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Background: Lipopolysaccharide decreases intestinal contractility and induces the production of cytokines, which play an important role in the pathogenesis of sepsis., Aim: The objective of the present study was to examine the role of Toll-like receptor 4, IκB kinase, and the proteasome in the intestinal alterations induced by lipopolysaccharide., Methods: Sepsis was induced in rabbits by intravenous injection of lipopolysaccharide. Contractility studies of rabbit duodenum were performed in an organ bath. Expressions of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA were determined by RT-PCR on rabbit duodenum., Results: Neomycin and polymyxin B (Toll-like receptor 4 inhibitors), IKK NBD peptide (IκB kinase complex inhibitor), and MG-132 (proteasome inhibitor) blocked partially the effects of lipopolysaccharide on the acetylcholine-, prostaglandin E2-, substance P-, and KCl-induced contractions in the longitudinal and circular smooth muscle of rabbit duodenum. Lipopolysaccharide increased the mRNA expression of interleukin-6 and interleukin-8 in duodenal tissue, and this effect was partly reversed by neomycin, polymyxin B, IKK NBD peptide, and MG-132. IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA expressions was not affected by lipopolysaccharide treatment., Conclusions: Toll-like receptor 4, the IκB kinase complex, and the proteasome could be therapeutic targets in the treatment of sepsis symptoms in the intestine.

Functional gastrointestinal diseases (FGID) are worldwide prevalent conditions. Pharmacological treatments can be ineffective, leading the population to turn to herbal or traditional remedies. Helichrysum stoechas (L.) Moench is a medicinal plant traditionally used in the Iberian Peninsula to treat digestive disorders, but its effects on gastrointestinal motility have not been scientifically demonstrated. The aim of this work was to evaluate the antispasmodic effect of a polyphenolic extract of H. stoechas (HSM), its mechanism of action and its antioxidant activity. Isometric myography studies were performed in rat ileum, and malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) levels were measured in rat jejunum. HSM reduced the integrated mechanical activity of spontaneous contractions. In Ca2+-free medium, HSM reduced the concentration–response curve of CaCl2 similarly to verapamil. Pre-incubation with the extract blocked the contraction induced by Bay K8644, KCl and carbachol. L-NAME, ODQ, Rp-8-Br-PET-cGMPS, KT-5823, apamin, TRAM-34 and charybdotoxin reduced the relaxant effect of the extract on spontaneous contractions. MDA+4-HDA levels in LPS-treated tissue were reduced by the extract, showing antioxidant activity. In conclusion, HSM showed antispasmodic activity through inhibition of Ca2+ influx, activation of the NO/PKG/cGMP pathway and opening of Ca2+-activated K+ channels. The results suggest that H. stoechas could help in the prevention or treatment of FGIDs. [ABSTRACT FROM AUTHOR]

Objectives Lipopolysaccharide (LPS) has been shown to alter intestinal contractility. Toll-like receptor 4 (TLR4), K+ channels and mitogen-activated protein kinases (MAPKs) have been proposed to be involved in the mechanism of action of LPS. The aim of this study was to determine the role of TLR4, K+ channels and MAPKs (p38, JNK and MEK1/2) in the local effect of LPS on the acetylcholine (ACh)-induced contractions in rabbit small intestine in vitro. Methods Segments of rabbit duodenum were suspended in the direction of longitudinal or circular smooth muscle fibres in a thermostatically controlled organ bath. Key findings LPS (0.3 µg/ml) reduced the contractions induced by ACh (100 µ m) in the longitudinal and circular smooth muscle of the duodenum after 90 min of incubation. Polymyxin (TLR4 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor) and U0126 (MEK1/2 inhibitor) antagonized the effects of the LPS on ACh-induced contractions in duodenal smooth muscle. Incubation with the blockers of K+ channels, TEA, apamin, charybdotoxin, iberiotoxin, glibenclamide or quinine, did not reverse the effect of LPS on ACh-induced contractions. Conclusions These results suggest that the effect of LPS on ACh-induced contractions in the rabbit duodenum might be mediated by TLR4 and p38, JNK1/2 and MEK1/2 MAPKs. [ABSTRACT FROM AUTHOR]

Abstract: Background: Lipopolysaccharide (LPS) is a causative agent of sepsis. Many alterations, such as intestinal motility disturbances, have been attributed to LPS. Aims: Here we investigated the role of c-Jun NH2-terminal kinases (JNK) in the effect of LPS on intestinal motility, the oxidative stress status and the cyclooxygenese-2 (COX-2) expression. Methods: Rabbits were injected with either (1) saline, (2) LPS, (3) SP600125, a specific JNK inhibitor, or (4) SP600125+LPS. Duodenal contractility was studied in an organ bath. The formation of products of oxidative damage to proteins (carbonyls) and lipids [malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] was quantified by spectrophotometry in the intestine and plasma. The protein expression of p-JNK, total JNK, and COX-2 was measured by Western blot, and p-JNK was localized by immunohistochemistry. Results: LPS decreased the contractions evoked by acetylcholine and prostaglandin E2 and KCl-induced contractions. LPS increased phospho-JNK and COX-2 expressions and the levels of carbonyls and MDA+4-HDA. SP600125 blocked the effect of LPS on the acetylcholine, prostaglandin E2, and KCl-induced contractions, the levels of carbonyls and MDA+4-HDA, and the p-JNK and COX-2 expressions. p-JNK was detected in the smooth muscle cells of duodenum. Conclusion: Our results suggest that JNK is involved in the mechanism of action of LPS in the intestine. [Copyright &y& Elsevier]

Abstract: The mediators of the pathophysiological symptoms of septic shock are not completely understood. The intracellular signalling mechanisms of lipopolysaccharide (LPS)-induced effects need further investigation. This study investigates (1) the role of COX-2 in the effect of LPS on (a) the KCl, acetylcholine and prostaglandin E2-induced contractions of rabbit duodenum and (b) the oxidative stress status in plasma and intestine and (2) the relationship between p38 MAPK and COX-2 expression in rabbit duodenum. Rabbits were injected i.v. with either (1) saline, (2) LPS, (3) SB203580, a p38 MAPK inhibitor, (4) SB203580+LPS, (5) NS-398, a COX-2 inhibitor or (6) NS-398+LPS. Contractility studies were performed by suspending pieces of duodenum in an organ bath in the direction of longitudinal and circular smooth muscle fibres. The formation of products of oxidative damage to proteins (carbonyls) and lipids [malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] was quantified in intestinal tissue and plasma. The protein expression of COX-2 was measured by western blot. The KCl, acetylcholine and prostaglandin E2-induced contractions decreased with LPS. In addition, LPS increased the levels of carbonyls and MDA+4-HDA in plasma and duodenum as well as COX-2 expression in duodenal tissue. All these effects were blocked by NS-398. The p38 MAPK inhibitor SB203580 blocked the effect of LPS on COX-2 expression. These results suggest that the effect of LPS on KCl, acetylcholine and prostaglandin E2-induced contractions in the rabbit duodenum and oxidative stress might be mediated by an increase in COX-2 expression through the p38 MAPK pathway. [ABSTRACT FROM AUTHOR]