BACKGROUND:The Glu27Glu genotype in the beta-2-adrenergic receptor (ADRB2) is associated with fat mass, body mass index and obesity in females. In our population, we previously found an association of higher body mass index (BMI) among women who reported more physical activity and carried the Glu27 allele as compared to non carriers with the same level of activity. OBJECTIVE: To examine the lipid metabolism differences, both at rest and during submaximal exercise in ADRB2 Glu27Glu vs Gln27Gln obese women. SUBJECTS: Eight obese women with the Glu27Glu genotype (age, 43 AE 5 y; body mass index (BMI), 31.7 AE 0.9 kg=m 2 ; percentage fat mass, 42.0 AE 1.3; WHR, 0.83 AE 0.02; and VO 2max , 21.6 AE 0.9 ml=kg=min) were compared with seven obese women with the Gln27Gln genotype (age, 43 AE 5 y; BMI, 33.9 AE 1.3 kg=m 2 ; percentage fat mass, 41.6 AE 1.2; WHR, 0.83 AE 0.02; and VO 2max , 20.6 AE 0.8 ml=kg=min). MEASUREMENTS: The ADRB2 polymorphism was identified by PCR-RFLP. Respiratory quotient was determined by indirect calorimetry at baseline, during 1 h of walking on a treadmill and 1 h after the exercise. Plasma triglycerides, glycerol, FFA, hydroxybutyrate, glucose and lactate were assayed by spectrophotometric methods. Insulin, leptin and progesterone were measured by radioimmunoassay. Adrenaline and noradrenaline were quantified by high performance liquid chromatography. RESULTS: The ADRB2 Glu27Glu subjects had lower plasma glycerol (P ¼ 0.047) and lower hydroxybutyrate (P ¼ 0.001) throughout the study than the Gln27Gln group. Plasma triglycerides (P ¼ 0.001), lactate (P < 0.05) and serum insulin (P < 0.05) remained higher in the Glu27Glu group vs the Gln27Gln group. The respiratory quotient (RQ) was higher in the Glu27Glu obese women along the study (P ¼ 0.046), and fat oxidation was significantly lower in this group during the recovery (P ¼ 0.048). The other variables did not differ statistically between groups. CONCLUSION: These data suggest that both lipolysis and fat oxidation promoted by an acute submaximal exercise intervention could be blunted in the polymorphic ADRB2 Glu27Glu group of our female obese population.

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The aim of this study was to observe the relationship of the beta2-adrenoceptor (ADRB2) gene polymorphism Gln27Glu in a group of obese female subjects submitted to an acute physical activity test. Six Glu27/Glu27 obese women were compared with six Gln27/Gln27 obese women (coupled by age, BMI, waist circumference, percentage of fat mass and absence of smoking). These groups were selected after having genotyped 91 obese subjects (BMI>30 kg/m2, age 20-60). Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to genotype the obese population. The physical activity challenge consisted of a Maximal effort trial (VO2 max) following the Bruce protocol on a walking treadmill. The frequency for the Glu allele was 0.42, which is similar to other Caucasian populations. In basal conditions, subjects with the Glu27/Glu27 genotype showed a higher value of plasma insulin, while circulating glucose levels were similar in both groups. Also, diastolic arterial pressure was higher in the Glu27/Glu27 obese women. After the VO2 max trial, the Glu27 group had a significantly higher respiratory exchange ratio than the Gln27 group suggesting a lower post- exercise fat oxidation. These results provide evidence about a possible impact of the Gln27Glu polymorphism in the ADRB2 gene concerning a better response to exercise in obese Gln27 female subjects, in which basal insulinemia may play a role.