Paradoxical regulation of ChAT and nNOS expression in animal models of Crohn's colitis and ulcerative colitis

Abstract

Morphological and functional changes in the enteric nervous system (ENS) have been reported in inflammatory bowel disease. We examined the effects of inflammation on the expression of choline acetyltransferase (ChAT) and nNOS in the muscularis externae of two models of colonic inflammation, trinitrobenzene sulfonic acid (TNBS)-induced colitis, which models Crohn's disease-like inflammation, and DSS-induced colitis, which models ulcerative Colitis-like inflammation. In TNBS colitis, we observed significant decline in ChAT, nNOS, and protein gene product (PGP) 9.5 protein and mRNA levels. In DSS colitis, ChAT and PGP9.5 were significantly upregulated while nNOS levels did not change. The nNOS dimer-to-monomer ratio decreased significantly in DSS- but not in TNBS-induced colitis. No differences were observed in the percentage of either ChAT (31 vs. 33%)- or nNOS (37 vs. 41%)-immunopositive neurons per ganglia or the mean number of neurons per ganglia (55 ± 5 vs. 59 ± 5, P > 0.05). Incubation of the distal colon muscularis externae in vitro with different types of inflammatory mediators showed that cytokines decreased ChAT and nNOS expression, whereas H₂O₂, a component of oxidative stress, increased their expression. NF-κB inhibitor MG-132 did not prevent the IL-1β-induced decline in either ChAT or nNOS expression. These findings showed that TNBS- and DSS-induced inflammation differentially regulates the expression of two critical proteins expressed in the colonic myenteric neurons. These differences are likely due to the exposure of the myenteric plexus neurons to different combinations of Th1-type inflammatory mediators and H₂O₂ in each model.

Alterations in the distal colon innervation in Winnie mouse model of spontaneous chronic colitis

“…Our results demonstrated that the number of cholinergic (ChAT-IR excitatory muscle motor and interneurons) and nitrergic (NOS-IR inhibitory muscle motor and interneurons) neurons in the myenteric plexus were unaltered in the distal colon of Winnie mice. These results are consistent with findings in rats with DSS-induced colitis (Winston et al 2013) and in patients with ulcerative colitis (Neunlist et al 2003). Further studies are needed to investigate the gene expression of proteins regulating the synthesis of ACh and NO which can be altered, even though the number of neurons is not changed, leading to intestinal dysmotility (Winston et al 2013).…”

“…Some studies reported increase, while others reported decrease or no change in the number of myenteric neurons in tissues from animal models of intestinal inflammation and from IBD patients (Table 2). Decreased number of neurons in the myenteric plexus in both wholemount preparations and cross-sections was reported in most animal models of chemically-induced intestinal inflammation, except a study reporting no changes in wholemount preparations and crosssections of the colon from rats with DSS-induced colitis (Winston et al 2013). In human tissues, most of the studies were performed in transverse or cross-sections showing either increase, decrease or no change in the number of myenteric neurons (Table 2).…”

“…Intestinal inflammation induces morphological and functional changes in the ENS (Mawe et al 2009). Functional changes involve shifts in the amount and proportion of neurotransmitters and neuropeptides in the ENS of IBD patients and animal models of intestinal inflammation (Boyer et al 2005;Neunlist et al 2003;Winston et al 2013). Alterations in electrophysiological properties of enteric neurons and in neurotransmission between enteric neurons and to the intestinal muscles have been found in animal models of intestinal inflammation (Linden et al 2003;Lomax et al 2005;Nurgali et al 2007Nurgali et al , 2009Nurgali et al , 2011.…”

“…Alterations in electrophysiological properties of enteric neurons and in neurotransmission between enteric neurons and to the intestinal muscles have been found in animal models of intestinal inflammation (Linden et al 2003;Lomax et al 2005;Nurgali et al 2007Nurgali et al , 2009Nurgali et al , 2011. These changes in the ENS correlate with intestinal dysmotility (Krauter et al 2007;Lomax et al 2007a;Winston et al 2013). Alterations in the structure and function of cholinergic and noradrenergic nerve fibers innervating the gut wall and synapsing on the enteric neurons have been observed in patients with IBD (Straub et al 2008), as well as in animal models of intestinal inflammation (Lomax et al 2010;Swain et al 1991).…”

Histoarchitectonics of the Enteric Nervous System in the Colon of Adult Male C57BL/6 Mice

“…[6,12]. В большинстве работ, выполненных в по-следние десятилетия, для выявления структур ЭНС применяют гистологические [4], гисто-химические [14], иммуногистохимические (ИГХ) [15] и иммунофлуоресцентные (ИФ) методы [8,9,16]. ИГХ и ИФ методы позволя-ют оценивать как нейроны различных мор-фофункциональных типов и глиальные клет-ки, так и их отростки, не выявляемые при ру-тинном гистологическом окрашивании.…”