The aim of the present study was to study the influence of fatty acids on the adrenergic control of lipolysis both in vitro and in vivo. Human subcutaneous adipose tissue explants were cultured for 48 h in the presence of 100 µM bromopalmitate (BrPal), and lipolysis was measured in isolated adipocytes. In control conditions, β-AR-dependent activation of lipolysis by epinephrine was almost undetectable, and could be fully restored by pharmacological blockade of α2-AR-dependent antilipolysis. After BrPal treatment, epinephrine became fully lipolytic and was no longer influenced by α2-AR-blockade. Radioligand binding analysis revealed that BrPal treatment led to a significant reduction in the coupling of α2-AR to G proteins. In parallel, a chronic and significant increase in plasma fatty acids resulting from a 4-day high-fat diet (HFD) was accompanied by an impairment of the amplifying effect of the α2-AR antagonist phentolamine on exercise-induced lipolysis (measured in the subcutaneous adipose tissue with the use of a microdialysis probe) normally observed after a low-fat diet. In conclusion, in vitro and in vivo studies showed that fatty acids impair α2-AR-dependent antilipolysis.
Key words:
Adipocyte - Culture - Catecholamines - Microdialysis - Lipolysis
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Jean-Sebastien Saulnier-Blache
INSERM U317, CHU Ranguiel
Université de Paul Sabatier
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