Effects and mechanism of changes of local neurotransmitters in rats' pylorus and bile reflux to the stomach with stress ulcer

A Review of the Role of Flavonoids in Peptic Ulcer (2010-2020)

Peptic ulcers are characterized by erosions on the mucosa of the gastrointestinal tract that may reach the muscle layer. Their etiology is multifactorial and occurs when the balance between offensive and protective factors of the mucosa is disturbed. Peptic ulcers represent a global health problem, affecting millions of people worldwide and showing high rates of recurrence. Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most important predisposing factors for the development of peptic ulcers. Therefore, new approaches to complementary treatments are needed to prevent the development of ulcers and their recurrence. Natural products such as medicinal plants and their isolated compounds have been widely used in experimental models of peptic ulcers. Flavonoids are among the molecules of greatest interest in biological assays due to their anti-inflammatory and antioxidant properties. The present study is a literature review of flavonoids that have been reported to show peptic ulcer activity in experimental models. Studies published from January 2010 to January 2020 were selected from reference databases. This review refers to a collection of flavonoids with antiulcer activity in vivo and in vitro models.

The protective effects of calcitonin gene-related peptide on gastric mucosa injury of gastric ischemia reperfusion in rats

Gastric mucosa is one of the most vulnerable tissues in human and animal. However, little is known about the effects of calcitonin gene-related peptide (CGRP) on gastric mucosa injuries induced by gastric ischemia reperfusion. The purpose of the present study was to investigate the protective effects and mechanism of CGRP on gastric mucosa injury after gastric ischemia reperfusion in rats. Thirty-six healthy Wistar rats were randomly divided into CGRP-treated, sham-operated, and control groups. Twelve rats were involved in each group. These groups were further divided into 24-h and 48-h subgroups. Gastric ischemia reperfusion injury (GI-RI) rat model was established by a 30-min celiac artery occlusion by an artery clamp, followed by 24 h or 48 h of reperfusion. CGRP (1 μg/ml) at the dose of 3 μg/kg was given intraperiloneally (IP) at the beginning of reperfusion for rats in CGRP-treated group. Saline as vehicle (3 ml/kg body weight), IP, was administered at the beginning of reperfusion for rats in control group. Sham-operated animals were subjected to an operation without GI-RI. Twenty-four hours or 48 h after operation, the samples were taken out and processed for calculating stomach mucous membrane damage index according to Guth method, detecting pathological changes of gastric mucosa tissue by light microscopy and observing the expression of gastrin (Gas) and somatostatin (SST) by immunohistochemical staining. The results showed the following: (i) gastric mucosa with diffuse edema, splinter hemorrhage and erosion, numerous endothelial cells necrosis, mucosa dissociation, and infiltration of inflammatory cells were observed in both control and CGRP-treated animals, especially in the earlier period (24 h) and then gradually healing. CGRP administration could reduce the damage of gastric mucosa. The injury index of gastric mucosa was lower in CGRP-treated group as compared with that in control group (P < 0.01). (ii) Gas expression in gastric antrum mucosa was lower in CGRP-treated group than that in control group (P < 0.01). SST expression in gastric antrum mucosa was higher in CGRP-treated group than that in control group (P < 0.01). It is concluded that CGRP regulated the secretion of Gas and SST and thus alleviated the damage of gastric mucosa induced by ischemia and reperfusion. CGRP might be a potential candidate for clinical therapy on modulating gastric mucosal protection and maintaining gastric mucosal integrity after ischemia and reperfusion of the stomach.

Detection of endogenous DNA adducts, O-carboxymethyl-2'-deoxyguanosine and 3-ethanesulfonic acid-2'-deoxycytidine, in the rat stomach after duodenal reflux

The endogenous DNA adducts O(6)-carboxymethyl-deoxyguanosine (O(6)-CM-dG) and 3-ethanesulfonic acid-deoxycytidine (3-ESA-dC) are produced from N-nitroso bile acid conjugates, such as N-nitrosoglycocholic acid (NO-GCA) and N-nitrosotaurocholic acid (NO-TCA), respectively. Formation of these DNA adducts in vivo was here analyzed by 32P-postlabeling in the glandular stomach of rats subjected to duodenal content reflux surgery. In this model, all duodenal contents, including bile acid conjugates, flow back from the jejunum into the gastric corpus. The levels of O(6)-CM-dG found at 4 and 8 weeks after surgery were 40.9 +/- 9.4 and 56.3 +/- 3.2 per 10(8) nucleotides, respectively, whereas the sham operation groups had values of 5.8 +/- 2.3 and 5.9 +/- 0.5 per 10(8) nucleotides. Moreover, adduct spots corresponding to 3-ESA-dC were detected in both duodenal reflux and sham operation groups and levels in the duodenal reflux groups were around four-fold elevated at 11.2 +/- 1.0 and 8.9 +/- 1.0 per 10(8) nucleotides after 4 and 8 weeks, respectively. When the duodenal reflux animals were treated with a nitrite trapping agent, thiazolidine- 4-carboxylic acid (thioproline, TPRO), the levels of O(6)-CM-dG and 3-ESA-dC were reduced to the same levels as in the sham operation animals. These observations suggest that NO-TCA and NO-GCA are formed by nitrosation of glycocholic acid and taurocholic acid, respectively, and these nitroso compounds produce DNA adducts in the glandular stomach of rats subjected to duodenal content reflux surgery.

Therapy insight: Prophylaxis of stress-induced gastrointestinal bleeding in critically ill patients

Stress-induced gastrointestinal bleeding is associated with increased morbidity and mortality in critically ill patients. Within the past few decades, the incidence of stress-induced gastrointestinal bleeding has decreased. Prophylaxis of stress-induced gastrointestinal bleeding, which is aimed at preventing morbidity and mortality, has to be achieved with as few adverse effects as possible. Data indicate that not all critically ill patients need prophylaxis for stress-induced gastrointestinal bleeding. The main risk factors associated with clinically important hemorrhage are mechanical ventilation for >48 h, and coagulopathy (thrombocyte count <50/nl, partial thromboplastin time (PTT) >2 times the upper limit of the normal range, international normalized ratio (INR) >1.5). Ranitidine is more effective than sucralfate for the prevention of clinically important bleeding. Immediate-release omeprazole is as effective as cimetidine, and is more efficient at increasing the intragastric pH. As yet, however, there is no firm evidence that any of the drugs used for prophylaxis of stress-induced gastrointestinal bleeding in critically ill patients decrease mortality or the length of hospital stay. When to stop prophylaxis is decided on clinical grounds rather than on the basis of data from clinical studies.