The Impact of Full-Length, Trimeric and Globular Adiponectin on Lipolysis in Subcutaneous and Visceral Adipocytes of Obese and Non-Obese Women.

Contribution of individual adiponectin isoforms to lipolysis regulation remains unknown. We investigated the impact of full-length, trimeric and globular adiponectin isoforms on spontaneous lipolysis in subcutaneous abdominal (SCAAT) and visceral adipose tissues (VAT) of obese and non-obese subjects. Furthermore, we explored the role of AMPK (5'-AMP-activated protein kinase) in adiponectin-dependent lipolysis regulation and expression of adiponectin receptors type 1 and 2 (AdipoR1 and AdipoR2) in SCAAT and VAT. Primary adipocytes isolated from SCAAT and VAT of obese and non-obese women were incubated with 20 µg/ml of: A) full-length adiponectin (physiological mixture of all adiponectin isoforms), B) trimeric adiponectin isoform or C) globular adiponectin isoform. Glycerol released into media was used as a marker of lipolysis. While full-length adiponectin inhibited lipolysis by 22% in non-obese SCAAT, globular isoform inhibited lipolysis by 27% in obese SCAAT. No effect of either isoform was detected in non-obese VAT, however trimeric isoform inhibited lipolysis by 21% in obese VAT (all p<0.05). Trimeric isoform induced Thr172 p-AMPK in differentiated preadipocytes from a non-obese donor, while globular isoform induced Ser79 p-ACC by 32% (p<0.05) and Ser565 p-HSL by 52% (p = 0.08) in differentiated preadipocytes from an obese donor. AdipoR2 expression was 17% and 37% higher than AdipoR1 in SCAAT of obese and non-obese groups and by 23% higher in VAT of obese subjects (all p<0.05). In conclusion, the anti-lipolytic effect of adiponectin isoforms is modified with obesity: while full-length adiponectin exerts anti-lipolytic action in non-obese SCAAT, globular and trimeric isoforms show anti-lipolytic activity in obese SCAAT and VAT, respectively

Adipose Tissue Secretion and Expression of Adipocyte-Produced and Stromavascular Fraction-Produced Adipokines Vary during Multiple Phases of Weight-Reducing Dietary Intervention in Obese Women.

International audienceContext: Obesity is associated with altered plasma levels of adipokines involved in the development of insulin resistance and obesity-related metabolic disturbances. Objective: The aim was to investigate diet-induced changes in adipokine production in sc abdominal adipose tissue (SAT) during a 6-month, multiphase, weight-reducing dietary intervention. Design, Setting, Participants, and Interventions: Forty-eight obese women followed a dietary intervention consisting of a very low-calorie diet (VLCD) (1 month), followed by a weight-stabilization (WS) period, which consisted of a low-calorie diet (2 months), and a weight-maintenance diet (3 months). Main Outcome Measures: Before and at the end of the VLCD and WS, samples of plasma and SAT were obtained. In a subgroup of 26 women, secretion of adipokines was determined in SAT explants, and in a subgroup of 22 women, SAT mRNA expression was measured. Results: Body weight decreased and insulin sensitivity increased during the intervention. Plasma levels, SAT mRNA expression, and secretion rates of adipocyte-produced adipokines (leptin, serum amyloid A, and haptoglobin) decreased during the VLCD and increased during the WS period. Adipokines produced mainly from stroma-vascular cells (IL-6, IL-8, IL-10, IL-1Ra, TNFα, plasminogen activator inhibitor-1, and monocyte chemoattractant protein-1) increased or remained unchanged during VLCD and decreased to levels equal to or lower than prediet levels during the WS period. The diet-induced changes in homeostasis model assessment of insulin resistance correlated with changes in leptin plasma levels during VLCD, WS, and the entire dietary intervention period. Conclusions: Diet-induced regulation of adipokine production in SAT differs according to their cellular origin (adipocytes vs. stroma-vascular cells) and diet phase (VLCD vs. WS). Insulin-sensitivity changes were associated only with those of plasma leptin

Expression of Lipolytic Genes in Adipose Tissue Is Differentially Regulated During Multiple Phases of Dietary Intervention in Obese Women

The aim of this study was to investigate the time-course of the expression of key lipolysis-regulating genes in the subcutaneous adipose tissue (SCAT) during different phases of a 6-month dietary intervention. Fifteen obese women (BMI 34.7+/-1.0 kg.m(-2)) underwent a 6-month dietary intervention consisting of 1 month very low calorie diet (VLCD), followed by 2 months low calorie diet (LCD) and 3 months weight maintenance diet (WM). At each phase of the dietary intervention, a needle microbiopsy of the abdominal SCAT was obtained to evaluate mRNA expression of key lipolysis-regulating genes and a hyperinsulinemic euglycemic clamp (HEC) was performed. Dietary intervention induced a body weight reduction of 9.8 % and an improvement of insulin sensitivity as assessed by a HEC. Compared to pre-diet levels, mRNA levels of the adrenergic beta(2)-receptor in SCAT were higher at the end of VLCD and not different at the end of LCD and WM. In contrast, the expression of the adrenergic alpha(2)-receptor was lower at the end of VLCD and LCD compared to the pre-diet levels and did not differ at WM. Adipose triglyceride lipase and hormone-sensitive lipase levels were lower than the pre-diet levels at the end of LCD only, while phosphodiesterase-3B and the insulin receptor levels did not change throughout the dietary intervention. The results suggest that the regulation pattern of the genes that are involved in the control of lipolysis is different at the respective phases of the dietary intervention and depends on the duration of the diet and the status of energy balance.status: publishe

Effect of hyperinsulinemia and very-low-calorie diet on interstitial cytokine levels in subcutaneous adipose tissue of obese women.

International audienceAim: Type II diabetes and obesity are associated with an enhanced release of a number of adipocytokines. Hyperinsulinemia - frequently present in type II diabetes and obesity - might be one of the drivers of the enhanced production of adipocytokines. The aim of this study was to investigate the interstitial levels of cytokines in subcutaneous adipose tissue (SCAT) in response to hyperinsulinemia and the effect of weight-reducing hypocaloric diet on this regulation in obese subjects. Methods: 13 obese pre-menopausal women participated in the study. Concentrations of 7 cytokines were measured in plasma and in AT interstitial fluid collected by microdialysis method during euglycemic-hyperinsulinemic clamp and during control infusion of physiological saline. A subgroup of 6 women underwent a 4-week very-low-calorie diet (VLCD). Microdialysis during the clamp was performed before and at the end of VLCD. Results: Hyperinsulinemia induced an increase of monocyte chemoatractant protein (MCP-1) and IL-6 SCAT interstitial and plasma levels, and elevated IL-8 levels in SCAT. The relative changes of IL-6 levels in the dialysate correlated with changes of IL-8 and MCP-1. The interstitial and plasma levels of IL-1beta, IL-10, TNFalpha and plasminogen activator inhibitor (PAI-1) remained unchanged in response to hyperinsulinemia. VLCD resulted in an enhancement of the hyperinsulinemia-induced augmentation of MCP-1, IL-6 and IL-8 interstitial levels. Conclusion: Hyperinsulinemia upregulates the interstitial levels of MCP 1, IL-6 and IL-8 in SCAT in obese women while it does not affect IL-1beta, IL-10, TNFalpha and PAI-1 levels. Hypocaloric diet associated with weight reduction enhances the hyperinsulinemia-induced up-regulation of MCP 1, IL-6 and IL-8 in SCAT. Key words: cytokine, hyperinsulinemia, microdialysis, adipose tissue

Catecholamine and insulin control of lipolysis in subcutaneous adipose tissue during long-term diet-induced weight loss in obese women

The aim of this study was to investigate the evolution of the adrenergic and insulin-mediated regulation of lipolysis during different phases of a 6-mo dietary intervention. Eight obese women underwent a 6-mo dietary intervention consisting of a 1-mo very low-calorie diet (VLCD) followed by a 2-mo low-calorie diet (LCD) and 3-mo weight maintenance (WM) diet. At each phase of the dietary intervention, microdialysis of subcutaneous adipose tissue (SCAT) was performed at rest and during a 3-h hyperinsulinemic euglycemic clamp. Responses of dialysate glycerol concentration (DGC) were determined at baseline and during local perfusions with adrenaline or adrenaline and phentolamine before and during the last 30 min of the clamp. Dietary intervention induced a body weight reduction and an improved insulin sensitivity. DGC progressively decreased during the clamp, and this decrease was similar during the different phases of the diet. The adrenaline-induced increase in DGC was higher at VLCD and LCD compared with baseline condition and returned to prediet levels at WM. In the probe with adrenaline and phentolamine, the increase in DGC was higher than that in the adrenaline probe at baseline and WM, but it was not different at VLCD and LCD. The results suggest that the responsiveness of SCAT to adrenaline-stimulated lipolysis increases during the calorie-restricted phases due to a reduction of the α(2)-adrenoceptor-mediated antilipolytic action of adrenaline. At WM, adrenaline-stimulated lipolysis returned to the prediet levels. Furthermore, no direct relationship between insulin sensitivity and the diet-induced changes in the regulation of lipolysis was found.status: publishe

The effect of AICAR, full-length, trimeric and globular adiponectin isoforms on Ser79 ACC and Ser565 HSL phosphorylation.

<p>Levels of phospho-Ser79-ACC (A) and phospho-Ser565-HSL (B) were investigated in differentiated preadipocytes derived from SCAAT after 24-hour treatment with 2 mM AICAR, 10 µg/ml full-length adiponectin, 10 µg/ml trimeric adiponectin and 10 µg/ml globular adiponectin expressed as % change over the control experiment. (C) A representative western blot of p-ACC, p-HSL and tubulin as a loading control. N = 4 for each treatment * p<0.05 for comparison with the control experiment.</p

Anthropometric and biochemical variables of subjects.

*<p>p<0.05 for differences between obese and non-obese.</p

Primers used for qPCR analysis.

<p>Primers used for qPCR analysis.</p

Gene expression of AdipoR1 and AdipoR2 in SCAAT and VAT of obese and non-obese subjects.

<p>(A) Relative gene expression of AdipoR1 and AdipoR2 in SCAAT and VAT of obese and non-obese subjects as the ratio of the gene of interest expression/geometric mean of the expression of three control genes (ACTB, RPLP0, PPIA). (B) Ratio of AdipoR1/AdipoR2 relative expression in SCAAT and VAT of both groups. N = 9 for obese and N = 6 for non-obese subjects * p<0.05 for comparison between SCAAT and VAT, ^† p<0.05 for comparison between AdipoR1 and AdipoR2 expression.</p