Action of Lipopolysaccharide on Interstitial Cells of Cajal from Mouse Small Intestine

Abstract

Background and Purpose: Lipopolysaccharide (LPS) induces intestinal dysmotility by alteration of smooth muscle and enteric neuronal activities. However, there is no report on the modulatory effects of LPS on the interstitial cells of Cajal (ICCs). We investigated the effect of LPS and its signal transduction in ICCs. Methods: We performed whole-cell patch clamp and RT-PCR in cultured ICCs from mouse small intestine. Results: LPS suppressed the generation of pacemaker currents of ICCs. The mRNA transcripts for Toll-like receptor 4 (TLR4) were expressed in ICCs. However, the inhibitory action of LPS on pacemaker currents from TLR4^+/+ mice was not present in TLR4^–/– mice. The inhibitory effects of LPS on ICCs were blocked by glibenclamide (an inhibitor of ATP-sensitive K⁺ channels), NS-398 (a COX-2 inhibitor), AH6808 [a prostaglandin E₂ (PGE₂)-EP₂ receptor antagonist], ODQ (an inhibitor of guanylate cyclase) and L-NAME [an inhibitor of nitric oxide synthase (NOS)]. Furthermore, genistein and herbimycin A (tyrosine kinase inhibitors) blocked the LPS-induced inhibitory action on pacemaker activity in ICCs. Conclusions: LPS can activate ICCs to release NO and PGE₂ through TLR4 activation. The released NO and PGE₂ inhibit pacemaker currents by activating ATP-sensitive K⁺ channels. The LPS actions are mediated by tyrosine kinase signaling pathways.

The traditional herbal medicine, Ge-Gen-Tang, inhibits pacemaker potentials by nitric oxide/cGMP dependent ATP-sensitive K+ channels in cultured interstitial cells of Cajal from mouse small intestine

“…We will study this issue in the near future. Even the level of NOS is very low, researchers could observe the effect of L-NAME on ICCs electrophysiologically with cultured ICCs (Kim et al, 2006;Choi et al, 2008;Choi et al, 2010;Ahn et al, 2010;Zuo et al, 2012Zuo et al, , 2013Shahi et al, 2014;Jiao et al, 2014;Wu et al, 2015). L-NAME is a nonspecific NOS inhibitor.…”

Regulatory Roles of Endogenous Mitogen-Activated Protein Kinases and Tyrosine Kinases in the Pacemaker Activity of Colonic Interstitial Cells of Cajal

“…Thus, ICCs are a basic determinant in regulating GI motility; disorders in GI motility are associated with the disruption or loss of ICCs [14,15] . MAP and tyrosine kinases mediate lipopolysaccharide-and H 2 O 2 -induced effects on the pacemaker currents of small intestine ICCs [16,17] . These findings suggest that MAP and tyrosine kinases play an important role in the regulation of GI motility by affecting the pacemaker activity of ICCs.…”

Multiple exposures to poultry barn air and lipopolysaccharide synergistically increase the pulmonary expression of TLR-4 and IL-1β

“…Quantitative real-time PCR was performed using SYBR green chemistry. Primer sequences used for amplification of TLR4 gene were 5′-TGCTGAGTTTCTGATCCATGC-3′ and 5′-TGGCTAGGACTCTGATCATGG-3′ 21 and for IL-1β was 5′-TGTAATGAAAGACGGCACACC-3′ and 5′-TCTTCTTTGGGTATTGCTTGG-3′. 22 The real-time PCR reaction was carried out as duplicate and β-actin was used as endogenous control.…”