Change in β₁-adrenergic receptor protein concentration in adipose tissue correlates with diet-induced weight loss

The aim of the present study was to examine gene expression and protein concentrations of β₁- and β₂-adrenergic receptors in subcutaneous adipose tissue in obese subjects in response to weight loss. Eighteen obese subjects were studied during diet-induced weight loss. β-Adrenergic receptor mRNA levels were quantified by reverse transcription-PCR–HPLC. β-Adrenergic receptor protein concentrations were measured by Western blotting using fluorescence laser scanning for detection. Subjects lost 12.8±0.8 kg (mean±S.E.M.) during diet treatment. There was a 34% decrease in the β₁-adrenergic receptor mRNA level (0.92±0.09 compared with 0.61±0.06 amol/μg of DNA; P<0.002). β₂-Adrenergic receptor mRNA did not decrease significantly. β₂-Adrenergic receptor protein concentration decreased 37% (25.5±7.1 compared with 16.0±5.6 arbitrary units/ng of DNA; P=0.008), whereas β₁-adrenergic receptor protein concentration did not decrease significantly. The degree of weight loss was correlated with the concentration of β₁-adrenergic receptor protein (r=0.65, P<0.003) and changes in receptor protein concentration (r=0.50, P=0.035) during the very-low-calorie diet. In conclusion, the present study demonstrates a relationship between β₁-adrenergic receptor protein concentration in adipose tissue and the degree of weight loss. This relationship is not directly related to energy expenditure and deserves further investigation.