Using [²H]water to quantify the contribution of de novo palmitate synthesis in plasma: enabling back-to-back studies

Abstract

An increased contribution of de novo lipogenesis (DNL) may play a role in cases of dyslipidemia and adipose accretion; this suggests that inhibition of fatty acid synthesis may affect clinical phenotypes. Since it is not clear whether modulation of one step in the lipogenic pathway is more important than another, the use of tracer methods can provide a deeper level of insight regarding the control of metabolic activity. Although [H]water is generally considered a reliable tracer for quantifying DNL in vivo (it yields a homogenous and quantifiable precursor labeling), the relatively long half-life of body water is thought to limit the ability of performing repeat studies in the same subjects; this can create a bottleneck in the development and evaluation of novel therapeutics for inhibiting DNL. Herein, we demonstrate the ability to perform back-to-back studies of DNL using [H]water. However, this work uncovered special circumstances that affect the data interpretation, i.e., it is possible to obtain seemingly negative values for DNL. Using a rodent model, we have identified a physiological mechanism that explains the data. We show that one can use [H]water to test inhibitors of DNL by performing back-to-back studies in higher species [i.e., treat nonhuman primates with platensimycin, an inhibitor of fatty acid synthase]; studies also demonstrate the unsuitability of [C]acetate.

Resolution of NASH and hepatic fibrosis by the GLP-1R and GCGR dual-agonist cotadutide via modulating mitochondrial function and lipogenesis

“…After exchange, 2H-enriched acetone is extracted with chloroform and assayed by gas chromatography–mass spectrometry. 37 Hepatic palmitate and glyceride enrichments and content were assessed in saponified extracts spiked with internal standards (1,1,2,3,3- 2 H 2 ]Glycerol and Heptadecanoic acid) 32 , 38 . Glucose fluxes were assessed using non–steady-state equations (volume of distribution of glucose= 130 ml/kg).…”

Protein fractional synthesis rates within tissues of high- and low-active mice

“…More studies are needed to examine whether other metabolic parameters are able to differentiate the physical activity level. The methods used in the present study make it possible to explore the utilization of multiple energy substrates such as fatty acid oxidation and glycogen storage in the liver and muscle [6], whereas others also measured fatty acid and lipid synthesis using D 2 O [37,38]. In addition, protein breakdown analysis of the different tissues would provide a more complete metabolic picture in regards to the physical activity level.…”

Dependence of Biocatalysis on D/H Ratio: Possible Fundamental Differences for High-Level Biological Taxons

“…Recent studies on the effects of low concentrations of deuterium on rats and mice show that the organism accelerates its metabolism [ 43 , 52 , 53 , 54 ]. In this regard showed that one could use ddw water to test inhibitors of de novo lipogenesis (DNL) by performing back-to-back studies in higher species, treat nonhuman primates with platensimycin, an inhibitor of fatty acid synthase [ 55 ]. Broad varieties of morphological and physiological changes were observed in deuterium-treated cells and organisms, including changes in fundamental processes such as cell division or energy metabolism [ 56 ].…”