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Characterisation of fatty acid metabolism in different insulin-resistant phenotypes by means of stable isotopes

Published online by Cambridge University Press:  19 January 2017

Ellen E. Blaak*
Affiliation:
Department of Human Biology, Maastricht University, Maastricht, The Netherlands
*
Corresponding author: Prof E. E. Blaak, email e.blaak@maastrichtuniversity.nl
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Abstract

The obese insulin resistant and/or prediabetic state is characterised by systemic lipid overflow, mainly driven by an impaired lipid buffering capacity of adipose tissue, and an impaired capacity of skeletal muscle to increase fat oxidation upon increased supply. This leads to the accumulation of bioactive lipid metabolites in skeletal muscle interfering with insulin sensitivity via various mechanisms. In this review, the contribution of dietary v. endogenous fatty acids to lipid overflow, their extraction or uptake by skeletal muscle as well as the fractional synthetic rate, content and composition of the muscle lipid pools is discussed in relation to the development or presence of insulin resistance and/or an impaired glucose metabolism. These parameters are studied in vivo in man by combining a dual stable isotope methodology with [2H2]- and [U-13C]-palmitate tracers with the arterio-venous balance technique across forearm muscle and biochemical analyses in muscle biopsies. The insulin-resistant state is characterised by an elevated muscle TAG extraction, despite similar supply, and a reduced skeletal muscle lipid turnover, in particular after intake of a high fat, SFA fat meal, but not after a high fat, PUFA meal. Data are placed in the context of current literature, and underlying mechanisms and implications for long-term nutritional interventions are discussed.

Information

Type
Conference on ‘New technology in nutrition research and practice’
Copyright
Copyright © The Author 2017 
Figure 0

Fig. 1. (Colour online) Impaired muscle lipid turnover after a high fat, high saturated fat (SFA) meal in insulin-resistant subjects. The muscle of insulin-resistant subjects either in the overweight of prediabetic state is characterised by an increased postprandial (VLDL)–TAG extraction and a reduced fractional synthesis of muscle diacylglycerol (DAG) and TAG after a high fat, SFA meal and a reduced fasting transcriptional oxidative profile. We hypothesise that an increased proportion of the SFA is retained in the NEFA (FFA) pool, leading to a higher saturated fatty acyl-CoA content and an increased ceramide formation, which may in turn affect insulin sensitivity. Based on(11).