Biotinylated Dextran Amine (BDA) For Observing The Local Axonal Transport In Rabbit Sciatic Nerve: An Experimental Study

Biotinylated dextran amine(BDA) for observing the local axonal transport in rabbit sciatic nerve : An experimental studyBy now we can't detect the regeneration quality in earlier period after peripheral nerve injury or therapeutic suture,and it's responsible for poorly recovery of peripheral nerve. Lots of authors explore some methods involving immunohistochemistry technique and isotopic tracing base on the axonal metabolism behavior of peripheral nerve. However, all of these failed to study the axinal transport of peripheral nerve with different injury severity, and not provide methods to directly visualize the local axinal transport of peripheral nerve. Neural tracer is used in anterograde and retrograde neuroanatomical labelling to elucidate long range anatomical connections within the nervous system. But botinylated dextran, a versatile anterograde and retrograde neuronal tracer, Here we have used it in our experiment to investigate the possibility of evaluating the local axoplasm of peripheral nerve and the changes of axoplasm in traumatic injured sciatic nerve with different injury severity.I,The feasibility of biotinylated dextran amine(BDA) for observing the local axinal transport of peripheral nerveBDA was injected into the sciatic nerve trunk of 24 adult rabbit by a microsyringe with different concentration and different volume,and saline was injected into the matched control nerve. Sampling the sciatic nerve after a survival period of 6 to 48 hours and viewing the sample under the light microscope and confocal microscopy. Result1. Light microscopy :(1) BDA injected region: Following a diaminobenaidine reaction, positive labeled nerve fiber is stained with brown and purpl substance. Both myelin sheath and axis-cylinder were stained, though the boundary of myelin sheath and axis-cylinder is clear. No positive stained fiber can be detected in matched control nerve. (2) Positive stained fiber can be viewed after 6 hours following injection of 10% BDA solution in the proximal to the ligation of sciatic nerve. (3) No definite positive stain can be confirmed in the area proximal to the injection or the region between injection site and proximal to the ligation.2. Confocal microscopy:(1)The distribution of neural tracer is in axis-cylinder,myelin sheath and nerve capsule.(2)To compare the distribution of BDA in the injection region,it is a special pattern in the area proximal to the ligation,which the axis-cylinder was brightly labeled while the myelin sheath is fluorescenced weakly. (3)The accumulation of labeled substances could be detected after 6h following injection of BDA.(4)No definite fluorecence can be confirmed in the area proximal to the injection or the region between injection site and proximal to the ligation.3. No positive labeled nerve fiber could be viewed in the matched control nerve or the nerve injected with 0.1%BDA solution by way of either histochemistry technique(light microscopy) or confocal microscopy.Conclusion (1) The use of neural tracer BDA permits the directly identification of labeled axonal transport of sciatic nerve without difficult processing .(2)Instantaneously,the tracer volume is too minimal in one site of the peripheral nerve trunk to be detected until it reachs some certain extent of accumulation. II,The changes of axoplasm in injured sciatic nerve with different traumatic injury severity Fifty adult rabbit were divided into several experimental group with different injury of sciatic nerve trunk: nerve crush with forceps used in microsurgery,nerve ligation injury with 4-0 silk suture, transected injury,autoplastic transplantation.1,2,3,4,6 weeks after nerve injury,10%BDA solution was injected into the sciatic nerve trunk by a microsyringe proximal to the injury site.Sampling the sciatic nerve following pressure injection of BDA with survival time of 12h, and sections be directly examined undera microscope and confocal microscopy after some proces of sample. Result 1. Pathologiesof different in...