Dysregulation of the Enteric Nervous System in the Mid Colon of Complement Component 3 Knockout Mice with Constipation Phenotypes

Abstract

Complement component 3 (C3) contributes to neurogenesis, neural migration, and synaptic elimination under normal and disease conditions of the brain, even though it has not been studied in the enteric nervous system (ENS). To determine the role of C3 in the regulatory mechanism of ENS during C3 deficiency-induced constipation, the changes in the markers of neuronal and interstitial cells of Cajal (ICCs), the markers for excitatory and inhibitory transmission of ENS, and expression of C3 receptors were analyzed in the mid colon of C3 knockout (KO) mice at 16 weeks of age. Prominent constipation phenotypes, including the decrease in stool parameters, changes in the histological structure, and suppression of mucin secretion, were detected in C3 KO mice compared to wildtype (WT) mice. The expression levels of the neuron specific enolase (NSE), protein gene product 9.5 (PGP9.5), and C-kit markers for myenteric neurons and ICCs were lower in the mid colon of C3 KO mice than WT mice. Excitatory transmission analysis revealed similar suppression of the 5-hydroxytryptamine (5-HT) concentration, expression of 5-HT receptors, acetylcholine (ACh) concentration, ACh esterase (AChE) activity, and expression of muscarinic ACh receptors (mAChRs), despite the mAChRs downstream signaling pathway being activated in the mid colon of C3 KO mice. In inhibitory transmission analysis, C3 KO mice showed an increase in the nitric oxide (NO) concentration and inducible nitric oxide synthase (iNOS) expression, while neuronal NOS (nNOS) expression, cholecystokinin (CCK), and gastrin concentration were decreased in the same mice. Furthermore, the levels of C3a receptor (C3aR) and C3bR expression were enhanced in the mid colon of C3 KO mice compared to the WT mice during C3 deficiency-induced constipation. Overall, these results indicate that a dysregulation of the ENS may play an important role in C3 deficiency-induced constipation in the mid colon of C3 KO mice.

Complement C3-Deficiency-Induced Constipation in FVB/N-C3em1Hlee/Korl Knockout Mice Was Significantly Relieved by Uridine and Liriope platyphylla L. Extracts

“…However, the citations in this study were sufficiently reasonable to compare the constipation phenotypes between studies, because most previous results using Lop-induced models have been published by our team [23,26,27,29]. Also, the important information on the role and action mechanism of C3 deficiency on the constipation of C3 KO mice was only provided by our team [18][19][20][21]. Therefore, this study is not simply conducted to compare the efficacy of drug candidates for constipation in both animal models, but to evaluate the possibility of new treatments for constipation caused by other biological causes.…”

“…During the induction of constipation, the inducible nitric oxide synthase (iNOS)-mediated cyclooxygenase-2 (COX-2) induction pathway, inflammasome pathway, and the nuclear factor-kappa B (NF-κB) pathway were activated in the mid colon of C3 KO mice [19]. Also, the excitatory and inhibitory transmissions of the enteric nervous system (ENS) were significantly suppressed, and the distribution of the neuronal cells and intestinal cells of Cajal (ICC) was decreased in C3 KO mice [20]. Furthermore, the C3-deficiency-induced constipation was accompanied by fecal microbiota dysbiosis, which included decreases in the Anaerocolumna (97%), Caecibacterium (97%), Christensenella, Kineothrix, and Oscillibacter populations, as well as increases in the Prevotellamassilia (484%), Reuthenibacterium (140%), Prevotella, Eubacterium, Culturomica, Bacteroides, and Muribaculum populations [21].…”