RVLM: Selective Projections to the Thoracic Autonomic Cell Column from the Region Containing C1 Adrenaline Neurons

By Christopher A. Ross and Donald J. Reis

The purpose of this study was to determine the organization of projections from the RVLM to the thoracic spinal cord and to compare these to the distribution of PNMT-containing terminals in the intermediolateral column (IML).  This was done by first staining for TH and PNMT. Next, some animals had horseradish peroxidase injected into their spinal cord or adrenal medulla to act as a retrograde tracer. Additionally, some animals had HRP injected into their RVLM to act as an anterograde tracer.

The results showed that a large proportion of the projections from the RVLM to the IML are made up of PNMT-containing C1 neurons. This finding, along with previous findings that demonstrated that stimulation of the RVLM results in pressor responses and that lesions of the C1 regions cause a drop in MAP, leads us to believe that the C1 neurons play an important role in blood pressure regulation.

-BH