Morphological identification of thoracolumbar spinal afferent nerve endings in mouse uterus. Issue 8 (21st November 2020)

• Record Type: Journal Article
• Authors: Dodds, Kelsi N.; Kyloh, Melinda A.; Travis, Lee; Beckett, Elizabeth A. H.; Spencer, Nick J.
• Is Part Of: Journal of comparative neurology. Volume 529:Issue 8(2021)
• Page Start: 2029
• Page End: 2041
• Publication Date: 2020-11-21
• Subjects: calcitonin gene‐related peptide -- dorsal root ganglia -- nodose ganglia -- spinal nerve -- uterus -- vagus nerve -- visceral pain; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.25070
• Languages: English
• ISSNs: 0021-9967

Abstract

Abstract: Major sensory innervation to the uterus is provided by spinal afferent nerves, whose cell bodies lie predominantly in thoracolumbar dorsal root ganglia (DRG). While the origin of the cell bodies of uterine spinal afferents is clear, the identity of their sensory endings has remained unknown. Hence, our major aim was to identify the location, morphology, and calcitonin gene‐related peptide (CGRP)‐immunoreactivity of uterine spinal afferent endings supplied by thoracolumbar DRG. We also sought to determine the degree of uterine afferent innervation provided by the vagus nerve. Using an anterograde tracing technique, nulliparous female C57BL/6 mice were injected unilaterally with biotinylated dextran into thoracolumbar DRG (T13‐L3). After 7–9 days, uterine horns were stained to visualize traced nerve axons and endings immunoreactive to CGRP. Whole uteri from a separate cohort of animals were injected with retrograde neuronal tracer (DiI) and dye uptake in nodose ganglia was examined. Anterogradely labeled axons innervated each uterine horn, these projected rostrally or caudally from their site of entry, branching to form varicose endings in the myometrium and/or vascular plexus. Most spinal afferent endings were CGRP‐immunoreactive and morphologically classified as "simple‐type." Rarely, uterine nerve cell bodies were labeled in nodose ganglia. Here, we provide the first detailed description of spinal afferent nerve endings in the uterus of a vertebrate. Distinct morphological types of spinal afferent nerve endings were identified throughout multiple anatomical layers of the uterine wall. Compared to other visceral organs, uterine spinal afferent endings displayed noticeably less morphological diversity. Few neurons in nodose ganglia innervate the uterus. Abstract : Here, we provide the first detailed description of spinal afferent nerve endings in the uterus of a vertebrate. This was achieved using an in vivo anterograde tracing technique from thoracolumbar (T13‐L3) dorsal root ganglia in female mice. Our key findings revealed that at least three distinct morphological types of spinal afferent nerve ending can be readily identified throughout multiple layers of the uterine wall; the vast majority of which are peptidergic (immunoreactive to calcitonin gene‐related peptide).