Helicobacter pylori and gastric acid secretion

Helicobacter pylori (H. pylori) infection leads to profound changes in gastric physiology. Several clinical and animal studies have been performed to clarify the influence of H. pylori on gastric acid secretion. Published data, however, are not consistent throughout. Infection of the gastric antrum, which can be observed mainly in duodenal ulcer patients, increases gastrin release and consecutively acid output. The net effect of corpus and antrum gastritis, such as in patients with gastric cancer, is to decrease acid secretion. Chronic H. pylori infection may finally promote gastric atrophy with irreversibly diminished acid secretion but in earlier stages of this infection eradication of H. pylori normalizes gastric secretory activity.     

Characteristics of gastritis in patients with Helicobacter pylori-positive reflux esophagitis

BACKGROUND AND AIM: The influence of Helicobacter pylori on gastric acid secretion differs with the status of gastritis. The histological characteristics of gastritis in H. pylori-positive patients with reflux esophagitis have not been fully investigated. We therefore studied the pattern of endoscopic gastric mucosal atrophy and degree of histological gastritis in such patients. METHODS: Subjects comprised 41 H. pylori-positive patients with reflux esophagitis, 41 age- and sex-matched patients with duodenal ulcer, and 41 patients with early gastric cancer. The endoscopic pattern of gastric mucosal atrophy was reviewed, and the degree of histological gastritis in biopsy specimens from the antrum and corpus was assessed in accordance with the updated Sydney system. RESULTS: The grade of endoscopic and histological gastric mucosal atrophy in patients with reflux esophagitis was significantly lower than that in patients with gastric cancer, and the histological scores for antral atrophy and metaplasia in patients with reflux esophagitis tended to be lower than those in patients with duodenal ulcer. In patients with reflux esophagitis and duodenal ulcer, the scores for antral inflammation and activity tended to be higher than those for the corpus. Conversely, the inflammation and activity score in patients with early gastric cancer showed a corpus-predominant gastritis pattern. CONCLUSION: In H. pylori-positive patients with reflux esophagitis, the degree of endoscopic gastric mucosal atrophy is low and histologically there is an antral-predominant gastritis pattern. Therefore, gastric acid secretion in H. pylori-positive patients with reflux esophagitis may be augmented by H. pylori infection.     

The role of gastrin in ulcer pathogenesis.

Duodenal ulcer patients are characterized by an antrum-predominant, body-sparing, nonatrophic Helicobacter pylori (H. pylori) gastritis, which results in increased gastrin release and increased acid secretion. The increased gastrin release is caused by the infection impairing the acid-mediated inhibitory control of gastrin release. The elevated levels of the gastrin stimulate the healthy uninflamed, non-atrophic acid-secreting region of the stomach to secrete excess amounts of acid. The increased gastrin also exerts trophic effects on the oxyntic mucosa, causing hyperplasia of both the enterochromaffin-like cells and the parietal cells. These trophic changes in the mucosa further enhance its ability to secrete acid. The increased acid secretion results in an increased duodenal acid load, causing gastric metaplasia of the duodenal bulb and eventually the development of ulceration. In H. pylori-infected subjects without duodenal ulceration, a different pattern of gastritis is seen. This includes atrophy of the antrum, which reduces the number of G-cells and thus the degree of hypergastrinaemia induced by the antral infection. There are usually also varying degrees of inflammation and atrophy of the acid-secreting mucosa, which impair its ability to secrete acid in response to gastrin stimulation. The combined effects of the atrophy of the antrum and the inflammation of the antrum of the body mucosa therefore prevent H. pylori-induced acid hypersecretion and may result in varying degrees of hypochlorhydria. The particular pattern of gastritis that a subject develops in response to H. pylori infection and their likelihood of developing a duodenal ulcer is likely to be determinded by host genetic factors plus dietary factors.     

Acid secretion and serum gastrin levels in individuals with Campylobacter pylori

Campylobacter pylori may cause gastritis and has been proposed as an etiologic factor in the development of peptic ulcer. However, it may be an acid-sensitive microbe and before it can be implicated in the pathogenesis of peptic ulcer, it should be consistently found in ulcer patients with normal acid secretion. Thirty-six patients with C. pylori by Warthin-Starry stain underwent gastric analysis; 25 were normochlorhydric and 11 hypochlorhydric. Ulcers were present in 19 normochlorhydric patients (10, gastric; 9, duodenal) and 2 hypochlorhydric patients (gastric). Median basal acid output was higher for those with duodenal ulcer (38 mmol/h) than gastric ulcer (28 mmol/h) or miscellaneous endoscopic features (33 mmol/h). The hypergastrinemia seen in 12 patients with negative secretin provocation tests was believed to be due to various nongastrinoma conditions. Campylobacter pylori was found in 6 normogastrinemic patients with elevated acid output and in 1 gastrinoma patient with marked acid hypersecretion. Histologic chronic gastritis was present in all subjects and 29 had active chronic gastritis. Twenty-three patients were taking H2-receptor antagonists at the time of diagnosis which did not seem to interfere with culture results. Using standard acid secretory tests, we conclude that C. pylori can survive in a wide range of acid conditions.     

Morphological and functional restoration of parietal cells in Helicobacter pylori associated enlarged fold gastritis after eradication

BACKGROUND/AIM: Helicobacter pylori infections are associated with hypochlorhydria in patients with pangastritis. It has previously been shown that eradication of H pylori leads to an increase in acid secretion in H pylori associated enlarged fold gastritis, suggesting that H pylori infection affects parietal cell function in the gastric body. The aim of this study was to evaluate the effects of H pylori infection on parietal cell morphology and function in hypochlorhydric patients. PATIENTS/METHODS: The presence of H pylori infection, mucosal length, and inflammatory infiltration were investigated in six patients with enlarged fold gastritis and 12 patients without enlarged folds. Parietal cell morphology was examined by immunohistochemistry using an antibody against the alpha subunit of H(+),K(+)-ATPase and electron microscopy. In addition, gastric acid secretion and fasting serum gastrin concentration were determined before and after the eradication of H pylori. RESULTS: In the H pylori positive patients with enlarged fold gastritis, fold width, foveolar length, and inflammatory infiltration were increased. In addition, the immunostaining pattern of H(+), K(+)-ATPase was less uniform, and the percentage of altered parietal cells showing dilated canaliculi with vacuole-like structures and few short microvilli was greatly increased compared with that in H pylori positive patients without enlarged folds. After eradication, fold width, foveolar length, and inflammatory infiltrates decreased and nearly all parietal cells were restored to normal morphology. On the other hand, altered parietal cells were negligible in H pylori negative patients. In addition, the basal acid output and tetragastrin stimulated maximal acid output increased significantly from 0.5 (0.5) to 4.1 (1.5) mmol/h and from 2.5 (1.2) to 13.8 (0.7) mmol/h (p<0.01), and fasting serum gastrin concentrations decreased significantly from 213.5 (31.6) to 70.2 (7.5) pg/ml (p<0.01) after eradication in patients with enlarged fold gastritis. CONCLUSION: The morphological changes in parietal cells associated with H pylori infection may be functionally associated with the inhibition of acid secretion seen in patients with enlarged fold gastritis.     

Changes in gastric acid secretion assayed by endoscopic gastrin test before and after Helicobacter pylori eradication

BACKGROUND: It remains controversial whether or not Helicobacter pylori infection causes altered gastric acid secretion. A novel test for evaluating gastric acid secretion (endoscopic gastrin test; EGT) has recently been developed. AIM: To investigate by EGT the effects of H pylori eradication on the state of gastric acid secretion in patients with peptic ulcer. METHODS: Twenty six patients with duodenal ulcer and 33 with gastric ulcer, for all of whom H pylori infection had been documented, were studied by EGT, histological examination of gastric mucosa, and measurement of plasma gastrin levels before and one and seven months after H pylori eradication. RESULTS: In patients with duodenal ulcer, the mean EGT value before H pylori eradication was higher than that in H pylori negative controls, but it had decreased significantly seven months after the treatment. In contrast, the mean EGT value of patients with gastric ulcer before H pylori eradication was lower than that in H pylori negative controls, but it had increased one month after the treatment; this was followed by a slight decrease at seven months. In both groups, mean EGT values seven months after the treatment were not significantly different from the mean control value. CONCLUSIONS: The reduced acid secretion in gastric ulcer patients and gastric acid hypersecretion in duodenal ulcer patients were both normalised after the clearance of H pylori.     

Should we eradicate Helicobacter pylori in patients with recurrent gastro-oesophageal reflux disease?

The 1998 Guidelines of the American College of Gastroenterology recommend that diagnostic testing for Helicobacter pylori infection should only be performed if treatment is intended, and that testing for H. pylori is not indicated in patients on long-term treatment with a proton pump inhibitor (PPI) for gastro-oesophageal reflux disease (GORD). Moreover, a recent evidence-based workshop evaluating major clinical strategies for the management of GORD reported, with an 'A' category (maximum of evidence), that eradication of H. pylori does not heal or prevent relapse of GORD. In detail, it seems that H. pylori infection per se has no effect on the pathogenic mechanisms determining either reflux or its complications. The relationship between H. pylori and oesophagitis is mediated by the effect of H. pylori on gastric acid secretion; in particular, by the proximal extension of gastritis and related impairment of gastric secretory function. In general, if the corpus is infected, the amount of acid available for reflux is less and the probability of excessive oesophageal acid exposure leading to oesophagitis reduced. However, the clinical relevance of corpus H. pylori infection as a biological antisecretory agent (and of H. pylori eradication) seems small or absent, at least in the long run. Conversely, the previous claim of an increased risk of atrophic gastritis in H. pylori-infected patients treated long term with PPI drugs appears not to be confirmed by subsequent studies. In conclusion, H. pylori infection may, in some circumstances, be moderately favourable and, in other circumstances, it may be neutral, with respect to the management of GORD.     

IS HELICOBACTER PYLORI‐INDUCED ENLARGED FOLD GASTRITIS A HIGH‐RISK FACTOR FOR GASTRIC CARCINOMA?

It is now a generally accepted fact that Helicobacter pylori is an important cause of gastric carcinoma. The International Agency for Research on Cancer classified H. pylori as a group 1 carcinogen. We previously reported that H. pylori‐positive subjects had enlarged folds (fold width = 5 mm); that is, ‘enlarged fold gastritis’. Helicobacter pylori‐induced enlarged fold gastritis is accompanied by a massive infiltration of inflammatory cells, profound production of interleukin‐1β (IL‐1β) and hepatocyte growth factor (HGF), which decrease gastric acid secretion and increase the proliferation rate of the gastric epithelial cells. In addition, there is increased mutagenicity of gastric juice, and mucosal 8‐hydroxydeoxyguanosine (8‐OhdG) levels. Fold width improves and these factors recover to within a normal range with the eradication of H. pylori. The odds ratio for gastric carcinoma and the prevalence of diffuse‐type early gastric carcinoma in the body region increased with an increase in fold width. Therefore, enlarged fold gastritis may be a major risk factor for gastric carcinoma among H. pylori‐infected people. We propose that H. pylori‐infected persons with enlarged fold gastritis are a potential population for the prevention of gastric carcinoma via the use of antibiotics.     

慢性胃炎患者胃内pH值相关因素分析

背景：传统观点认为胃酸分泌随年龄增加和胃黏膜萎缩而减少,但也有研究持不同观点。目的：研究慢性胃炎患者胃内pH值与性别、年龄、糖尿病、萎缩和幽门螺杆菌（H.pylori）感染之间的相关性。方法：共纳入67例慢性胃炎患者,采用pH试纸测定胃液pH值,病理切片结合快速尿素酶试验或^13C-尿素呼气试验检测H.pylori感染情况。分析不同因素与慢性胃炎患者胃内pH值的相关性。结果：67例患者中,慢性非萎缩性胃炎患者35例（52．2％）,慢性萎缩性胃炎32例（47．8％）;H.pylori阳性21例（31．3％）,H.pylori阴性46例（68．7％）。平均胃内pH值为2．86,胃内pH值随年龄增长呈升高的趋势（P=0．15）。Logistic回归分析显示胃内pH值与性别（P=0．17）、年龄（P=0．06）、糖尿病（P=0．75）、萎缩（P=0．67）和H.pylori感染（P=0．11）均无相关性。结论：性别、年龄、糖尿病、萎缩和H.pylori感染不是影响慢性胃炎患者胃内pH值的重要因素。     

Reversal of fundic atrophy after eradication of helicobacter pylori

Objectives: We sought to evaluate the effect of Helicobacter pylori eradication in patients with fundic atrophic gastritis.
Methods: Acid secretion, gastric emptying, and histology were evaluated in 20 patients with fundic atrophic gastritis and H. pylori infection. After investigation, 10 patients (Group 1) received an eradicating treatment and 10 (Group 2) did not receive any treatment. One year later, the baseline investigations were repeated. Subsequently, patients in Group 2 received the same treatment given to patients in Group 1 and were reevaluated 12 months later. A further follow-up was performed in both groups 36 months after the treatment.
Results: At 1-yr follow-up, all the patients in Group 1 were H. pylori negative whereas all the patients in Group 2 were still infected. In Group 1, there was a significant improvement of both fundic atrophy and acid secretion, compared with baseline ( p < 0.01 ). In Group 2, no substantial modification of either histological or functional parameters was observed at the first follow-up; conversely, a significant ( p < 0.01 ) improvement of fundic atrophy and acid secretion was detected in these patients 12 months after eradication of the bacterium. Histological pattern remained unchanged at 36 months of follow-up in both groups. Gastric emptying remained, on the average, unaffected by the treatment; however, three patients with delayed gastric emptying at entry had normal gastric emptying after eradication of H. pylori.
Conclusions: Our data suggest that mucosal atrophy can be reduced or even reversed by the eradication of H. pylori , and this is associated with a recovery of gastric function.     

Influence of H pylori on plasma ghrelin in patients without atrophic gastritis

AIM:To determine the association between H pylori infection and serum ghrelin levels in patients without atrophic gastritis.METHODS:Fifty consecutive patients(24 males and 26 females)with either H pylori-positive gastritis(n = 34)or H pylori-negative gastritis(n = 16)with normal gastric acid secretion determined by 24-h pHmetry and without atrophic gastritis in histopathology were enrolled in this study.Thirty-four H pylori-infected patients were treated with triple therapy consisting of a daily regimen of 30 mg lansoprazole bid,1 g amoxicillin bid and 500 mg clarithromycin bid for 14 d,followed by an additional 4 wk of 30 mg lansoprazol treatment.H pylori infection was eradicated in 23 of 34(67.6%)patients.H pylori-positive patients were given eradication therapy.Gastric acidity was determined via intragastric pH catethers.Serum ghrelin was measured by radioimmunoassay(RIA).RESULTS:There was no signifficant difference in plasma ghrelin levels between H pylori-positive and H pylori-negative groups(81.10 ± 162.66 ng/L vs 76.51 ± 122.94 ng/L).In addition,there was no significant difference in plasma ghrelin levels and gastric acidity levels measured before and 3 mo after the eradication therapy.CONCLUSION:H pylori infection does not influence ghrelin secretion in patients with chronic gastritis without atrophic gastritis.     

Hypotheses on the pathogenesis and natural history of Helicobacter pylori-induced inflammation.

Although Helicobacter pylori is now recognized as playing an etiologic role in chronic gastritis and peptic ulcer disease, information on the pathogenesis and natural history of infection is limited. A model is proposed in which luminal H. pylori secrete substances that mediate inflammation that is beneficial to the organism but ultimately deleterious for the host; in addition to tissue damage, inflammation also affects gastric secretory function. In this model, the host may attempt to suppress the inflammatory response, and the adequacy of this postulated down-regulation determines pathological and clinical outcome. The effects of the inflammatory process on gastrin-hydrochloric acid homeostasis may be of critical importance in the pathogenesis of peptic ulcer disease. Because the long-term consequences of H. pylori colonization reflect the continued presence of the organism in the host over years or decades, it may be useful to consider this as a "slow" bacterial infection.     

Duodenal ulcer, Helicobacter pylori, and gastric secretion.

Patients with chronic dyspepsia were categorised by macroscopic appearance at oesophagogastroduodenoscopy as having duodenal ulceration (DU), other diagnosed lesions such as reflux oesophagitis, carcinoma of stomach, etc, or no organic lesion (non-ulcer dyspepsia, NUD). Material was collected to identify gastric infection with Helicobacter pylori (H pylori) by CP urease test, culture, and histological examination and to make the microscopic diagnosis of active chronic gastritis. Each patient in the DU and NUD categories was then invited to volunteer for a gastric secretion study in which maximal gastric secretion in response to histamine was measured. Sixty two gastric secretion tests were performed (31 DU, 31 NUD). The presence of H pylori was associated with active chronic gastritis (100%). DU patients secreted more acid than the NUD patients. H pylori positivity was associated with decreased maximal gastric secretion in both groups. There was a positive correlation between smoking and maximal acid output shown only in H pylori negative but not in H pylori positive patients. These findings were clear cut when all corrections of maximal gastric secretion were made for pyloric loss, duodenogastric reflux, and stature. This study failed to show any aetiological link between H pylori and DU by increased maximal gastric secretion.     

Helicobacter pylori infection prevents erosive reflux oesophagitis by decreasing gastric acid secretion

BACKGROUND: Helicobacter pylori infection is less prevalent and atrophic gastritis is less extensive in patients with reflux oesophagitis than those without it, but few studies have examined this relationship directly. AIMS: We investigated the relationship between H pylori infection, acid secretion, and reflux oesophagitis in Japanese subjects. SUBJECTS: A total of 105 patients with erosive reflux oesophagitis were compared with 105 sex and age matched patients without reflux oesophagitis. METHODS: The diagnosis of H pylori infection was made by histological examination of gastric mucosal biopsy specimens, rapid urease test, and detection of serum IgG antibodies. Acid secretion was assessed by the endoscopic gastrin test. RESULTS: H pylori infection was present in 36 patients with erosive reflux oesophagitis (34.3%) and in 80 control subjects (76.2%) (odds ratio 0.163, 95% confidence interval 0.09-0.29). Overall acid secretion was significantly greater in patients with reflux oesophagitis. Among H pylori positive patients, acid secretion was greater in patients with reflux oesophagitis than those without oesophagitis. CONCLUSION: In Japan, erosive reflux oesophagitis occurs most often in the absence of H pylori infection and gastric hyposecretion. Even in the presence of H pylori infection, reflux oesophagitis is more likely to develop in patients without gastric hyposecretion. H pylori infection may inhibit reflux oesophagitis by inducing hypoacidity.     

How does Helicobacter pylori cause duodenal ulcer disease: The bug, the host, or both?

Abstract Helicobacter pylori infection is the most common cause of duodenal ulcer disease, yet duodenal ulcer is an uncommon outcome of H. pylori infection. We reviewed the possible explanations such as differences in the host or in the strain of H. pylori. Host factors reviewed included genetic susceptibility to H. pylori infection and excess gastric acid secretion. The role of potential H. pylori virulence factors not present in all strains such as the cagA gene and the results of other molecular methods to identify disease-specific differences among isolates was also reviewed. Although cure of H. pylori infection resolves gastrin releasing peptide stimulated acid secretion there was no change in parietal cell mass. Twin studies have shown genetic differences in H. pylori susceptibility. There was no difference in the prevalence of the cagA gene between H. pylori infected asymptomatic volunteers and duodenal ulcer patients ( P = 1.0). DNA-DNA hybridization of whole genomic DNA in solution and cluster analysis of rep-PCR genomic DNA fingerprints suggest that isolates from patients with duodenal ulcer disease are different from those obtained from individuals with asymptomatic gastritis. Cluster analysis of the rep-PCR DNA fingerprints revealed two major groups of the strains; one set consisted of strains from patients with duodenal ulcer disease and the second cluster consisted largely of strains from individuals with asymptomatic gastritis. Recent molecular studies suggest that disease-specific cell lineages or strains may exist among H. pylori isolates leading to the various outcomes observed in patients with H. pylori infection.     

Higher gastric mucin secretion and lower gastric acid output in first-degree relatives of gastric cancer patients

BACKGROUND: Patients infected by Helicobacter pylori who have first-degree relatives with gastric cancer have an 8-fold increased risk of developing gastric cancer themselves. Mucins are high-molecular-weight glycoproteins that play a cardinal role in the protective mechanism of the gastric epithelium. AIM: To study gastric acid and mucin secretion in dyspeptic patients with and without a family history of gastric cancer and H. pylori infection. MATERIALS AND METHODS: Twenty-six dyspeptic patients underwent esophago-gastro-duodenoscopy, gastric biopsies, and acid and mucin secretory tests. The sample was divided by family history of gastric cancer and H. pylori status. RESULTS: Patients who were infected by H. pylori had a significantly higher degree of inflammation than those who were not. H. pylori-positive patients with a positive family history had a lower basal and maximal gastric acid output than infected patients with no family history and noninfected controls, and a higher basal and maximal mucin output than infected patients with no family history. MUC5AC was the major mucin species expressed in gastric juice. CONCLUSIONS: In patients with relatives with gastric cancer, H. pylori infection is associated with a more severe inflammatory reaction consisting of decreased gastric acid secretion and increased mucin secretion.     

Association of Helicobacter pylori with gastroduodenal diseases

Helicobacter pylori was first cultured in vitro in 1982. This bacterium is a spiral gram-negative rod which grows under microaerophilic conditions. The ecological niche is the mucosa of the human stomach which had been thought to be aseptic before the discovery of this bacterium. This organism causes a long-lasting infection throughout a person's life if there is no medical intervention. Numerous persons are infected with the organism around the world, and the rate of infection in Japan is nearly 50% of the population. However, the route of infection remains unclear because the organism has not been isolated from any environment other than several animals. H. pylori is now recognized as a causative agent of gastritis and peptic ulcers. Though gastritis, and especially chronic active gastritis, is observed at least histologically in all persons with H. pylori, peptic ulcers develop in only some infected persons. Specific factors in the host and/or the bacteria are needed for the development of peptic ulcer disease. Furthermore, H. pylori is considered to be related to the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma, especially those of low grade. Also, H. pylori infection is a major determinant for initiating the sequence of events leading to gastric cancer. In some patients with low-grade gastric MALT lymphoma, the eradication of H. pylori led to a regression of lesion. Gastric cancer has been induced in Mongolian gerbils with long-term H. pylori infection. The combinations of drugs, which consist of an antisecretory agent (acid-suppressing agent) and antimicrobial agents, are used for the eradication of the organism. Eradication therapy is recommended at least for patients with peptic ulcers.     

H+/K+-adenosine triphosphatase mRNA in gastric fundic gland mucosa in patients infected with Helicobacter pylori.

BACKGROUND: How Helicobacter pylori infection affects gastric acid secretion has not been made clear. This study aimed to elucidate the effects of H. pylori infection on H+/K+-adenosine triphosphatase (ATPase) mRNA in gastric fundic gland mucosa. METHODS: Twenty patients with chronic gastritis and H. pylori infection were treated with lansoprazole and antibiotics. Before and 1 month after treatment gastroduodenoscopy was performed, and changes in the amount of H+/K+-ATPase mRNA in the fundic gland mucosa, gastric juice pH, and serum gastrin levels were determined. RESULTS: The amount of H+/ K+-ATPase mRNA in the fundic gland mucosa was increased in patients with eradication of H. pylori, in whom significant decreases in gastric juice pH and serum gastrin levels were observed. No significant changes were observed in patients without eradication of H. pylori. CONCLUSIONS: These results suggest that one of the mechanisms by which H. pylori infection suppresses acid secretion is by the inhibition of proton pump synthesis in parietal cells.     

Effect of age, Helicobacter pylori infection, and gastritis with atrophy on serum gastrin and gastric acid secretion in healthy men.

Gastric acid secretion has been considered to decline with increasing age but this view is being re-evaluated as the importance of Helicobacter pylori infection emerges. This study aimed to determine the effect of age, H pylori, and gastritis with atrophy on the serum gastrin concentration, gastric secretory volumes, and acid output in healthy, asymptomatic men. Young men (mean (SD) age 22.9 (0.6) years; n = 22) were compared with old men (72.9 (1.2) years; n = 28) in respect of basal serum gastrin and basal, sham fed, pentagastrin stimulated maximal and peak acid secretion. Antral, corpus, and fundal biopsy specimens were taken for histology and H pylori status (histology, culture, and rapid urease test). H pylori associated gastritis was present in three of 22 young (13.6%) and 16 of 28 old (57.1%) men. Gastritis with atrophy was present in 11 old subjects, 10 of whom were H pylori positive. These subjects had higher mean (SD) serum gastrin concentrations than old subjects without atrophy and young subjects (61.8 (9.2); 40.0 (2.9); 36.8 (2.3) pmol/l respectively; p < 0.001). H pylori infected subjects had higher gastrin values than uninfected subjects, overall (55.3 (5.9); 36.0 (1.8) pmol/l; p < 0.001) and in subjects without atrophy (45.3 (4.2); 36.0 (1.8) pmol/l; p < 0.03). In subjects without H pylori infection, gastrin values did not differ with age (old 37.1 (1.7); young 35.4 (2.1) pmol/l). The maximal gastric secretory volume was lower in old subjects with atrophy. Acid output (mmol/h) in subjects with atrophy was lower than in subjects with no atrophy (basal: 3.0(1.1); 5.1(0.7); p=NS; sham led: 5.4 (1.4); 9.3 (0.8); p<0.02; maximal: 18.9 (4.0); 31.4(1.8); p<0.002; peak: 25.1(5.3); 43.4(2.7); p<0.003). However, acid secretion in old subjects without atrophy was not different to that in young subjects, irrespective of H pylori status. These results did not differ when acid output was expressed as mmol/h/kg lean body mass or mmol/h/kg fat free body weight. Using multiple linear regression analysis, gastritis with atrophy was the only factor that had an independent negative effect on acid secretion. In healthy men without atrophy, gastric acid secretion is preserved with ageing and is independent of H pylori status. Atrophy, which is closely related to H pylori infection, is associated with a decline in acid secretion. Increased basal serum gastrin is related to both atrophy and H pylori infection but not to ageing per se.     

Effects of cyclooxygenase-2 inhibitor on gastric acid secretion in Helicobacter pylori-infected C57BL/6 mice.

BACKGROUND: Helicobacter pylori-associated body gastritis inhibits gastric acid secretion. The aim of this study was to determine the effects of H. pylori infection on gastric acid secretion and further determine whether cyclooxygenase-2 was involved. METHODS: C57BL/6 mice (n = 40) were inoculated with the Sydney strain of H. pylori. Control mice (n = 40) were treated with vehicle only. Half of the infected and control mice were fed an experimental diet containing etodolac (10 mg/kg/day) from 1 week after inoculation until the end of the experiment. Before, 12 and 24 weeks after inoculation, the gastric acid secretion, prostaglandin E2 (PGE2) levels in the gastric mucosa, and gastritis scores according to the updated Sydney system were determined. Immunohistochemical staining of COX-2 protein was also performed. RESULTS: No significant changes in gastric acid secretion, gastritis scores or PGE2 levels in the gastric mucosa were observed in uninfected groups with or without etodolac treatment during the study period. In the H. pylori-infected group without etodolac treatment, gastric acid secretion was significantly decreased with increases in PGE2 levels in the gastric mucosa 24 weeks after inoculation compared with the controls. Gastritis score for activity was significantly higher, and strong staining for COX-2 protein was observed in the H. pylori-infected group. In the H. pylori-infected group with etodolac treatment, PGE2 in the gastric mucosa was decreased and acid secretion was restored to the same level as in the control group. CONCLUSION: One of the mechanisms by which H. pylori infection inhibits gastric acid secretion is increased release of PGE2 produced by COX-2, which is induced by H. pylori infection.