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Serum immunoreactive-leptin concentrations in normal-weight and obese humans
R V Considine1, M K Sinha, M L Heiman
1Division of Endocrinology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA.
The New England Journal of Medicine
|February 1, 1996
Summary
Obese individuals have significantly higher serum leptin concentrations and adipocyte ob mRNA levels than normal-weight individuals. This suggests a widespread leptin resistance in human obesity.
Area of Science:
- Endocrinology
- Metabolism
- Genetics
Background:
- Leptin, a hormone from adipocytes, regulates body weight.
- Mutations in the ob gene cause obesity in animals, but human leptin physiology is poorly understood.
Purpose of the Study:
- To measure serum leptin concentrations and adipocyte ob mRNA levels in obese and normal-weight humans.
- To investigate the relationship between leptin levels, body fat percentage, and weight changes.
Main Methods:
- Radioimmunoassay was used to measure serum leptin in 136 normal-weight and 139 obese subjects.
- Adipocyte ob messenger RNA (mRNA) content was determined in a subset of subjects.
- Leptin levels and mRNA were re-measured in obese subjects after weight loss and maintenance.
Main Results:
- Obese subjects had significantly higher serum leptin (31.3 ng/mL) than normal-weight subjects (7.5 ng/mL).
- Serum leptin and adipocyte ob mRNA strongly correlated with body fat percentage (r=0.85 and r=0.68, respectively).
- Weight loss reduced leptin levels and mRNA, which increased during weight maintenance.
Conclusions:
- Elevated serum leptin concentrations in obese individuals correlate with body fat percentage.
- Findings suggest that most obese humans exhibit insensitivity to endogenous leptin production, indicating leptin resistance.