Sex differences in lipolysis-regulating mechanisms in overweight subjects: effect of exercise intensity.
OBJECTIVE
To explore sex differences in the regulation of lipolysis during exercise, the lipid-mobilizing mechanisms in the subcutaneous adipose tissue (SCAT) of overweight men and women were studied using microdialysis.


METHODS
Subjects matched for age, BMI, and physical fitness performed two 30-minute exercise bouts in a randomized fashion: the first test at 30% and 50% of their individual maximal oxygen uptake (Vo(2max)) and the second test at 30% and 70% of their Vo(2max).


RESULTS
In both groups, an exercise-dependent increment in extracellular glycerol concentration (EGC) was observed. Whatever the intensity, phentolamine [alpha-adrenergic receptor (AR) antagonist] added to a dialysis probe potentiated exercise-induced lipolysis only in men. In a probe containing phentolamine plus propranolol (beta-AR antagonist), no changes in EGC occurred when compared with the control probe when exercise was performed at 30% and 50% Vo(2max). A significant reduction of EGC (when compared with the control probe) was observed in women at 70% Vo(2max). At each exercise power, the plasma non-esterified fatty acid and glycerol concentrations were higher in women. Exercise-induced increase in plasma catecholamine levels was lower in women compared with men. Plasma insulin decreased and atrial natriuretic peptide increased similarly in both groups.


CONCLUSIONS
Overweight women mobilize more lipids (assessed by glycerol) than men during exercise. alpha(2)-Anti-lipolytic effect was functional in SCAT of men only. The major finding is that during low-to-moderate exercise periods (30% and 50% Vo(2max)), lipid mobilization in SCAT relies less on catecholamine-dependent stimulation of beta-ARs than on an increase in plasma atrial natriuretic peptide concentrations and the decrease in plasma insulin.
Moro
Cédric
C
Institut National de la Santé et de la Recherche Médicale U858, Laboratoire de Pharmacologie Médicale et Clinique, Faculté de Médecine, 37 Allées Jules Guesde, 31073 Toulouse, France.
Pillard
Fabien
F
de Glisezinski
Isabelle
I
Crampes
François
F
Thalamas
Claire
C
Harant
Isabelle
I
Marques
Marie-Adeline
MA
Lafontan
Max
M
Berlan
Michel
M
D000273:Adipose Tissue / Q000378:metabolism; D015992:Body Mass Index; D002395:Catecholamines / Q000378:metabolism; D015444:Exercise; D005260:Female; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D020738:Leptin / Q000378:metabolism; D008066:Lipolysis; D008297:Male; D017551:Microdialysis; D050177:Overweight / Q000175:diagnosis / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D012737:Sex Factors; D050151:Subcutaneous Fat / Q000378:metabolism*
D002395:Catecholamines; D007328:Insulin; D020738:Leptin; D018341:Receptors, Adrenergic, alpha-2; D005990:Glycerol; D010100:Oxygen