VGLUT1 and VGLUT2 Innervation in autonomic regions of intact and transected rat spinal cord

Llewellyn‐Smith, Ida J., et al. "VGLUT1 and VGLUT2 innervation in autonomic regions of intact and transected rat spinal cord." Journal of Comparative Neurology 503.6 (2007): 741-767. This paper looked at the innervation of autonomic regions of the spinal cord via VGLUT1 and VGLUT2 vesicles before and after spinal cord injury induced by complete spinal cord transections. VGLUT1 and VGLUT2 mRNA were also examined in order to look at protein synthesis before and after the spinal cord was transected. What the study found was that the majority of sympathetic pre-ganglionic neurons, as well as parasympathetic pre-ganglionic neurons are innervated by VGLUT2 vesicles in rats with an intact spinal cord. However, it was found that autonomic interneurons seems to be innervated more by VGLUT1 vesicles in rats without spinal transections. After spinal transections were performed at the level of T4/T5 in rats, no significant difference in VGLUT2 innervation of the IML were found. The most plausible explanation for this being that the IML is highly innervated by interneurons which would not have been affected by the spinal cord being transected. On the other hand, it was discovered that 11 weeks following a spinal cord transection VGLUT1 immunoreactivity significantly increased. Although no mechanism was verified for the increase seen, it can be extrapolated that after a spinal injury there is a certain neuroplasticity occurring at the level of the spinal cord in order to produce the increases of VGLUT1 observed. It also seems that the plasticity taking place is creating hyper-excitable reflexes in comparison to rats with an intact spinal cord. This information is important to our study, to know that spinal plasticity is possible when using manganese as a retrograde tracer in order to study neural activity at the level of the RVLM. ~JI