Site differences in human subcutaneous adipose tissue metabolism in obesity

Subcutaneous adipose tissue classification

The developments in the technologies based on the use of autologous adipose tissue attracted attention to minor depots as possible sampling areas. Some of those depots have never been studied in detail. The present study was performed on subcutaneous adipose depots sampled in different areas with the aim of explaining their morphology, particularly as far as regards stem niches. The results demonstrated that three different types of white adipose tissue (WAT) can be differentiated on the basis of structural and ultrastructural features: deposit WAT (dWAT), structural WAT (sWAT) and fibrous WAT (fWAT). dWAT can be found essentially in large fatty depots in the abdominal area (periumbilical). In the dWAT, cells are tightly packed and linked by a weak net of isolated collagen fibers. Collagenic components are very poor, cells are large and few blood vessels are present. The deep portion appears more fibrous then the superficial one. The microcirculation is formed by thin walled capillaries with rare stem niches. Reinforcement pericyte elements are rarely evident. The sWAT is more stromal; it is located in some areas in the limbs and in the hips. The stroma is fairly well represented, with a good vascularity and adequate staminality. Cells are wrapped by a basket of collagen fibers. The fatty depots of the knees and of the trochanteric areas have quite loose meshes. The fWAT has a noteworthy fibrous component and can be found in areas where a severe mechanic stress occurs. Adipocytes have an individual thick fibrous shell. In conclusion, the present study demonstrates evident differences among subcutaneous WAT deposits, thus suggesting that in regenerative procedures based on autologous adipose tissues the sampling area should not be randomly chosen, but it should be oriented by evidence based evaluations. The structural peculiarities of the sWAT, and particularly of its microcirculation, suggest that it could represent a privileged source for regenerative procedures based on autologous adipose tissues.

Direct evidence of lipid translocation between adipocytes and prostate cancer cells with imaging FTIR microspectroscopy

Various epidemiological studies show a positive correlation between high intake of dietary FAs and metastatic prostate cancer (CaP). Moreover, CaP metastasizes to the bone marrow, which harbors a rich source of lipids stored within adipocytes. Here, we use Fourier transform infrared (FTIR) microspectroscopy to study adipocyte biochemistry and to demonstrate that PC-3 cells uptake isotopically labeled FA [deuterated palmitic acid (D(31)-PA)] from an adipocyte. Using this vibrational spectroscopic technique, we detected subcellular locations in a single adipocyte enriched with D(31)-PA using the upsilon(as+s)(C-D)(2+3) (D(31)-PA): upsilon(as+s)(C-H)(2+3) (lipid hydrocarbon) signal. In addition, larger adipocytes were found to consist of a higher percentage of D(31)-PA of the total lipid found within the adipocyte. Following background subtraction, the upsilon(as)(C-D)(2+3) signal illuminated starved PC-3 cells cocultured with D(31)-PA-loaded adipocytes, indicating translocation of the labeled FA. This study demonstrates lipid-specific translocation between adipocytes and tumor cells and the use of FTIR microspectroscopy to characterize various biomolecular features of a single adipocyte without the requirement for cell isolation and lipid extraction.

Effects of 10 days of endurance exercise training on the suppression of whole body and regional lipolysis by insulin

The aim of this study was to evaluate in premenopausal women (10 sedentary obese women) the effects of 10 days of exercise on the suppression of whole body and regional lipolysis by insulin. Lipolysis was determined using 2H5-glycerol infusion and microdialysis of sc adipose tissue during a two-stage hyperinsulinemic-euglycemic clamp [10 (LO) and 20 (MO) mU/m x min]. Microdialysis probes were positioned in abdominal and femoral sc adipose tissue to monitor interstitial glycerol and blood flow. Basal plasma glycerol was 86.7 +/-17.0 and 100.3 +/- 19.8 micromol/L before and after training, respectively (P < 0.05). Plasma glycerol was suppressed to a greater extent after [to 47 +/- 5% (LO) and 42 +/- 5% (MO) of basal] than before [to 62 +/- 8% (LO) and 55 +/- 8% (MO) of basal] training. The rate of appearance of glycerol was suppressed to 49 +/- 7% and 40 +/- 5% of basal during LO and to 38 +/- 5% and 30 +/- 4% of basal during MO (P < 0.05) before and after training, respectively. There were no differences in the suppression of lipolysis in abdominal as well as femoral sc adipose tissue as evidenced by similar reductions in dialysate glycerol levels before and after training in each of these tissues. The results indicate that the antilipolytic response to insulin can be improved through endurance exercise training. Intraabdominal adipose tissue or skeletal muscle may be the site of improved antilipolytic response to insulin after training, as improvement was not evident in abdominal or femoral sc adipose tissue.

Regional differences in adipocyte lactate production from glucose

Having shown that lactate is an important product of glucose metabolism by rat epididymal adipocytes, we investigated possible regional differences in adipocyte lactate production and the role of the animals' nutritional state and stage of development. [U-14C]glucose metabolism, lactate production, and response to insulin were measured in fat cells isolated from four adipose regions (subcutaneous, epididymal, retroperitoneal, and mesenteric) from young lean and older fatter rats, killed either in the fed state or after fasting for 48 h. In the absence of insulin, mesenteric fat cells from either age group metabolized significantly more glucose per cell and converted more glucose to lactate than cells from other depots, regardless of nutritional state. Adipocytes from fasted lean rats showed a significant increase (approximately 30%) in the relative glucose conversion to lactate in all depots when compared with cells from fed lean rats. Fasting of older fatter rats, however, had limited effects on the relative adipocyte glucose conversion to lactate since lactate production was already high (40-50% of glucose metabolized). Mesenteric fat cells had the lowest relative response to insulin, possibly due to the high basal rate of glucose metabolism. These findings indicate that differences exist among adipose regions in the rates of glucose metabolism, lactate production and response to insulin. The anatomical location of the mesenteric adipose depot, coupled with a high metabolic rate and blood perfusion, suggests that mesenteric adipocytes may provide a unique and more direct contribution of metabolic substrates for hepatic metabolism than adipocytes from other depots.

Controversies in plastic surgery: suction-assisted lipectomy (SAL) and the hCG (human chorionic gonadotropin) protocol for obesity treatment

The advent of SAL (suction-assisted lipectomy) has dramatically increased the number of obese patients coming to our consultation offices. Despite several articles suggesting a conservative approach to fat suction, some reports insinuate that SAL might be a useful tool for obesity treatment. This hypothesis is refuted by a vast body of evidence that concludes that the adipose tissue may regenerate in adult humans. Therefore, surgical procedures are not advised as the method of choice to manage the disease. On the other hand, the terms obesity and being overweight may not be interchangeable. Obesity may be a disease whereas being overweight is a sign of the disease. Consequently, proper preoperative selection of candidates for SAL becomes mandatory. The hCG (human chorionic gonadotropin) method for obesity treatment appears to be a complete program for the management of obesity. It contains pharmacologic, dietetic, and behavior modification aspects in a 40-day course of treatment. Some data suggest hCG to be lipolytic, thus explaining former clinical observations regarding body fat redistribution in treated patients. hCG commercial preparations contain beta-endorphin, an opioid peptide linked to mood behavior. This article speculates on the possible actions of the complex hCG beta-endorphin in the neuromodulation of mood and energy metabolism. The method comprises a behavior modification that helps in handling the patient better. There are some correlations between a current behavior modification program and the basic guidelines contained in the hCG protocol. Thus, the hCG method appears to be a reasonable alternative in the management of a long-standing, unsolved problem of human metabolism.

Acute adaptation in adrenergic control of lipolysis during physical exercise in humans

During prolonged exercise, the free fatty acids derived from adipocyte lipolysis are the principal fuel utilized by muscles. In humans, the lipid mobilization from adipose tissue is mainly regulated by insulin and catecholamines: the latter hormones have both beta-adrenergic stimulatory and alpha 2-adrenergic inhibitory effects on lipolysis. The aim of this study was to determine whether rapid alterations in the peripheral action of the regulatory hormones occur during physical work and whether they are of importance for the enhanced lipid mobilization. The acute effects of exercise on the regulation of lipolysis were investigated in isolated adipocytes removed from the gluteal region of 14 healthy volunteers before and immediately after the exercise period. Exercise induced a 20-35% significant increase in the lipolytic response to noradrenaline alone and in combination with the selective alpha 2-antagonist yohimbine and to the pure beta-agonist isoproterenol in isolated adipocytes. The antilipolytic effects of both the alpha 2-agonist clonidine and insulin were unaffected by exercise. Exercise did not influence the specific adipocyte receptor binding of 125I-cyanopindolol (beta-adrenergic receptor), [3H]yohimbine (alpha-adrenergic receptor), and mono-125I-[Tyr A14]insulin (insulin receptor). In conclusion, a single period of submaximal exercise increases adipocyte lipolytic responsiveness to catecholamines through an increased beta-adrenoceptor-mediated effect at steps distal to the receptor binding. Thus the increased peripheral action of catecholamines may be of importance for the observed enhanced lipid mobilization during physical work.

Differences in adipose tissue fatty acid composition between black and white men in New Orleans

We report fatty acid composition in perirenal and buttock adipose tissue in 714 deceased black and white men aged 25-44 yr in New Orleans. Percent saturated fatty acids were higher (p less than 0.001) whereas percent monounsaturated fatty acids were lower (p less than 0.001) in perirenal than in buttock fat. Percent linoleic acid was similar in both races. We conclude that dietary intake of linoleic acid is similar in both races. The trend of decreasing linoleic acid with advancing age suggests that either intake of linoleic acid progressively decreases or its mobilization rate increasingly exceeds deposition rate or both. Percent palmitoleic acid (16:1) is lower (p less than 0.001) and that of stearic acid (18:0) is higher (p less than 0.001) in blacks than in whites. We believe no explanation can rest solely on differences in habitual dietary fat intake.