Axotomy-induced plasticity of sensory neurons supplying porcine caudal mesenteric ganglions.

摘要

The objectives of this study were to establish whether the dorsal root ganglion (DRG) neurons supplying the porcine caudal mesenteric ganglion (CaMG) contained substance P (SP) and calcitonin gene related peptide (CGRP) and to determine which changes in the expression pattern of these peptides might be induced by a mechanical injury applied to the processes of the neurons. This study was carried out in consecutive frozen serial sections of DRG taken from 8-week old pigs (n=12), in which the neuronal tracer fast blue (FB) had been injected 3 weeks previously into the right CaMG. Six animals were randomly chosen for ipsilateral ganglionectomy. Eventual changes in the chemical phenotypes of the injured cells were studied a week later using routine double-immunofluorescence labelling. FB+ neurons contained SP and CGRP (32 and 42%, respectively). The vast majority of SP- and CGRP-IR afferent cells belonged to the class of medium (64 and 59%, respectively) and small neurons (32 and 37%, respectively). A colocalization of SP and CGRP was observed in 22% of FB+ neurons. The resection of CaMG resulted to an increase in the number of FB+ cells containing SP (55%) and a significant decrease in the number of CGRP-IR neurons associated with CaMG (29%). These results suggested that sensory neurons associated with porcine CaMG contained SP and CGRP and that a resection of CaMG was able to induce profound changes in the expression pattern of the studied peptides, implying deep mechanical injury-induced adaptative changes in the studied afferent neurons..