipid deposition in non‐adipose tissues, inducing lipotoxic response and the development of metabolic disorders. During weight gain, adipocytes expand in size, decreasing adipose tissue capillary density and creating areas characterized by excessively low oxygen concentrations (hypoxia). It is not clear how hypoxia modulates adipose tissue TG clearance and fatty acid delivery. Objective The purpose of this study was to investigate the effects of different hypoxia concentrations on lipogenic (store TG) and lipolytic functions (deliver fatty acids) of human differentiated preadipocytes. Methods Differentiated human preadipocytes were exposed to different oxygen concentrations (3%, 10%, and 21%) either during differentiation (14d, continuous exposure) or acutely for 24h after differentiation (acute exposure). Gene expression of lipogenic enzymes and regulating factors will be determined by real‐time PCR. Lipoprotein lipase (LPL) activity was measured using the EnzChek Lipase Substrate and lipolytic rate was determined by measuring glycerol release over 3 hours. Results In differentiated human preadipocytes, a dose‐dependent reduction in LPL activity was observed in both acute and continuous hypoxia (6‐fold reduction under 3% O 2 p<0.001, 2‐fold reduction under 10% O 2 , p<0.05, compared to 21% O 2 ). Basal lipolysis was significantly higher during acute hypoxia (3%) session (p<0.05). No differences in isoproterenol‐ and epinephrine‐stimulated lipolytic responses were observed in subcutaneous abdominal preadipocytes between normoxia and acute hypoxia (3%). Conclusions These preliminary results suggest that acute and continuous hypoxia strongly inhibits LPL activity and increases basal lipolysis. These observation supports the hypothesis that hypoxia may adversely affect adipose tissue storage functions, which could in turn contribute to ectopic fat storage, lipotoxicity and a greater prevalence of metabolic disorders in individual with excess adiposity. Support or Funding Information This study was supported by the Natural Sciences and Engineering Research Council of Canada as well as the University of Ottawa.
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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) | 0.002 | 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".