Plasma Free Fatty Acid Storage in Subcutaneous and Visceral Adipose Tissue in Postabsorptive Women

Abstract

1OBJECTIVE-We assessed the direct (VLDL-triglycerides [VLDL-TG] independent) storage of circulating free fatty acids (FFAs) in visceral and subcutaneous fat in postabsorptive women.RESEARCH DESIGN AND METHODS-Twelve women (BMI 29.6 Ϯ 6.6 kg/m 2 ) received an identical, intravenous bolus dose of [1-14 C]oleate followed by timed subcutaneous fat biopsies (abdominal and femoral) and then omental fat biopsy during tubal ligation surgery. Regional fat masses were assessed by combining dual-energy X-ray absorptiometry and computed tomography scanning. Separately, we assessed the fraction of FFA tracer entering VLDL-TG over the time representing the delay in collecting omental fat.RESULTS-Site-specific fat specific activity (SA) (dpm/g lipid) decreased as a function of fat mass in both upper-body subcutaneous (UBSQ) and visceral fat depots. These patterns are consistent with dilution of a relatively fixed amount of FFA tracer within progressively greater amounts of fat. Interestingly, femoral SA did not vary as a function of lower-body subcutaneous (LBSQ) fat mass. [1-14 C]oleate storage per million LBSQ adipocytes was positively associated with LBSQ fat mass, but no significant relationships were observed in UBSQ or visceral fat depot. The fraction of [1-14 C]oleate stored in UBSQ, LBSQ, and visceral fat was 6.7 Ϯ 3.2, 4.9 Ϯ 3.4, and 1.0 Ϯ 0.3%, respectively. Only ϳ4% of the tracer traversed VLDL-TG over 9.5 h. CONCLUSIONS-The increase in FFA tracer storage per adipocyte as a function of LBSQ fat mass implies that LBSQ adipocytes, in contrast to UBSQ and omental adipocytes, store more FFA in women with greater adiposity. The direct FFA storage pathway might play a role in favoring lower-body fat accumulation in women.

Body composition determines direct FFA storage pattern in overweight women

“…However, we were unable to demonstrate any association between the UBSQ FM and the FFA storage per gram lipid or per 10 6 fat cells. However, this is in accord with previous reports of lower (14) or unchanged (13) storage efficiency in relation to increasing UBSQ FM and indicates that direct FFA uptake is not downregulated despite increased FM, thereby leading to the observed greater UBSQ storage in UBO women. In contrast, meal fatty acid storage has been reported to be downregulated in obesity (18).…”

“…This hitherto less explored pathway accounted for the disposal of ϳ8% of FFA into subcutaneous adipose tissue in women (22), and FFA storage has been reported to be greater in LBSQ fat compared with UBSQ fat in women (13). In addition, in women, direct FFA storage per adipocyte increased as a function of fat mass (FM) in subcutaneous leg fat, whereas this was not the case in either UBSQ fat or visceral fat (14). This could indicate that the direct FFA storage pathway might play a role in favoring lower body fat accumulation in some women.…”

“…The ex vivo 14 C-labeled VLDL-TG sample was kept at 5°C until the examination day, where it was reinfused into the participant. Sterility of the VLDL-TG solution was ensured by the culture before infusion.…”

A novel ELISA for measuring CD36 protein in human adipose tissue

“…Of equal interest is that the dramatic decline in omental CD36 content as a function of adipocyte size in women would tend to reduce fatty acid uptake as fat cell size/visceral fat mass increases. This is consistent with our observations regarding meal fatty acid ( 12 ) and direct plasma FFA storage ( 13 ) in omental adipose tissue in women.…”

Pathophysiology of Human Visceral Obesity: An Update

“…In women, meal-derived fatty acid storage increases in proportion to lower body subcutaneous fat mass, while no association is found between relative lipid uptake in abdominal subcutaneous fat and adiposity measures (272). A preservation of the relative capacity to store fatty acids in adipose tissue from the thigh and femoral regions with increasing adiposity may promote the development of the gynoid fat partitioning phenotype in women.…”