De novo lipogenesis in adipose tissue of lean and obese women: applicationof deuterated water and isotope ratio mass spectrometry

OBJECTIVE: To evaluate the feasibility of using deuterated water and isotop e ratio mass spectrometry to measure de novo fatty acid synthesis in adipos e tissue, and to compare this parameter in obese and lean women. SUBJECTS: Six lean and six obese premenopausal Caucasian women in the main study and three obese Pima Indians in a pilot study. MEASUREMENTS: Deuterated water was administered orally twice daily for 14 d ays to create stable deuterium enrichment in body water, during which serie s of brood samples were collected to measure body water deuterium enrichmen t and deuterium incorporation into plasma total Triacylglycerol (TG) fatty acids and total cholesterol. Subcutaneous fat at different sites were sampl ed at the beginning and the end of deuterium administration to measure deut erium incorporation into TG fatty acids. RESULTS: Fractional de novo synthesis rate of TG fatty acids in adipose tis sue was 0.014+/-0.005 and 0.014+/-0.007% in lean and obese Caucasian women, corresponding to 2+/-0.7 and 5.6+/-3.2g (P=0.3) of fatty acids synthesized daily, respectively. Plasma TG fatty acids and cholesterol synthesis rates were comparable to those reported previously. A pilot study showed that de novo lipid synthesis in adipose tissue of obese Pima Indians was also quan titatively minor. CONCLUSION: Human adipose tissue, like the liver, does not make a major con tribution to whole body lipogenesis under eucaloric conditions. A combinati on of deuterated water and isotope ratio mass spectrometry is a useful rese arch tool for studying accumulation of de novo synthesized lipids in human adipose tissue.