A Viral Vector Injection into the Rat Spinal Cord for Retrograde Neuronal Tracing

Take a microinjector with a microneedle containing a highly efficient retrograde transport or HiRet viral vector.

The glycoproteins in the HiRet virus envelope facilitate its entry into neurons via synapses. The virus also carries a gene encoding a fluorescent protein.

Take an anesthetized rat with an exposed lumbar spinal cord 1 to 4.

Using the midline of the spinal cord as a reference, position the needle above the injection site.

Lower the needle into the spinal cord.

Begin administering the virus at a controlled rate.

Allow sufficient time for viral diffusion before withdrawing the needle.

Neuronal receptors bind with viral glycoproteins, facilitating virus entry via the synapse and transport through the axon to the soma, a process called retrograde transport.

The viral gene gets integrated with the host genome, enabling the expression of fluorescent proteins.

These viruses also travel through connected neurons, enabling tracking of neuronal pathways.

Place the needle at the midline of the spinal cord and use the Vernier scale on the micromanipulator to direct the needle laterally 0.8 millimetres. Then lower the needle to the spinal cord until it is indenting, but not puncturing the dur