The expression of two isoforms of insulin-like growth factor-1(IGF-1) mRNA in rat skeletal muscle induced by one to four weeks of electrical stimulation

Objective: Through investigating the effects of electrical stimulation on expression of growth factors in homologous muscle, to discuss mechanism of electrical stimulating promoting the skeletal muscle growing and cross education. Method: Thirty SD rats were randomly divided into five groups：control，1 week，2 week，3 week and 4 week and stimulating the right triceps surae was stimulated by electrical stimulator. Using real-time quantitative PCR measurement to measure two alternative splices of IGF-1(IGF-1Ea and MGF) and MyoG mRNA expressing of gastrocnemius and right biceps brachii. Result: IGF-1Ea mRNA expression of muscle was increased 1.55，3.99，5.11，5.27 fold respectively, and from first week to third week, IGF-1Ea mRNA expressing consecutively kept increased, but compared with the third week, there was no increasing at the fourth week. MGF mRNA of muscles increased 3.97，4.05、4.13、4.24 fold respectively and MyoG increased 2.14， 2.48， 2.99， 3.02 fold respectively, there was no significant increase from 1—4weeks. However in the contralateral hind limb and forelimb skeletal muscles, the growth factors were no statistical significance. Conclusion: The processing of long-time electrical stimulation promote muscle function, the growth facts were playing a key role in the process of muscle regeneration and repairment;However no significant effects of electrical stimulation on the expression of these regulatory factors were observed in the non-stimulated contralateral hind limb and forelimb muscles, indicating that the expression of these regulatory factors was caused by direct electrical-mechanical stimulation, while the neural-endocrine might not play a main role in it.