The effect of eight weeks of moderate and high intensity resistance training on miR-23a, Atrogin-1 and MuRF gene expression in fast and slow twitch muscles in Wistar older rats

Muscle atrophy is an active process controlled by specific signaling pathways and transcriptional programs. Atrogin-1/MAFbx and MuRF1 are up-regulated in different models of muscle atrophy and is responsible for increased protein degradation through the ubiquitin proteasome pathway. The purpose of this study was to investigate the effect of moderate and high intensity resistance training on miR-23a, Atrogin-1 and MuRF gene expression in fast and slow twitch muscles in elderly rats.

Thirty male Wistar rats (23 months old) were randomly divided into three groups (n=10) including moderate-intensity resistance training, high-intensity resistance training and the control groups. Resistance training were performed during eight weeks of climbing a ladder with high intensity (80% Maximum voluntary carrying capacity/MVCC) and moderate intensity (60% of MVCC) for 5 days a week. Isolation of Soleus muscle and Flexor halluces longus (FHL) was performed immediately after blood sampling in sterile conditions. MiR-23a, Atrogin-1 and MuRF expression were measured by RT-PCR method in Soleus and FHL muscles. The statistical analysis was performed by One-way & Two-way ANOVA tests with significance level of p<0.05.

The results showed that the expression of MuRF and Atrogin-1 genes in both resistance groups were significantly lower than those the control group and miR-23a expression expression in both high and moderate resistance groups was significantly higher than the control group (p<0.05). But there was no significant difference between the effect of high and moderate intensity resistance training on miR-23a, MuRF, and Atrogin-1 expression in both muscles (p>0.05).

It seems that resistance training with moderate and high-intensity can decrease the resting levels and gene expression of factors associated with muscular atrophy (miR-23a) and its target genes (Atrogin-1, MuRF) in older rats, and these exercises could lead to the prevention of sarcopenia.