Abstract:

BACKGROUND: Low frequency electric stimulus can release skeletal muscle atrophy, but the effect on muscle fiber type remains unclear. In addition, the relationship between electric stimulus and endogenous insulin-like growth factor-1 (IGF-1) expression still not unified.
OBJECTIVE: To investigate effect of low frequency electronic stimulus on different type skeletal muscle atrophy and endogenous insulin-like growth factor-1 after sciatic nerve transaction.
METHODS: SD male rats were divided into 3 groups. Rats in the model and denervation groups were prepared for left sciatic denervation models, and stimulated by 2 Hz electrical stimulus, twice a day, 20 minutes per time. Rats in the normal control and model groups were regularly raised. After 30 days, the animals were killed and the gastrocnemius was removed for detection of diameter and number of muscle fiber; expression of IGF-1 was measured by immunohistochemistry.   
RESULTS AND CONCLUSION: The diameter of type Ⅰ and Ⅱ fibers were decreased, and the type Ⅰ fiber proportion increased after denervation. Compared with the model group, the diameter of typeⅠand Ⅱ fibers were increased, especially more obviously in type Ⅰ fiber in the electronic stimulus group (P < 0.05). Simultaneously, the IGF-1 expression of the electronic stimulus group was higher than that of the model group (P < 0.05). The result demonstrated that 2 Hz electrical stimulus can up-regulate IGF-1 expression and alleviate the muscle atrophy of type Ⅰ fibers.