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Barbara Antuna-Puente, Emmanuel Disse, May Faraj, Marie-Eve Lavoie, Martine Laville, Rémi Rabasa-Lhoret and Jean-Philippe Bastard

Objective

To evaluate the validity of a new lipid-based index (Disse index) in assessing insulin sensitivity (IS) compared with the hyperinsulinemic-euglycemic (HIEG) clamp in overweight and obese, non-diabetic, postmenopausal women, before and after a weight loss intervention.

Research design and methods

Association between Disse index and the HIEG clamp was evaluated in 86 non-diabetic postmenopausal overweight and obese women before and after weight loss. Percentage changes (%Δ) were calculated for several fasting indices and compared with %Δ of HIEG clamp.

Results

We observed a strong correlation between Disse index and HIEG clamp (r=0.69, P<0.001). This association was higher than those of homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI), and McAuley indices while no significant difference was observed with Revised-QUICKI. Percent change of Disse index (pre- versus post-weight loss program) was significantly correlated with %Δ of HIEG clamp (r=0.34, P<0.01). This correlation was similar to those observed for the other indices tested.

Conclusions

We validated the reliability of Disse index in assessing IS in non-diabetic post-menopausal overweight and obese women, before and after weight loss intervention. Disse index may be useful not only for insulin resistant diagnostics in this type of population, but also for the IS follow-up after a weight-loss program and weight stabilization. The presence of lipid elements in this fasting index improves the estimation of IS in overweight and obese non-diabetic post-menopausal women and could add more information about peripheral IS.

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David H St-Pierre, Rémi Rabasa-Lhoret, Marie-Ève Lavoie, Antony D Karelis, Irene Strychar, Eric Doucet and Lise Coderre

Background

Ghrelin levels are decreased upon food intake, but the impact of specific diet-derived macronutrients on its regulation remains unclear. In addition, because of ghrelin's association with body weight regulation, it is important to understand the mechanisms regulating its levels in obese individuals.

Objective

To examine the effect of specific macronutrients on ghrelin levels in overweight and obese postmenopausal women.

Methods

Thirty-five subjects underwent a euglycemic/hyperinsulinemic clamp (EHC) to examine glucose disposal and total ghrelin (TotG) and acylated ghrelin (AG) levels. Macronutrient intake was evaluated with a 3-day food questionnaire.

Results

Under fasting conditions, positive associations were observed between fiber intake and TotG and AG levels. Fasting AG also correlated positively with the intake of total energy, as well as monounsaturated and polyunsaturated lipids. Importantly, fiber consumption explained up to 26 and 23% of the variation in TotG and AG respectively. During the EHC, TotG levels were significantly reduced at all times, while AG was decreased at 60 min only. TotG area under the curve (AUC) values were positively associated with fiber and polyunsaturated lipid intake, while AG AUC values correlated positively with fiber, total energy, carbohydrate, and lipid intake. Interestingly, fiber intake explained up to 21% of the variation in TotG AUC, while total energy intake predicted up to 21% of the variation in the AG AUC.

Conclusion

The present study suggests that fiber intake is an important regulator of ghrelin levels both in fasting and in hyperinsulinemic conditions. Overall, these results reinforce the importance of the intimate association between eating habits and gastrointestinal hormonal regulation.

Free access

Marthe Moldes, Geneviève Beauregard, May Faraj, Noël Peretti, Pierre-Henri Ducluzeau, Martine Laville, Rémi Rabasa-Lhoret, Hubert Vidal and Karine Clément

Objective: Adiponutrin is a new transmembrane protein specifically expressed in adipose tissue. In obese subjects, short- or long-term calorie restriction diets were associated with a reduction in adiponutrin gene expression. Adiponut.rin mRNA level was previously shown to be negatively correlated with fasting glucose plasma levels and associated with insulin sensitivity of non-diabetic obese and non-obese subjects. The purpose of the present work was to get more insight into the regulation of adiponutrin gene expression by insulin and/or glucose using clamp studies and to examine its potential dysregulation in subjects with a deterioration of glucose homeostasis.

Methods: Adiponutrin gene expression was quantified by reverse transcriptase-quantitative PCR in s.c. adipose tissue of healthy lean subjects after an euglycemic hyperinsulinemic clamp (EGHI), a hyperglycemic euinsulinemic clamp, and a hyperglycemic hyperinsulinemic (HGHI) clamp. Adiponutrin gene expression was also analyzed in patients with different levels of insulin resistance.

Results: During EGHI, insulin infusion induced adiponutrin gene expression 8.4-fold (P = 0.008). Its expression was also induced by glucose infusion, although to a lesser extend (2.2-fold, P = 0.03). Infusion of both insulin and glucose (HGHI) had an additive effect on the adiponutrin expression (tenfold, P = 0.008). In a pathological context, adiponutrin gene was highly expressed in the adipose tissue of type-1 diabetic patients with chronic hyperglycemia compared with healthy subjects. Conversely, adiponutrin gene expression was significantly reduced in type-2 diabetics (P = 0.01), but remained moderately regulated in these patients after the EGHI clamp (2.5-fold increased).

Conclusion: These results suggest a strong relationship between adiponutrin expression, insulin sensitivity, and glucose metabolism in human adipose tissue.

Free access

David H St-Pierre, Jean-Philippe Bastard, Lise Coderre, Martin Brochu, Antony D Karelis, Marie-Éve Lavoie, Florin Malita, Jonathan Fontaine, Diane Mignault, Katherine Cianflone, Pascal Imbeault, Éric Doucet and Rémi Rabasa-Lhoret

Objective: Recent reports have suggested that the existence of associations between hormonal dysregulation and chronic upregulation of inflammatory markers, which may cause obesity-related disturbances. Thus, we examined whether acylated ghrelin (AcylG) and total ghrelin (TotG) levels could be associated with the following inflammatory markers: C-reactive protein (CRP), tumor necrosis factor α (TNF-α), and soluble TNF receptor 1 (sTNF-R1).

Design: Cross-sectional study consisting of 50 overweight and obese postmenopausal women.

Methods: AcylG and TotG levels were assessed at 0, 60, 160, 170, and 180 min of the euglycemic/hyperinsulinemic clamp (EHC). We evaluated insulin sensitivity, body composition, and blood lipid profiles as well as fasting concentrations of CRP, TNF-α, and sTNF-R1.

Results: In fasting conditions, sTNF-R1 was negatively correlated with AcylG (r = −0.48, P < 0.001) levels. In addition, AcylG/TotG was associated negatively with sTNF-R1 (r = −0.44, P = 0.002) and positively with TNF-α (r = 0.38, P = 0.009) values. During the EHC, TotG (at all time points) and AcylG (at 60 and 160 min) values were significantly decreased from fasting concentrations. AcylG maximal reduction and area under the curve (AUC) values were correlated to sTNF-R1 (r = −0.35, P = 0.02 and r = −0.34, P = 0.02, respectively). Meanwhile, the AcylG/TotG AUC ratio was associated negatively with sTNF-R1 (r = −0.29, P < 0.05) and positively with TNF-α (r = 0.36, P = 0.02). Following adjustments for total adiposity, sTNF-R1 remained correlated with fasting and maximal reduction AcylG values. Similarly, AcylG/TotG ratios remained significantly correlated with sTNF-R1 and TNF-α. Importantly, 23% of the variation in sTNF-R1 was independently predicted by fasting AcylG.

Conclusion: These results are the first to suggest that both fasting and EHC-induced AcylG profiles are correlated with fasting values of sTNF-R1, a component of the TNF-α system. Thus, AcylG may act, at least in part, as one mediator of chronic inflammatory activity in human obesity.