Gastric Serotonin Biosynthesis and Its Functional Role in L-Arginine-Induced Gastric Proton Secretion.

Among mammals, serotonin is predominantly found in the gastrointestinal tract, where it has been shown to participate in pathway-regulating satiation. For the stomach, vascular serotonin release induced by gastric distension is thought to chiefly contribute to satiation after food intake. However, little information is available on the capability of gastric cells to synthesize, release and respond to serotonin by functional changes of mechanisms regulating gastric acid secretion. We investigated whether human gastric cells are capable of serotonin synthesis and release. First, HGT-1 cells, derived from a human adenocarcinoma of the stomach, and human stomach specimens were immunostained positive for serotonin. In HGT-1 cells, incubation with the tryptophan hydroxylase inhibitor p-chlorophenylalanine reduced the mean serotonin-induced fluorescence signal intensity by 27%. Serotonin release of 147 ± 18%, compared to control HGT-1 cells (set to 100%) was demonstrated after treatment with 30 mM of the satiating amino acid L-Arg. Granisetron, a 5-HT3 receptor antagonist, reduced this L-Arg-induced serotonin release, as well as L-Arg-induced proton secretion. Similarly to the in vitro experiment, human antrum samples released serotonin upon incubation with 10 mM L-Arg. Overall, our data suggest that human parietal cells in culture, as well as from the gastric antrum, synthesize serotonin and release it after treatment with L-Arg via an HTR3-related mechanism. Moreover, we suggest not only gastric distension but also gastric acid secretion to result in peripheral serotonin release.

EGF and BMPs Govern Differentiation and Patterning in Human Gastric Glands.

BACKGROUND & AIMS: The homeostasis of the gastrointestinal epithelium relies on cell regeneration and differentiation into distinct lineages organized inside glands and crypts. Regeneration depends on Wnt/ß-catenin pathway activation, but to understand homeostasis and its dysregulation in disease, we need to identify the signaling microenvironment governing cell differentiation. By using gastric glands as a model, we have identified the signals inducing differentiation of surface mucus-, zymogen-, and gastric acid-producing cells. METHODS: We generated mucosoid cultures from the human stomach and exposed them to different growth factors to obtain cells with features of differentiated foveolar, chief, and parietal cells. We localized the source of the growth factors in the tissue of origin. RESULTS: We show that epidermal growth factor is the major fate determinant distinguishing the surface and inner part of human gastric glands. In combination with bone morphogenetic factor/Noggin signals, epidermal growth factor controls the differentiation of foveolar cells vs parietal or chief cells. We also show that epidermal growth factor is likely to underlie alteration of the gastric mucosa in the precancerous condition atrophic gastritis. CONCLUSIONS: Use of our recently established mucosoid cultures in combination with analysis of the tissue of origin provided a robust strategy to understand differentiation and patterning of human tissue and allowed us to draw a new, detailed map of the signaling microenvironment in the human gastric glands.

Indomethacin can induce cell death in rat gastric parietal cells through alteration of some apoptosis- and autophagy-associated molecules.

In clinical medicine, indomethacin (IND, a non-steroidal anti-inflammatory drug) is used variously in the treatment of severe osteoarthritis, rheumatoid arthritis, gouty arthritis or ankylosing spondylitis. A common complication found alongside the therapeutic characteristics is gastric mucosal damage. This complication is mediated through apoptosis and autophagy of the gastrointestinal mucosal epithelium. Apoptosis and autophagy are critical homeostatic pathways catalysed by caspases downstream of the gastrointestinal mucosal epithelial injury. Both act through molecular signalling pathways characterized by the initiation, mediation, execution and regulation of the cell regulatory cycle. In this study we hypothesized that dysregulated apoptosis and autophagy are associated with IND-induced gastric damage. We examined the spectra of in vivo experimental gastric ulcers in male Sprague-Dawley rats through gastric gavage of IND. Following an 18-hour fast, IND was administered to experimental rats. They were sacrificed at 3-, 6- and 12-hour intervals. Parietal cells (H+ , K+ -ATPase ß-subunit assay) and apoptosis (TUNEL assay) were determined. The expression of apoptosis-signalling caspase (caspases 3, 8, 9 and 12), DNA damage (anti-phospho-histone H2A.X) and autophagy (MAP-LC3, LAMP-1 and cathepsin B)-related molecules in gastric mucosal cells was examined. The administration of IND was associated with gastric mucosal erosions and ulcerations mainly involving the gastric parietal cells (PCs) of the isthmic and upper neck regions and a time-dependent gradual increase in the number of apoptotic PCs with the induction of both apoptotic (upregulation of caspases 3 and 8) cell death and autophagic (MAP-LC3-II, LAMP-1 and cathepsin B) cell death. Autophagy induced by fasting and IND 3 hours initially prompted the degradation of caspase 8. After 6 and 12 hours, damping down of autophagic activity occurred, resulting in the upregulation of active caspase 8 and its nuclear translocation. In conclusion we report that IND can induce time-dependent apoptotic and autophagic cell death of PCs. Our study provides the first indication of the interactions between these two homeostatic pathways in this context.

Ultra-structural study of the indomethacin-induced apoptosis and autophagy in rat gastric parietal cells.

BACKGROUND AND AIM OF THE WORK: Indomethacin (IND), a non-steroidal anti-inflammatory drug, can induce gastric mucosal ulcerations. To date, the ultra-structural changes in the parietal cells (PCs) of the gastric mucosa following the intake of IND are mostly unknown. We carried out the current investigation to get insights into this issue. MATERIALS AND METHODS: We established an animal model consisting of 35 adult male Sprague Dawley rats. The animals were divided into three groups, including; control (normal feeding), fasting, and indomethacin-treated groups. After treatment of 18-h fasting rats with IND, they were sacrificed at 3, 6, and 12-h intervals. The morphological features, including the apoptotic, and autophagic changes in the gastric mucosa PCs were examined using transmission electron microscopy. RESULTS: In normal feeding animals (control group), the gastric PCs were present in various stages of activity. Fasting was associated with the predominance of the inactive parietal cells with features of up-regulated autophagy. In the IND -treated animals (at 3-h interval), PCs showed prominent autophagic changes, and subtle apoptotic cell death. In the IND -treated animals (at 6-12-h interval), PCs showed prominent apoptotic changes, and subtle autophagic features. CONCLUSIONS: Our study indicates that IND treatment could induce gastropathy through time-dependent alterations in the autophagic and apoptotic machinery of PCs. Further studies are needed to examine the underlying molecular mechanisms.

Chronic in vivo exposure to Helicobacter pylori VacA: Assessing the efficacy of automated and long-term intragastric toxin infusion.

Helicobacter pylori (Hp) secrete VacA, a diffusible pore-forming exotoxin that is epidemiologically linked to gastric disease in humans. In vitro studies indicate that VacA modulates gastric epithelial and immune cells, but the in vivo contributions of VacA as an important determinant of Hp colonization and chronic infection remain poorly understood. To identify perturbations in the stomachs of C57BL/6 or BALB/C mice that result specifically from extended VacA exposure, we evaluated the efficacy of administering purified toxin using automated infusion via surgically-implanted, intragastric catheters. At 3 and 30 days of interrupted infusion, VacA was detected in association with gastric glands. In contrast to previously-reported tissue damage resulting from short term exposure to Hp extracts administered by oral gavage, extended infusion of VacA did not damage stomach, esophageal, intestinal, or liver tissue. However, several alterations previously reported during Hp infection were detected in animals infused with VacA, including reduction of the gastric mucus layer, and increased vacuolation of parietal cells. VacA infusion invoked an immune response, as indicated by the detection of circulating VacA antibodies. These foundational studies support the use of VacA infusion for identifying gastric alterations that are unambiguously attributable to long-term exposure to toxin.

Na+-K+-2Cl- cotransporter 2 located in the human and murine gastric mucosa is involved in secretagogue-induced gastric acid secretion and is downregulated in lipopolysaccharide-treated mice.

Na+-K+-2Cl- cotransporter (NKCC) is expressed at exceptionally high levels in gastric parietal cells. Bumetanide, a potent loop diuretic that blocks NKCC, usually causes a decrease in gastric acid secretion. Endotoxaemia causes hypochlorhydria in vivo, in which lipopolysaccharide (LPS) plays an important role. This study aimed to investigate the effect of NKCC2 on gastric acid secretion and its alteration in LPS-treated mice. The scanning ion-selective electrode technique and real-time pH titration combined with RNA interference were used to determine the effects of bumetanide on gastric acid secretion. Immunochemistry and Western blotting were performed to investigate the changes in NKCC2 expression in LPS-treated mice. Immunoreactivity of NKCC1 and NKCC2 was mainly observed near the basolateral and apical membranes of parietal cells, respectively. Pretreatment with bumetanide reduced the histamine-stimulated H+ flux in the mouse gastric mucosa. The apical, but not the basolateral, addition of bumetanide inhibited forskolin- or histamine/3-isobutyl-1-methylxanthine(IBMX)-induced gastric acid secretion. In vivo treatment with NKCC2 siRNA inhibited forskolin-induced acid secretion. Upon histamine stimulation, the majority of NKCC2 was targeted to the apical membrane in the gastric mucosa and in primary cultured parietal cells. The expression of NKCC2 and vesicle-associated membrane protein-2 (VAMP2), but not that of H+/K+-ATPase, was decreased in the gastric mucosa of LPS-treated mice. Blocking apical NKCC2, but not basolateral NKCC1, by bumetanide inhibited secretagogue-induced gastric acid secretion, during which the membrane trafficking of NKCC2 may be necessary. The downregulation of NKCC2 and VAMP2 may be related to the reduced gastric acid secretion induced by LPS.

The Physiology of the Gastric Parietal Cell.

Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria. However, a fine balance of activators and inhibitors of parietal cell-mediated acid secretion is required to ensure proper digestion of food, while preventing damage to the gastric and duodenal mucosa. As a result, parietal cell secretion is highly regulated through numerous mechanisms including the vagus nerve, gastrin, histamine, ghrelin, somatostatin, glucagon-like peptide 1, and other agonists and antagonists. The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl. Inhibition of the H+-K+-ATPase is the most efficacious method of preventing harmful gastric acid secretion. Proton pump inhibitors and potassium competitive acid blockers are widely used therapeutically to inhibit acid secretion. Stimulated delivery of the H+-K+-ATPase to the parietal cell apical surface requires the fusion of intracellular tubulovesicles with the overlying secretory canaliculus, a process that represents the most prominent example of apical membrane recycling. In addition to their unique ability to secrete gastric acid, parietal cells also play an important role in gastric mucosal homeostasis through the secretion of multiple growth factor molecules. The gastric parietal cell therefore plays multiple roles in gastric secretion and protection as well as coordination of physiological repair.

Cystine/Glutamate Antiporter (xCT) Is Required for Chief Cell Plasticity After Gastric Injury.

BACKGROUND & AIMS: Many differentiated epithelial cell types are able to reprogram in response to tissue damage. Although reprogramming represents an important physiological response to injury, the regulation of cellular plasticity is not well understood. Damage to the gastric epithelium initiates reprogramming of zymogenic chief cells into a metaplastic cell lineage known as spasmolytic polypeptide-expressing metaplasia (SPEM). The present study seeks to identify the role of xCT, a cystine/glutamate antiporter, in chief cell reprogramming after gastric injury. We hypothesize that xCT-dependent reactive oxygen species (ROS) detoxification is required for the reprogramming of chief cells into SPEM. METHODS: Sulfasalazine (an xCT inhibitor) and small interfering RNA knockdown were used to target xCT on metaplastic cells in vitro. Sulfasalazine-treated wild-type mice and xCT knockout mice were analyzed. L635 or DMP-777 treatment was used to chemically induce acute gastric damage. The anti-inflammatory metabolites of sulfasalazine (sulfapyridine and mesalazine) were used as controls. Normal gastric lineages, metaplastic markers, autophagy, proliferation, xCT activity, ROS, and apoptosis were assessed. RESULTS: xCT was up-regulated early as chief cells transitioned into SPEM. Inhibition of xCT or small interfering RNA knockdown blocked cystine uptake and decreased glutathione production by metaplastic cells and prevented ROS detoxification and proliferation. Moreover, xCT activity was required for chief cell reprogramming into SPEM after gastric injury in vivo. Chief cells from xCT-deficient mice showed decreased autophagy, mucus granule formation and proliferation, as well as increased levels of ROS and apoptosis compared with wild-type mice. On the other hand, the anti-inflammatory metabolites of sulfasalazine did not affect SPEM development. CONCLUSIONS: The results presented here suggest that maintaining redox balance is crucial for progression through the reprogramming process and that xCT-mediated cystine uptake is required for chief cell plasticity and ROS detoxification.

Noncaloric Sweeteners Induce Peripheral Serotonin Secretion via the T1R3-Dependent Pathway in Human Gastric Parietal Tumor Cells (HGT-1).

The role of sweet taste in energy intake and satiety regulation is still controversial. Noncaloric artificial sweeteners (NCSs) are thought to help reduce energy intake, although little is known about their impact on the satiating neurotransmitter serotonin (5-HT). In the gastrointestinal (GI) tract, 5-HT regulates gastric acid secretion and gastric motility, both part of the complex network of mechanisms regulating food intake and satiety. This study demonstrated a stimulating impact compared to controls (100%) on 5-HT release in human gastric tumor cells (HGT-1) by the NCSs cyclamate (50 mM, 157% ± 6.3%), acesulfame potassium (Ace K, 50 mM, 197% ± 8.6%), saccharin (50 mM, 147% ± 6.7%), sucralose (50 mM, 194% ± 11%), and neohesperidin dihydrochalcone (NHDC, 1 mM, 201% ± 13%). Although these effects were not associated with the sweet taste intensity of the NCSs tested, involvement of the sweet receptor subunit T1R3 in the NCS-evoked response was demonstrated by mRNA expression of TAS1R3, co-incubation experiments using the T1R3 receptor antagonist lactisole, and a TAS1R3 siRNA knockdown approach. Analysis of the downstream signaling revealed activation of the cAMP/ERK/Ca2+ cascade. Co-treatment experiments with 10 mM glucose enhanced the 5-HT release induced by cyclamate, Ace K, saccharin, and sucralose, thereby supporting the enhancing effect of glucose on a NCS-mediated response. Overall, the results obtained identify NCSs as potent inducers of 5-HT release via T1R3 in human gastric parietal cells in culture and warrant in vivo studies to demonstrate their efficacy.

Modulations in extracellular calcium lead to H+-ATPase-dependent acid secretion: a clarification of PPI failure.

The H+,K+-ATPase was identified as the primary proton secretory pathway in the gastric parietal cell and is the pharmacological target of agents suppressing acid secretion. Recently, we identified a second acid secretory protein expressed in the parietal cell, the vacuolar H+-ATPase (V-type ATPase). The aim of the present study was to further characterize H+-ATPase activation by modulations in extracellular calcium via the calcium sensing receptor (CaSR). Isolated gastric glands were loaded with the pH indicator dye BCECF-AM [2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester] to measure intracellular pH. Experiments were conducted in the absence of sodium and potassium to monitor H+-ATPase-specific transport activity. CaSR was activated with the calcimimetic R568 (400 nM) and/or by modulations in extracellular Ca2+. Elevation in calcium concentrations increased proton extrusion from the gastric parietal cell. Allosteric modification of the CaSR via R568 and calcium increased vacuolar H+-ATPase activity significantly (ΔpH/minlowCa2+(0.1mM) = 0.001 ± 0.001, ΔpH/minnormalCa2+(1.0mM) = 0.033 ± 0.004, ΔpH/minhighCa2+(5.0mM) = 0.051 ± 0.005). Carbachol significantly suppressed calcium-induced gastric acid secretion via the H+-ATPase under sodium- and potassium-free conditions. We conclude that the V-type H+-ATPase is tightly linked to CaSR activation. We observed that proton pump inhibitor (PPI) exposure does not modulate H+-ATPase activity. This elevated blood calcium activation of the H+-ATPase could provide an explanation for recurrent reflux symptoms while taking a PPI therapy. NEW & NOTEWORTHY This study emphasizes the role of the H+-ATPase in acid secretion. We further demonstrate the modification of this proton excretion pathway by extracellular calcium and the activation of the calcium sensing receptor CaSR. The novelty of this paper is based on the modulation of the H+-ATPase via both extracellular Ca (activation) and the classical secretagogues histamine and carbachol (inactivation). Both activation and inactivation of this proton pump are independent of PPI modulation.

Activation of Secretagogue Independent Gastric Acid Secretion via Endothelial Nitric Oxide Synthase Stimulation in Rats.

BACKGROUND/AIMS: L-arginine is an important mediator of cell division, wound healing, and immune function. It can be transformed by the nitric oxide synthase (NOS) to nitric oxide (NO), an important cell signaling molecule. Recent studies from our laboratory demonstrate specific effects of L-arginine (10mM) exposure on gastric acid secretion in rat parietal cells. METHODS: Studies were performed with isolated gastric glands and the pH sensitive dye BCECF-AM +/- L-arginine to examine its effects on acid secretion. The direct NO-donor diethylamine NONOate sodium salt hydrate, was also used while monitoring intracellular pH. The specific inhibitor of the intracellular NO signal cascade ODQ was also used. RESULTS: We found that gastric proton extrusion was activated with application of L-arginine (10mM), in a separate series when L-arginine (10mM) + L-NAME (30µM) were added there was no acid secretion. Addition of the NO-donor diethylamine NONOate sodium salt hydrate (10µM) also induced acid secretion. When the selective sGC-inhibitor ODQ was added with NONOate we did not observe acid secretion. CONCLUSION: We conclude that L-arginine is a novel secretagogue, which can mediate gastric acid secretion. Furthermore, the intake of L-arginine causes direct activation of the H+, K+ ATPase and increased proton extrusion from parietal cells resulting in the increased risk for acid-related diseases. The NO/sGC/cGMP pathway has never been described as a possible intracellular mechanism for H+, K+ ATPase activation before and presents a completely new scientific finding. Moreover, our studies demonstrate a novel role for L-NAME to effectively eliminate NOS induced acid secretion and thereby reducing the risk for L-arginine inducible ulcer disease.

Mitochondrial Iron Accumulation in Parietal and Chief Cells in Iron Pill Gastritis Following Billroth II Gastrectomy: Case Report Including Electron Microscopic Examination.

Iron pill gastritis has been shown to be associated with superficial gastric erosion and deposition of iron in lamina propria and gastric antral glands. However, iron absorption in gastric parietal and chief cells is rare. We present a case of a 62-year-old man with iron deficiency anemia. His past medical history is significant for Billroth II surgery. His medications include ferrous sulphate 325mg. Esophagogastroduodenoscopy showed diffuse circumferential abnormal mucosa at the gastro-jejunal anastomosis. The mucosa was erythematous and violaceous. Biopsy showed reactive gastropathy with iron deposits predominantly in macrophages, parietal cells, and chief cells. These findings were confirmed by iron stain and later by electron micrography of the gastric mucosa that showed iron deposits in mitochondria and cytoplasm of the parietal and chief cells.

Lgr5-expressing chief cells drive epithelial regeneration and cancer in the oxyntic stomach.

The daily renewal of the corpus epithelium is fuelled by adult stem cells residing within tubular glands, but the identity of these stem cells remains controversial. Lgr5 marks homeostatic stem cells and 'reserve' stem cells in multiple tissues. Here, we report Lgr5 expression in a subpopulation of chief cells in mouse and human corpus glands. Using a non-variegated Lgr5-2A-CreERT2 mouse model, we show by lineage tracing that Lgr5-expressing chief cells do not behave as corpus stem cells during homeostasis, but are recruited to function as stem cells to effect epithelial renewal following injury by activating Wnt signalling. Ablation of Lgr5+ cells severely impairs epithelial homeostasis in the corpus, indicating an essential role for these Lgr5+ cells in maintaining the homeostatic stem cell pool. We additionally define Lgr5+ chief cells as a major cell-of-origin of gastric cancer. These findings reveal clinically relevant insights into homeostasis, repair and cancer in the corpus.

Gastrin induces parathyroid hormone-like hormone expression in gastric parietal cells.

Parietal cells play a fundamental role in stomach maintenance, not only by creating a pathogen-free environment through the production of gastric acid, but also by secreting growth factors important for homeostasis of the gastric epithelium. The gastrointestinal hormone gastrin is known to be a central regulator of both parietal cell function and gastric epithelial cell proliferation and differentiation. Our previous gene expression profiling studies of mouse stomach identified parathyroid hormone-like hormone (PTHLH) as a potential gastrin-regulated gastric growth factor. Although PTHLH is commonly overexpressed in gastric tumors, its normal expression, function, and regulation in the stomach are poorly understood. In this study we used pharmacologic and genetic mouse models as well as human gastric cancer cell lines to determine the cellular localization and regulation of this growth factor by the hormone gastrin. Analysis of PthlhLacZ/+ knock-in reporter mice localized Pthlh expression to parietal cells in the gastric corpus. Regulation by gastrin was demonstrated by increased Pthlh mRNA abundance after acute gastrin treatment in wild-type mice and reduced expression in gastrin-deficient mice. PTHLH transcripts were also observed in normal human stomach as well as in human gastric cancer cell lines. Gastrin treatment of AGS-E gastric cancer cells induced a rapid and robust increase in numerous PTHLH mRNA isoforms. This induction was largely due to increased transcriptional initiation, although analysis of mRNA half-life showed that gastrin treatment also extended the half-life of PTHLH mRNA, suggesting that gastrin regulates expression by both transcriptional and posttranscriptional mechanisms.NEW & NOTEWORTHY We show that the growth factor parathyroid hormone-like hormone (PTHLH) is expressed in acid-secreting parietal cells of the mouse stomach. We define the specific PTHLH mRNA isoforms expressed in human stomach and in human gastric cancer cell lines and show that gastrin induces PTHLH expression via transcription activation and mRNA stabilization. Our findings suggest that PTHLH is a gastrin-regulated growth factor that might contribute to gastric epithelial cell homeostasis.

A single transcription factor is sufficient to induce and maintain secretory cell architecture.

We hypothesized that basic helix-loop-helix (bHLH) MIST1 (BHLHA15) is a "scaling factor" that universally establishes secretory morphology in cells that perform regulated secretion. Here, we show that targeted deletion of MIST1 caused dismantling of the secretory apparatus of diverse exocrine cells. Parietal cells (PCs), whose function is to pump acid into the stomach, normally lack MIST1 and do not perform regulated secretion. Forced expression of MIST1 in PCs caused them to expand their apical cytoplasm, rearrange mitochondrial/lysosome trafficking, and generate large secretory granules. Mist1 induced a cohort of genes regulated by MIST1 in multiple organs but did not affect PC function. MIST1 bound CATATG/CAGCTG E boxes in the first intron of genes that regulate autophagosome/lysosomal degradation, mitochondrial trafficking, and amino acid metabolism. Similar alterations in cell architecture and gene expression were also caused by ectopically inducing MIST1 in vivo in hepatocytes. Thus, MIST1 is a scaling factor necessary and sufficient by itself to induce and maintain secretory cell architecture. Our results indicate that, whereas mature cell types in each organ may have unique developmental origins, cells performing similar physiological functions throughout the body share similar transcription factor-mediated architectural "blueprints."

Gastric mucosal cracked and cobblestone-like changes resulting from proton pump inhibitor use.

BACKGROUND AND AIM: Use of proton pump inhibitors (PPI) is histologically associated with oxyntic gland dilatations. Two interesting mucosal changes are often detected endoscopically in patients who use PPI: gastric cracked mucosa (GCM) and gastric cobblestone-like mucosa (GCSM). The aim of the present study was to clarify the relationship between PPI use and these mucosal changes. METHODS: This was a single-center observational study. All successive subjects who underwent a routine esophagogastroduodenoscopy (EGD) between August and November 2014 in Hokkaido University Hospital were enrolled. Endoscopists carried out the assessment blinded to the use of PPI and checked for GCSM and GCM using original diagnostic criteria for GCM and GCSM. Subjects were divided into two groups: those who used PPI (PPI group) and those who did not (control group). Endoscopic findings and backgrounds were compared between the two groups. RESULTS: A total of 538 patients were analyzed (control group: 374 patients, men/women: 204/170, median age: 65.2 years; PPI group: 164 patients, men/women: 89/75, median age: 67.1 years). GCM was detected in 54 (10.0%) subjects, and GCSM was detected in 18 (3.3%) subjects. There was a significant difference in the prevalence rate of GCM between the control group (14/374, 3.7%) and the PPI group (40/164, 24.4%) (P < 0.01). GCSM was significantly more prevalent in the PPI group (15/164, 9.1%) than in the control group (3/374, 0.8%) (P < 0.01). CONCLUSION: Novel GCM and GCSM endoscopic findings in the corpus area seem to be strongly associated with PPI use.

Targeted Apoptosis of Parietal Cells Is Insufficient to Induce Metaplasia in Stomach.

Parietal cell atrophy is considered to cause metaplasia in the stomach. We developed mice that express the diphtheria toxin receptor specifically in parietal cells to induce their death, and found this to increase proliferation in the normal stem cell zone and neck but not to cause metaplastic reprogramming of chief cells. Furthermore, the metaplasia-inducing agents tamoxifen or DMP-777 still induced metaplasia even after previous destruction of parietal cells by diphtheria toxin. Atrophy of parietal cells alone therefore is not sufficient to induce metaplasia: completion of metaplastic reprogramming of chief cells requires mechanisms beyond parietal cell injury or death.

Secretagogue-dependent and -independent transport of zinc hydration forms in rat parietal cells.

Prolonged exposure to gastric acid is a leading cause of gastroesophageal reflux disease (GERD) and esophagitis. With the ever increasing number of patients showing insensitivity to proton-pump-inhibitor (PPI) therapy with recurrence of symptoms over time, alternative treatment options remain an important issue. Previous studies from our laboratory have shown that a zinc sulfate salt can inhibit HCl generation at the cellular level of the parietal cell. In this paper, we examine the difference between two hydration forms of ZnSO4 (monohydrate H2O and heptahydrate 7H2O) in their entry characteristics into the parietal cell under several physiological conditions associated with acid secretion. Using the Zn sensitive fluorochrome Newport Green, we examined the rate of Zn entry in Δfluorescent units/second (ΔFU/second), at two different concentrations for both hydration states on both fasted and non-fasted animals. In a separate series of studies, we examined the effects of secretagogues on the entry rates and transport mechanisms. Exposure of the secretagogue carbachol transformed the resting parietal cell to an activated state and represents a stimulated condition through the neuronal pathway. The hormonal activation of the parietal cell was achieved by using histamine. Non-fasted conditions were considered to be a state between hormonal and neuronal activation. To demonstrate that ZnSO4 enters the parietal cell through the NKCC1 co-transporter, the inhibitor bumetanide was applied during secretagogue-stimulated acid secretion. Both salts, monohydrate and heptahydrate ZnSO4, show a concentration-dependent cell entry under all conditions studied. During stimulated acid secretion, induced through either the neuronal or the hormonal pathway, heptahydrate ZnSO4 enters the parietal cell significantly faster than monohydrate ZnSO4, whereas monohydrate ZnSO4 exhibits faster entry during resting conditions in fasted animals. At 30 µM following stimulation with histamine, heptahydrate ZnSO4 enters the cell faster than monohydrate ZnSO4 (ΔFU/second 30 µM ZnSO4*7H2O + histamine = 1.782, ΔFU/second 30 µM ZnSO4*H2O+histamine = 1.038, respectively). Three hundred micromolar, heptahydrate ZnSO4 shows a faster entry into the cells (ΔFU/second ZnSO4*7H2O300µM + carbachol = 4.02407) compared to monohydrate ZnSO4 (ΔFU/second ZnSO4*H2O300µM + carbachol = 3.225) following exposure to carbachol. The mechanism of entry of both salts was found to be predominantly via the basolateral NKCC1 transporter with the rate of zinc entry decreasing to minimal values (ΔFU/second = 0.275) after application of bumetanide during stimulated conditions.