Hypocaloric diet reduces exercise-induced alpha 2-adrenergic antilipolytic effect and alpha 2-adrenergic receptor mRNA levels in adipose tissue of obese women.
Previous investigations have shown that alpha 2-adrenoceptor (alpha 2-AR) stimulation blunts lipid mobilization during physiological activation of the sympathetic nervous system promoted by exercise in sc abdominal adipose tissue (SCAAT) in obese men. To investigate the effect of a low calorie diet (LCD) on the alpha 2-adrenergic responsiveness and on the expression of alpha 2-AR and beta 2-adrenoceptor (beta 2-AR) in SCAAT, 11 obese women (weight: 99.1 +/- 4.6 kg; body mass index: 34.3 +/- 1.1 kg/m(2)) received a 12-wk diet providing 500 kcal/d less than their usual diet. The exercise-induced alpha 2-adrenergic antilipolytic effect was investigated in SCAAT before and at the end of LCD. Changes in extracellular glycerol concentration and local blood flow were measured in SCAAT during a 45-min exercise bout (50% of heart rate reserve) using a control microdialysis probe and a probe supplemented with the alpha2-AR antagonist phentolamine. SCAAT biopsies were performed for determination of mRNA levels using RT-competitive PCR. Plasma catecholamine responses to exercise bout were not different before and at the end of LCD. Before LCD, the exercise-induced increase in extracellular glycerol concentration was potentiated by phentolamine supplementation, while this potentiating effect of the alpha-antagonist was not observed at the end of LCD. No changes were observed for beta 2-AR and hormone-sensitive lipase mRNA levels, while alpha 2-AR mRNA level was significantly decreased in adipose tissue during LCD. These findings show that alpha 2-AR-mediated antilipolytic action is reduced by a moderate hypocaloric diet and that down-regulation of alpha 2-AR mRNA levels may participate in the decrease of the alpha 2-adrenergic effect revealed by microdialysis.
Stich
V
V
Department of Sport Medicine and Obesity Unit, Charles University, Prague, 10000 Czech Republic.
Marion-Latard
F
F
Hejnova
J
J
Viguerie
N
N
Lefort
C
C
Suljkovicova
H
H
Langin
D
D
Lafontan
M
M
Berlan
M
M
D000005:Abdomen; D000273:Adipose Tissue / Q000098:blood supply / Q000378:metabolism*; D000328:Adult; D004038:Diet, Reducing; D002149:Energy Intake; D015444:Exercise / Q000502:physiology*; D005110:Extracellular Space / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005990:Glycerol / Q000097:blood / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D009765:Obesity / Q000178:diet therapy* / Q000378:metabolism*; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000378:metabolism*; D018341:Receptors, Adrenergic, alpha-2 / Q000235:genetics*; D011943:Receptors, Adrenergic, beta / Q000235:genetics; D012039:Regional Blood Flow / Q000502:physiology
D005230:Fatty Acids, Nonesterified; D012333:RNA, Messenger; D018341:Receptors, Adrenergic, alpha-2; D011943:Receptors, Adrenergic, beta; D019344:Lactic Acid; D005990:Glycerol