Android fat depot is more closely associated with metabolic syndrome than abdominal visceral fat in elderly people

Background

Fat accumulation in android compartments may confer increased metabolic risk. The incremental utility of measuring regional fat deposition in association with metabolic syndrome (MS) has not been well described particularly in an elderly population.

Methods and Findings

As part of the Korean Longitudinal Study on Health and Aging, which is a community-based cohort study of people aged more than 65 years, subjects (287 male, 75.9±8.6 years and 278 female, 76.0±8.8 years) with regional body composition data using Dual energy X-ray absorptiometry for android/gynoid area, computed tomography for visceral/subcutaneous adipose tissue (VAT/SAT), and cardiometabolic markers including adiponectin and high-sensitivity CRP were enrolled. We investigated the relationship between regional body composition and MS in multivariate regression models. Mean VAT and SAT area was 131.4±65.5 cm² and 126.9±55.2 cm² in men (P = 0.045) and 120.0±46.7 cm² and 211.8±65.9 cm² in women (P<0.01). Mean android and gynoid fat amount was 1.8±0.8 kg and 2.5±0.8 kg in men and 2.0±0.6 kg and 3.3±0.8 kg in women, respectively (both P<0.01). VAT area and android fat amount was strongly correlated with most metabolic risk factors compared to SAT or gynoid fat. Furthermore, android fat amount was significantly associated with clustering of MS components after adjustment for multiple parameters including age, gender, adiponectin, hsCRP, a surrogate marker of insulin resistance, whole body fat mass and VAT area.

Conclusions

Our findings are consistent with the hypothesized role of android fat as a pathogenic fat depot in the MS. Measurement of android fat may provide a more complete understanding of metabolic risk associated with variations in fat distribution.     

The expression of FTO in human adipose tissue is influenced by fat depot,adiposity, and insulin sensitivity

Objective: The fat mass and obesity associated (FTO) gene is related to obesity, but the regulation of FTO expression in adipose tissue is not fully understood. We investigated FTO expression in paired subcutaneous and omental adipose tissues (SAT and OAT) from healthy women undergoing gynecological surgeries, and its relation with adiposity and insulin sensitivity. Design and Methods: FTO expression in SAT of type 2 diabetic patients treated or not with Rosiglitazone was also compared. Results: Both the mRNA and protein levels of FTO were higher in OAT from women than in SAT. Only OAT FTO protein levels negatively correlated with BMI and body fat mass, whereas SAT FTO mRNA levels were negatively correlated with subcutaneous fat deposition. In addition, SAT FTO mRNA and protein levels were increased in insulin resistant women (high HOMA) compared to insulin sensitive women (low HOMA), whereas OAT FTO expression was not different between these two subgroups. Interestingly, FTO mRNA levels were increased in SAT of type 2 diabetic patients, and treatment of diabetics with Rosiglitazone improved insulin sensitivity and reduced SAT FTO mRNA levels. Lastly, FTO expression was transiently increased in the early phase of 3T3‐L1 cell differentiation, which coincides with the induction of PPARγ2 expression. However, partial reduction of FTO did not impact PPARγ2 expression and adipocyte differentiation. Conclusion: Therefore, FTO gene expression is higher in OAT than in SAT in lean to moderately obese women. OAT FTO expression is associated with adiposity, whereas SAT FTO expression is associated with insulin sensitivity. These associations are independent of an effect of FTO on adipocyte differentiation.     

Sympathetic denervation of one white fat depot changes norepinephrine content and turnover in intact white and brown fat depots

It is well-established that the sympathetic nervous system (SNS) regulates adipocyte metabolism and recently it has been reported that sensory afferents from white fat overlap anatomically with sympathetic efferents to white fat. The studies described here characterize the response of intact fat pads to selective sympathectomy (local 6-hydroxydopamine (6OHDA) injections) of inguinal (ING) or epididymal (EPI) fat in male NIH Swiss mice and provide in vivo evidence for communication between individual white and brown fat depots. The contralateral ING pad, both EPI pads, perirenal (PR), and mesenteric (MES) pads were significantly enlarged 4 weeks after denervating one ING pad, but only intrascapular brown adipose tissue (IBAT) increased when both ING pads were denervated. Denervation of one or both EPI pad had no effect on fat depot weights. In an additional experiment, norepinephrine turnover (NETO) was inhibited in ING, retroperitoneal (RP), MES, and IBAT 2 days after denervation of both EPI or of both ING pads. NE content was reduced to 10-30% of control values in all fat depots. There was no relation between early changes in NETO and fat pad weight 4 weeks after denervation, even though the reduction in NE content of intact fat pads was maintained. These data demonstrate that there is communication among individual fat pads, presumably through central integration of activity of sensory afferent and sympathetic efferent fibers, that changes sympathetic drive to white adipose tissue in a unified manner. In specific situations, removal of sympathetic efferents to one pad induces a compensatory enlargement of other intact depots.     

Occurrence of positional isomers of octadecenoic and hexadecenoic acids in human depot fat

Positional isomers of hexadecenoic aud octadecenoic acids of human adipose tissue have been separated by gas-liquid chromatography and their amounts determined by oxidative cleavage (MnO(4) and IO(4)). The following isomeric octadecenoic acids were present: 7-octadecenoic acid (0.4%), 8- (1.9%), 9- (73.0%), 10- (2.5%), 11- (19.0%) and 12- (3.2%). The hexadecenoic acids have also been shown to be a mixture of positional isomers, in which the cis-9-isomer predominates. 10-Hexadecenoic and 12-octadecenoic acids could conceivably be precursors of linoleic acid. The following branched fatty acids have also been determined in human depot fat: 13-methyltetradecanoic, 12-methyltetradecanoic, 14-methylpentadecanoic, 14-methylhexadecanoic, and 16-methylheptadecanoic acid. They were present in percentages of 0.02-0.6% and their identification rests solely on comparison of their gas-liquid chromatographic retention times with those of synthetic compounds.     

Structure and amount of positional isomers of monounsaturated fatty acids in human depot fat

Positional isomers of decenoic, dodecenoic, and tetradecenoic acids of human adipose tissue have been separated by gas-liquid chromatography and their amounts determined by oxidative cleavage. The following acids have been shown to be present: 7-decenoic, 8-decenoic, 9-decenoic, 7-, 8-, and 9-dodecenoic, and 7-, 8-, 9-, and 11-tetradecenoic acids. Among all isomers of the even-numbered acids from C(10) to C(18) the cis-9-isomer predominates. With increasing chain length, however, the content of 9-isomer decreases and the number of isomers increases. No 3- or 5-enoic acids could be detected. The origin and biosynthesis of all isomers are discussed.     

Effects of diet, age, strain and anatomical site on fat depot triglyceride and fatty acid content in rats.

OM rats fed a high fat ration were heavier, fatter and had fat depots which weighed at least three times as much as those fed a low fat (grain) ration. S rats fed a high fat ration showed slight increase in fat depot weights and no increase in body weight or fat when compared to rats of the same strain fed grain. For both strains of rats fed either diet for 4, 10 or 20 wk following weaning, there was a lower percentage of TG in the inguinal depot than in the epididymal or perirenal-retroperitoneal fat depots. There was a tendency for rats fed a high fat ration to have a higher percentage of TG in adipose tissues than rats fed grain, but the differences were not significant as long as age, anatomical site and strain were constant. Strain and age had no significant effect on the percentage of TG in fat depots. The fatty acid composition of the fat depots was effected by ration, but not by age, strain or anatomical site of the fat depot.     

Fatty acid content of depot fat in the northern fur seal (Callorhinus ursinus)

The fatty acid content of depot fat samples from 15 northern fur seals (Callorhinus ursinus) were determined by gas-liquid chromatography. Callorhinus ursinus has a high proportion of short chain saturated acids: C10, C11, C12, C13, C15. Unsaturated longer chain acids C16:1, and C16:2, and C18:1 also were found. Results obtained are compared to a previously reported milk lipid analysis of the northern fur seal.