The effect of resistance-aerobic training on the gene expression of FNDC5, myostatin and hypertrophy or hyperplasia in the gastrocnemius muscle of immature rats

Among the many variables that affect muscle growth are myokines and myostatin. This study looked at how resistance-aerobic training affected the expression of genes related to fibronectin type III domain-containing protein 5 (FNDC5), myostatin and hypertrophy or hyperplasia in the immature rats’ gastrocnemius muscle.

A total of ten male Wistar rats, aged two weeks were randomly divided into two control (five rats) and training (five rats) groups.  The resistance training program consisted of three sessions each week for six weeks, during which time the participants would carry a weight and climb a one-meter ladder 26 times. For six weeks, on alternate days, aerobic exercise consisted of jogging on a treadmill at an intensity between 25 and 50% of a rat’s maximum speed. All of the rats were dissected and their skeletal muscles isolated 48 hours after the previous training session and after fasting for 8 hours. FNDC5 and myostatin expression were measured using Real-Time PCR. Using light microscopy, hypertrophy and hyperplasia were quantified. Prism software was used to analyze the data using an independent t-test at the p≤0.05 level.

Following six weeks of training, the training group had higher gene expression of FNDC5 (p=0.04) and hypertrophy (p=0.004) than the control group, but decreased gene expression of myostatin (p=0.01) in comparison. Nonetheless, there was no statistically significant difference between the two groups gastrocnemius muscle hyperplasia (p=0.22).

It appears that resistance-aerobic exercise accompanied by increased expression of FNDC5 genes and decreased myostatin gene expression increased fast twitch fiber hypertrophy. This approach shows that muscle tissue in animal samples before puberty is trainable, independent of natural growth.