Reversion by histamine H2-receptor antagonists of plasma membrane alterations in ethanol-induced gastritis

Anti-Inflammatory Activities of an Anti-Histamine Drug, Loratadine, by Suppressing TAK1 in AP-1 Pathway

Loratadine is an anti-histamine routinely used for treating allergies. However, recent findings have shown that Loratadine may also have anti-inflammatory functions, while their exact mechanisms have not yet been fully uncovered. In this paper, we investigated whether Loratadine can be utilized as an anti-inflammatory drug through a series of in vitro and in vivo experiments using a murine macrophage cell line and an acute gastritis mouse model. Loratadine was found to dramatically reduce the expression of pro-inflammatory genes, including MMP1, MMP3, and MMP9, and inhibit AP-1 transcriptional activation, as demonstrated by the luciferase assay. Therefore, we decided to further explore its role in the AP-1 signaling pathway. The expression of c-Jun and c-Fos, AP-1 subunits, was repressed by Loratadine and, correspondingly, the expression of p-JNK, p-MKK7, and p-TAK1 was also inhibited. In addition, Loratadine was able to reduce gastric bleeding in acute gastritis-induced mice; Western blotting using the stomach samples showed reduced p-c-Fos protein levels. Loratadine was shown to effectively suppress inflammation by specifically targeting TAK1 and suppressing consequent AP-1 signaling pathway activation and inflammatory cytokine production.

Humulene Inhibits Acute Gastric Mucosal Injury by Enhancing Mucosal Integrity

This study was designed to determine whether α-humulene, a major constituent in many plants used in fragrances, has a protective role against gastric injury in vivo and in vitro. A rat model of hydrochloric acid (HCl)/ethanol-induced gastritis and human mast cells (HMC-1) were used to investigate the mucosal protective effect of α-humulene. α-Humulene significantly inhibited gastric lesions in HCl/ethanol-induced acute gastritis and decreased gastric acid secretion pyloric ligation-induced gastric ulcers in vivo. In addition, α-humulene reduced the amount of reactive oxygen species and malondialdehyde through upregulation of prostaglandin E2 (PGE2) and superoxide dismutase (SOD). In HMC-1 cells, α-humulene decreased intracellular calcium and increased intracellular cyclic adenosine monophosphate (cAMP) levels, resulting in low histamine levels. α-Humulene also reduced the expression levels of cytokine genes such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF) by downregulating nuclear factor-κB (NF-κB) nuclear translocation. Finally, α-humulene upregulated the expression levels of mucin 5AC (Muc5ac), Muc6, trefoil factor 1 (Tff1), trefoil factor 2 (Tff2), and polymeric immunoglobulin receptor (pigr). α-Humulene may attenuate HCl/ethanol-induced gastritis by inhibiting histamine release and NF-κB activation and stimulating antioxidants and mucosal protective factors, particularly Muc5ac and Muc6. Therefore, these data suggest that α-humulene is a potential drug candidate for the treatment of stress-induced or alcoholic gastritis.

High α-tocopherol dosing increases lipid metabolism by changing redox state in damaged rat gastric mucosa and liver after ethanol treatment

Regeneration of ethanol-injured rat gastric mucosa must undergo changes in major metabolic pathways to achieve DNA replication and cell proliferation. These events are highly dependent on glucose utilization and inhibited by vitamin E (VE) (α-tocopherol) administration. Therefore, the present study aimed at assessing lipid metabolism in the gastric mucosa and ethanol-induced gastric damage and the effect of α-tocopherol administration. For this, rates of fatty acid β-oxidation and lipogenesis were tested in gastric mucosa samples. Through histological analysis, we found loss of the mucosa's superficial epithelium, which became gradually normalized during the recovery period. Proliferation of gastric mucosa occurred with augmented formation of β-oxidation by-products, diminished synthesis of triacylglycerols (TGs), as well as of phospholipids, and a reduced cytoplasmic NAD/NADH ratio, whereas the mitochondrial redox NAD/NADH ratio was much less affected. In addition, α-tocopherol increased palmitic acid utilization in the gastric mucosa, which was accompanied by the induction of 'mirror image' effects on the cell redox state, reflected in an inhibited cell gastric mucosa proliferation by the vitamin administration. In conclusion, the present study shows, for the first time, the role of lipid metabolism in the adaptive cell gastric mucosa changes that drive proliferation after a chronic insult. Moreover, α-tocopherol increased gastric mucosa utilization of palmitic acid associated with energy production. These events could be associated with its antioxidant properties in co-ordination with regulation of genes and cell pathways, including changes in the cell NAD/NADH redox state.

Syzygium aromaticum water extract attenuates ethanol‑induced gastric injury through antioxidant effects in rats

The aim of the present study was to investigate whether Syzygium aromaticum water extract (SAWE) has a protective effect against ethanol‑induced gastric injury in rats. Acute gastric injury was induced via intragastric administration of absolute ethanol at a dose of 5 ml/kg. SAWE (250 or 500 mg/kg/day) or cimetidine (100 mg/kg/day), which was used as a positive control, were administered to the rats 2 h prior to ethanol administration for 3 days. All rats were sacrificed 24 h following the final ethanol administration. To examine whether SAWE has a gastroprotective effect, assays were performed to assess the contents of malondialdehyde (MDA) and glutathione (GSH), the activities of catalase, glutathione‑S‑transferase and superoxide dismutase, and an immune-linked immunosorbent assay was performed for prostaglandin E2 (PGE2) production in gastric tissues by hematoxylin and eosin and periodic acid-Schiff staining. Histological assessment of the gastric wall was performed. Compared with ethanol treatment alone, treatment with SAWE at a dose of 250 mg/kg/day significantly decreased the gastric MDA content and increased the GSH content, catalase activity, and production of gastric PGE2. Histological assessment showed that SAWE attenuated inflammatory cell infiltration and the loss of epithelial cells. These findings suggested that SAWE protected against ethanol‑induced gastric mucosal injury in the rats. These effects appeared to be associated with antioxidant activity, activation of the production of PGE2, suppression of inflammatory cell infiltration and loss of epithelial cells in the gastric mucosa. Collectively, SAWE may be beneficial in the prevention of gastric disease associated to oxidative stress.

Curcuma aromatica Water Extract Attenuates Ethanol-Induced Gastritis via Enhancement of Antioxidant Status

Curcuma aromatica is an herbal medicine and traditionally used for the treatment of various diseases in Asia. We investigated the effects of C. aromatica water extract (CAW) in the stomach of rats with ethanol-induced gastritis. Gastritis was induced in rats by intragastric administration of 5 mL/kg body weight of absolute ethanol. The CAW groups were given 250 or 500 mg of extract/kg 2 h before administration of ethanol, respectively. To determine the antioxidant effects of CAW, we determined the level of lipid peroxidation, the level of reduced glutathione (GSH), the activities of catalase, degree of inflammation, and mucus production in the stomach. CAW reduced ethanol-induced inflammation and loss of epithelial cells and increased the mucus production in the stomach. CAW reduced the increase in lipid peroxidation associated with ethanol-induced gastritis (250 and 500 mg/kg, p < 0.01, resp.) and increased mucosal GSH content (500 mg/kg, p < 0.01) and the activity of catalase (250 and 500 mg/kg, p < 0.01, resp.). CAW increased the production of prostaglandin E₂. These findings suggest that CAW protects against ethanol-induced gastric mucosa injury by increasing antioxidant status. We suggest that CAW could be developed for the treatment of gastritis induced by alcohol.

α-Tocopherol administration blocks adaptive changes in cell NADH/NAD+ redox state and mitochondrial function leading to inhibition of gastric mucosa cell proliferation in rats

In experimentally induced chronic gastritis, a compensatory mucosal cell proliferation occurs with enhanced glucose oxidative metabolism linked to lipoperoxidative events. Therefore, this study was aimed at assessing the participation of cell NAD/NADH redox state and mitochondrial functions during gastric mucosa proliferation and the effects of in vivo α-tocopherol (vitamin E) administration. Glucose oxidation and oxygen consumption were tested in gastric mucosa samples obtained from rats with gastritis and from those also treated with α-tocopherol. Gastric mucosal mitochondria were isolated and structural and functional parameters were determined. Succinate oxidation, ADP phosphorylation, mitochondrial enzyme activities, and membrane lipid composition were measured. In addition, parameters indicative of cellular NAD/NADH redox state, proliferation, apoptosis, and nitric oxide (NO) metabolism were also determined. After ethanol withdrawal, the damaged gastric mucosa increased glucose and oxygen consumption, events associated with a more reduced cytoplasmic NAD/NADH ratio. Enhanced mitochondrial oxidative phosphorylation and increased mitochondrial enzyme activities occurred early, accompanied by recovery of lost mitochondrial protein and lipid composition in the gastric mucosa, events associated with increased NO production. When mitochondrial function and structural events were normalized, apoptosis was initiated as assessed by the mitochondrial Bax/Bcl2 ratio. Treatment with α-tocopherol inhibited cell proliferation and blocked enhanced glucose utilization, mitochondrial substrate oxidation, and changes in redox state, delaying the onset of these adaptive metabolic changes, whereas it inhibited cell proliferation. In conclusion, α-tocopherol could abolish damage-induced "stress" signaling by desynchronizing mitochondrial adaptive responses, including mitochondria biogenesis, and consequently NAD/NADH redox, which seems to regulate gastric mucosal cell proliferation.

Gastroprotective effect of Achyranthes aspera Linn. leaf on rats

OBJECTIVE

The study was aimed at evaluating the antiulcer activity of ethanolic extract of Achyranthes aspera (EEAA) leaf.

METHODS

The anti-ulcer assays were performed on pylorus ligation and chronic ethanol induced ulcer model. The effects of the EEAA on gastric content volume, pH, free acidity, total acidity and ulcer index were evaluated.

RESULTS

The percentage of ulcer protection (59.55% and 35.58%) was significantly (P < 0.001) higher in the groups treated with the high dose of EEAA (600 mg/kg), it also reduced the volume of gastric juice and total acidity whereas, gastric pH was increased significantly.

CONCLUSIONS

The results of this study show significant gastroprotective activity of EEAA may be due to presence of phyto-constituents like flavanoids, saponins and tannins.

Novel role of famotidine in downregulation of matrix metalloproteinase-9 during protection of ethanol-induced acute gastric ulcer

Gastric ulcer is a multifaceted process including acid secretion, reactive oxygen species generation, prostaglandin inhibition, and extracellular matrix (ECM) degradation. Matrix metalloproteinases (MMPs) have the ability to cleave and remodel the ECM. We investigated the activity and expression of MMP-9 and -2 in ethanol-induced acute gastric ulceration in rats. We found that severity of gastric ulcer was strongly correlated with increasing doses of ethanol and increased secretion of proMMP-9. ProMMP-9 was upregulated approximately 25-fold at maximum ulcer index. Increased secretion of proMMP-9 was associated with increased expression of tumor necrosis factor-alpha and interleukin-6. We examined the effect of H(2)-receptor antagonists and antioxidants on proMMP-9 secretion and synthesis during prevention of ethanol-induced gastric ulcer. Our data reveal that famotidine dose dependently blocked increased secretion and synthesis of proMMP-9 during gastroprotection and arrested infiltration of inflammatory cells as well as oxidative stress in rat gastric tissues. Similar to H(2)-receptor antagonists, N-acetylcysteine and dimethyl sulfoxide, well-known antioxidants, inhibited proMMP-9 upregulation to the control level. In conclusion, ethanol-induced gastric ulceration is associated with increased expression of proMMP-9 that can be attenuated by H(2)-receptor antagonists and antioxidants. These findings furnish a novel MMP-9-mediated pathway and its inhibition via proinflammatory cytokines by famotidine in ethanol-induced gastric ulceration.

Rate of oxidant stress regulates balance between rat gastric mucosa proliferation and apoptosis

We have characterized an experimental model of ethanol-induced chronic gastritis in which a compensatory mucosal cell proliferation is apparently regulated by lipoperoxidative events. Therefore, the present study is an attempt to further assess the participation of oxidant stress during gastric mucosa proliferation, by administering alpha-tocopherol (vitamin E) to rats with gastritis. A morphometric analysis was done, and parameters indicative of oxidant stress, cellular proliferation (including cyclin D1 levels), apoptotic events, and activities of endogenous antioxidant systems were measured in gastric mucosa from our experimental groups. After ethanol withdrawal, restitution of surface epithelium coincided with increased lipid peroxidation and cell proliferation and further active apoptosis. High alpha-tocopherol dosing (100 IU/kg bw) showed a clear antioxidant effect, abolished cell proliferation, and promoted an early and progressive apoptosis, despite vitamin E also enhancing levels of endogenous antioxidants. Indicators of cell proliferation inversely correlated with apoptotic events, and this relationship was blunted by administering vitamin E, probably by affecting translocation of active cyclin D1 into the nucleus. In conclusion, alpha-tocopherol administration inhibited cell proliferation, leading to a predominance of apoptotic events in ethanol-induced gastric damage. Therefore, the timing and magnitude of lipoperoxidative events seemed to synchronize in vivo cell proliferative and apoptotic events, probably by changing the cell redox state.

Reversing gastric mucosal alterations during ethanol-induced chronic gastritis in rats by oral administration of Opuntia ficus-indica mucilage

AIM: To study the effect of mucilage obtained from cladodes of Opuntia ficus-indica (Cactaceae) on the healing of ethanol-induced gastritis in rats.

METHODS: Chronic gastric mucosa injury was treated with mucilage (5 mg/kg per day) after it was induced by ethanol. Lipid composition, activity of 5’-nucleotidase (a membrane-associated ectoenzyme) and cytosolic activities of lactate and alcohol dehydrogenases in the plasma membrane of gastric mucosa were determined. Histological studies of gastric samples from the experimental groups were included.

RESULTS: Ethanol elicited the histological profile of gastritis characterized by loss of the surface epithelium and infiltration of polymorphonuclear leukocytes. Phosphatidylcholine (PC) decreased and cholesterol content increased in plasma membranes of the gastric mucosa. In addition, cytosolic activity increased while the activity of alcohol dehydrogenases decreased. The administration of mucilage promptly corrected these enzymatic changes. In fact, mucilage readily accelerated restoration of the ethanol-induced histological alterations and the disturbances in plasma membranes of gastric mucosa, showing a univocal anti-inflammatory effect. The activity of 5’-nucleotidase correlated with the changes in lipid composition and the fluidity of gastric mucosal plasma membranes.

CONCLUSION: The beneficial action of mucilage seems correlated with stabilization of plasma membranes of damaged gastric mucosa. Molecular interactions between mucilage monosaccharides and membrane phospholipids, mainly PC and phosphatidylethanolamine (PE), may be the relevant features responsible for changing activities of membrane-attached proteins during the healing process after chronic gastric mucosal damage.

Enhanced intracellular calcium promotes metabolic and secretory disturbances in rat gastric mucosa during ethanol-induced gastritis

Changes in the Ca(2+) homeostasis have been implicated in cell injury and death. However, Ca(2+) participation in ethanol-induced chronic gastric mucosal injury has not been elucidated. We have developed a model of ethanol-induced chronic gastric injury in rats, characterized by marked alterations in plasma membranes from gastric mucosa and a compensatory cell proliferation, which follows ethanol withdrawal. Therefore, the present study explored the possible role of intracellular Ca(2+) in the oxidative metabolism and in acid secretion in this experimental model. Glucose oxidation was greatly enhanced in the injured mucosa, as evaluated by CO(2) production by isolated mucosal preparations incubated with (14)C-radiolabeled glucose in different carbons. Oxygen consumption and acid secretion (aminopyrine accumulation) were also stimulated. A predominating secretory status was morphologically identified by electron microscopy in oxyntic cells of gastric mucosa from ethanol-treated rats. A coupling between secretory and metabolic effects induced by ethanol (demonstrated by an inhibitory effect of omeprazole in both parameters) was found. These ethanol-induced effects were also inhibited by addition of Ca(2+) chelators to isolated gastric mucosa samples. Lanthanum, a Ca(2+) channel blocker, inhibited ethanol-promoted increase of oxidative metabolism. In addition, a stimulated Ca(2+) uptake by mucosal minces and increased in vivo Ca(2+) levels in cytosolic and mitochondrial fractions, were also noticed. Enhanced glucose and oxygen consumptions were associated with higher ATP and NADP+ availability, whereas cytosolic NAD/NADH ratio (assessed by mucosal levels of lactate and pyruvate) was not significantly modified by the chronic ethanol administration. In conclusion, changes in Ca(2+) homeostasis, probably mainly due to increased extracellular Ca(2+) uptake, could mediate secretory and metabolic alterations found in the gastric mucosa from rats chronically treated with ethanol.

Gastric mucosal cell proliferation in ethanol-induced chronic mucosal injury is related to oxidative stress and lipid peroxidation in rats

The oxygen free radicals-induced lipid peroxidation (LP) has been implicated in the pathogenesis of acute ethanol-induced gastric mucosal lesions. However, the role of LP in the generation of chronic gastric mucosal injury is unknown. We have developed a model of chronic mucosal injury induced by continuous ethanol ingestion for 5 days and characterized by marked alterations in plasma membranes from gastric mucosa. Therefore, LP was evaluated in this experimental model. Indicators of peroxidative activity, mucosal glutathione content, thymidine kinase activity (an index of cell proliferation), and histamine H2-receptor (H2R) binding constants were quantified in animals undergoing gastric mucosal damage. The effect of famotidine, a H2R antagonist that readily ameliorates the chronic mucosal injury, was also tested. Increased free radicals and LP levels were detected during gastritis; however, a second, higher peak of LP was noted in mucosal plasma membranes after ethanol withdrawal (recovery period). This further increase of LP coincided with active cell proliferation, decreased mucosal glutathione levels, and diminished specific cimetidine binding by H2R. Administration of famotidine accelerated the mucosal proliferative process, inducing the second lipoperoxidative episode sooner, and preserved the content of glutathione. In addition, LP correlated directly with cell proliferation and inversely with mucosal membrane cimetidine binding. In conclusion, LP seems to be involved in chronic ethanol-induced gastric mucosal injury. However, a further enhancement of plasma membrane LP occurred, associated with increased DNA synthesis and diminished cimetidine binding by membrane H2R. Therefore, increased LP could also participate in the compensatory mucosal proliferation initiated after ethanol withdrawal.