The Research On Relationship Between Protease-activated Receptor-2 And Acute Gastric Mucosal Lesion After Seawater Immersing Trauma

BackgroundAcute gastric mucosal lesion(AGML) is a usual complication derived from clinical serious disease, serious trauma and psychosis in clinic, with higher incidence and mortality rate. At present, its precise pathogenesis is not very clear yet. It has been generally considered that many factors, such as weakened gastric mucosal defense, augmented impairment factors and neuroendocrinal dysfunction, can induce AGML. During the development of AGML, gastric acid plays an important role and is considered as the most common endogenetic injurious factor, while hexosamine and phospholipid are important local protective factors. Some neuropeptides participate in the occurrence and development of AGML.During seawar the wounded soldiers often fall into the seawater with basic and hyperosmotic characteristics. This is a serious stress condition. The research on the seawater immersion trauma is rarely reported. Those former animal model of AGML can not imitate the true pathophysiological condition of seawater immersion trauma.The protease-activated receptor-2(PAR-2) is abundant in the epithelium throughout gastrointestinal tract. Intravenous administration of calcitonin geng-related peptide(CGRP) and neurokinin A(NKA) has a protective effect on the gastric mucosa. SLp-NH2, a specific agonist of PAR-2, can stimulate the release of CGRP and NKA from capsaicin-sensitive sensory neurons in gastric mucosa. These two neuropeptides can exert gastric mucosal protection by inducing the mucus secretion, inhibiting acid secretion and increasing gastric mucosal blood flow transiently. However, the dynamic changes of CGRP and NKA of gastric mucosa and plasma levels in rats with open abdominal trauma after seawater immersion have not been reported yet. So do the expression of PAR-2mRNA and protein in gastric mucosa.The present study was based on the above-mentioned progresses.Objective1. The animal model of AGML in rats with open abdominal trauma after artificial seawater immersion was made to study the changes of function and ultrastructureof gastric parietal cells.2. To investigate the dynamic changes of CGRP, NKA levels of gastric mucosa and plasma levels as well as hexosamine and phospholipid in gastric mucosa of rats with open abdominal trauma after seawater immersion.3. To investigate the expression of PAR-2 mRNA and protein in gastric mucosa of rats with open abdominal trauma after seawater immersion.4. To explore the significance of SLp-NH2 on gastric mucosal damage in rats with open abdominal trauma after artificial seawater immersion in order to provide new way of prevention and treatment of AGML during the seawar wound.Methods1. Under the stress of both open abdominal trauma and artificial seawater immersion the gastric mucosal ulcer index(IU) of SD rats was evaluated grossly and histologically after Ih, 2h, 3h stress according to Outh standard. The pH value of gastric juice was measured by the pH meter pH. The histopathological changes of gastric mucosa were observed by light microscope(LM) and the ultrastructural changes of parietal cells were observed by transmission electron microscope(TEM).2. The dynamic changes of CGRP and NKA levels of gastric mucosa and plasma were detected by enzyme immunoassay(EIA) and radioimmunoassay(RIA) respectively. The levels of hexosamine were determined by chromatometry. The phospholipid in gastric mucosa was detected by the modified chemical method.3. The immunohistochemistry(iHC) technique, RT-PCR and Western blot were employed to detect the expression of PAR-2 in gastric mucosa of rats with open abdominal trauma after seawater immersion.4. To investigate the effect of SLp-NH2(0.02, 0.2, 2umol/kg) pretreatment half an hour before stress on the levels of CGRP and NKA of gastric mucosa and plasma levels in gastric mucosa of two-hour-length stress rats as well as hexosamine and phospholipid. The pretreatment of normal saline and ranitidine were also performed as control.Results1. There was no lesion in normal r...