Effect of an acute long-duration exercise bout on skeletal muscle lipid droplet morphology, GLUT 4 protein, and perilipin protein expression

PurposeSmaller lipid droplet morphology and GLUT 4 protein expression have been associated with greater muscle oxidative capacity and glucose uptake, respectively. The main purpose of this study was to determine the effect of an acute long-duration exercise bout on skeletal muscle lipid droplet morphology, GLUT4, perilipin 3, and perilipin 5 expressions.MethodsTwenty healthy men (age 24.0 & PLUSMN; 1.0 years, BMI 23.6 & PLUSMN; 0.4 kg/m(2)) were recruited for the study. The participants were subjected to an acute bout of exercise on a cycle ergometer at 50% VO(2)max until they reached a total energy expenditure of 650 kcal. The study was conducted after an overnight fast. Vastus lateralis muscle biopsies were obtained before and immediately after exercise for immunohistochemical analysis to determine lipid, perilipin 3, perilipin 5, and GLUT4 protein contents while GLUT 4 mRNA was quantified using RT-qPCR.ResultsLipid droplet size decreased whereas total intramyocellular lipid content tended to reduce (p = 0.07) after an acute bout of endurance exercise. The density of smaller lipid droplets in the peripheral sarcoplasmic region significantly increased (0.584 & PLUSMN; 0.04 to 0.638 & PLUSMN; 0.08 AU; p = 0.01) while larger lipid droplets significantly decreased (p < 0.05). GLUT4 mRNA tended to increase (p = 0.05). There were no significant changes in GLUT 4, perilipin 3, and perilipin 5 protein levels.ConclusionThe study demonstrates that exercise may impact metabolism by enhancing the quantity of smaller lipid droplets over larger lipid droplets.

Automated summary

The study aimed to investigate the impact of acute long-duration exercise on skeletal muscle lipid droplet morphology, GLUT4, perilipin 3, and perilipin 5 expressions. The results showed that after acute endurance exercise, lipid droplet size decreased, total intramyocellular lipid content tended to reduce, the density of smaller lipid droplets in the peripheral sarcoplasmic region increased, and larger lipid droplets decreased. However, there were no significant changes in GLUT4, perilipin 3, and perilipin 5 protein levels.