RESUMO
BACKGROUND: Myogenic regulatory factors Myf-5 is an importance gene involved in muscle occurrence process to adjust and control, start and maintain the skeleton muscle cell growth. It has a possible relation with denervated skeletal muscle atrophy. OBJECTIVE: To detect the expression of Myf-5 gene in different skeletal muscle sitas and different periods following denervatad skeletal muscle atrophy.DESIGN, TIME AND SE'I-rlNG: Randomized control animal experiment was performed in the Shanxi Medical University between March and April in 2008. MATERIALS: A total of 24 Sprague-Dudley male rats was selected and divided randomly into four groups, with six in each, Le. sham operated group (innervations), denervated 2 d group, denarvated 7 d group and denervatad 28 d group. METHODS: Sham operations were made only for the rats in the sham operated group and sciatic nerve were not cut off. Sciatic nerves were cut off more than one centimeter at the mid-level of their right lower limb for the rats in denervated groups. The rats were executed by vertebrae dislocation method at 2, 7, 28 days after denervation. The skeletal muscles of the right lower limb (tibialis anterior, soleus, gastrocnemius and plantar) were dissected and dissociated. MAIN OUTCOME MEASURES: Myf-5 mRNA expression was detected by reverse transcription-polymerase chain reaction. Immunohistochemical stain (ABC method) with polyclonal antibody against Myf-5 protein was performed and the gray value was counted.RESULTS: Expressions of Myf-5 mRNA in denervatad skeletal muscle were up-regulated at 2, 7, 28 days in the eady stage of denervation (P < 0.05). The number of Myf-5 antibody positive-stained cell nuclei was the most in satellite cells at 28 days following denervation. CONCLUSION: At the early stage of denervated skeletal muscle atrophy in SD rats, expressions of Myf-5 in different skeletal muscles are all up-regulated. Denervation of rat skeletal muscle raises the Myf-5 expression in satellites cells.
RESUMO
BACKGROUND: MyoD expression of skeletal muscle of rats increases distinctly in the earlier period of denervation, which can greatly postpone denervated skeletal muscle atrophy. The clinical test testifies that electrical stimulation is an effective method to cure denervated muscle atrophy. But the influence of electrical stimulation on MyoD expression during denervated muscle atrophy is still unproved. OBJECTIVE: To discuss the influences of electrical stimulation on the gene expression of MyoD of skeletal muscle of rats. DESIGN, TIME AND SETTING: Randomized control animal experiment was performed in the Animal Experimental Center of Shanxi Medical University between July and November in 2008. MATERIALS: A total of 36 healthy Sprague-Duwley rats of either gender were divided randomly into three groups, control group, denervation group and electrical stimulation group. Each group contained 12 rats. METHODS: Standard models of right sciatic nerve dissociation and gastrocnemius denervation were established in right limb of each rat in denervation group and electrical stimulation group. Thirty-minute electrical stimulation was given to the denervated gastrocnemius muscle of each rat of electrical stimulation group once a day. The rats were executed at 2, 7, 14, 28 days after denervation to dissect and dissociate their gastrocnemius muscles of the right lower limbs. MAIN OUTCOME MEASURES: MyoD mRNA expression was detected by reverse transcription polymerase chain reaction, and MyoD protein level by immunohistochemistry. RESULTS: The expression of MyoD mRNA and MyoD protein level in specimens of denervation group and electrical stimulation group were up-regulated at 2, 7, 14, 28 days after denervation, with significant differences compared with blank control group (P