Location and peptide content of pelvic neurons supplying the muscle and lamina propria of the rat vas deferens.

Retrograde tracing and immunohistochemistry have identified the location within the rat pelvic plexus of neurons which project to the vas deferens, and their neurochemical properties. The fluorescent tracers, Fast Blue and FluoroGold, were injected into the wall of the vas deferens and labelled neurons located within the ventral part of the major pelvic ganglion (MPG) and the adjacent accessory ganglia (AG). Most neurons were located in ganglia ipsilateral to the injection site. Noradrenergic neurons were defined as those containing immunoreactivity for tyrosine hydroxylase (TH). Five groups of dye-labelled neurons could be identified immunohistochemically, noradrenergic neurons containing neuropeptide Y (NPY) (60-70%), and four types of non-noradrenergic neurons, NPY-only neurons (5-10%), NPY neurons containing vasoactive intestinal peptide (VIP) (3-5%), neurons containing only VIP (15-25%) and neurons containing galanin (GAL) (2-5%). Noradrenergic axons, and axons containing NPY or GAL were primarily located within the muscle, whereas most VIP axons were found as a dense plexus within the lamina propria. Very few peptide-containing varicose nerve terminals surrounded dye-labelled (vas deferens-projecting) pelvic neurons. Thus, no peptide marker was found for most of the preganglionic inputs supplying postganglionic neurons which project to the vas deferens. These studies have shown that pelvic neurons supplying the vas deferens have a discrete location within the rat pelvic ganglia and that they comprise at least five neurochemical groups, providing innervation to the muscle and lamina propria. The preganglionic connections with these noradrenergic and non-noradrenergic (possible cholinergic) pathways, and further examination of the role of mucosal innervation remain to be determined.