[Study on early motor neurotrophism of denervated red and white muscles]

To investigate the early change of brain-derived neurotrophic factor (BDNF) in denervated red and white muscles and the regeneration of nerves innervating the muscles and to discuss the effect of the target organs on regeneration of the injured nerves.

Forty Wistar rats were divided into 5 groups. The sciatic nerves in 4 groups were sheared to make the models of the denervated muscles and the other one as control group. The amount of BDNF in muscles was measured with immunohistochemistry 1 day, 3 days, 7 days and 14 days after injury. The models of the regeneration of the nerves were made in another 15 rats whose sciatic nerves were disconnected with forceps. The nerve conduction velocity and electromyogram were tested with neuroelectrophysiology 7 days and 14 days after injury.

The expression of BDNF in soleus increased significantly on the 1st day, the 3rd day and the 7th day (P<0.01); the expression in gastrocnemius was lower, but there was no significant difference (P>0.05) on the 1st day, the 3rd day, the 7th day and the 14th day when compared with control group. After 14 days of injury in the nerves innervating GAS and SOL, the nerve conduction velocities and the amplitudes of wave M recovered to (36.60+/-7.40)% and (19.9+/-6.4)% of normal value, and (42.50+/-3.50)% and (13.7+/-4.0)% of normal value respectively; there were no significant differences between the two muscles (P>0.05).

There is difference in BDNF amount between the denervated red and white muscles, but the recovery of the two kinds of the motor nerves is similar, and the neurotrophism of denervated muscles was determined by all kinds of neurotrophic factors.