Changes in the lingual muscles of obese rats induced by high-fat diet feeding

ObjectiveTo elucidate the influences of obesity on the properties and volume of lingual (genioglossus and geniohyoid) muscles in obese rats.MethodsWe analysed the accumulation of triacylglycerol and the diameter of myofibres in the lingual muscles using histochemistry, and the MyHC composition using real-time PCR in rats fed a high-fat diet for 10 weeks. In the genioglossus and geniohyoid muscles, the percentage of oil droplet areas in the obesity group were 3.6 and 2.5 times greater than those in the control group, respectively (p < 0.025). The diameters of the slow myofibres in the genioglossus and geniohyoid muscles were approximately 20% greater in the obesity group than in the control group (p < 0.0001), while that of the fast myofibres in the geniohyoid muscle was approximately 10% greater in the obesity group than in the control group (p < 0.0001). No significant difference in the expressions of any of the MyHC isoforms studied was found in any of the muscles studied between the obesity and control groups.ConclusionHigh-fat diet feeding induced the fat deposition in the myofibre and influenced the structure of the lingual (genioglossus and geniohyoid) muscles.