Research Of The Therapy In Spinal Cord Injury With Adenovirus-mediated GDNF Transfer In Vivo And CAMP

Objective This test researched the therapy in spinal cord injury of rats with adenovirus-mediated GDNF transfer in vivo and cAMP to explore the new methods prompting regeneration of spinal cord nerves.Methods 90 SD rats were made into moderate spinal cord injury models by Nystr?m style with compression of 35g for 5minutes. These rats were randomly distributed into cAMP group with 15 rats , control group,Ad-GDNF group and Ad–GDNF + cAMP group with 25 rats in each group. The cAMP group were infused cAMP(10mmol/L) in the subarachnoid space, 1μl/h altogether 72μl. The Ad-GDNF group were injected Ad-GDNF(1×10~9pfu/ml)2ul in the spinal lesion area. Ad-GDNF+cAMP group were first injected Ad-GDNF then infused cAMP in the subarachnoid space. The control group weren't injected Ad-GDNF or infused cAMP. The expressions of GDNF mRNA were detected in control group,Ad-GDNF group and Ad-GDNF+cAMP group by RT-PCR at 1w,2w,4w after the operation and immunohistochemistry stain at 1w,4w after the operation. The function of hindlimb movements were evaluated by BBB scales in each group at 1d,3d,5d,1w,2w,4w after the operation. The recovery process of spinal cord injury was evaluated by pathological analysis in each group at 1w,2w,4w after the operation. The spinal axons were traced with biotinylated dextran amione (BDA) in each group at 4w after the operation.Results The GDNF expressions of Ad-GDNF group and Ad-GDNF+cAMP group were much more than control group(p<0.01)at 1w,2w,4w after the operation and lasted a long period.Ad-GDNF group and Ad-GDNF+cAMP group had many GDNF-positive neurons while control group also had some positive neurons at 1w after operation. Ad-GDNF group and Ad-GDNF+cAMP group still had some GDNF-positive neurons but control group had few positive neurons at 4w after operation. Motive function in each group recovered rapidly in 1-2w after the operation, especially Ad-GDNF group and Ad-GDNF+cAMP group(p<0.05).There was not significant difference between Ad-GDNF group and Ad-GDNF+cAMP group ( p > 0.05 ) . Ad-GDNF+cAMP group were better than Ad-GDNF group and Ad-GDNF group were better than control group and cAMP group as for the recovery of hindlimb movements(p<0.05)at 4w after the operation. There was not significant difference between control group and cAMP group(p>0.05)after the operation.There was not significantly different pathological changes in each group(p>0.05)at 1w after operation. Ad-GDNF group and Ad-GDNF+cAMP group had a better functional residual tissue than control group and cAMP group(p<0.05)at 2w after operation. There was no significant difference between Ad-GDNF group and Ad-GDNF+cAMP group ( p > 0.05 ) . There was a similar consequence at 4w after the operation but the residual white matter was significantly more in Ad-GDNF+cAMP group than in Ad-GDNF group(p<0.05). There was not significant difference between control group and cAMP group(p>0.05)after the operation.There were lots of regenerated axons in Ad-GDNF+cAMP group and Ad-GDNF group had few regenerated axons but no evident regenerated axons were found in control group and cAMP group at 4w after the operation.Conclusions GDNF is beneficial to the recovery of spinal cord injury, but the effect is limited. Using GDNF together with cAMP can evidently prompt functional recovery of spinal cord injury and induce the axonal regeneration.