Saeed Daneshyar
Fatemeh Jalali Moghim

Mitochondria is a dynamic organelle complicated by fusion and fission processes. Mitochondrial fusion results in an elongation of mitochondria and an expansion of its network (۱). The key molecular regulators of the fusion are mitofusin ۱ (Mfn۱), mitofusin ۲ (Mfn۲) (۲).It is established that endurance training can facilitate the mitochondrial dynamic (۴). However, the training interventions of most previous studies were short-term and continuous bases and the effect of High-intensity interval training (HIIT) on the mitochondrial dynamics such as fusion has not been well explored.Thus, this study aimed to study the effect of CET and HIIT on fusion regulators i.e MFN۱ and MFN۲ in skeletal muscle of Wistar rats.Twenty-four male Wistar rats with a mean of nine weeks in age and a mean of ۳۲۰ g in weight were provided in the Biotechnology Center of Shahid Sadoughi University. The rats were divided into three groups including Control (n=۸), CET (n=۸), and HIIT. The training-group rats were submitted by an exercise on a treadmill with ۱۰° inclination for eight weeks (۵ days/week). The CET-group rats run ۳۰ min by ۷۰% vVo۲peak. The rats of HIIT were exercise-trained on six interval occasions so that they ran at ۹۰% vVo۲peak for ۳-minutes followed by a ۲-minute active recovery at ۵۰% vVo۲peak for ۲-minutes. The gene expression of MFN۱ and MFN۲ in the Soleus muscle was determined by Real-Time PCR.There were no significant differences in MT۱ gene expression among studies groups (P>۰.۰۵). The gene expression of MT۲ was higher in CET group as compared to Control (۲.۶-fold; P=۰.۰۳). However, the HIIT group did not show a significantly higher in MT۲ expression as a comparison to control (۱.۴-fold; P=۰.۰۹). Moreover, it was not observed a significant difference between HIIT and CET groups in MFN۲ (۱.۲-fold; P=۰.۱۳).The results indicated that MT۲ expression, as a fusion marker, was increased by CET but not by HIIT. These would suggest that continuous endurance training compared to high-intensity interval training may be effective in the elongation of mitochondria and expanding the mitochondrial network.

Mitochondrial dynamic؛ Mitochondrial fusion؛ Mitofusin ۲؛ Continuous endurance training؛High-Intensity Interval Training