Effects of Treadmill Running on Intramyocellular Lipid Deposition and VEGFB Expression in Soleus Muscle of High-fat Diet Mice / 中国运动医学杂志

Objective To observe the effect of treadmill running on skeletal muscle lipid deposition,and the expression of vascular endothelial growth factor-B(VEGFB)and its receptor in soleus muscles of high-fat diet mice.Methods Thirty-two 5-week-old C57BL/6 male mice were randomly divided into a control group(n=8)and a high-fat diet group(n=24),and fed with normal and high-fat diet respectively.Eight weeks later,16 obesity mice were selected from the latter group and randomly divided into a sedentary group(n=8)and a treadmill running group(n=8).The running group underwent treadmill running at 25 m/min for an hour every day,five days a week for 8 weeks,while the other two groups did not do any exercises.The weight was measured before the mice were killed.The soleus lipid deposition level was determined using oil red O staining,The expression of VEGFR1 and Neuropilin-1(NRP1)was determined using the immunohistochemical staining,while the mRNA expression of VEGFB,VEG-FR1,NRP1 and peroxisome proliferator-activated receptor-γcoactivator-1α (PGC-1α) was detected using the real-time PCR.Results Compared with the control group,a significant increase was observed in the weight and the soleus lipid deposition of the high-fat diet group,while there were no significant differences in the expression of VEGFB,NRP1,VEGFR1 and PGC-1α.mRNA between the two groups.Compared with the sedentary obese mice,significant decrease in the body weight and soleus lipid deposition,significant increase in VEGFR1 mRNA expression,but no significant changes in the expression of VEGFB,NRP1 and PGC-1α mRNA were observed in the treadmill-running obese mice.Conclusion The treadmill running has no effect on the VEGFR1 expression in soleus of obese mice,but significantly up-regulates the expression of its receptors.It indicates that the treadmill running can lower the intramyocellular lipid deposition as it can strengthen the VEGFB/VEGFR1 in soleus muscles.

Intermuscular Adipose Tissue Content and Intramyocellular Lipid Fatty Acid Saturation Are Associated with Glucose Homeostasis in Middle-Aged and Older Adults

BACKGROUND: Insulin resistance is associated with the higher content of intermuscular adipose tissue (IMAT) and the saturation of intramyocellular lipid (IMCL), but a paucity of data exist in humans. This study examined associations among IMAT content, IMCL saturation, and fasting glucose concentration in middle-aged and older adults with overweight or obesity. METHODS: Seventy-five subjects (26 males, 49 females) were recruited and thigh muscle and IMAT were assessed using magnetic resonance imaging. Vastus lateralis tissue was acquired from a subset of nine subjects and IMCL content and saturation were assessed using nonlinear dual complex microscopy. RESULTS: The characteristics of the 75 subjects were as follows: age 59±11 years, body mass index 30±5 kg/m², fasting glucose concentration 5.2±0.5 mmol/L, fasting insulin concentration 12.2±7.3 µU/mL, fasting homeostatic model assessment of insulin resistance (HOMA-IR) 2.9±2.0 (mean±SD). IMAT to muscle tissue (MT) volume ratio was positively associated with the saturated fatty acid to unsaturated fatty acid ratio in IMCL. IMAT:MT was positively associated with fasting glucose concentration and HOMA-IR. IMCL saturation was positively associated with fasting glucose concentration while muscle cell area, IMCL area, and % IMCL in muscle cell were not associated with fasting glucose concentration. CONCLUSION: These results indicate that higher intermuscular fat content and IMCL saturation may impact fasting glucose concentration in middle-aged and older adults with overweight or obesity. The centralization of adipose tissue in the appendicular region of the body may promote insulin resistance.

CHARACTERISTICS OF INTRAMYOCELLULAR LIPID CONTENT IN SKELETAL MUSCLES OF OVERWEIGHT MEN AND ENDURANCE-TRAINED ATHLETES / 体力科学

This study used proton magnetic resonance spectroscopy (¹H-MRS) to investigate differences in muscle group specific intramyocellular lipid (IMCL) storage characteristics associated with elevated muscle lipid storage, and to determine whether IMCL content is associated with maximal aerobic capacity. Seven healthy men [untrained (UT)], four overweight (OW) and six endurance-trained (T) subjects volunteered for this study. Data were acquired, using ¹H-MRS, from the tibialis anterior (TA), medial gastrocnemius (MG) and soleus (SOL) muscles. The IMCL content in TA was approximately twice as high in T subjects than in UT and OW subjects. In MG, IMCL was higher in OW and T subjects compared with UT subjects. A linear relationship existed between the VO₂max and IMCL in TA and a curve of second-degree relationship between the VO₂max and IMCL in MG. These results suggest that elevated IMCL deposits in TA might reflect enhancement of aerobic capacity, whereas the IMCL accretion in MG might reflect not only aerobic capacity but also overweight and obese conditions in men.