Basal fat oxidation and after a peak oxygen consumption test in obese women with a beta2 adrenoceptor gene polymorphism

The Glu27Glu genotype in the beta2-adrenergic receptor (ADRB2) has been linked to a higher fat deposition and obesity in females. Also, in our population, it has been described that physically active women carrying the Glu allele had a higher BMI as compared to non-carriers performing the same level of activity. Since exercise may counterbalance a gene predisposition to obesity, we tested the hypothesis of a potential different metabolic response among ADRB2 Gln27Gln versus Glu27Glu obese women when submitted to a peak oxygen consumption test on a treadmill. In our study, 10 obese women with the Gln27Gln genotype were compared to 9 matched obese women bearing the Glu27Glu genotype. The ADRB2 polymorphism was identified by PCR-RFLP, fat oxidation was determined by indirect calorimetry and blood measurements were carried out following conventional procedures. The ADRB2 Glu27Glu subjects had lower plasma glycerol levels (P = 0.026), while plasma triglycerides (P <0.001) and the insulin:glucose ratio were higher (P = 0.046) as compared to the Gln27Gln group along the peak oxygen consumption trial intervention. There was a significantly lower fat oxidation (P = 0.024) in the Glu27Glu obese women during the recovery compared to Gln27Gln obese individuals. These data suggest that exercise would not benefit equally the two ADRB2 polymorphism homozygous groups, since both lipolysis and fat oxidation promoted by a peak oxygen consumption test appear to be blunted in the polymorphic Glu27Glu obese group.