Introduction: In a condensed chromatin formation, the DNA is hardly accessible for transcription factors; thus, gene expression requires nucleosome unfolding. A key role in condensing of chromatin structure is played by HDAC4. Thus, the aim of this study was to evaluate the effect of a single bout of resistance exercise on hdac4 gene expression in fast and slow twitch skeletal muscles in male Wistar rats.

Materials & methods: The subjects of this experimental study were15 rats that provisioned from Pasteur Institute and housed under natural conditions (temperature, light/dark (12-h) cycle, with ad Libitum access to food and water). The rats were randomly assigned into experimental (n=10) and control groups (n=5); the exercise group performed a session exercise (Climbing of a one meter ladder, plus 80% of their weight). After three and six hours, the rats were anaesthetized and killed, then to determine hdac4 gene expression rate, the soleus and EDL muscles were removed, to determine expression rate, the Quantitative Real time RT-PCR was used. Data were analyzed by one sample and independent t test.

Findings: The results indicated that in response to an acute exercise, the expression of hdac4 gene in EDL muscle significantly (p=0.0013) increased at 3h and it remained unchanged (p=0.058) 6h after exercise, while in soleus muscle the hdac4 expression remained unchanged at 3h (p=0.18) and 6h (p=0.45) after exercise.

Discussion & Conclusions: It seems that fast twitch type muscles have more plasticity than slow type fiber to response exercise and possibly chromatin condenseness increase in fast-twitch fibers after exercise.