Gastric Cytoprotection Research Articles

Antiulcer Effect of Aqueous Ethanolic Extracts of Pseudocedrela kotschyi (Schweinf) Harms (Meliaceae) and Ximenia americana L. (Olacaceae).

This study aimed to provide pharmacological evidence of Pseudocedrela kotschyi and Ximenia americana in preventing or healing peptic ulcers claimed by traditional healers in Burkina Faso. The trunk bark of Pseudocedrela kotschyi and the roots bark of Ximenia americana (Olacaceae) were macerated in mixed ethanol/water (80:20), respectively, to obtain dried extracts. Two models of hydrochloric acid (HCl, 0.3 M/ethanol, 60%) and hypothermic stress-induced peptic ulcer were used. The cytoprotective effect of individual or combined plant extracts was assessed at 1; 10; 30mg/kg. bw. Then, the healing effect of the extracts at 10mg/kg.bw was evaluated within 21 days of treatment on the hydrochloric acid-induced ulcer model. The extracts' antioxidant activity and phenolic content were assessed to support the plant extracts' efficiency. The extracts of P. kotschyi and X. americana at 10 mg/kg.bw reduced ulceration index in hydrochloric acid- and hypothermic stress-ulcer models by more than 83% and 65%, respectively. The extract from X. americana at 10mg/kg.bw allowed complete ulcer healing but not the association of the two plant extracts. The plant extracts had IC50of inhibition of DPPH radical lower than 5μg/mL and total ferric reducing antioxidant power of more than 77 mg EQAA/100mg. The total polyphenolic content was 64.82 ±0.99 and 53.75 ±1.39 mg EGA/g of dried extract of P. kotschyi and X. americana, respectively. X. americana extract is better than the combined two plant extracts in gastric cytoprotection and ulcer healing. Further investigations are needed to highlight mechanism-based effects.

EVALUATION OF ANTI-ULCER ACTIVITY OF METHANOLIC EXTRACT OF LAGENARIA SICERARIA

Introduction: Ulcer is a common gastrointestinal disorder and can be characterized by inflamed lesions of the mucosa and tissue that protect the gastrointestinal tract. These ulcers can develop when the imbalance occurs between the gastroprotective (mucus, bicarbonate, and prostaglandins) and aggressive (acid, pepsin, bile salts, and Helicobacter pylori bacteria). According to research and as other species from genus Lagenaria shows analgesic, anti-inflammatory, immunomodulatory, antihyperlipidemic, diuretic, and antihelmintic activities on the fruit of Lagenaria siceraria.
 Methods: The anti-ulcer activity of methanolic extract of Lagenaria siceraria fruits was investigated in pylorus ligation, ethanol-induced, Asprin induced and Cold-restraint stress-induced ulcer models in Wistar rats. In all models, the common parameter determined was the ulcer index.
 Results: The extract (100 mg/kg & 200 mg/kg) showed a significant (P<0.005) reduction in gastric volume, free acidity, and ulcer index as compared to control. This present study indicates that Lagenaria siceraria fruit extract has potential anti-ulcer activity in these models.
 Discussion: MELS caused a significant decrease in the gastric volume, free acidity, and total acidity compared to the control group, indicating an antisecretory mechanism. Several scientific studies revealed that phytoconstituents like flavonoids, tannins, terpenoids, and saponin were responsible for gastroprotective agents. Further studies are needed to find out their exact mechanism of action on gastric acid secretion and gastric cytoprotection.

Safety Profile, In Vitro Anti-Inflammatory Activity, and In Vivo Antiulcerogenic Potential of Root Barks from Annona senegalensis Pers. (Annonaceae).

Annona senegalensis (Annonaceae) is a tropical shrub widely distributed in Burkina Faso. This plant is traditionally used as a medicine against many pathologies including typhoid fever, gastrointestinal disorders, ulcers, and inflammatory and infectious diseases. The present study was conducted to evaluate the anti-inflammatory and antiulcer properties of Annona senegalensis root bark extracts. Therefore, toxicity tests were first performed, followed by other biological tests. For this purpose, we first undertook to evaluate the toxicity tests before considering the other biological tests in a second step. The results showed that the extracted fractions had a significant effect for the different methods used (protein denaturation inhibition activity, hyaluronidase inhibition activity, and xanthine oxidase inhibition activity). However, of the extracted fractions used, the ethyl acetate fraction was the most anti-inflammatory fraction. The antiulcer activity was evaluated using the best bioactive fraction. The antiulcer effect of the ethyl acetate fraction may be due to both the reduction of gastric acid secretion and gastric cytoprotection. The results of this study also showed that the bioactive fraction reduced ethanol-induced ulceration and pyloric ligation in a dose-dependent manner, and at the highest dose (200 mg/kg), the effect was similar to that of the reference drug. In summary, the ethyl acetate fraction was found to have the best anti-inflammatory and antiulcerogenic activities. The ethyl acetate fraction at a dose of 200 mg/kg also showed a rather interesting level of cytoprotection. The anti-inflammatory and antiulcer activities could be due to the different secondary metabolites contained in the fractions extracted from Annona senegalensis, notably flavonoids, triterpenoids, steroids, saponins, and tannins. As the mechanisms of action are still little or not understood, we will consider in the future identifying the phytoconstituents and the mechanisms of action involved in the results.

Gastric Cytoprotection as Basis of Gastrointestinal Mucosa Protection and Repair in Erosive Ulcerative Lesions of Various Aetiologies

Aim.Assessment of efficacy and the mechanism of action of gastrointestinal mucosa (GM) protection in current treatment settings with methylmethionine-sulfonium chloride (vitamin U) to illustrate its applicability in erosive ulcerative lesions of various aetiologies.Key points.Aside to damage prevention in exposure to aggressive agents, gastroprotection implies healing promotion under the preserved level of hydrochloric acid secretion. Prostaglandins (PG) and SH-antioxidants are key mediators of gastroprotection in acute and chronic damage. SH-containing endogenous substances (L-cysteine, D,L-methionine, GSH) and exogenous molecules (methylmethionine-sulfonium chloride (MMSC), N-acetylcysteine) prevent damage due to the ability to absorb/neutralise free radicals released in xenobiotic-triggered cell damage, inhibit TNF-α expression, reduce the aspirin-induced leukocyte-endothelium adhesion and stimulate mucin release. In experiment, MMSC prevented the ethanol-induced GM damage, stimulated mucin release and its redistribution on the GM surface; in clinical trials, MMSC effectively facilitated remission in duodenal ulcer.Conclusion.Preparations exerting a protective effect on gastroduodenal mucosa, such as methylmethionine-sulfonium chloride (vitamin U), may improve basic treatment settings and facilitate remission in erosive ulcerative lesions of upper gastrointestinal tract.

Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals.

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

Stress Gastric Ulcers and Cytoprotective Strategies: Perspectives and Trends.

Stress gastric ulceration is a clinical condition leading to morbidity/mortality and complex etiopathological factors are involved. Pharmacotherapy of such gastric mucosal lesions is not consistent and novel strategies are being explored. Targeting gastrointestinal factors have showed equivocal results and there is a possibility of involvement of extra-gastrointestinal factors. Stress is a highly interactive biological response in which the brain plays a key role. The involvement of brain substrates like the limbic system (amygdala, cortex, hippocampus) and behavioral traits has been investigated and research data has shown that the limbic brain-gut axis may be involved in the regulation of gastric mucosal integrity during stressful situations. The amygdaloid complex, its connections with other limbic structures and their neural networks act in tandem to contribute to both stress ulceration and gastroprotection. Complex neurotransmitter interactions in these areas involving biogenic amines and neuropeptides have been shown to modulate stress ulcerogenesis in experimental models. The immune system and brain-immune interactions also appear to play a decisive role in the genesis of such stress gastric lesions and the possibility of a brain-gut-immune axis has been proposed during stress gastric lesions. More recent studies have shown the involvement of oxidative stress and nitric oxide as well as their interactions during such stress gastric pathology, indicating the possible role of antioxidants and NO modulators as gastroprotective agents for stress ulceration. In view of the complex pathophysiology, multiple targets and lack of consistent therapeutic modalities, newer/alternative hypotheses are constantly emerging, which could be explored for effective treatment strategies aimed at gastric cytoprotection. Herbal agents with adaptogenic properties could be worth exploring in this regard as some of these phytopharmaceutical agents used in traditional medicine have been shown to exhibit gastric cytoprotection as part of their anti-stress profile. Further, their interactions with brain neurotransmitters and immune mechanisms and their relative safety could make them prospective leads for stress ulcer prophylaxis and treatment.

Gastric cytoprotection as a basis for defense and restoration of gastrointestinal mucosa in erosive-ulcerative lesions of different etiologies

Aim: to analyze the mechanism of action and effectiveness of gastrointestinal (GI) tract mucosa defense within the scope of latest treatment scheme using the example of MMSC (Vitamin U) and to present possibility of its use in erosive-ulcerative lesions of different etiologies.General findings:Conclusion: Medications, that exert protective effect on gastroduodenal mucosa, MMSC (vitamin U), particularly, could be used for the purpose of main treatment schemes fortification and remission maintaining in erosive-ulcera- tive damage of upper GI tract.

A181 ENDOSCOPIC BALLOON DILATION IS EFFECTIVE AND SAFE IN THE MANAGEMENT OF NSAID-INDUCED NON-ULCERATIVE GASTRIC OUTLET OBSTRUCTION

Abstract Background We describe an unusual case of NSAID-induced gastric outlet obstruction (GOO) in the absence of malignancy or ulcers. This was successfully managed conservatively with drug withdrawal and serial endoscopic balloon dilation (EBD). Aims Case Report Methods Case Report and Literature Review Results A 58-year-old woman with 20-year history of daily Ketorolac use for osteoarthritis presented with iron deficiency anemia (IDA) of 58 g/L and post-prandial emesis for 2 months. There was no overt GI bleeding. Gastroscopy revealed severe erosive esophagitis and GOO with no ulcers. After a negative CT imaging ruled out extrinsic malignant compression, GOO was managed with EBD. Examination of the duodenum post-EBD revealed complete atrophy and scalloping. Focused biopsies reveal chronic gastritis, complete villous atrophy in the duodenum; ruled out H. Pylori, celiac disease, amyloidosis and dysplasia. EUS negative for infiltrative disease or regional adenopathy. Vitamin B12, anti-TTG I IgA, HLA DQ2/8 were normal. These findings made drug-induced enteropathy the top contender. PPI therapy was initiated and NSAID discontinued. Five serial EBD were performed over 4 months to 18mm. A pureed diet was tolerated after 2 dilations. Follow-up at 3 months showed partial recovery of enteropathy and pyloric stenosis. No adverse events were seen. The severe esophagitis was likely an erosive process secondary to reflux from GOO. Her IDA is likely multifactorial: Severe enteropathy and GOO may have led to chronic malabsorption; occult GI bleeding from erosions or ulcers that have healed may further contribute. Ketorolac could explain the enteropathy. COX-1 inhibition leads to decreased gastric cytoprotection. In rat models, COX-2 inhibition has been suggested to delay gastric healing and dysregulated immune response to food antigens in the small bowel [4–6]. NSAID-induced GOO almost always occur in the context of peptic ulcer disease [1,2]. A similar case [3] found pyloric stenosis in a 75-year old woman with esophagitis and ulcer-induced pyloric stenosis. They postulate that post ulcerative healing led to benign pyloric stenosis and explained the absence of ulcers. Historically, surgical intervention and stent placement have played a major role in the management of benign mechanical GOO. EBD has replaced surgical intervention as first line therapy [7] showing promising results beyond 3 months post EBD[8], sparing patients from surgery related morbidity. An algorithm has been suggested by us [Img 1] for the management of benign GOO. Conclusions We present an unusual case of NSAID-induced mechanical GOO and enteropathy. This case highlights these entities as rare but serious complications of chronic NSAID use. Management of benign mechanical GOO should be individualized. Prudence with prescribing NSAIDs to at risk populations is recommended. Funding Agencies None

Why ‘gastric cytoprotection' is still relevant: A complex pathophysiologic response or a single mechanism?

Why ‘gastric cytoprotection' is still relevant: A complex pathophysiologic response or a single mechanism?

The Protective Potential of Phyllanthus niruri and Corilagin on Gastric Lesions Induced in Rodents by Different Harmful Agents.

The gastroprotective effect of the methanol extract of Phyllantus niruri and its main constituent, corilagin, were studied in vivo. The extract (50, 125, or 250 mg/kg, p. o.) inhibited ethanol-induced lesions in rats by 43 % (p < 0.001), 69 % (p < 0.001), and 99 % (p < 0.001), respectively. It also inhibited the formation of indomethacin-induced gastric ulcers in rats by 80 % (p < 0.01), 89 % (p < 0.01), and 97 % (p < 0.01). A decrease in lipid hydroperoxide levels (p < 0.01) and in myeloperoxidase activity (p < 0.05) evidenced a reduction of oxidative damage and neutrophil infiltration in gastric tissues from ulcerated mice using ethanol/HCl. Potent in vitro free radical scavenger activity (IC50 = 0.07) using the DPPH assay was observed. In contrast, the extract (250 mg/kg, i. d.) did not show antisecretory activity in pylorus-ligated rats, and also failed to inhibit the H+,K+-ATPase activity in vitro. However, in pylorus-ligated rats, the extract (50, 125, and 250 mg/kg, i. d.) increased adhered mucus content by 22 % (p < 0.05), 28 % (p < 0.01), and 38 % (p < 0.01), respectively. The involvement of prostaglandins, nonprotein endogenous sulfhydryl compounds, α2-receptors, and endogenous nitric oxide in the gastroprotection elicited by the extract was also evaluated. Finally, corilagin reduced the lesion area of ethanol-induced gastric ulcers in mice by 88 % (30 mg/kg, p. o.; p < 0.001). Based on these results, it has been concluded that P. niruri methanol extract possesses gastroprotective activity by different and complementary pathways, which together promote an improvement in gastric cytoprotection. The presence of corilagin may partially explain the effectiveness of the extract against gastric damage.

Role of peroxisome proliferator-activated receptors alpha and gamma in gastric ulcer: An overview of experimental evidences.

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. Three subtypes, PPARα, PPARβ/δ, and PPARγ, have been identified so far. PPARα is expressed in the liver, kidney, small intestine, heart, and muscle, where it activates the fatty acid catabolism and control lipoprotein assembly in response to long-chain unsaturated fatty acids, eicosanoids, and hypolipidemic drugs (e.g., fenofibrate). PPARβ/δ is more broadly expressed and is implicated in fatty acid oxidation, keratinocyte differentiation, wound healing, and macrophage response to very low density lipoprotein metabolism. This isoform has been implicated in transcriptional-repression functions and has been shown to repress the activity of PPARα or PPARγ target genes. PPARγ1 and γ2 are generated from a single-gene peroxisome proliferator-activated receptors gamma by differential promoter usage and alternative splicing. PPARγ1 is expressed in colon, immune system (e.g., monocytes and macrophages), and other tissues where it participates in the modulation of inflammation, cell proliferation, and differentiation. PPARs regulate gene expression through distinct mechanisms: Ligand-dependent transactivation, ligand-independent repression, and ligand-dependent transrepression. Studies in animals have demonstrated the gastric antisecretory activity of PPARα agonists like ciprofibrate, bezafibrate and clofibrate. Study by Pathak et al also demonstrated the effect of PPARα agonist, bezafibrate, on gastric secretion and gastric cytoprotection in various gastric ulcer models in rats. The majority of the experimental studies is on pioglitazone and rosiglitazone, which are PPARγ activators. In all the studies, both the PPARγ activators showed protection against the gastric ulcer and also accelerate the ulcer healing in gastric ulcer model in rats. Therefore, PPARα and PPARγ may be a target for gastric ulcer therapy. Finally, more studies are also needed to confirm the involvement of PPARs α and γ in gastric ulcer.

"Gastric cytoprotection" is still relevant.

Although Andre Robert's historic article on "gastric cytoprotection" in 1979 introduced this new name and concept, gastroprotective drugs (e.g. sofalcone, sucralfate), which prevent and/or accelerate healing of gastric ulcers without inhibiting acid secretion, were known in Japan before or around that time. But since Robert's studies were solely focused on prostaglandins (PG), they became the center of gastrointestinal research for more than 30 years. As endogenous products, PG were implicated in mediating the gastroprotective effect of other drugs such as sofalcone and sucralfate, despite that the cyclooxygenase inhibitor indomethacin diminished but never abolished gastroprotection by other drugs. Another group of endogenous substances, that is, sulfhydryls (SH), investigated in parallel with PG, also seem to play a mechanistic role in gastroprotection, especially since SH alkylators like N-ethylmaleimide counteract virtually any form of gastroprotection. In Robert's terms of "prevention of chemically induced acute mucosal lesions," so far no single mechanism could explain the beneficial effects of diverse protective agents, but I argue that these two endogenous substances (i.e. PG, SH), in addition to histamine, are the main mechanistic mediators of acute gastroprotection: PG and histamine, because as mediators of acute inflammation, they increase vascular permeability (VP), and SH scavenge free radicals. This is contrary to the search for a single mechanism of action, long focused on enhanced secretion of mucus and/or bicarbonate that may contribute but cannot explain all forms of gastroprotection. Nevertheless, based on research work of the last 30 years, in part from our lab, a new mechanistic explanation of gastroprotection may be formulated: it's a complex but orderly and evolution-based physiologic response of the gastric mucosa under pathologic conditions. Namely, one of the first physiologic defense responses of any organ is inflammation that starts with rapid vascular changes (e.g. increased VP and blood flow), followed by cellular events (e.g. infiltration by acute and chronic inflammatory cells). Thus, PG and histamine, by increasing VP create a perivascular edema that dilutes and delays toxic agents reaching the subepithelial capillaries. Otherwise, damaging chemicals may induce severe early vascular injury resulting in blood flow stasis, hypoxia, and necrosis of surrounding epithelial and mesenchymal cells. In this complex response, increased mucus and/or bicarbonate secretion seem to cause luminal dilution of gastrotoxic chemicals that is further reinforced by a perivascular, histodilutional component. This mechanistic explanation would encompass the protective actions of diverse agents as PG, small doses of histamine, motility stimulants, and dilute irritants (i.e. "adaptive cytoprotection"). Thus, although markedly increased VP is pathologic, slight increase in VP seems to be protective, that is, a key element in the complex pathophysiologic response during acute gastroprotection. Over the years, "gastroprotection" was also applied to accelerated healing of chronic gastroduodenal ulcers without reduction of acid secretion. The likely main mechanism here is the binding of angiogenic growth factors (e.g. basic fibroblast growth factor, vascular endothelial growth factor) to the heparin-like structures of sucralfate and sofalcone. Thus, despite intensive research of the last 30 years, gastroprotection is incompletely understood, and we are still far away from effectively treating Helicobacter pylori-negative ulcers and preventing nonsteroidal anti-inflammatory drugs-caused erosions and ulcers in the upper and lower gastrointestinal tract; hence "gastric cytoprotection" research is still relevant.

IN VITRO AND IN VIVO EVALUATION OF THE GASTRORETENTIVE FLOATING DOSAGE FORM

The aim of the present investigation was to develop and optimize gastro retentive floating system of Pantoprazole f or the efficient treatment of acid related disorders and H. Pylori infections. Floating tablets were developed using central composite design (CCD), and optimization was done by employing resp onse surface methodology . The floating tablets were prepared wit h HPMC K 4 M/Ethyl cellulose and natural seed polymer of Delonix regia by wet granulation technique. Buoyancy was achieved by adding an effervescent mixture of sodium bicarbonate and anhydrous citric acid. The Optim ized formulation (BS 3 ) showed no significan t change in physical appearance, drug content, total buoyancy time, or in vitro dissolution pattern after storage at 40°C/75 % relative humidity for 1 month. The best formulation was selected based on in vitro characteristics and was used for the in vivo r adiographi c studies by incorporating BaSO 4 . Evaluation of Gastric retention using x - Ray imaging studies were performed on rabbit to justify the increased gastric residence time of the dosage form in the stomach, based on the floating principle. Further the floating tablets were evaluated for its antiulcer activity in Male wristar rats by ethanol induced ulcer in comparison with standard. The floating formulation shows excellent buoyancy and better gastric cytoprotection when compare d with standard drug.

Evidence for the gastric cytoprotective effect of centrally injected agmatine.

Agmatine (decarboxylated arginine) exerts cytoprotective action in several tissues, such as in the brain, heart or kidneys, but there is still controversy over the effects of agmatine on the gastric mucosa. The aim of the present study was to reveal the potential gastroprotective action of agmatine by using an acid-independent ulcer model to clarify which receptors and peripheral factors are involved in it. Gastric mucosal damage was induced by acidified ethanol. Mucosal levels of calcitonin gene-related peptide (CGRP) and somatostatin were determined by radioimmunoassay. For analysis of gastric motor activity the rubber balloon method was used. It was found that agmatine given intracerebroventricularly (i.c.v., 0.044-220 nmol/rat) significantly inhibited the development of ethanol-induced mucosal damage, while in the case of intraperitoneal injection (0.001-50mg/kg i.p.) it had only a minor effect. The central gastroprotective action of agmatine was completely antagonized by mixed alpha2-adrenoceptor and imidazoline I1 receptor antagonists (idazoxan, efaroxan), but only partially by yohimbine (selective alpha2-adrenoceptor antagonist) and AGN 192403 (selective I1 receptor ligand, putative antagonist). It was also inhibited by the non-selective opioid-receptor antagonist naloxone and the selective δ-opioid receptor antagonist naltrindole, but not by β-funaltrexamine and nor-Binaltorphimine (selective μ- and κ-opioid receptor antagonists, respectively). Furthermore, the effect of agmatine was antagonized by bilateral cervical vagotomy and by pretreatment with indomethacin and NG-nitro-l-arginine. Agmatine also reversed the ethanol-induced reduction of gastric mucosal CGRP and somatostatin content, but did not have any significant effect on gastric motor activity. These results indicate that agmatine given centrally induces gastric cytoprotection, which is mediated by central imidazoline I1 receptors, alpha2-adrenoceptors and δ-opioid receptors. Activation of these receptors induces the release of different mucosal protective factors, such as NO, prostaglandins, CGRP and somatostatin by a vagal-dependent mechanism. Alterations of gastric motility are not likely to contribute to the observed protective effect.

Cyclooxygenases: Proliferation and differentiation

Prostaglandins are formed from arachidonic acid by the action of cyclooxygenase and subsequent downstream synthetases. Mainly two cyclooxygenase isoforms have been identified which are now known as cyclooxygenase-1 and cyclooxygenase-2. Both iso-enzymes transform arachidonic acid to prostaglandins, but differ in their distribution and their physiological roles. The two isoenzymes are similar in protein structure but are produced by divergent genes and have different biological functions. Cyclooxygenase-1 is a constitutively expressed enzyme in most mammalian tissues and maintains normal cellular physiological functions, such as platelet aggregation and gastric cytoprotection; while cyclooxygenase-2 is normally expressed at a very low level in most tissues and is highly inducible by growth factors, cytokines, and tumour promoters. In several studies, the effect of cyclooxygenases on different cell types has been investigated. This review focuses on cyclooxygenases function, cell proliferation and differentiation. Key words : Cyclooxygenases, proliferation, differentiation, prostaglandins, tumor.

Gastric Cytoprotection Beyond Prostaglandins: Cellular and Molecular Mechanisms of Gastroprotective and Ulcer Healing Actions of Antacids

Gastric Cytoprotection Beyond Prostaglandins: Cellular and Molecular Mechanisms of Gastroprotective and Ulcer Healing Actions of Antacids

Gastric Cytoprotection Beyond Prostaglandins: Cellular and Molecular Mechanisms of Gastroprotective and Ulcer Healing Actions of Antacids

This article updates current views on gastric mucosal defense, injury, protection and ulcer healing with a focus on mucosal protective and ulcer healing actions of antacids. The gastric mucosa is continuously exposed to a variety of noxious factors, both endogenous such as: 0.1N hydrochloric acid, pepsin, bile acids, lysolecithin, H. pylori toxins and exogenous such as NSAIDs, ethanol and others. Gastric mucosal integrity is maintained by pre-epithelial, epithelial and post-epithelial defense mechanisms permitting the mucosa to withstand exposure to the above damaging factors. When mucosal defense is weakened or overwhelmed by injurious factors, injury develops in the form of erosions or ulcers. In the late 1970s Andre Robert and coworkers discovered that microgram amounts of a prostaglandin E2 analog protects the gastric mucosa against a variety of ulcerogenic and necrotizing agents - even such strong inducers of injury as 100% ethanol and boiling water. They proposed a new concept of cytoprotection. Subsequently, other compounds, such as sulfhydryls, sucralfate and epidermal growth factor were shown to exert protective action on gastric mucosa. Additionally, some antacids have been shown to exert a potent mucosal protective action against a variety of injurious factors and accelerate healing of erosions and gastric ulcers. These actions of antacids, especially hydrotalcite - the newest and the most extensively studied antacid - are due to activation of prostaglandin synthesis; binding to and inactivation of pepsin, bile acids and H. pylori toxins; induction of heat shock proteins; and, activation of genes encoding growth factors and their receptors.

Irsogladine : Overview of the Mechanisms of Mucosal Protective and Healing- Promoting Actions in the Gastrointestinal Tract

Irsogladine, a mucosal protective drug, was developed in Japan for the treatment of peptic ulcer disease and acute gastritis. This drug is superior to gefarnate, the same therapeutic category drug, in a randomized, controlled and double-blind clinical study in 1987. The mechanisms of irsogladine's actions are apparently different from those of antisecretory drugs. Irsogladine increases intracellular cyclic adenosine 3',5'-monophosphate content via non-selective inhibition of phosphodiesterase isozymes and exhibits gastric cytoprotection partly mediated by endogenous nitric oxide. These effects may account for a variety of actions of irsogladine in the gastrointestinal tract, including facilitation of gap junctional intercellular communication, inhibition of the reduced gastric mucosal blood flow response, suppression of reactive oxygen generation and so on. Since 1984, more than 60 papers have been published to further verify the effects of irsogladine on gap junctional intercellular communication, tight junction, nitric oxide production and neutrophil migration as well as Helicobacter pylori-related pathological changes in the stomach as well as the adverse reactions induced in the stomach or the small intestine by various drugs, including nonsteroidal anti-inflammatory drugs, bisphosphonates or selective serotonin re-uptake inhibitors. In this article, we review recent advances in understanding the mechanisms of irsogladine's actions and the most recent data in experimental as well as clinical studies.

Su1758 Adaptive Gastric Cytoprotection is Mediated by Prostaglandin EP1- but Not EP4-Receptors

Su1758 Adaptive Gastric Cytoprotection is Mediated by Prostaglandin EP1- but Not EP4-Receptors

Acetaminophen and Ibuprofen Overdosage

Acetaminophen and Ibuprofen Overdosage