Proliferative enteropathy (PPE)-induced changes in the expression of DBH, VAChT and NOS in the neurons of intramural ganglia of the porcine ileum

As enteric neurons are regarded to be highly adaptive in their response to various pathological states, including inflammation, it appears to be of interest to study the chemical coding of neurons in the intramural ganglia of the ileum wall in the course of porcine proliferative enteropathy (PPE) evoked by Lawsonia intracellularis. The study was performed on 12 juvenile pigs of the Large White Polish breed. The pigs were divided into the control (C, n = 6) group and the group consisting of pigs with clinically diagnosed Lawsonia intracellularis infection (E, n = 6). In E group animals the infection was confirmed with a PCR-based test. All the animals were sacrificed and segments of the ileum being pathologically changed were processed for double-labelling immunofluorescence using antibody against protein gene-product 9.5 (PGP 9.5) combined with antibody for dopamine β-hydroxylase (DβH), vesicular acetylcholine transporter (VAChT) or nitric oxide synthase (NOS). Immunohistochemistry revealed in the inner submucous plexus (ISP) and outer submucous plexus (OSP) an increase of the number of neurons containing DβH and VAChT in the E group. Interestingly, a decrease in the number of DβH- and VAChT-positive neurons in meynteric plexus (MP) ganglia of the E group animals was observed. The most remarkable difference in the chemical coding of enteric neurons between the control and PPE-suffering pigs was a significant increase of the number of NOS-positive nerve cells in the MP and OSP of the infected animals. The present results show that acetylcholine, catecholamines and NO may be involved in the regulation of functions of the porcine enteric nerve pathways not only under physiological, but also pathological conditions.