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Brown adipose tissue and its uncoupling protein in chronically hypoxic rats
1Department of Physiology, McGill University, Montreal, Quebec, Canada.
Clinical Science (London, England : 1979)
|December 24, 1997
Summary
Hypoxia significantly reduces thermogenin (UCP/Act) in brown adipose tissue, especially in older rats and with chronic exposure. This impacts non-shivering thermogenesis, with effects varying by age and duration of oxygen deprivation.
Area of Science:
- Physiology
- Environmental Medicine
- Metabolic Research
Background:
- Hypoxia is known to decrease thermogenesis.
- Brown adipose tissue (BAT) is a major site of non-shivering thermogenesis.
- The impact of hypoxia on BAT function requires further investigation.
Purpose of the Study:
- To investigate the effects of hypoxia on brown adipose tissue (BAT) in rats of different ages.
- To determine if hypoxia alters BAT mass, protein, DNA, and thermogenin (uncoupling protein) content.
- To assess the influence of hypoxia on BAT's response to cold exposure.
Main Methods:
- Rats of different ages (25-day-old, 64-day-old, and 3.5-month-old) were exposed to normobaric or hypobaric hypoxia.
- Measurements included haematocrit, body mass, BAT mass, protein, and DNA concentration.
- Thermogenin (UCP/Act) content was quantified using immunoblotting after electrophoretic separation.
Main Results:
- Hypoxic rats exhibited higher haematocrit and lower body mass.
- In young rats, hypoxia had minimal effects on BAT mass and composition.
- In older rats and with chronic hypoxia, thermogenin (UCP/Act) content was significantly reduced (40-50% of control).
Conclusions:
- Chronic hypoxia minimally affects total protein and DNA content in brown adipose tissue.
- However, hypoxia can significantly reduce thermogenin (uncoupling protein) levels in BAT.
- The extent of reduction in thermogenin depends on the age of the rats and the duration of hypoxic exposure.