A 12-week aerobic exercise intervention results in improved metabolic function and lower adipose tissue and ectopic fat in high-fat diet fed rats

Abstract

Investigations of long-term exercise interventions in humans to reverse obesity is expensive and is hampered by poor compliance and confounders. In the present study, we investigated intrahepatic and muscle fat, visceral and subcutaneous fat pads, plasma metabolic profile and skeletal muscle inflammatory markers in response to 12-week aerobic exercise in an obese rodent model. Six-week-old male Wistar rats (n=20) were randomized to chow-fed control (Control, n=5), sedentary high-fat diet (HFD, n=5), chow-fed exercise (Exercise, n=5) and HFD-fed exercise (HFD+Exercise, n=5) groups. The exercise groups were subjected to 12 weeks of motorized treadmill running at a speed of 18 m/min for 30 min/day. Differences in post-intervention measures were assessed by analysis of covariance (ANCOVA), adjusted for baseline bodyweight and pre-intervention measures, where available. Post-hoc analyses were performed with Bonferroni correction. Plasma metabolic profile was worsened and fat pads, ectopic fat in muscle and liver and inflammatory markers in skeletal muscle were elevated in sedentary HFD-fed animals relative to chow-fed controls. HFD+Exercise animals had significantly lower leptin (P=0.0004), triglycerides (P=0.007), homeostatic model assessment of insulin resistance (HOMA-IR; P=0.065), intramyocellular lipids (IMCLs; P=0.003), intrahepatic lipids (IHLs; P<0.0001), body fat% (P=0.001), subcutaneous adipose tissue (SAT; P<0.0001), visceral adipose (P<0.0001) and total fat mass (P<0.0001), relative to sedentary HFD-fed animals, despite only modestly lower bodyweight. Messenger RNA (mRNA) expression of inflammatory markers Interleukin 6 (IL6) and Tumor necrosis factor α (TNFα) were also reduced with aerobic exercise in skeletal muscle. Our results suggest that 12 weeks of aerobic exercise training is effective in improving metabolic health, fat depots, ectopic fat and inflammation even against a high-fat dietary background.

Aerobic Exercise Prevents Chronic Inflammation and Insulin Resistance in Skeletal Muscle of High-Fat Diet Mice

“…Skeletal muscle insulin resistance is a hallmark of obesity and type 2 diabetes mellitus [27]. Aerobic exercise reduces inflammation and improves insulin resistance in many tissues, including skeletal muscle [28]. In this study, we demonstrated that 8 weeks of aerobic exercise mitigated HFD-induced weight gain, insulin resistance, and chronic inflammation in the skeletal muscle of mice.…”

The role of exercise-induced myokines in promoting angiogenesis

“…In obese adolescents, serum IGF-1 concentration is reduced, 4 weeks of moderate exercise can increase the activity but not the concentration of IGF-1 (Yang et al, 2018). Although IL-6 mRNA expression in skeletal muscle of high-fat diet rats is higher than that in the control mice, it could be reduced to a much lower level with aerobic exercise (Gopalan et al, 2021;Shirvani et al, 2021). While for diabetic patients, 6 months of resistance training had no effect on serum IL-6 concentration under the same weight loss condition (Miller et al, 2017).…”

The effects of exercise on skeletal and heart muscle citrate synthase and carnitine palmitoyltransferase mRNA expressions in high-calorie fed rats

“…Our histopathological findings indicate that high-fat nutrition and sedentary lifestyle may cause fat droplet accumulation within the skeletal muscle as expected. Moreover, GC/S muscle weight gain of high calorie fed sedentary rats was found to be related with an increase in adipose tissue mass together with intramyocellular lipid droplet accumulation (Gopalan et al 2021). However, aerobic exercise reduces fat droplet content in the skeletal muscle without significant differences in CPT-I and II mRNA expression levels.…”