Effect of diet-induced obesity and metabolic syndrome on skeletal muscles of Ossabaw miniature swine

Abstract

TY. Effect of diet-induced obesity and metabolic syndrome on skeletal muscles of Ossabaw miniature swine. Am J Physiol Endocrinol Metab 300: E848 -E857, 2011. First published February 8, 2011 doi:10.1152/ajpendo.00534.2010.-Ossabaw swine fed excess kilocalorie diet develop metabolic syndrome (MS) characterized by obesity, hypertension, insulin resistance, and glucose intolerance with/ without dyslipidemia. The purpose of this study was to test the hypothesis that MS would have a detrimental effect on skeletal muscle structure and cause changes in the expression of myosin heavy chains (MHCs). Adult male Ossabaw swine were fed for 24 wk highfructose or high-fat/cholesterol/fructose diets to induce normolipidemic MS (MetS) or dyslipidemic MS (DMetS), respectively, and were compared with the lean swine on control diet. MetS swine showed mild MS, lacking increases in total and low density lipoprotein (LDL) cholesterol, both of which were highly upregulated in DMetS swine. There was an ϳ1.2-fold increase in the cross-sectional areas of muscle fibers in MetS and DMetS groups compared with control for biceps femoris and plantaris muscles. In plantaris muscles, DMetS diet caused an ϳ2-fold decrease in slow MHC mRNA and protein expression and an ϳ1.2-to 1.8-fold increase in the number of intramyocellular lipid (IMCL) droplets without large changes in the size of the droplets. There was a trend to the decrease in slow MHC expression in muscles of swine on MetS diet. The number of IMCL droplets in muscle fibers of the MetS group was comparable to controls. These data correlate well with the data on total plasma cholesterol (control ϭ 60, MetS ϭ 70, and DMetS ϭ 298 mg/dl) and LDL (control ϭ 29, MetS ϭ 30, and DMetS ϭ 232 mg/dl). We conclude that structural changes observed in skeletal muscle of obese Ossabaw swine correlate with those previously reported for obese humans. obesity; fiber type composition; intramyocellular lipids; myosin heavy chains SKELETAL MUSCLE CONSTITUTES more than 40% of the total body weight and is one of the most important organs for glucose homeostasis. The mass and composition of skeletal muscle are critical for its functions. Obesity is a major risk factor for the development of both insulin resistance and noninsulin-dependent diabetes mellitus (NIDDM). Obesityrelated abnormalities lead to excessive accumulation of triglycerides and fatty acids in skeletal muscle fibers in the form of intramyocellular lipids (IMCL). IMCL accumulation is strongly associated with the impairment of glucose metabolism, oxidative stress, deficiency in energy production, insulin resistance, and eventually the development of type 2 diabetes (reviewed in Refs. 3 and 26).The fiber type composition of skeletal muscle has strong effects on metabolism and utilization of glucose and lipids. Lillioja et al. (22) showed that in vivo insulin action determined by the euglycemic clamp was positively correlated with the percentage of type 1 fibers and negatively correlated with the percentage of type 2b/x fibers in vastus lateralis ...

Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues

“…Few reports exist whereby this phenomenon even is evident in domesticated (meat) animals, but three studies are available evaluating this event in pigs. [133][134][135] In a study utilizing pigs of different body composition, Reiter et al demonstrated that genetic preference for leanness resulted in lower genetic markers for variables of adiposity and lipid metabolism within adipose tissue over pigs of more conventional body composition. 134 However, select skeletal muscle markers for oxidative metabolism of lipids were higher in the leaner pig group; suggesting that intramyocellular lipid is processed more rapidly in lean-type pigs over conventional pigs of similar age and such metabolism is heightened by application of commercially available b-adrenergic agents.…”

“…134 Utilizing genetically small pigs, which are isolated from other breeds, it was shown that diets to mimic dyslipidemic metabolic syndrome resulted in greater accumulation of intramyocellular lipid, but did not result in greater overall numbers of lipid droplets in pigs. 133 Moreover, skeletal muscle contractile proteins appear altered when excess lipid was incorporated Abbreviations: BF, biceps femoris; LD, longissimus dorsi; ST, semitendinosus; RF, rectus femoris; FCN, fat cell number; FCS, fat cell size.…”

Food preferences and aversions in human health and nutrition: how can pigs help the biomedical research?

“…Val-Laillet et al, 2010a, 2010band 2010c. Thus, conventional pigs and minipigs are often used as models of high-fat and/or high-carbohydrate diet-induced obesity (Val-Laillet et al, 2010a, 2010b, 2010c, Clark et al, 2011), diabetes (Bellinger et al, 2006Liu et al, 2007) or atherosclerosis (Xi et al, 2004). With regard to hormonal regulation of feeding behaviour, pigs and humans share some taste receptors and hormones that are involved in appetite/satiety regulation.…”

“…Gö ttingen minipigs also have a high propensity The pig model in human nutrition (Gandarillas and Bas, 2009) Differences in the relative absorptive surface areas of the GIT (e.g. faster nutrient absorption in humans than in rats; DeSesso and Jacobson, 2001) Ability to develop human diseases Obesity (Val-Laillet et al, 2010a, 2010band 2010cClark et al, 2011), diabetes (Bellinger et al, 2006Liu et al, 2007), atherosclerosis (Xi et al, 2004;Miyoshi et al, 2010).…”

“…Another interesting factor is that pigs can develop some of the same disease as humans, such as obesity, diabetes, or cardiovascular diseases such as atherosclerosis (for a review, see Jokinen et al, 1985). For instance, miniature Ossabaw pigs have a 'thrifty genotype' that confer them with a naturally increased predisposition to the development of obesity or insulin resistance in response to high-fat/high-carbohydrate diets (Dyson et al, 2006;Clark et al, 2011). Gö ttingen minipigs also have a high propensity The pig model in human nutrition 123 Table 1 A non-exhaustive comparison of features and strains in pigs and rodents, highlighting the similarities or discrepancies of these models with humans, and their advantages and limitations for studies on human nutrition and eating disorders Pigs Rodents…”