Distribution of noradrenergic neurons in the female rat pelvic plexus and involvement in the genital tract innervation

Abstract

The involvement of the pelvic plexus noradrenergic neurons in the innervation of the genital tract was studied in the female rat. Several small ganglia were observed in addition to the paracervical ganglion and immunocytochemistry for tyrosine hydroxylase was performed to examine the distribution and number of the noradrenergic neurons. 5069 ± 1525 nerve cell bodies were counted in the paracervical ganglion and 9.0 ± 0.8% of them were noradrenergic, displaying a clear somatotopic distribution in the ventro-medial part of the ganglion. Some accessory ganglia were located ventral to the main paracervical ganglion. 414 ± 149 nerve cell bodies were found in the accessory ganglia, of which 20.4 ± 3.1% were noradrenergic. Ganglia along the vesical branch of the hypogastric nerve, referred to as an hypogastric plexus, contained 233 ± 83 neurons among which 12.7 ± 7.2% were noradrenergic. Bilateral removal of the pelvic plexus produced degeneration of all the tyrosine hydroxylase-immunoreactive nerve fibres in the lower part of the uterus and in the cervix. In contrast, excision of the paracervical ganglia and the accessory ganglia caused no significant change in this innervation pattern. Combined retrograde tracing study and immunocytochemistry for tyrosine hydroxylase revealed a very small number of noradrenergic neurons also labelled with fluoro-Gold. Both findings suggest a limited involvement of the pelvic plexus noradrenergic neurons in the innervation of the lower genital tract.