The Effect of an 8-Week Resistance Training on ActRIIβ in Fast- and Slow-twitch Skeletal Muscles and Plasma Levels of GDF8, GDF11 and GASP-1 in Old Male Rats

Changing the concentration of growth factors and their receptors can affect sarcopenia (age-related muscular atrophy). The aim of this study was to determine the effects of an 8-week resistance training on ActRIIβ in fast- and slow-twitch (FT & ST) skeletal muscles and plasma levels of GDF8, GDF11 and GASP1 in old male rats. This study was conducted as a two-group experimental design with 14 old male rats with age range 24 to 27 months and weighing 440±24g. After the familiarization training, the rats were randomly divided into 2 groups of 7 control and training. The training protocol was included 8 weeks climbing from a 1 meter ladder. 5cc blood was taken from the left ventricle, 48 hours after the last session, for measurement of GDF8, GDF11 and GASP-1 by ELISA method. The soleus (SOL) muscle (ST) and flexor hallucis longus (FHL) muscle (FT) of rats were taken for measurement of ActRIIB by IHC method. Independent t-test was applied for statistical analysis of the data (p<0.05). Comparisons between groups showed that 8-week resistance training have a significant effects on GDF11 (P=0.001), GDF8/GDF11 (P=0.001), GDF8 (P=0.027) and ActRIIβ in SOL muscle (P=0.013), but no between-groups differences were observed in GASP-1(P=0.704) and ActRIIβ in FHL muscle (P=0.325). It seems that resistance training can reduce sarcopenia by favorable effects on growth factors and their receptors. However, more studies are needed in this regard.