Effects Of Recombinant DNA Vaccine Encoding Multiple Domains Related To Inhibition Of Neurite Outgrowth On The Expression Of NGF Following Spinal Cord Injury

It is well known that the injured neurons do not regenerate their transected axons in the adult central nervous system (CNS) of mammals. While a lack of neurotrophic factors (NTFs) is one cause; the other is the inhibition of neurite regeneration by axonal growth inhibitory factors; e.g. NogoA, Mag and TnR. It has been shown that the delivery of neurotrophic factors or the blocking of inhibitors in the injured spinal cord can stimulate neuronal survival and axonal regeneration. The application of a DNA vaccine against these inhibitory molecules have been shown to promote axonal regeneration in a spinal cord injury model. But the mechanism has not been elucidated. This experiment was designed to investigate whether the level of nerve growth factor family in the injured spinal cord was changed after immunization with DNA vaccine encoding multiple domains related to inhibition of neurite outgrowth. Sprague- Dawley rats were divided into three groups: the intact group: without plasmid treatment or lesion; the control group: without plasmid treatment and lesion; the immunized group: with recombinant DNA vaccine treatment and lesion. After antisera were generated in the vaccinated animals, the spinal cord dorsal hemisection was performed. All groups of animals were killed under anesthesia at 3, 7, 14 and 21 days post operation (dpo) and the level of NGF in the spinal cord was determined using western-blot analysis. Results: Following spinal cord lesion, the level of NGF in normal control rats decreased compared with that in the intact group at the 3^rd day. Though the level of NGF increased with the time goes on, the maximum value of NGF did not exceed that in the intact group all the time. It is showed that the endogenous NGF is stimulated to improve recovery. But it is too week...