Do sensory calcitonin gene-related peptide nerve fibres in the rat pelvic plexus supply autonomic neurons projecting to the uterus and cervix?

Abstract

Sensory nerve fibres containing calcitonin gene-related peptide (CGRP) innervate neurons of the paracervical ganglion (PCG) in the female rat pelvic plexus. We have combined retrograde tracing with immunocytochemistry to investigate whether CGRP-immunoreactive (-IR) fibres supply neurons targeting the genital tract. Of the total neurons projecting to either the uterine horns or the cervix, 38 and 41% received CGRP-IR innervation, respectively. All these neurons displayed choline acetyltransferase-IR, thus are cholinergic. They were found throughout the PCG and other pelvic plexus ganglia, namely accessory ganglia (AG) and hypogastric plexus (HP). Pelvic nerve section showed that afferent fibres in these nerves provided most of the CGRP-IR fibres supplying uterine- or cervical-related neurons in the PCG/AG, none in HP. It is suggested that such sensory-motor network may provide a local pathway for reflex control of genital tract activity, acting through cholinergic nerve projections.