Departamento de Farmacología y Fisiología, Unidad de Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, 50013 Zaragoza, Spain.
Eur J Pharmacol. 2010 Dec 1;648(1-3):171-8. doi: 10.1016/j.ejphar.2010.08.041. Epub 2010 Sep 9.
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.
内毒素（LPS）诱导的效应的细胞内信号转导机制需要进一步研究。本研究探讨了（1）COX-2 在 LPS 对（a）兔十二指肠 KCl、乙酰胆碱和前列腺素 E₂ 诱导收缩的作用和（b）血浆和肠内氧化应激状态中的作用；（2）兔十二指肠中 p38 MAPK 和 COX-2 表达之间的关系。兔静脉注射（1）生理盐水、（2）LPS、（3）p38 MAPK 抑制剂 SB203580、（4）SB203580+LPS、（5）COX-2 抑制剂 NS-398 或（6）NS-398+LPS。通过将十二指肠段悬挂在器官浴中，在纵向和环形平滑肌纤维的方向上进行收缩性研究。在肠组织和血浆中定量测定蛋白质（羰基）和脂质[丙二醛（MDA）和 4-羟烯醛（4-HDA）]氧化损伤产物的形成。通过 Western blot 测定 COX-2 的蛋白表达。LPS 使 KCl、乙酰胆碱和前列腺素 E₂ 诱导的收缩减弱。此外，LPS 增加了血浆和十二指肠中羰基和 MDA+4-HDA 的水平以及十二指肠组织中 COX-2 的表达。所有这些作用均被 NS-398 阻断。p38 MAPK 抑制剂 SB203580 阻断了 LPS 对 COX-2 表达的影响。这些结果表明，LPS 对兔十二指肠中 KCl、乙酰胆碱和前列腺素 E₂ 诱导的收缩以及氧化应激的作用可能是通过 p38 MAPK 途径增加 COX-2 表达介导的。
