Irisin/FNDC5 influences myogenic markers on skeletal muscle following high and moderate-intensity exercise training in STZ-diabetic rats.

In the present study, we investigated the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on irisin and expression of myogenic markers (paired box 7 (Pax7), myogenic differentiation 1 (MyoD), myogenin) in skeletal muscle of diabetic rats. Eighty-four male Wistar rats (6 weeks of age) were randomly divided into seven groups ( = 12): basic control (Co Basic), 8 weeks control (Co 8w), diabetes mellitus (DM), HIIT, DM + HIIT, MICT, and DM + MICT groups. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ). The protocol was characterized by running on a rodent treadmill with moderate intensity (60-70% ), 60 min per session, 5 days/week, for 6 weeks. HIIT consisted of six 3-min runs at a high intensity (80-90% ) alternated with 2-min running at low intensity (50% ), 30 min per session, 5 days/week, for 6 weeks. Results showed that DM decreased myoblast markers compared to Co Basic and Co 8w groups. Fibronectin type III domain-containing protein 5 (FNDC5) mRNA decrease was correlated with myoblast markers (Pax7  = 0.632,  = 0.027; MyoD  = 0.999,  = 0.001; myogenin  = 1.000,  = 0.001) in DM group. DM + MICT significantly increased gene expression of MyoD, myogenin, and FNDC5 compared to DM and DM + HIIT. The results also showed that the intensity and duration of exercise on the treadmill were effective in stimulating irisin and myogenic markers after DM.