Mediation of changes in paraventricular vasopressin and oxytocin mRNA content to the medullary vagal complex and spinal cord of the rat.

Retrograde tracing was combined with in situ hybridization to demonstrate that a small percentage of neurons of the paraventricular hypothalamic nuclei (PVN) which project to the spinal cord or the medullary vagal complex contain the mRNA to produce the peptides vasopressin or oxytocin. These projection neurons respond to salt loading with an upregulation of mRNA for these peptides. The present study provides an anatomical basis for a direct regulatory influence of PVN neurons on preganglionic neurons in the spinal cord and medulla.