Changes of axonal count of white matter and recovery of motor function induced by nerve growth factor in rats with spinal cord injury

Lei ZHANG; Yuanwu MEI

ABSTRACT

BACKGROUND:

Neurotrophic factors have been conformed to have the effects of promoting the survival, differentiation and axonal regeneration of the injured neurons, so that the structural integrity of the injured spinal cord can be reserved as much as possible.

OBJECTIVE:

To observe the effects of nerve growth factor (NGF) on the neural regeneration and motor function following spinal cord injury in rats.

DESIGN:

A randomized controlled observation.

SETTING:

Department of Neurology, Union Hospital affiliated to Tongji Medical College, Huazhong University of Science and Technology.MATERIALS Thirty healthy adult male Wistar rats of common degree, were provided by the Experimental Animal Center, Tongji Medical College of Huazhong University of Science and Technology.

METHODS:

The experiment was carried out in the Department of Neurology, Union Hospital of Tongji Medical College,Huazhong University of Science and Technology. The 30 rats were randomly divided into NGF-treated group (n=15) and control group (n=15). ① T8 spinal injury was induced by the improved Allen method. ③ The improved Rivlin method (namely, slope test) was used to assess the motor function following spinal cord injury in rats before model establishment and at 3 days, 1, 2 and 3 weeks after treatment respectively. ④ At 2 days and 3 weeks postoperatively, 7 rats in the NGF-treated group and 8 rats in the control group were selated and the cross-sectional tissue(0.5 cm) of the injured spinal cord was removed, fixed in neutral formalin, dehydrated, and embedded with paraffin, and then cut into 5 μm sections.MAIN OUTCOME

MEASURES:

① The results of the slope test before model establishment and at 3 days,1, 2 and 3weeks after treatment respectively; ② Axonal count in white matter at 2 days and 3 weeks after model establishment.

RESULTS:

① The scores of slope test after spinal cord injury at 1, 2 and 3 weeks postoperatively in the NGF-treated group were obviously higher than those in the control group [(45.2±3.2), (51.2±3.8), (53.4±4.6)°; (45.2±3.2), (51.2±3.8),(53.4±4.6)°, P ＜ 0.05].② At 3 weeks after treatment, a few dispersal and heterogeneous NGF200 spots were observed in the white matter of rats in the control group, but there were plentiful and symmetrical NGF200 spots in the NGF-treated group. The axonal count in white matter at 3 weeks following spinal cord injury in the NGF-treated group was obviously higher than that in the control group (363.6±34.2, 187.5±32.1, P＜ 0.05).

CONCLUSION:

NGF can promote the neural regeneration following spinal cord injury to a certain extent, and help to im prove the functional recovery.