PNMT-containing terminals synapse directly on sympathetic preganglionic neurons in the rat

by. Teresa A. Milner, Shaun F. Morrison, Cory Abate and Donald J. Reis

The purpose of this study was to determine whether PNMT-containing terminals in the intermediolateral (IML) nucleus influence sympathetic nerve discharge through synapses directly on sympathetic preganglionic neurons (SPNs). This was done by using the peroxidase anti-peroxidase method to localize PNMT-containing terminals. Additionally, horseradish peroxidase (HRP) retrograde identification of SPNs was used to determine whether or not PNMT-containing terminals made direct contact with SPNs. The results showed that PNMT-containing terminals synapse directly on SPNs. This allows us to classify C1s as premotor neurons of the sympathetic nervous system.

Another interesting finding from this study is that PNMT-containing terminals form both asymmetric (excitatory) and symmetric (inhibitory) synapses with dendrites in the IML.

-BH