Abstract: Objective To compare the differences between Adeno Associated Virus (AAV) and Biotinylated Dextran Amine (BDA) in anterograde tracing of mouse corticospinal tract (CST), and to explore the advantages of the application of AAV in anterograde tracing of mouse CST axons as a neural tracer. Methods AAV8-CAG-GFP-2A and BDA were stereotactically injected into the mouse sensorimotor cortex of normal and spinal cord injury mice respectively, and immunohistochemistry was employed to observe the distribution of the labeled CST axons. The relative fluorescence of axon bundles and branches was analyzed. Results It was shown that both AAV and BDA could label the bundles of corticospinal tract and surrounding axon branches projecting into the gray matter of cervical and thoracic cords in both coronal and saggital sections of normal and spinal cord injury mice. Meanwhile, more axon branches were labeled in the AAV injected mice compared with those in the BDA injected ones. Conclusions AAV exhibits more superior performance in mouse CST axon tracing in comparison with BDA, and can be applied as a better neural tracer for the morphological study of mouse CST and related neural circuits.

Key words: Adeno Associated Virus, Biotinylated Dextran Amine, corticospinal tract