Impaired in vivo stimulation of lipolysis in adipose tissue by selective β2-adrenergic agonist in obese adolescent girls

Studies performed in adults with long-standing obesity suggest a reduced lipolytic sensitivity to catecholamines in subcutaneous abdominal adipose tissue (AT). We used microdialysis to study the in situ lipolytic effects of dobutamine (selective beta (1)-agonist) and terbutaline (selective beta (2)-agonist) on glycerol release (lipolytic index) in abdominal subcutaneous AT in 10 obese girls aged 13-17 years, BMI 38 +/- 2.1 kg/m(2) and in 7 lean girls aged 11-17 years, BMI 21 +/- 1.1 kg/m(2), and compared them with 10 obese women aged 21-39 years, BMI 36 +/- 1,6 kg/m(2) and 10 lean women aged 18-42 years, BMI 21 +/- 0.4 kg/m(2). Terbutaline at 10(-6) mol/l stimulated glycerol release more efficiently in lean girls than in obese girls (peak response similar to 350 vs. 150% of control, P < 0.01). At the lower concentration of agonist, no significant difference was seen. In women, terbutaline was more effective in lean than in obese women in stimulating glycerol release at both 10(-8) mol/l (peak response lean <similar to>175% vs, obese 125% of control) and 10(-6) mol/l (similar to 300 vs. 150% of control, P < 0.05). No significant difference in glycerol release between obese and lean girls or women was detected with selective <beta>(1)-stimulation. Our data demonstrate a specific impairment in the capacity of beta (2)-adrenergic agonists to promote lipolysis in subcutaneous abdominal adipose tissue of obese adolescent girls and women. Thus, decreased mobilization of fat during activation of the adrenergic system might be present early in the development of adolescent obesity.