[Effect of Neuritin protein on axonal regeneration after acute spinal cord injury in rats].

OBJECTIVE: To investigate the effects of Neuritin on the regeneration of the neural axons after acute spinal cord injury (SCI) in rats.

METHODS: The model of acute SCI at T10 was established in 54 adult healthy Wistar rats (half males and half females) weighing 250-300 g by using the improved Allen's weight-drop method. The rats were randomly divided into 3 groups. 100 microL (6 microg) Neuritin and His protein was injected into group A (n = 24) and group B (n = 24), respectively, through subarachnoid catheter. Six rats from each group were killed 3, 7, 14, and 28 days after injury to receive Basso, Beattie and Bresnahan (BBB) locomotor rating scaling, HE staining observation, and immunohistochemistry staining observation for neurofilament 200 (NF-200) and growth associated protein 43 (GAP-43). Group C (n = 6) served as sham-operated group receiving laminectomy without spinal injury and with an empty catheter in the subarachnoid space and received the above observations 7 days after injury.

RESULTS: BBB scale: after operation, the scale of groups A and B was increased over time; group A was significantly higher than group B from 14 days (P < 0.05); group C was higher than groups A and B at different time points after operation (P < 0.05). HE staining: in group C, the injured spinal tissue was normal after operation; from 7 days after operation, group A presented deeper-stained nissl body, less physaliferous cells, and more nerve synapses when compared with group B. NF-200 and GAP-43 immunohistochemistry observation: in group C, there was just little positive expression; while in groups A and B, positive expression of NF-200 and GAP-43 was evident in the spinal cord from 7 days after operation. Mean density integral absorbency (IA) value of NF-200 and GAP-43: group A was higher than group B at each time point (P < 0.05) and group C was lower than groups A and B at each time point (P < 0.05).

CONCLUSION: Local application of exogenous Neuritin can promote the axonal regeneration after acute SCI in rats and the recovery of the locomotion function of hind-limbs in rats.