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Decrease of subcutaneous adipose tissue lipolysis after exposure to hypoxia during a simulated ascent of Mt Everest
I de Glisezinski1, F Crampes, I Harant
1Laboratoire des Adaptations de l'Organisme à l'Exercice Musculaire, Unité INSERM U317, C.H.U. Purpan, Toulouse, France.
Pflugers Archiv : European Journal of Physiology
|January 29, 2000
Summary
Prolonged high-altitude exposure significantly reduced lipid mobilization in adipose tissue. This occurred through decreased lipolytic pathway efficiency and altered anti-lipolytic effects, impacting free fatty acid levels.
Area of Science:
- Physiology
- Altitude Medicine
- Metabolism
Background:
- High altitude is associated with weight loss, potentially linked to changes in adipose tissue metabolism.
- Understanding the effects of prolonged hypoxia on lipolysis is crucial for explaining altitude-induced physiological adaptations.
Purpose of the Study:
- To investigate the impact of sustained hypobaric hypoxia on adipose tissue lipolysis.
- To correlate changes in lipolysis with observed weight loss at high altitudes.
Main Methods:
- Eight male subjects underwent 31 days of simulated high-altitude exposure (up to 8848 m) after acclimatization.
- Subcutaneous adipose tissue biopsies were analyzed in vitro before and after hypoxia to assess lipolytic responses.
- Plasma free fatty acid concentrations were measured.
Main Results:
- Fat mass, adipocyte volume, and spontaneous lipolysis remained unchanged.
- In vitro lipolytic responses to epinephrine, isoproterenol, growth hormone (GH), and parathormone (PTH) significantly decreased.
- Plasma free fatty acid levels were significantly reduced.
- Anti-lipolytic effects of alpha2-adrenergic stimulation increased, while insulin's anti-lipolytic activity decreased.
Conclusions:
- Prolonged hypobaric hypoxia significantly impairs lipid mobilization from adipose tissue.
- Reduced lipolysis is mediated by decreased beta-adrenergic, GH, and PTH pathway efficiency and enhanced alpha2-adrenergic and insulin anti-lipolytic effects.