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Recently, viruses are wildly used for experimental neural tract tracing because they can infect and replicate within neurons and are transported within the axons. However, issues of continued virus gene expression, pathogenicity and reversion to wild type still remain. The recombinant adeno-associated virus (AAV), a virus with a single strain DNA, is considerable a safe neural tracer because of its special properties of (1) the specific integration, non-pathogenecity of wild-type and non-replication without helper virus and (2) AAV could infect the non-mitotic neurons. The purposes of this study are : (1) to evaluate the efficacy of AAV to be as a novel neural tracer; (2) to study the origins of the afferent fiber of the superior cervical ganglion (SCG) of the rabbits. AAV and /or HRP were injected into the unilateral SCG of the rabbits. Three days after the tracer injected, rabbits were sacrificed by perfusion with Ringer's solution and fixative. The bilateral SCG, stellate ganglion, nodose ganglion, trigeminal ganglion, dorsal root ganglia and the spinal cord from C1 to L1 were removed and sectioned, then processed for HRP and β-Gal histochemical reactions. Results show that: (1) the HRP labeling neurons were located in the ipsilateral intermediolateral nucleus (IML) of the spinal segments from C8 to T7 and the ipsilateral stellate ganglion; (2) the AAV positive neurons were found in bilateral SCG, trigeminal ganglion and dorsal root ganglia from C1 to L5 but not in the IML and stellate ganglion. Results suggest that AAV appeared to be able to label the sensory neurons rather than the sympathetic preganglionic neurons.
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