Translocation of heme oxygenase-1 to mitochondria is a novel cytoprotective mechanism against non-steroidal anti-inflammatory drug-induced mitochondrial oxidative stress, apoptosis, and gastric mucosal injury

The mechanism of action of heme oxygenase-1 (HO-1) in mitochondrial oxidative stress (MOS)-mediated apoptotic tissue injury was investigated. MOS-mediated gastric mucosal apoptosis and injury were introduced in rat by indomethacin, a non-steroidal anti-inflammatory drug. Here, we report that HO-1 was not only induced but also translocated to mitochondria during gastric mucosal injury to favor repair mechanisms. Furthermore, mitochondrial translocation of HO-1 resulted in the prevention of MOS and mitochondrial pathology as evident from the restoration of the complex I-driven mitochondrial respiratory control ratio and transmembrane potential. Mitochondrial translocation of HO-1 also resulted in time-dependent inhibition of apoptosis. We searched for the plausible mechanisms responsible for HO-1 induction and mitochondrial localization. Free heme, the substrate for HO-1, was increased inside mitochondria during gastric injury, and mitochondrial entry of HO-1 decreased intramitochondrial free heme content, suggesting that a purpose of mitochondrial translocation of HO-1 is to detoxify accumulated heme. Heme may activate nuclear translocation of NF-E2-related factor 2 to induce HO-1 through reactive oxygen species generation. Electrophoretic mobility shift assay and chromatin immunoprecipitation studies indicated nuclear translocation of NF-E2-related factor 2 and its binding to HO-1 promoter to induce HO-1 expression during gastric injury. Inhibition of HO-1 by zinc protoporphyrin aggravated the mucosal injury and delayed healing. Zinc protoporphyrin further reduced the respiratory control ratio and transmembrane potential and enhanced MOS and apoptosis. In contrast, induction of HO-1 by cobalt protoporphyrin reduced MOS, corrected mitochondrial dysfunctions, and prevented apoptosis and gastric injury. Thus, induction and mitochondrial localization of HO-1 are a novel cytoprotective mechanism against MOS-mediated apoptotic tissue injury.

[Effects of Na-FA on gastrointestinal movement and gastric ulcer in mice]

OBJECTIVE

To research the effects of Na-FA on gastrointestinal movement and gastriculcer in mice.

METHODS

Using charcoal powder as an indicator, the effects of FA-Na on bowel movement of mice was evaluated by determining the propulsive percent-age of charcoal powder in normal mice, inhibition of small intestinal propulsion model induced by Compound Diphenoxylate and spleen asthenia and diarrhea model caused by Rheum officinale Baill; The acute gastric ulcer model was induced by intragastric alcohol given orally, the protective effect of FA-Na given ahead on gastric injury was evaluated, the ulcer index and the inhibition ratio of ulcer was calculated.

RESULTS

FA-Na (intragastric administration) had inhibit effect on normal mice and diarrhea model caused by Rheum officinale, significantly synergetic effect on gastrointestinal asynersis induced by Compound Diphenoxylate, and protective effect on mice gastric mucosal injury cause by dehydrated alcohol. Compared with the positive control drug Ranitidine, the ulcer index and ulcer inhibition ratio large doses of FA-Na had no significant difference.

CONCLUSION

The acute toxicity of FA-Na is very low, it has the effects of antidiarrheal and anti-gastric ulcer.

[Effect of acupuncture on contents of beta-endorphin in the plasma and hypothalamus in rats with stress-induced gastric mucosal injury]

OBJECTIVE

To explore the mechanism of acupuncture in preventing and treating stress-induced gastric mucosal injury from the view of brain-gut axis.

METHODS

Forty male Wister rats were randomly divided into normal control, model 1, treatment, model 2 and prevention groups (n=8). Gastric mucosa injury model was established by intragastric perfusion of dehydrated alcohol (1.0 mL/rat). Rats of the treatment group were treated with acupuncture after modeling, while those of the prevention group treated first, followed by modeling. The time of modeling in model 1 group and model 2 group was simultaneous with that of the treatment group and prevention group respectively. Acupuncture was applied to "Zusanli"(ST 36), "Zhongwan" (CV 12) and "Neiguan" (PC 6) for 20 min, once daily for 5 days. Before sampling the tissues, 10% charcoal suspension was intragastric perfused 1 h for analyzing the rate of gastrointestinal propulsion(distance from the upper end of the charcoal powder to the cardia/total length of the cardia to the anus x 100%). Gastric mucosal ulcer index was measured by using Guth's method. The contents of beta-endorphin(beta-EP)in plasma and hypothalamus were determined by enzyme-linked immunosorbent assay.

RESULTS

Compared with the normal control group, the gastrointestinal propulsion rates were decreased considerably in the two model groups (P < 0.05), while the gastric mucosal ulcer indexes and the contents of beta-EP in both plasma and hypothalamus were increased significantly in the model groups (P < 0.05, P < 0.01). Compared with the corresponding model groups, the gastrointestinal propulsion rate was increased remarkably in the prevention group (P < 0.05), and the gastric mucosal ulcer indexes and the contents of plasma beta-EP level were decreased obviously in both treatment and prevention groups (P < 0.05, P < 0.01). The contents of hypothalamic beta-EP were increased further in the later two groups (P < 0.01).

CONCLUSION

Acupuncture of ST 36, CV 12 and PC 6 can promote the repair of gastric mucosal injury and improve gastrointestinal function, which may be related to its effects in reducing plasma beta-EP and upregulating hypothalamic beta-EP level. Acupuncture also has a better effect in preventing gastric mucosal injury.

Gastric mucosal injury activates bFGF gene expression and triggers preferential translation of high molecular weight bFGF isoforms through CUG-initiated, non-canonical codons

Basic fibroblast growth factor (bFGF or FGF-2) is a pleiotropic growth factor that promotes growth of mesenchymal and epithelial cells, stimulates angiogenesis and neuroprotection. Moreover, exogenous bFGF by stimulating angiogenesis promotes healing of gastroduodenal ulcers and cardiac and brain injury. All these actions were demonstrated in regard to 18kDa bFGF isoform that is secreted by cells via an ER/Golgi-independent pathway and activates FGF receptors. However in some transformed and stressed cells and in some tissues (e.g. brain) the single copy bFGF gene encodes multiple gene products: 18 kDa and also higher molecular weight (HMW) bFGF isoforms: ∼21 and ∼22 kDa in rodents, and ∼22, ∼23 and ∼24 kDa in humans. The biologic roles of these HMW bFGF isoforms in vivo remain unknown. In this study we demonstrated that in normal, uninjured gastric mucosa, bFGF is almost exclusively expressed as 18kDa isoform translated through a classical AUG (methionine) codon. In contrast, in injured gastric mucosa of rat, bFGF gene is preferentially translated to HMW bFGF isoforms through alternative CUG (leucine) initiation codon. Gastric mucosal injury caused in rats a significant increase in bFGF mRNA at 8 and 24h vs. normal mucosa and a significant increase in bFGF protein at 24-72h, mainly due to increased expression of ∼21 and ∼22 kDa HMW bFGF isoforms. This is first demonstration that gastric mucosal injury and repair triggers local activation of bFGF gene with preferential translation of HMW bFGF isoforms through a non-canonical CUG codon. This study uncovered CUG-initiated HMW bFGF translation as a novel regulatory mechanism operating in vivo during gastric injury repair.

[Effect of plasma of healthy subjects undergoing moxibustion on ethanol-injured human gastric epithelial GES-1 cells in vitro and the involved mitochondrial apoptosis pathway]

OBJECTIVE

To observe the effect of plasma derived from healthy volunteers undergoing moxibustion (moxibustion plasma) on alchol-injured human gastric epithelial GES-1 cells in vitro, and expression of heat shock protein 70 (HSP 70, cell apoptosis inhibitory protein), apoptosis inducing factor (AIF), Smac (a mitochondrial protein), and Caspase 3 and Caspase 9 (the latter 3 proteins are also involved in cell apoptosis) in order to study its mechanisms underlying protecting gastric mucous membrane.

METHODS

Twenty-four healthy volunteer subjects (half men and half women) were randomized into acupoint-moximustion (A-M) [Zhongwan(CV 12), Guanyuan (CV 4) and Zusanli (ST 36)] group and non-acupoint-moxibustion (NA-M, 3 cun right to CV 12 and CV 4.1 cun medial to ST 36 ) group (n = 12/group). Moxibustion was applied to the above-mentioned 3 acupoints and non-acupoints for 30 min, once daily for 10 days. Venous blood of the subjects was collected before and after moxibustion. The cultured GES-1 cells were divided into: control group. ethanol-injury group (model), A-M plasma group (A-M-P, plasma got from volunteers undergoing A-M), and NA-M plasma group (NA-M-P,plasma got from volunteers accepting NA-M). The GES-1 cells of the latter 3 groups were treated with 8% ethanol for duplicating cell injury model. Apoptosis was detected by flowcytometry. Expression of HSP 70, second mitochondria-derived activator of Caspase (Smac) and AIF proteins of GES-1 cells were assayed by western blotting, and the immunoactivity of cysteinyl aspirate-specific proteinase-3 and 9 (Caspase-3, 9) was detected by immunocytochemistry.

RESULTS

In comparison with the control group, the apoptosis rate, the expression of HSP 70, Smac and AIF proteins, and the immunoactivity of Caspase-3 and Caspase-9 of the model group were increased significantly (P < 0.01). Compared with the model group, the apoptosis rate of GES-1 cells, the expression of Smac and AIF proteins, and the immunoactivity of Caspase-3 and Caspase-9 in the A-M-P group, the apoptosis rate, the expression of Smac and the immunoactivity of Caspase-3 and Caspase-9 in the NA-M-P group were all down-regulated considerably (P < 0.05, P < 0.01). In comparison with the model group, HSP 70 expression of the A-M-P group was up-regulated significantly (P < 0.01). The apoptosis rate of GES-1 cells, the expression levels of Smac, AIF, Caspase-3 and Caspase-9 were significantly lower in the A-M-P group than in the NA-M-P group (P < 0.05, P < 0.01), while the expression of HSP 70 was apparently higher in the A-M-P group than in the NA-M-P group (P < 0.01).

CONCLUSION

Plasma derived from the subjects undergoing moxibustion of Zusanli (ST 36), Zhongwan (CV 12) and Guanyuan (CV 4) can inhibit apoptosis of GES-1 cells in vitro, which is closely related to its effects in up-regulating intracellular HSP 70 expression and down-regulating mitochondrial apoptosis protein expression of AIF. Smac, Caspase-3 and Caspase-9.

[Warm-needle moxibustion therapy may reduce aspirin-induced gastric mucosal injury in rats]

OBJECTIVE

To observe the effect of warm-needle moxibustion on the gastric mucosal injury caused by anti-rheumatic dose of Aspirin.

METHODS

Forty SD rats were equally randomized into blank group, model group, warm needling group and Omeprazole (for relieving peptic ulcer) group, with 10 rats in each. The rats were forced to undergo 12 hours' fasting and 4 hours' water-deprivation before the experiments. Normal saline (10 mL/kg) was given to the rats in the blank group. Gastric mucosa lesion model was established by intragastric infusion of aspirin (420 mg/kg). Warm needling was applied to "Zhong-wan" (CV 12), "Xiawan" (CV 10), "Zusanli" (ST 36) and "Neiguan" (PC 6) for 30 min, once a day for 7 days. The rats of the Omeprazole group were fed with Omeprazole( 10 mg/100 g body weight) once a day for 7 days. According to Guth's method, the ulcer index (UI) of the gastric mucosa was calculated following killing the rats. The activity of superoxide dismutase (SOD) and the levels of malondialdehyde (MDA) in the serum and gastric mucosa were detected with hydroxylamine method and thiobarbituric acid method, respectively.

RESULTS

Compared with the blank group, the gastric UI, MDA levels of both serum and gastric mucosa in the model group were increased obviously (P<0. 01), while serum and gastric mucosal SOD activity in the model group were decreased considerably (P<0. 01). In comparison with the model group, the gastric UI, and both serum and gastric mucosal MDA contents in the warm needling group and Omeprazole group were down-regulated significantly (P<0. 01), whereas both serum and mucosal SOD activity in the warm needling group and serum SOD activity in the Omeprazole group were up-regulated significantly (P<0. 01). Comparison between the warm needling group and Omeprazole group showed that the UI, both serum and gastric mucosal SOD activity, and serum MDA level of the former group were evidently higher than those of the Omeprazole group (P<0. 05), but gastric mucosal MDA level of the warm needling group was apparently lower than that of the Omeprazole group (P<0.05).

CONCLUSION

Warm-needle moxibustion can reduce the gastric lesion (ulcer) caused by aspirin in the rat, which may be closed associated with its effects in up-regulating both serum and gastric mucosal SOD activity and down-regulating both serum and gastric mucosal MDA levels.

Low-dose aspirin delays gastric healing after Helicobacter pylori eradication

BACKGROUND AND AIM

Helicobacter pylori (H. pylori) and aspirin are the major causes of gastric injury, and eradication of H. pylori can restore mucosal injury such as gastric ulcer. The aim of the present study was to investigate the effects of low-dose aspirin on the healing process, determined by endoscopic features, after H. pylori eradication.

METHODS

From 2001 to 2008, 12,887 patients underwent endoscopic examination at our hospital. From these, 100 patients with and 100 patients without H. pylori infection were analyzed to identify the endoscopic features characteristic of H. pylori-infected stomach. Based on these characteristic features, we observed the healing process of 89 patients not taking low-dose aspirin and 12 patients taking low-dose aspirin for 6 months, 1 year, and 5 years, which was successful in eradicating H. pylori.

RESULTS

Diffuse redness (DR) of the fundic mucosa was the characteristic feature of H. pylori-infected stomach, whereas reddish streaks (RS) on the greater curvature of the antrum was the characteristic finding in non-infected stomach. In the no aspirin group, DR faded by 6 months and new expression of RS was observed 1 year after H. pylori eradication. In contrast, in the aspirin group, both fading of DR and the expression of RS were observed 5 years after eradication.

CONCLUSION

Low-dose aspirin delayed the early phase of the healing process in the gastric mucosa after H. pylori eradication.

[Mast cell and substance P are involved in the process of acupoint sensitization induced by acute gastric mucosal injury]

OBJECTIVE

To observe changes of mast cells (MCs) number and morphology, and substance P (SP) expression in Evans blue (EB) extravasated region around acupoint "Pishu" (BL 20) and "Weishu" (BL 21) after acute gastric mucosal injury (AGMI) so as to investigate the mechanism underlying visceral problems-induced acupoint activation.

METHODS

Thirty adult Wistar rats were randomly divided into normal control (n = 15) and AGMI groups (n = 15). AGMI model was duplicated by perfusing the rats with 0.5 mol/L HCl (1 mL/100 g) after fasting for 20 h. Five hours after AGMI, the rats were treated by tail-intravenous injection of EB dye (5 mg/100 g, 50 mg/mL in normal saline) for inducing dye-plasma extravasation in the skin around BL 20, BL 21 regions, etc. at the back. The rats of the normal control group were treated with tail-intravenous injection of 0.9% NaCl. The skin and subcutaneous tissues (2 mmx 2 mm) of extravasated EB dye points (BL 20 or BL 21 region) and those 2 mm lateral to the extravasated EB dye points in the model group and the corresponding points in the normal control group were sampled (followed by fixing them in 4% paraformaldehyde), sectioned and stained by toluidine blue (for labeling MCs). The expression of SP in the extravasated EB dye skin and subcutaneous tissues was detected by immunohistochemistry (n = 5) and western blot (n = 5) respectively. The number of MCs in these samples was counted and the degranulation rate of MCs calculated.

RESULTS

The total number of MCs and the number of degranulated MCs were significantly more in the EB extravasation points (corresponding to BL 20/BL 21 area) of AGMI group than those in the control spots of AGMI group and than those in the normal control group (P < 0.05, P < 0.001). The degranulation rate of MCs was significantly higher in the EB extravasation points of AGMI group than those in the control spots of AGMI group and in the normal control group (P < 0.01). In comparison with normal control group, the SP expression level was increased consideraly in the control spots of AGMI group and AGMI group (P < 0.01).

CONCLUSION

After AGMI, the numbers of MCs and the degranulated MCs, and the SP expression level in BL 20/BL 21 area were increased significantly, suggesting an involvement of MCs and SP in the process of AGMI-induced activation of acupoints.

Nutritional and environmental factors affecting plasma ghrelin and leptin levels in rats

We examined which factors suppress the rise of ghrelin secretion under hunger in 16-h-starved rats, and compared the responses of plasma ghrelin and leptin levels to various exogenous and endogenous stimuli in intact rats. Although an acute expansion of the stomach by infusion of 6 ml air or 3 ml water in rats starved for 16 h did not change the level of plasma acyl-ghrelin 3 ml corn starch solution, corn oil, or 20% ethanol significantly decreased it. Vagotomy inhibited suppression by nutrients but not by ethanol. Chronic infusion of ethanol into the stomach for 3 weeks in free-feeding rats caused widespread injury of the stomach mucosa, and increased both plasma ghrelin levels and the number of ghrelin cells. In intact rats, low temperature did not change ghrelin levels, but increased leptin levels. On the other hand, restriction stress decreased plasma ghrelin levels, but had the reverse effect on plasma leptin levels. Although insulin decreased and 20% glucose increased plasma glucose levels, they both decreased plasma ghrelin levels. Insulin elevated plasma leptin levels, but glucose had no effect. These results indicate that 1) acyl-ghrelin secretion from the stomach under fasting condition is suppressed by nutrients but not by mechanical expansion of the stomach; 2) high and low environmental temperature, stress, or administration of insulin reciprocally affect plasma levels of ghrelin and leptin; and 3) an increase of stomach ghrelin cell number and plasma ghrelin levels after chronic ethanol treatment may be involved in restoration of gastric mucosae.

[Distribution of the activated acupoints after acute gastric mucosal injury in the rat]

OBJECTIVE

To observe the dynamic distribution of the extravasated Evans Blue (EB) dye points (neurogenic inflammatory response) at the skin after acute gastric mucosal injury (AGMI) and its relation to the related regular acupoints in the locations in rats.

METHODS

A total of 70 Wistar rats were randomized into normal control (n=10), normal saline (n=10), and AGMI (n=50) groups. The AGMI group was further divided into 5 h, 2 d, 3 d, 4 d and 5 d subgroups with 10 rats in each. AGMI model was duplicated by intragastric perfusion of diluted hydrochloric acid (HCl, 0.5 mol/L). Evans Blue Dye (50 mg/kg, 50 mg/mL in 0.9% saline) was given to the rats before AGMI modeling. The plasma extravasated EB points at the skin of the whole body were observed after removal of the hair.

RESULTS

The extravasated EB points presented a nerve-segmental distribution, with the proportion of the points in the location being 47.5% for "Geshu" (BL 17),58. 82% for "Jizhong" (GV 6), 88.23% for "Pishu" (BL 20), 82.35% for "Weishu" (BL21), 17.64% for "Zhongwan" (CV 12), and 5.88% for "Shangwan" (CV 13), respectively. The plasma extravasation of EB seldom appeared in normal rats and only fewer points were found in rats accepted administration of 0.9% saline. Significant differences were found between model and normal control groups, and between model and normal saline groups in the numbers of the extravasated EB points (P < 0.01, P < 0.05). The number of the extravasated EB points was related to the phase of gastric mucosa injury, being most on the 2nd and 3rd day after modeling and disappearing gradually along with the natural repair of AGMI.

CONCLUSION

AGMI promotes the plasma extravasation of EB and the extravasated EB points present a nerve-segmental distribution and have a higher corresponding rate with some acupoints including "Pishu" (BL 20), "Weishu" (BL 21), etc., suggesting an activation of the normally silent acupoints under diseased conditions.

Gastric necrosis and perforation as a severe complication of pancreatic pseudocyst

Patients with acute pancreatitis may present with stress-related gastrointestinal mucosal lesions. But severe gastrointestinal complications such as gastric perforation are very rare. Here, we report a 40-year-old man who was admitted due to acute pancreatitis and pseudocyst formation. During hospitalization, panendoscopic examination found multiple scattered stress ulcers over the gastric antrum and a large ulcerative area with suspicious malignant features at the body and fundus. The patient received surgical intervention due to worsening of his clinical condition. Postoperative findings showed a perforation of the gastric wall at the region in contact with the pseudocyst, and microscopic examination found diffuse ischemia and necrosis with intravascular thrombus and emboli in gastric vessels. We suggest keeping in mind that pancreatic pseudocyst may cause serious gastrointestinal complications including massive necrosis and perforation of the gastric wall.

[Observation on changes of the intragastric protein phosphorylation level involving electroacupuncture-induced improvement of the injured gastric mucosa in the rat]

OBJECTIVE

To study the effect of electroacupuncture (EA) of Stomach Meridian acupoints on changes o of the related protein phosphorylation in the gastric mucosa involving the repair of the injured gastric mucosa in the rat.

METHODS

A total of 20 SD rats were divided into control, model, acupoint and non-acupoint groups, with 5 cases in each. Gastric mucosa injury model was established by intragastric perfusion of dehydrated alcohol (0.8 ml/100 g). EA (4 Hz/50 Hz, 1-3 mA) was applied to "Zusanli" (ST 36), "Liangmen" (ST 21) and "Sibai" (ST 2), and the corresponding non-acupoints, once daily for 7 days. Gastric mucosal ulcer index (UI) was measured, and the profiling of the protein phosphorylation of interest in gastric mucosa cells was detected by antibody microarrays.

RESULTS

In comparison with control group, the gastric mucosal UI of model group was significantly higher than that of control group (P < 0.01), while the UI of EA group was significant lower than those of model group and non-acupoint group (P < 0.01), suggesting a recovery of the injured mucous membrane. Findings of protein array analysis indicated that a total of 720 kinds of phosphorylated proteins (> or = 1.5 folds) were found in the injured gastric mucosa. Compared to model group, the phosphorylation levels of 100 and 20 proteins were up-regulated, and 16 and 9 proteins down-regulated in acupoint and non-acupoint groups, respectively. The up-regulated proteins involve cell cycle mediation, cell proliferation, anti-apoptosis, and the regulation of the cell adhesion, cytoskeleton protein, inflammation, immune activities, etc. while the down-regulated proteins involve the down-regulation of the phosphorylation levels of the apoptosis proteins, adhesion proteins and cytoskeleton proteins, etc. In comparison to non-acupoint group, the phosphorylation levels of 100 proteins were up-regulated and 16 proteins down-regulated in acupoint group.

CONCLUSION

EA of acupoints of the Stomach Meridian can promote repair of the injured gastric mucosa, which may be related to its effects in regulating the levels of phosphorylation of many signaling proteins.

Clinical characteristics of patients with gastric perforation following endoscopic submucosal resection for gastric cancer

BACKGROUND/AIMS

The aim of this study was to evaluate the risk factors of perforation during endoscopic submucosal dissection (ESD).

METHODOLOGY

ESD was performed using a Flex knife in 64 patients with a total of 67 gastric tumors. Perforation occurred at the sites of a total of 4 lesions (5.9% [4/67]) for which conservative treatment had been effective. We evaluated several possible risk factors for perforation following ESD, such as tumor size, the location of the lesion, the operation time, and other clinical factors.

RESULTS

All the perforations occurred in the posterior wall of the gastric upper or middle body. In an analysis adjusted for age and sex, the tumor size (odds ratio (OR), 1.017; 95% confidence interval (CI), 1.004-1.030), the location of the lesion in an upper region (OR, 10.64; 95%CI, 1.160-10.00) and the operation time (OR, 1.017; 95%CI, 1.013-1.295) were significantly associated with the incidence of perforation. All perforations were transient, resolving within 7 days, and did not require surgical treatment.

CONCLUSIONS

A large tumor size, the location of the lesion in an upper region, and a long operation time are risk factors for perforation following ESD.

Protective effect of Carica papaya L leaf extract against alcohol induced acute gastric damage and blood oxidative stress in rats

The effects of Carica papaya leaf (CPL) aqueous extract on alcohol induced acute gastric damage and the immediate blood oxidative stress level were studied in rats. The results showed that gastric ulcer index was significantly reduced in rats pretreated with CPL extract as compared with alcohol treated controls. The in vitro studies using 2,2-Diphenyl-1-Picryl-Hydrazyl (DPPH) assay showed strong antioxidant nature of CPL extract. Biochemical analysis indicated that the acute alcohol induced damage is reflected in the alterations of blood oxidative indices and CPL extract offered some protection with reduction in plasma lipid peroxidation level and increased erythrocyte glutathione peroxidase activity. Carica papaya leaf may potentially serve as a good therapeutic agent for protection against gastric ulcer and oxidative stress.

The relationship between the control of pH and healing and symptom relief in gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GERD) is generally considered to be the result of a motility disorder which permits the abnormal and prolonged exposure of the lumen of the oesophagus to the acidic gastric contents. This view is supported by experimental data, intra-oesophageal pH measurement, and the dramatic results of symptom relief and healing seen with effective antisecretory treatment. Oesophageal mucosal injury is determined by the pH of the refluxate and duration of acid exposure. Most patients experience meal-stimulated reflux during the day and the more severe cases experience 24-h acid exposure. In contrast to the H2-receptor antagonists (H2RAs), the proton pump inhibitors (PPIs) are more effective at controlling meal-stimulated acid secretion when each is given in standard doses. Therefore, the degree and duration of acid suppression throughout 24 h is greater. Treatments which maintain intra-oesophageal pH > 4 for 96% or more of the 24 h normalize acid exposure and are associated with the highest healing rates. Peptic activity is minimized at or above pH 4. The time above pH 4 is significantly longer with the PPIs than with the H2RAs. Thus, the healing-time curves for GERD (grades II-IV) are shifted to the left for the PPIs which heal a significantly greater proportion of patients earlier than the H2RAs or sucralfate. Symptoms in GERD are related to the degree and duration of oesophageal acid exposure. Symptom relief is more rapid and complete with the PPIs than with the H2RAs or other treatments in standard doses.

Mechanical strain stress suppresses expression of HSP70 and wound restoration in gastric mucosal cells

The major heat shock protein, HSP70, is known to be involved in cytoprotection against environmental stresses mediated by their function as a "molecular chaperone." However, the influence of HSP70 on gastric mucosal healing under physical stimulation or stress is not completely understood. Rat gastric mucosal cells (RGM-1) were stably transfected with pBK-CMV containing the human HSP70 gene (7018-RGM-1) or pBK-CMV alone (pBK-CMV-12). Artificial wounds were created. Mechanical stretch was applied to 7018-RGM-1 cells or pBK-CMV-12 cells. The effect of mechanical stretch on HSP70 expression was assessed by Western blot analysis. Expression of HSP70 was decreased by mechanical stretch in pBK-CMV-12 cells. However, expression of HSP70 was not decreased by mechanical stretch in 7018-RGM-1 cells. Furthermore, the wound restoration of pBK-CMV-12 cells was suppressed under mechanical stretch condition. On the other hand, the wound restoration of 7018-RGM-1 cells was not affected by mechanical stretch. These results suggest that HSP70 plays an important role in gastric wound healing under physical stress.

[Compensatory gastroprotective role of glucocorticoid hormones]

Prostaglandings (PGs), nitric oxide (NO) and capsaicin-sensitive afferent neurons play a pivotal role in the defensive mechanisms against gastric mucosal injury. Glucocorticoid hormones released in response to ulcerogenic stimuli are naturally occurring gastroprotective factors and exert many of the same actions in the stomach as PGs, NO and capsaicin-sensitive afferent neurons. The results reviewed suggest that glucocorticoids exert a pivotal compensatory role in the maintenance of gastric mucosal integrity in the case of impaired gastroprotective mechanisms provided by PGs, NO and capsaicin-sensitive afferent neurons. The compensatory protective action of glucocorticoids may be provided by their maintenance of glucose homeostasis and gastric microcirculation.

Nociceptin/orphanin FQ prevents gastric damage induced by cold-restraint stress in the rat by acting in the periphery

The influence of peripheral nociceptin/orphanin FQ (N/OFQ) on cold restraint-induced gastric mucosal damage in the rat was investigated. Exposure to cold-restraint for 3 and 4h caused the formation of hemorrhagic lesions in the glandular portion of the stomach. N/OFQ dose-dependently decreased lesion formation, in the range 0.03-1 microg/kg/h i.p. Its effect was reversed by the selective NOP receptor antagonist [Nphe(1)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-101), 30 microg/kg/h ip. The selective NOP receptor agonist [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), 0.01-0.3 microg/kg/h i.p., similarly reduced lesion formation. Light and scanning electron microscopy confirmed the protective activity of N/OFQ. Cold-restraint stress causes a reduction in mucus content and in adhering mucus layer, partly counteracted by N/OFQ. These results suggest that N/OFQ counteracts acute stress-induced gastric mucosal damage by interacting with NOP receptor and by influencing mucous cell activity.

Isothiocyanate Inhibits Restitution and Wound Repair after Injury in the Stomach: Ex Vivo and in Vitro Studies

The role of isothiocyanate (ITC) in blocking epithelial restitution after injury and in the recovery of round wounds was examined in the ex vivo guinea pig stomach and in rat gastric mucosal-1 (RGM1) cells, respectively. For this, recovery of transepithelial electrical resistance and morphology after injury or the closure of round wounds was evaluated in the presence of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 4,4-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (H2DIDS) (two ITC groups), 4-acetamido-4-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) (one ITC group), or 4,4-diinitrostilbene-2,2'-disulfonic acid (DNDS) (no ITC groups). Wounded RGM1 cells were also incubated with bicarbonate-free buffer, ATP, barium, or phloretin to determine the mechanism of ITC inhibition. At 300 microM, DIDS or H2DIDS blocked restitution and wound repair by 100%, SITS blocked wound repair by 50%, and DNDS blocked wound repair by 2%. These results demonstrate the dependence of restitution and wound repair on ITC. ITC-binding purino (ATP) receptors and KATP channels were investigated as potential sites of inhibition, but they were found not to be the target of ITC in wound repair. Phloretin, blocking the monocarboxylate transporter (MCT), dose-dependently inhibited wound repair, and this result was exacerbated when the sodium bicarbonate cotransporter (NBC) was also blocked by bicarbonate-free conditions, resulting in 100% inhibition of wound repair with no reduction in viability when both transporters were blocked simultaneously. ITC potently inhibits both MCT and NBC, which may account for the inhibitory action of DIDS during restitution and wound repair. Reverse transcription-polymerase chain reaction data verified that MCT-1 is expressed in RGM1 cells. In conclusion, our results suggest that bicarbonate and monocarboxylate transport may work cooperatively to facilitate restitution of the gastric mucosa after injury.

Effect of chronic stress and L-carnitine on rat stomach

BACKGROUND AND AIM

L-Carnitine is an essential cofactor in the mitochondrial transfer of fatty acids, and it is also a scavenger of free radicals in mammalian tissues. The aim of the study was to determine the effect of L-carnitine on chronic restraint stress-induced gastric mucosal injury.

METHODS

Wistar rats were applied restraint stress (1 h/day) and L-carnitine (50 mg/kg) for 21 days. The lesion index, prostaglandin E(2) and mucus content, lipid peroxidation, superoxide dismutase, and catalase activity in gastric mucosa were evaluated.

RESULTS

Chronic restraint stress increased the lesion index, lipid peroxidation, and superoxide dismutase activity in gastric mucosa, and it decreased prostaglandin E(2) and mucus content. L-Carnitine treatment prevented the stress-induced increase in lesion index, lipid peroxidation and a stress-induced decline in prostaglandin E(2), and mucus content in gastric mucosa, but it increased catalase activity.

CONCLUSIONS

L-Carnitine prevents the occurrence of lesion by strengthening the gastric mucosal barrier and by reducing lipid peroxidation against the harmful effects of chronic restraint stress.

NSAID injury to the gastrointestinal tract: evidence that NSAIDs interact with phospholipids to weaken the hydrophobic surface barrier and induce the formation of unstable pores in membranes

In this review, we have discussed our current understanding of the barrier properties that are in place to protect the upper gastrointestinal mucosa from luminal acid, and the pathogenic mechanism by which nonsteroidal anti-inflammatory drugs (NSAIDs) induce injury to the gastrointestinal tract. The changes in our view of the importance of NSAID-induced cyclo-oxygenase (COX) inhibition on the pathogenesis and prevention of NSAID-induced gastrointestinal injury is presented. The focus of this paper has been placed on the effects of NSAIDs on the mucosal surface, and specifically the effect of these powerful drugs in inducing changes in the hydrophobicity, fluidity, biomechanical and permeability properties of extracellular and membrane phospholipids. Lastly, recent evidence is presented that salicylic acid and related NSAIDs may alter the stability of membranes, inducing the formation of unstable pores that may lead to back-diffusion of luminal acid and membrane rupture. This understanding of the interaction of NSAIDs with membrane phospholipids may prove valuable in the design of novel NSAID formulations with reduced gastrointestinal side-effects.

Estrogen and isoflavone attenuate stress-induced gastric mucosal injury by inhibiting decreases in gastric tissue levels of CGRP in ovariectomized rats

We have previously reported that CGRP plays a critical role in the reduction of stress-induced gastric mucosal injury by increasing gastric prostacyclin (PGI(2)) levels in rats. Estrogen has been shown to increase the production of CGRP in sensory neurons. Isoflavone has estrogen-like effects and is referred to as a phytoestrogen. Thus, we hypothesized that estrogen and isoflavone might inhibit ovariectomy (OVX)-induced decreases in gastric tissue levels of CGRP, thereby attenuating gastric mucosal injury. We examined these possibilities in the present study. The administration of estradiol and isoflavone for 4 wk completely reversed OVX-induced decreases in CGRP mRNA levels of dorsal root ganglion neurons (DRGs) in rats. OVX-induced decreases in gastric tissue levels of CGRP and 6-keto-PGF(1alpha), a stable metabolite of PGI(2), in rats were reversed by estradiol and isoflavone. Water-immersion restraint stress (WIR)-induced increases in gastric tissue levels of CGRP and 6-keto-PGF(1alpha) were inhibited in ovariectomized rats. This inhibition was completely reversed by estradiol and was partially, but significantly, reversed by isoflavone. WIR-induced gastric mucosal injury was exacerbated by OVX, which was reversed by estradiol and isofolavone. In vitro experiments using DRGs isolated from rats demonstrated that neither estradiol nor isoflavone enhanced CGRP release from DRGs, but the former enhanced it in the presence of anandamide, an endogenous agonist for vanilloid receptor-1. These observations suggest that estrogen and isoflavone might inhibit OVX-induced decreases in CGRP levels in DRGs by promoting transcription, thereby contributing to the attenuation of stress-induced gastric mucosal injury in OVX rats.