Role of High-affinity Choline Transporter 1 in Colonic Hypermotility in a Rat Model of Irritable Bowel Syndrome

BACKGROUND/AIMS: Irritable bowel syndrome (IBS) is a common disease characterized by intestinal dysmotility, the mechanism of which remains elusive. We aim to determine whether the high-affinity choline transporter 1 (CHT1), a determinant of cholinergic signaling capacity, modulates intestinal motility associated with stress-induced IBS. METHODS: A rat IBS model was established using chronic water avoidance stress (WAS). Colonic pathological alterations were evaluated histologically and intestinal motility was assessed by intestinal transit time and fecal water content (FWC). Visceral sensitivity was determined by visceromotor response to colorectal distension. RT-PCR, western blotting, and immunostaining were performed to identify colonic CHT1 expression. Contractility of colonic muscle strips was measured using isometric transducers. enzyme-linked immunosorbent assay was used to measure acetylcholine (ACh). We examined the effects of MKC-231, a choline uptake enhancer, on colonic motility. RESULTS: After 10 days of WAS, intestinal transit time was decreased and fecal water content increased. Visceromotor response magnitude in WAS rats in response to colorectal distension was significantly enhanced. Protein and mRNA CHT1 levels in the colon were markedly elevated after WAS. The density of CHT1-positive intramuscular interstitial cells of Cajal and myenteric plexus neurons in WAS rats was higher than in controls. Ammonium pyrrolidine dithiocarbamate partly reversed CHT1 upregulation and alleviated colonic hypermotility in WAS rats. Pharmacological enhancement of CHT1 activity by MKC-231 enhanced colonic motility in control rats via upregulation of CHT1 and elevation of ACh production. CONCLUSION: Upregulation of CHT1 in intramuscular interstitial cells of Cajal and myenteric plexus neurons is implicated in chronic stress-induced colonic hypermotility by modulation of ACh synthesis via nuclear factor-kappa B signaling.

Nimesulide, a selective cyclooxygenase-2 inhibitor inhibits telomerase activity by blocking activation of PKB in gastric cancer cell line / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the effects of nimesulide, a selective COX-2 inhibitor, on cell viability, telomerase and PKB activities in human gastric cancer cell line SGC7901 and to explore its molecular mechanism of selective growth inhibition.</p><p><b>METHODS</b>MTT assay was used to determine cell viability after incubation for 0, 12, 24, and 48 h in different concentrations (0, 25, 50, 100, 200 micro mol/L) of nimesulide and/or okadaic acid (300 nmol/L). Telomerase and protein kinase B (PKB) activities were detected using TRAP PCR-ELISA and nonradioactive IP-kinase assay.</p><p><b>RESULTS</b>Nimsulide caused a time and dose-dependent reduction of cell numbers of SGC7901. The telomerase and PKB activities were significantly inhibited, and the inhibition of telomerase activity was partly associated with decrease in PKB activity.</p><p><b>CONCLUSION</b>Selective COX-2 inhibitor nimesulide inhibits telomerase activity of gastric cancer cells by partly blocking the activation of protein kinase B. The results suggest an additional signaling pathway underlying the anti-cancer effect of COX-2 inhibitor.</p>

Interstitial cells of Cajal in the murine gallbladder / 中华消化杂志

Objective To demonstrate the morphology,distribution and ultrastructure of intersti- tial cells of Cajal (ICC) in the mouse gallbladder.Methods CD1 mice gallbladder tissue was stained with methylene blue for immunohistochemical examination by confocal microscopy and transmission elec- tron microscopy.Results The results revealed a dark blue network of ICC in the gallbladder.ICC were spindle-shaped,with thin and long processes in two poles.They were distributed in the all layers of the gall bladder wall.The ICC that had typical ultrastructure were adjacent to the smooth muscle and nerve cells. Conclusions Spindle-shaped ICC are present as a network structure in the gallbladder,which may act as slow wave pacemaker cells and have a major role in the transmission of signals from neurons to smooth muscle cells.