Objective To investigate the influence of clenbuterol on the expression of nerve growth factor (NGF) in denervated red and white muscles and the neurotrophism of the denervated muscles.Methods Sixty-four Wister rats, weighed 200-250 g, were divided into 8 groups(8 rats per group), including 4 experimental groups and 4 control groups. The denervated model was made in rats by dissection of sciatic nerves. Clenbuterol was given at a dose of 200 μg/kg per day in the experimental group, saline in the control group. The expression of NGF was measured with immunohistochemistry after 1, 3, 7 and 14 days of injury. The culture methods of dorsal root ganglions of the chick embryos were used to measure the neurotrophism of extracts of the muscles. Results Compared with the control groups, the NGF content of gastrocnemious(GAS) increased on the 1st day (Plt;0.05) and the NGF content of soleus(SOL) increased greatly on the 1st, 3rd and 7th dayafter injury in the experimental groups (Plt;0.01). In the experimental groups, the NGF amount of GAS reached the highest value on the 1st day after injury(Plt;0.01) and then decreased gradually. And the NGF amount of SOL had slight difference between different time. The NGF content of the SOL was higher than that of GASon the 7th day (Plt;0.05). The sensory neurotrophism of the extracts was similar between SOL and GAS.Conclusion Clenbuterol can change the expression of NGF in denervated muscles, but the change was different in SOL and GAS. The sensory neurotrophism of the denervated muscles were determined by all of the neurotrophic factors in them.
OBJECTIVE: To clarify the character of nerve growth factor (NGF) in the denervated red and white muscles and the relationship between the amount of NGF and sensitive neurotrophism of denervated red and white muscles. METHODS: The model of the denervated gastrocnemius and soleus was made by clipping the sciatic nerve of Wister rats. The immunohistochemistry was taken to measure the amount of NGF in muscles, and the neurotrophism of extracts of muscles was tested with culture of dorsal root ganglions at the 1st, 3rd, 7th and 14th days after injury. RESULTS: The amount of NGF in denervated gastrocnemius and soleus decreased, especially in soleus. The neruotrophism of the extracts of the two kinds of denervated muscles did not decrease; on the contrary, it increased after a week after injury. CONCLUSION: The injury of peripheral nerves causes the amount of NGF in the target tissues to increase, but the change is different between the denervated muscles; the neurotrophism of the extracts of musclesis determined by all kinds of neurotrophic factors, and can not be explained by a single factor.