Vitamin D release across abdominal adipose tissue in lean and obese men: The effect of ß-adrenergic stimulation.

Abstract

Obesity is characterized by a blunted lipolytic response in abdominal subcutaneous adipose tissue (SAT) and low circulating vitamin D levels. Here we investigated whether an impaired SAT lipolytic response coincides with an impaired SAT vitamin D release in eight lean and six obese men. 25‐hydroxyvitamin D3 [25(OH)D3] and 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] fluxes across SAT were measured using arterio‐venous blood sampling in combination with AT blood flow measurements after an overnight fast and during 1‐hr intravenous infusion of the non‐selective ß‐adrenergic agonist isoprenaline (20 ng·kg FFM−1·min−1). 1,25(OH)2D3 was released across abdominal SAT during isoprenaline infusion in lean [−0.01 (−0.04 to 0.00) pmol*100 g tissue−1*min−1, p = .017 vs. zero flux], but not in obese men [0.01 (0.00 to 0.02) pmol*100 g tissue−1*min−1, p = .116 vs. zero flux], and accompanied by an impaired isoprenaline‐induced lipolytic response in abdominal SAT of obese versus lean men. Isoprenaline had no significant effects on net 25(OH)D3 release across abdominal SAT and plasma vitamin D metabolites in lean and obese men. To conclude, a blunted isoprenaline‐mediated lipolysis is accompanied by reduced release of 1,25(OH)2D3 vitamin D across abdominal SAT in obesity.