| Background The widespread use of acid-suppressive drugs has prevented and controlled stress ulcer (SU) to a certain extent. But a growing number of reports indicate that the use of acid-suppressing drugs increases the occurrence of hospital-acquired pneumonia, community-acquired pneumonia occurs, Clostridium difficile-associated disease, enteric infections and other diseases . So in order to obtain safe and effective treatment, we also need to further study the pathogenesis of SU.Neuroendocrine disorder is a initiating factor of the SU. Gastric mucosal microcirculation disturbance is the basis of the pathogenesis of SU. In this process, a large number of inflammatory factors cause inflammatory response out of control which plays an important role in the occurrence and progress of the SU. Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is an important way for mediating signal transduction of many cytokines factors and inflammatory mediators. It is closely related to inflammatory response which promotes inflammatory progress of ulcerative colitis, colitis, acute pancreatitis, asthma, autoimmune arthritis and other diseases. The objective of this research is to discuss the role and molecular mechanism of JAK2/STAT3 signaling pathway in the gastric mucosal inflammatory response of SU rats. In this study, we will use water immersion and restraint stress (WRS) experiment to establish SU rat model and systematically discuss the relationship between inflammatory response mediated by JAK2/STAT3 signaling pathway and gastric mucosal injury of SU at the general, organization, molecular level from in vivo experiments. Meanwhile, we will use JAK2 specific inhibitor AG490 intervening and further observe whether alleviate gastric mucosal inflammatory response of SU by inhibiting JAK2/STAT3 signaling pathway.Objective the objective of this study is to discuss the role of JAK2/STAT3 signaling pathway in gastric mucosal inflammatory process and further elucidate the pathogenesis mechanism of SU in order to provide a new idea for SU prophylaxis,Method 96 male Sprague-Dawley (SD) rats weighing 200-250 g were randomly (random digital) divided into four groups (each group n=24). (1) normal control group (NC group), rats were not given WRS and inhibitor and they were injected intraperitoneally with the equal normal saline; (2) stress ulcer group (SU group), rats were given WRS to establish SU model and they were injected intraperitoneally with the equal normal saline 0.5 h before establishing SU model; (3) inhibitor group (AG490 group), they were injected intraperitoneally with 5 mg/kg AG490 0.5 h before establishing SU model; (4) dimethyl sulfoxide group (DMSO group), they were injected intraperitoneally with the equal 0.1%DMSO 0.5 h before establishing SU model. Four groups of rats were respectively taken six on 2 h,4 h,8 h,12 h after the beginning of experiment. Abdomen was cut open and then stomach was free for measure gastric mucosal blood flow (GMBF) and pH value of gastric juice. Stomach was taken out and placed in 10% neutral formalin 10min. Then, gastric lumen was cut open along big bend of stomach for observing the gross pathological changes and calculating the ulcer index (UI). Gastric tissue samples were collected for observing the changes of gastric mucosal tissue structure under the light microscope. Gastric mucosal tissue samples were collected for testing the expression of TNF-α, IL-1β and IL-6 in gastric mucosa by ELISA and the expression of JAK2, p-JAK2, STAT3 and p-STAT3 in gastric mucosa by Western Blot.Results1. The GMBF changes of rats in each group GMBF of SU group at each time point was lower than of the NC group (P＜0.05) and gradually increased with modeling time prolonged; GMBF of AG490 group was higher than SU group, but compared with the SU group it had no significant difference (P>0.05); There was no significant difference between the DMSO group and the SU group (P>0.05).2. The PH value changes in gastric juice of rats in each group PH value of SU group at each time point was lower than of the NC group (P＜0.05) and gradually increased with modeling time prolonged; pH value of AG490 group was higher than SU group, but compared with the SU group it had no significant difference (P>0.05); There was no significant difference between the DMSO group and the SU group (P>0.05).3. The UI changes in gastric mucosa of rats in each group UI of SU group at each time point was significantly higher than of NC group (P<0.05) and gradually increased with modeling time prolonged; UI of AG490 group was significantly lower than of NC group (P＜0.05) at each time point; DMSO group showed no significant difference with the SU group (P>0.05).4. The general changes in gastric mucosa of rats in each group Gastric mucosal surface of NC group was smooth with no hyperemia and erosion. After WRS 12 h, gastric mucosa appeared hyperemia, edema, diffuse bleeding, erosion and it widely distributed a little and linear ulcers. Gastric mucosal injury of AG490 group was significantly reduced compared with SU group. There was no significant difference between the DMSO group and SU group.5. The histological changes in gastric mucosa of rats in each group Light microscopy:after HE staining, gastric mucosal epithelial structure of NC group was intact, no cell shedding and gland neat. After WRS 12 h, gastric mucosal epithelial appeared obvious defect, cell extensive necrosis and shed, glandular structure disorder, and extensive infiltration of inflammatory cell. Gastric mucosa injury of AG490 group was significantly reduced compared with SU group. There was no significant difference between DMSO group and SU group.6. The expression changes of TNF-α, IL-1β and IL-6 in gastric mucosal tissue of rats in each group The expression of TNF-α, IL-1β and IL-6 in gastric mucosa of SU group were significantly higher than NC group at each time point (P＜0.05) and gradually increased with modeling time prolonged; The expression of TNF-α, IL-1β and IL-6 in gastric mucosa of AG490 group were significantly lower than in SU group (P＜0.05); There was no significant difference between DMSO and the SU group (P>0.05).7. The expression changes of JAK2, p-JAK2, STAT3 and p-STAT3 in gastric mucosal tissue of rats in each group Western Blot found the expression of JAK2 and STAT3 were similar (P>0.05). The expression of p-JAK2 and p-STAT3 were significantly increased in gastric mucosa of SU group compared with NC group (P<0.05) and gradually increased with modeling time prolonged; The expression of p-JAK2 and p-STAT3 were significantly decreased in gastric mucosa of AG490 group compared with SU group (P<0.05); There was no significant difference between DMSO group and SU group (P>0.05).Conclusion1. JAK2/STAT3 signaling pathways is involved in the gastric mucosa inflammatory process in SU rats.2. JAK2 specific inhibitor AG490 inhibits the expression of p-JAK2 and p-STAT3, and alleviates gastric mucosal injury mediated by gastric mucosal inflammatory response in SU rats, Which provided a new idea for SU prophylaxis. |
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