Regional and gender variations in adipose tissue lipolysis in response to weight loss

Catecholamine-induced lipolysis was investigated in 32 obese subjects (14 m en and 18 premenopausal women), aged 36-50 years, whose body mass index ran ged from 30 to 42 kg/m(2) Isolated subcutaneous (subc) abdominal and femora l adipocytes were studied before and after a 15-week weight reducing progra m, during which mean body weight loss averaged 9 vs. 10 kg in women and men , respectively (P < 0.0001). Participants were re-examined when they were w eight-stable, Fat cell weight decreased by about 15-20% in both depots (P v alues ranging from 0.01 to 0.05), Epinephrine (mixed alpha 2-/beta-adrenoce ptor (AR) agonist) induced antilipolysis at low concentrations and a net li polytic response at higher doses, irrespective of subjects' fatness and ana tomic location of fat. Basal lipolysis, maximal Lipolytic responses to isop renaline (beta-AR agonist), dobutamine and procaterol (beta 1- and beta 2-A R agonists, respectively) as well. as maximal antilipolytic effects of epin ephrine or UK-14304 (alpha 2-AR agonist) were similar before and after weig ht reduction, However, both beta- and beta 2-AR lipolytic sensitivities and the beta-AR density were increased in both genders after weight reduction, this effect being more marked in subc abdominal than in femoral adipocytes (P values ranging from 0.001 to 0.05), The alpha 2-AR antilipolytic sensit ivity was reduced in adipose cells from both regions in women, but only in subc abdominal adipocytes in men (P < 0.05), although the alpha 2-AR densit y remained unchanged after weight reduction. In conclusion, a moderate weig ht loss leads to a higher adipose cell lipolytic efficiency which is associ ated with changes at receptor levels (mainly an increased beta 2- and a dec reased alpha 2-AR sensitivities), in both genders.