The effect of dietary fat content on phospholipid fatty acid profile is muscle fiber type dependent

Abstract

IR has been linked to alterations and increased saturation in the phospholipid composition of skeletal muscles. We aimed to determine whether HFD feeding affects fatty acid (FA) membrane profile in a muscle fiber type-specific manner. We measured phospholipid FAs and expression of FA synthesis genes in oxidative soleus (SOL) and glycolytic extensor digitorum longus (EDL) muscles from rats fed either standard chow (standard laboratory diet, SLD) or a HFD. The HFD increased fat mass, plasma insulin, and leptin levels. Compared with EDL, SOL muscles preferentially accumulated C18 over C16 FAs and n-6 over n-3 polyunsaturated FAs (PUFAs) on either diet. With the HFD, SOL muscles contained more n-9 monounsaturated FAs (MUFAs) and n-6 PUFAs and less n-7 MUFAs and n-3 PUFAs than EDL muscles and had lower unsaturation index, a pattern known to be associated with IR. Stearoyl-CoA desaturase-1 expression was ϳ13-fold greater in EDL than in SOL muscles but did not change with the HFD in either muscle. The expression of Elongase-5 was higher, and that of Elongase-6 (Elovl6) was lower in EDL compared with SOL muscles with both diets. In EDL muscles, the expression of Elovl6 was lower in the HFD than in the SLD. The pattern of FA uptake, expression, and diet-induced changes in FA desaturating and elongating enzymes maintained higher FA unsaturation in EDL muscles. Accordingly, the fiber type composition of skeletal muscles and their distribution may be important in the development and progression of obesity and IR. skeletal muscle; stearoyl-coenzyme A desaturase; elongases; obesity HIGH-FAT DIET (HFD) feeding leads to obesity in rodents as well as in humans (15, 17) and, in skeletal muscles, to an increase in the intracellular content of lipids and resistance to the actions of insulin (IR) and leptin.Skeletal muscle represents 40 -50% of the total body mass and is the major tissue responsible for whole body insulinstimulated glucose disposal. Skeletal muscle fibers are divided into three major categories, types I, IIa, and IIb. Type I fibers are slow-twitch, oxidative (SO) fibers with a high mitochondrial content; type IIa fibers are fast-twitch, oxidative-glycolytic (FOG) fibers that are high in both mitochondrial and glycogenolytic enzymes; type IIb fibers are fast-twitch, glycolytic (FG) fibers that are high in the enzymes of glycogenolysis (22,59). Although the oxidative muscle fibers are highly dependent on lipids as a substrate, the glycolytic or oxidativeglycolytic fibers utilize either predominantly glucose or a fuel mixture with an important contribution of glucose as a substrate under normal feeding conditions (46). Oxidative muscles are more insulin sensitive and have a greater insulin binding capacity (5), kinase activity of insulin receptor (25), content of glucose transporter (GLUT)4 (26), and insulin-stimulated glucose uptake (35) than glycolytic muscles. In obesity and IR, the distribution of fiber types is shifted from oxidative toward glycolytic muscle fibers (21).In skeletal muscle, saturated fatty acids (S...

Metabolomic Analysis of Oxidative and Glycolytic Skeletal Muscles by Matrix-Assisted Laser Desorption/IonizationMass Spectrometric Imaging (MALDI MSI)

“…Fatty acids are supplied to the fiber either by fatty acids bound to albumin or by hydrolyzed triacylglycerides [35]; they were converted to acyl CoA, and then finally to acylcarnitines to enter the mitochondrial where they can undergo ß oxidation [35]. In terms of phosphatidylcholines (PCs), most of the identified PCs showed localization and higher abundance in the oxidative region were composed of 18:1 (oleic) fatty acid tail; this observation is also in concordance with literatures [36, 37] that showed higher amount of oleic fatty acid as PC fatty acid tail in SOL. One explanation to this difference in PC fatty acid tail composition between oxidative and glycolytic regions is that there is a greater number of long-chain fatty acid transporters in oxidative muscles compared to glycolytic [38]; this difference in fatty acid transporter population also explains the differences in acycarnitine abundance between the two regions.…”

Porcine intramuscular fat content and composition are regulated by quantitative trait loci with muscle-specific effects1

“…A plausible hypothesis that arises from our investigation is that the lack of concordance between GM and LTL QTL maps might be partly explained by geneticfactors related with niRNA expression. Previous studies performed in rats indicated the existence of differences in the gene expression profiles of certain muscles types (Donsmark et al, 2002;Janovská et al, 2010). Moreover, transcriptomic analyses performed in pigs are closely aligned with these results.…”

Fiber-type-specific sensitivities and phenotypic adaptations to dietary fat overload differentially impact fast- versus slow-twitch muscle contractile function in C57BL/6J mice

“…1C). A fiber-type-specific effect of HFD feeding on the intramyocellular lipid [33] and phospholipid FA content [34] in rodent muscles has been reported previously, showing accumulation in FT muscle (gastrocnemius [33] and EDL [34]) but not ST oxidative soleus muscle [33,34]. Changes in FA composition of FT EDL muscle largely reflected FA composition of the diets [17], suggesting storage of surplus dietary FAs in TAG.…”