Apocynin relieves inflammation in dextran sulfate sodium-induced ulcerative colitis mice: the role of NOXs-ROS-p38MAPK pathway / 生理学报

The study is aimed to explore the molecular mechanism of the treatment of apocynin in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice. 5% DSS was used to mimic the UC model, and 2% apocynin was applied to treat the UC mice. HE staining was used for histopathological evaluation. Chemiluminescence technique was used to measure reactive oxygen species (ROS) production, and the rate of consumption of NADPH inhibited by DPI was detected to determine the NADPH oxidases (NOXs) activity. Western blot was applied to identify the level of p38MAPK phosphorylation, Griess reaction assay to analyze NO production, immunoenzymatic method to determine prostaglandin E2 (PGE2) production, real time RT-PCR and Western blot to identify the expression of iNOS and COX2, and enzyme linked immunosorbent assay to detect inflammatory cytokines TNF-α, IL-6, IFN-γ, IL-1β. Rat neutrophils were separated, and then ROS production, NOXs activity, NO and PGE2 production, NOX1 and p-p38MAPK expression were detected. Compared with the UC group, apocynin decreased ROS over-production and NOXs activity (P < 0.01), reduced p38MAPK phosphorylation, inhibited NO, PGE2 and cytokines production (P < 0.01). Apocynin also decreased NOXs activity and ROS over-production (P < 0.01), inhibited p38MAPK phosphorylation and NOX1 expression, and reduced NO and PGE2 production (P < 0.01) in separated neutrophils from UC mice. Therefore, apocynin could relieve inflammation in DSS-induced UC mice through inhibiting NOXs-ROS-p38MAPK signal pathway, and neutrophils play an important role.

Study of the change and role of protein C system in ulcerate colitis / 生理学报

Hypercoagulable state and thrombosis are major lethal causes of ulcerate colitis (UC). The aim of the present study is to explore the change and role of protein C (PC) system in UC thrombosis. 4% dextran sulfate sodium (DSS) was used to induce the UC model, and the body weight, the length of colon, and the weight of spleen were measured after intake of DSS as drinking water for 1 week. The macroscore and microscore were examined. The quantity of macrophage in colon smooth muscle was observed by immunofluorescence, and TNF-α and IL-6 levels in plasma were evaluated by ELISA. Intravital microscopy was applied to observe colonic mucosal microvascular circulation, activities of PC and protein S (PS) were determined by immunoturbidimetry, endothelial cell protein C receptor (EPCR) and thrombomodulin (TM) expressions were detected by immunohistochemistry. In vitro, TNF-α and IL-6 levels were tested in supernatant of macrophage separated from colonic tissue. After stimulation of mouse colonic mucosa microvascular endothelial cells by TNF-α and IL-6 respectively, the activities of PC, PS, activated protein C (APC) were evaluated, and the expressions of EPCR and TM were detected by Western blotting. The results revealed that compared with control, the DSS mouse showed weight loss (P < 0.05), a shortened colon (P < 0.05), and swelled spleen (P < 0.05), accompanied by higher histological score (P < 0.05), as well as infiltration of macrophages, elevated TNF-α and IL-6 levels in plasma (P < 0.01). The intravital microscopy results revealed that compared with control, DSS mice showed significantly enhanced adhesion of leukocytes and colonic mucosal microvascular endothelial cells (P < 0.01), meanwhile, decreased activity of PC and PS in plasma (P < 0.01 or P < 0.05), and down-regulated expression of EPCR (P < 0.01). The degree of inflammation was negatively correlated with the PC activity. In vitro, TNF-α and IL-6 levels were increased in the supernatant of macrophages from DSS mice colonic tissue (P < 0.05), and after incubation of TNF-α or IL-6 with colonic mucosal microvascular endothelial cells, the APC activity was decreased (P < 0.05 or P < 0.01), and expression of EPCR was down regulated (P < 0.05). These results suggest that PC system is inhibited in UC mouse. Presumably, the mechanism may be due to the secretion of cytokines from macrophages and subsequential influence on the function of endothelia cells. Furthermore, enhancement of PC system activity may serve as a new strategy for the treatment of UC.

Role of orphan G protein-coupled receptor 55 in diabetic gastroparesis in mice / 生理学报

The aim of the present study was to explore the role of orphan G protein-coupled receptor 55 (GPR55) in diabetic gastroparesis (DG). Streptozotocin (STZ) was used to mimic the DG model, and the body weight and blood glucose concentration were tested 4 weeks after STZ injection (i.p.). Electrogastrogram and phenolsulfonphthalein test were used for detecting gastric emptying. Motilin (MTL), gastrin (GAS), vasoactive intestinal peptide (VIP), and somatostatin (SS) levels in plasma were determined using radioimmunology. Real-time PCR and Western blot were applied to identify the expression of GPR55 in gastric tissue, and immunohistochemistry was used to detect the distribution. The effect of lysophosphatidylinositol (LPI), an agonist of GPR55, was observed. STZ mice showed increased blood glucose concentration, lower body weight, decreased amplitude of slow wave, and delayed gastric emptying. LPI antagonized these effects of STZ. Compared to the control group, STZ caused significant decreases of MTL and GAS levels (P < 0.01), as well as increases of SS and VIP levels (P < 0.01). The changes of these hormones induced by STZ were counteracted when using LPI. GPR55 located in mice stomach, and it was up-regulated in DG. Although LPI showed no effects on the distribution and expression of GPR55 in normal mice, it could inhibit STZ-induced GPR55 up-regulation. These results suggest GPR55 is involved in the regulation of gastric movement of DG, and may serve as a new target of DG treatment. LPI, an agonist of GPR55, can protect against STZ-induced DG, and the mechanism may involve the change of GPR55 expression and modification of gastrointestinal movement regulating hormones.

Role of endogenous cannabinoid system in the gut / 生理学报

The plant Cannabis has been used in clinic for centuries, and has been known to be beneficial in a variety of gastrointestinal diseases, such as emesis, diarrhea, inflammatory bowel disease and intestinal pain. In this text, we'll review the components of the endogenous cannabinoid system as well as its role in the regulation of gastrointestinal activities, thus providing relative information for further study. Moreover, modulation of the endogenous cannabinoid system in gastrointestinal tract may provide a useful therapeutic target for gastrointestinal disorders.