Immunoreactive Gastrin Research Articles

Diagnostic accuracy of selective arterial calcium injection test for localization of gastrinoma.

The appropriate localization of gastrinoma is still difficult. We aimed to evaluate the diagnostic accuracy of selective arterial calcium injection (SACI) for localization of gastrinomas including multiple lesions. This retrospective study included ten patients with surgically proven gastrinomas (gastrinoma group) and six patients without any findings suggesting Zollinger-Ellison syndrome (non-gastrinoma group). For SACI, calcium gluconate was injected into the arteries supplying pancreas, duodenum, and liver. Blood samples from the hepatic vein were obtained before and 30, 60, and 120 seconds after each injection. The results were considered positive when the increase in serum immunoreactive gastrin (IRG) levels within 60 seconds of calcium gluconate injection were more than 80 pg/mL and more than 20% from baseline. We evaluated the efficacy of SACI by comparing the SACI responses with definitive locations diagnosed by clinical and histopathological findings. In the gastrinoma group, false-positive responses were confirmed in seven of the ten patients. False-negative response was observed in one of the feeding arteries of one patient with gastrinomas in multiple locations. Conversely, the greatest increase in serum gastrin levels from baseline at 30 seconds indicated the true-positive responses in all patients with gastrinomas. In the non-gastrinoma group, calcium gluconate injection into gastroduodenal artery evoked positive responses in five of the six patients. In conclusion, our data suggest the strongest gastrin response evoked by SACI indicates the definitive location in patients with gastrinomas. In contrast, SACI could not accurately locate multiple gastrin-secreting lesions due to poor specificity.

A primary hepatic gastrinoma accompanied by hyperplasia of multi-nodular Brunner\u2019s glands

BackgroundPrimary hepatic gastrinoma causing severe ulcerogenic syndrome is extremely rare. Herein, we report a case of primary hepatic gastrinoma accompanied by hyperplasia of multi-nodular Brunner’s glands in a patient who instead, preoperatively, was suspected of having multiple duodenal gastrinomas and hepatic metastasis.Case presentationA 57-year-old woman consulted a clinic complaining of melena, intermittent abdominal pain, diarrhea, and vomiting which had persisted for about 3 years. Six months before her presentation, she underwent segmental resection of the jejunum for acute peritonitis due to the spontaneous jejunal perforation. A blood test revealed that her serum immunoreactive gastrin (IRG) level was 12,037 pg/mL. Subsequently, she was transferred to our hospital. On computed tomography (CT), a hypervascular tumor of 23 mm in the segment 5 (S5) region of the liver was visualized. A selective arterial secretagogue injection test (SASI test) was performed twice. The first SASI test revealed that the hepatic tumor was a gastrinoma, and there was no gastrinoma in the duodeno-pancreatic region. Additionally, somatostatin receptor scintigraphy only visualized the tumor in the liver. However, the second SASI test, which was performed during the administration of a proton pump inhibitor and a somatostatin analog (octreotide acetate), revealed that there may have been gastrinomas existing not only in the liver but also in the upper part of the duodenum or the head of the pancreas. Duodenal endoscopy revealed multiple submucosal tumors in the first and the second portion of the duodenum, although a pathological examination of biopsied specimens obtained from the duodenal lesions was negative for malignant cells. Multiple endocrine neoplasia type 1 (MEN1) was excluded from her family history, and serum levels of both intact parathyroid hormone (iPTH) and calcium were within normal ranges. An anterior segmentectomy of the liver and pancreas-preserving total duodenectomy were performed on September 9, 2013. Postoperatively, her serum immunoreactive gastrin level decreased to less than 50 pg/mL. Pathological study of the resected specimens revealed a gastrinoma in the liver, but no gastrinoma in the duodenum. Interestingly, the duodenal submucosal tumor-like lesions were hyperplastic Brunner’s glands. Postoperatively, she has been well without recurrence of hypergastrinemia for 4 years.ConclusionWe report a case of primary hepatic gastrinoma in a patient who has been cured for 4 years postoperatively. The diagnosis was somewhat difficult due to the coexisting, multiple hyperplastic Brunner’s glands of the duodenum mimicking the submucosal neuroendocrine tumors, which might have developed due to long-term hypergastrinemia.

Immunohistochemical Study of Endocrine Cells in the Stomach and Small Intestine of the Lion (Panthera leo)

Abstract. The distribution and relative frequency of gastrointestinal endocrine cells were investigated in the stomach and small intestine (duodenum and jejunum) of a lion (Panthera leo). The present study was an immunohistochemical investigation of endocrine cells showing immunoreactivity for serotonin, gastrin, or cholecystokinin (CCK). Serotonin-immunoreactive (IR) cells were detected throughout the gastrointestinal tract with the highest frequency in the duodenum. Gastrin-IR cells were numerous in the pyloric region of the stomach and moderate numbers were also seen in the duodenum and jejunum. Moderate numbers of CCK-IR cells were only detected in the duodenum and jejunum.

Abstract 516: Intestinal Cell Gastrin Secretion is Regulated by a Sodium-Induced Increase in PPAR-A that is Mediated by Dopaminergic Stimulation

Recently a novel gastro-renal axis has been discovered for the regulation of renal sodium excretion at the moment of sodium ingestion. Cells in the digestive track secrete gastrin in response to sodium ingestion which stimulates an increase in renal sodium excretion. Dopamine is largely responsible for the regulation of sodium excretion in the kidney, and has also been shown to decrease sodium transport in intestines. We hypothesized that dopamine might also be involved with the regulation of gastrin secretion in a human intestinal gastrin secreting cell line (SW626, ATCC, Manassas VA) that also contains dopaminergic receptors. We used the ionophore monensin (MON) to increase intracellular sodium in SW626 cells in order to simulate an oral sodium load. We also stimulated the cells with the dopaminergic agonist SKF38393 (SKF, D 1 -like receptor agonist). These two manipulations (compared to vehicle VEH) caused increased relative gene expression of gastrin (ΔΔCt gastrin to actin, VEH 0.00638±0.00283; MON 0.3913372±0.0985926; SKF 0.2139286±0.0253672; P<0.01 VEH vs MON or SKF, N=6 per group). Peroxisome proliferator-activated receptor-alpha (PPAR-α) associates with the gastrin transcriptional promoter by CHIP-SEQ (ENCODE database) and PPAR-α activation by fenofibrate (FENO) has been shown to reduce blood pressure and increase sodium excretion. We hypothesized that PPAR alpha would increase gastrin expression. FENO increased the immunoreactive gastrin and this effect was blocked by a PPAR alpha antagonist GW6471 (VEH 16,440±2,438 RFU; FENO 42,639±4,891; FENO+GW 19,367±1,865; P<0.001 VEH vs FENO and FENO vs FENO+GW). Stimulation with MON or SKF also significantly stimulated the production of immunoreactive gastrin (VEH 16,440±2,438 RFU; MON 22,345±935; SKF 24,386±1,124; GW alone 10,235±1,214; P<0.05 VEH vs MON, SKF, or GW, N=6). SW626 appear to secrete gastrin, therefore we tested the ability of secreted gastrin obtained from the media bathing SW626 cells to bind to i22 human renal proximal tubule cells (RPTC). After incubation of i22 RPTC in SW626 media for 24 hours, we detected surface gastrin staining on the i22 RPTC. We conclude that gastrin is produced by SW626 cells, is secreted into the growth media, and can bind to cell surface receptors on RPTC.

Mercuric chloride-induced Gastrin/Cholecystokinin 8 immunoreactivity in the central nervous system of the terrestrial slug Semperula maculata: an immunohistochemical study

We measured the immunoreactivity of the neuropeptide gastrin cholecystokinin 8 (gastrin/CCK 8) in neurons of the terrestrial slug Semperula maculata following acute treatment with mercuric chloride (HgCl2). The distribution of gastrin/CCK 8 was analyzed in neurons of different regions, specifically from cerebral ganglia (procerebrum (pro-c), mesocerebrum (meso-c) and metacerebrum (meta-c). In the control group, neurons of pedal, pleural, parietal and visceral ganglia showed positive immunoreactivity using vertebrate antiserum against gastrin/CCK 8. Gastrin/CCK 8 immunoreactivity was also seen in the fibers and neuropil region of all ganglia. In the cerebral ganglion, 10, 12 and 8% of the neurons from pro-c, meso-c and meta-c, respectively, were stained with the antibody. The immunostaining was increased in neurons (giant, large, medium and small) after HgCl2 treatment. The treatment greatly increased the mucin content within the neurons. Exposure to HgCl2 enhanced gastrin immunoreactivity in the neurons and this increased with time. Results are discussed in the context of neuropathology in cerebral ganglia associated with the feeding behavior of Semperula maculata.

A Speculative Role for Stromal Gastrin Signaling in Development and Dissemination of Pancreatic Ductal Adenocarcinoma.

The peptide growth factor gastrin and its receptor, the G-protein coupled cholecystokinin receptor type B (CCKBR), play an integral role in the growth and progression of pancreatic ductal adenocarcinoma (PDAC). Gastrin immunoreactivity is found in the fetal pancreas but its expression is not detected in normal pancreas after birth, except when it is re-expressed in malignant lesions.

Abstract 1110: Differential expression of cholecystokinin receptors and their ligands in normal and neoplastic pancreas

Abstract Background: The gastrointestinal peptide gastrin has been identified in fetal pancreas up until week 14 where it is thought to play a role in growth and differentiation. Gastrin has also been identified as an important growth factor that stimulates pancreatic cancer through the CCK-B and CCK-C receptors by an autocrine mechanism. Hypothesis: It is hypothesized that gastrin re-expression is important to pancreatic carcinogenesis. Methods: The mRNA from normal human pancreas tissue was isolated and endpoint RT-PCR was performed to detect RNA levels of gastrin and CCK peptide, using gastrin specific and CCK peptide specific primers, respectively. PCR products were visualized on an ethidium bromide stained gel after electrophoresis. Normal human pancreatic tissue samples were evaluated for gastrin and CCK by immunohistochemistry. Tissues were flash frozen and sectioned at a thickness of 8-10uM. Non-specific sites were blocked, followed by exposure to either gastrin or CCK antisera. Peptide presence was assessed using AF568 (Alexa Fluor) goat anti-rabbit secondary antibody. Results: The end-point RT-PCR showed significant levels of CCK-B receptor and CCK peptide in normal pancreas samples. The gastrin end-point RT-PCR showed extremely low levels in all of the normal pancreas samples. Gastrin immunoreactivity was not detected in normal pancreas, however, staining of the positive control, an islet cell tumor, was reactive. The negative control, a GIST tumor, showed no staining as well. Conclusions: Normal pancreas possesses the receptor CCK-B and the peptide CCK. Gastrin is not present in normal pancreatic tissues, but is detected in neoplastic pancreatic samples. Therefore, the re-expression of gastrin plays a pivotal role in the development of pancreatic cancer and could be a potential trigger to pancreatic carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1110. doi:10.1158/1538-7445.AM2011-1110

Differential Expression of Cholecystokinin Receptors and Their Ligands in Normal and Neoplastic Pancreas

BackgroundThe gastrointestinal peptide gastrin has been identified in fetal pancreas where it is thought to play a role in growth and differentiation. Gastrin has also been identified as a growth factor that stimulates pancreatic cancer through the CCK‐B and CCK‐C receptors by an autocrine mechanism.HypothesisIt is hypothesized that gastrin re‐expression is important to pancreatic carcinogenesis.MethodsEndpoint RT‐PCR was performed on normal human pancreas mRNA to detect RNA levels of gastrin and CCK peptide. PCR products were visualized on an ethidium bromide stained gel after electrophoresis. Normal human pancreatic tissue samples were evaluated for gastrin and CCK by immunohistochemistry.ResultsThe end‐point RT‐PCR showed significant levels of CCK‐B receptor and CCK peptide in normal pancreas samples. The gastrin end‐point RT‐PCR showed low levels in all of the normal pancreas samples. Gastrin immunoreactivity was not detected in normal pancreas, however, staining of the positive control was reactive; the negative control showed no staining.ConclusionsNormal pancreas possesses the receptor CCK‐B and the peptide CCK. Gastrin is not present in normal pancreatic tissues, but is detected in neoplastic pancreatic samples. Therefore, the re‐expression of gastrin plays a pivotal role in the development of pancreatic cancer and could be a potential trigger to pancreatic carcinogenesis.

Immunolocalization of histamine H3 receptors on endocrine cells in the rat gastrointestinal tract.

The histamine H3 receptor (H3R) has been identified in the gastrointestinal tract of the rat by immunohistochemistry, using the first validated anti-H3 receptor antibody. Immunoreactivity to H3R was exclusively localized to the endocrine cells scattered in the gastrointestinal mucosa, with positive cells being prominently abundant in the gastric fundus, while they were rarely found in the other regions. In the fundus, positive cells were distributed in the lower half of the mucosa and their number significantly decreased after a 24 h-fasting period. Double-labeling studies were undertaken to identify the H3R-immunoreactive cell types in the fundic and antral mucosa. The H3R-immunoreactive cells were positive for chromogranin A. In the fundus, approximately 90% of cells positive to H3R were also positive to the histamine-forming enzyme, histidine decarboxylase. None of the cells expressing H3R displayed immunoreactivity for gastrin, somatostatin or ghrelin. Location, the influence of food deprivation and colocalization with histidine decarboxylase indicate that H3R positive cells correspond to the enterochromaffin-like cells (ECL).

In vivo release of gastrin into human gastric juice.

The release of antral gastrin has been examined in human subjects by infusing saline and albumin into their stomachs. Immunoreactive gastrin (IRG) was present in fasting serum but not in fasting gastric juice. Intragastric infusions of saline and albumin induced small but significant (P less than 0.05) rises in the serum concentrations of IRG. There was no significant difference between the magnitude of the serum gastrin responses to these two stimuli. The stimuli induced a rise in the luminal concentration of IRG which was sixfold greater than that in the serum concentration of IRG. The response to albumin was significantly greater than the response to saline (P less than 0.05). The IRG in gastric juice was chromatographically similar to heptadecapeptide gastrin. The stimuli also released IRG in patients with duodenal ulcers. The magnitude of the release into serum and gastric juice in these patients was significantly reduced by antrectomy (P less than 0.05).

Assessment of the secretin provocation test in the diagnosis of gastrinoma.

The effect of intravenous secretin on plasma immunoreactive gastrin is presumed to improve diagnostic accuracy in patients with a gastrinoma. To investigate this further, the secretin provocation test was performed in control patients (n = 10), patients with a primary duodenal ulcer (n = 10), patients who had previously had surgery for a duodenal ulcer (n = 20), patients with symptomatic recurrent peptic ulceration (n = 50) and 2 patients with a histologically proved gastrinoma. It was found that the secretin test gave a false positive result in 3 out of 10 symptomatic duodenal ulcer patients, 2 out of 20 patients who had had previous duodenal ulcer surgery and were now asymptomatic and 15 out of 50 patients with recurrent peptic ulceration. Both gastrinoma patients had positive secretin tests but there were no obvious criteria that separated the gastrin response of a gastrinoma patient from those with primary or recurrent peptic ulceration. It is concluded that the secretin test is probably of little value in both the screening and the diagnosis of a gastrinoma.

CCK2 gastrin receptor as a potential target for therapy in leukaemia cell lines

The gastrin CCK2 pathway has been implicated in the development of various cancers including leukaemia. An autocrine or intracrine pathway may exist in the leukaemia cell that is involved in stimulating proliferation. We tested four leukaemia cell lines, KU812, ML-1, MOLT-4 and U937 for the existence of the CCK2 receptor and gastrin precursor protein using immunoblotting. We also assessed the effect of CCK2 antagonist PD 135 and both gastrin 17 and glycine-extended gastrin on the proliferation of the cell lines. We found immunoreactive CCK2 and gastrin precursors present in all 4 cell lines. We also observed a stimulatory effect on proliferation by gastrin and glycine-extended gastrin on 2 and 3 of the cell lines respectively and an inhibitory effect of PD 135 on all 4 cell lines. These results demonstrate that the gastrin-gastrin receptor axis is a potential target for new therapeutic strategies.

Effect of omeprazole on gastric adenosine A1 and A2A receptor gene expression and function.

Adenosine has been shown to inhibit immunoreactive gastrin (IRG) release and to stimulate somatostatin-like immunoreactivity (SLI) release by activating adenosine A(1) and A(2A) receptors, respectively. Since the synthesis and release of gastrin and somatostatin are regulated by the acid secretory state of the stomach, the effect of achlorhydria on A(1) and A(2A) receptor gene expression and function was examined. Omeprazole-induced achlorhydria was shown to suppress A(1) and A(2A) receptor gene expression in the antrum and corporeal mucosa, but not in the corporeal muscle. Omeprazole treatment produced reciprocal changes in A(1) receptor and gastrin gene expression, and parallel changes in A(2A) receptor and somatostatin gene expression. The localization of A(1) and A(2A) receptors on gastrinsecreting G-cells and somatostatin-secreting D-cells, respectively, suggests that changes in adenosine receptor expression may modulate the synthesis and release of gastrin and somatostatin. Thus, the effect of omeprazole on adenosine receptor-mediated changes in IRG and SLI release was also examined in the vascularly perfused rat stomach. After omeprazole treatment, the A(1) receptor-mediated inhibition of IRG and SLI release induced by N(6)-cyclopentyladenosine (A(1) receptor-selective agonist) was not altered, but the A(2A) receptor-mediated augmentation of SLI release induced by 2-p-(2-carboxyethyl-)phenethylamino-5'-N-ethylcarboxamidoadenosine (A(2A)-selective agonist) was significantly attenuated. These findings agree well with the corresponding omeprazole-induced decrease in antral A(2A) receptor mRNA expression. Overall, the present study suggests that adenosine receptor gene expression and function may be altered by omeprazole treatment. Acid-dependent changes in adenosine receptor expression may represent a novel purinergic regulatory feedback mechanism in controlling gastric acid secretion.

Diabetic mastopathy mimicking neoplastic lesion — a case report

Ex vivo hemoperfused pancreaticoduodenal preparations from dogs have been used to study intraluminal and circulatory patterns of release of immunoreactive gastrin under basal conditions and after secretin stimulation. Bidirectional release of immunoreactive gastrin was maximal at 3 U/min secretin infusion, and release into pancreatic and duodenal juice exceeded that into portal venous blood. Molecular sieving chromatography of peptides with gastrin-like immunoreactivity recovered from duodenal and pancreatic juice indicated a single species of a molecular size equivalent to CCK8 and smaller than minigastrin (G-14). The exact identity has not been defined. This study demonstrates that secretin stimulates release of gastrin-like peptides into blood and lumen of extra-antral gastrin-producing tissues in the dog. Unidirectional gastrin release patterns from gastrinoma tissue may explain the paradoxical increase in plasma gastrin levels in response to secretin in patients with gastrinomas (Zollinger-Ellison syndrome).

Secretagogue activities in cod ( Gadus morhua) and shrimp ( Penaeus aztecus) extracts and alcalase hydrolysates determined in AR4-2J pancreatic tumour cells

Peptides with gastrin immunoreactivity were measured in cod muscle ( Gadus morhua) and shrimp heads ( Penaeus aztecus) extracts and alcalase hydrolysates and separated by two chromatographic steps. Secretagogue activities present in crude extracts fractions were examined with or without specific antagonists of CCK receptors in AR4-2J cells. Several sub-fractions significantly stimulate amylase release, up to 110%. These stimulatory effects could be completely inhibited by the presence of L 365, 260 specific antagonist of CCKB receptors. After hydrolysis of the raw material, the samples were partially fractionated by two chromatographic steps and potential active fractions detected by a gastrin-CCK radioimmunoassay. The molecular masses of the active fractions were lower than for the extracts. Stimulation of amylase release was higher than with extracts, and the inhibition by L 365, 260, less pronounced. These results show that some peptides remaining after hydrolysis or extraction still exert biological activities and have to be tested in nutritional studies.

Rat progastrin processing yields peptides with altered potency at the CCK-B receptor

Details of prohormone processing patterns are revealed by purification and characterization of molecular forms stored in the tissues where the hormones are expressed. Molecular forms of rat gastrin were purified from antral extracts by gel permeation, anion exchange, and reverse-phase HPLC. Amidated and glycine-extended gastrins were detected with specific antisera and their structures determined by mass spectrometry. In rats, the only form shorter than gastrin-17 observed contained 16 amino acids. These data suggest that two enzymes process the amino terminus of gastrin-17. Pyrrolidone carboxylic acid peptidase removes the amino terminal pyrrolidone carboxylic acid (pyroGlu), forming gastrin-16. In mammals other than rat, gastrin-16 is then cleaved by dipeptidyl peptidase IV to form gastrin-14. In rat, this reaction does not take place because of proline residues Pro 2-Pro 3- in gastrin-16. Gastrin-16 is found in sulfated and nonsulfated forms and comprises 28% of the total gastrin immunoreactivity. Glycine-extended forms of gastrin-16 and gastrin-17 comprises 45% of the total gastrin immunoreactivity. The sulfated forms of gastrin-16 and gastrin-17 bind to the CCK-B receptor transfected into CHO cells with 10-fold higher affinity than the nonsulfated forms of these peptides. Therefore, processing of rat progastrin may modulate the expression of gastrin biological activity.

Helicobacter pylori infection, gastrin, cyclooxygenase-2, and apoptosis in colorectal cancer

Helicobacter pylori (HP) infection is usually accompanied by an increased plasma level of gastrin, a potent mitogen able to induce cyclooxygenase (COX)-2. This study examined (a) the seroprevalence of HP, its cytotoxic protein, CagA, and cytokines (tumor necrosis factor alpha, interleukins 1beta and 8) in 80 patients with colorectal cancers, before and after the removal of tumor, compared with 160 age- and gender-matched controls; (b) the gene expression of gastrin and its receptors (CCKB-R) in the cancer tissue, (c) the plasma levels and tumor tissue contents of gastrin, and (d) the mRNA expression of COX-1, COX-2, and apoptotic proteins (Bax and Bcl2) in cancer tissue and intact colonic mucosa. Anti-HP IgG, anti-CagA IgG seroprevalence, and cytokine levels were analyzed by enzyme-linked immunosorbent assay tests; gene expressions of gastrin, CCKB-R, COX-1, COX-2, Bax, and Bcl2 by reverse transcriptase polymerase chain reaction; and gastrin by radioimmunoassay. The seroprevalence of HP, especially that expressing CagA, was significantly higher in cancer patients than in controls and did not change 1 week after tumor resection while plasma cytokines were significantly reduced after this operation. Both gastrin and CCKB-R mRNA were detected in the cancer tissue and the resection margin; similarly, COX-2 mRNA was expressed in most of cancers and their resection margin but not in intact colonic mucosa, where only COX-1 was detected. The colorectal cancer tissue contained several folds more immunoreactive gastrin than cancer resection margin and many folds more than the intact colonic mucosa. We conclude that colon adenocarcinoma and its resection margin overexpress gastrin, its receptors, CCKB-R, and COX-2, and that HP infection may contribute to colonic cancerogenesis via overexpression of gastrin and COX-2, which may account for the stimulation of the tumor growth and the reduction in apoptosis as documented by enhanced mRNA expression of anti-apoptotic Bcl2 over proapoptotic Bax proteins.

Implication of gastrin in cyclooxygenase-2 expression in Helicobacter pylori infected gastric ulceration

Gastroduodenal ulcerations have worldwide distribution and the infection with Helicobacter pylori (HP) has been implicated in pathogenesis of this disease. The HP infection is usually accompanied by hypergastrinemia and enhanced generation of prostaglandins (PG), both implicated in the pathogenesis of peptic ulcerations but no study has been undertaken to assess the relationship between the HP infection and coexpression of gastrin and cyclooxygenases (COX), the rate limiting enzymes in the PG production. Since HP infection, usually accompanying peptic ulcerations, results in increased release of gastrin, a potent gastric mitogen that might be capable to induce COX-2 and to generate PG, we decided 1) to compare the seroprevalence of HP and its cytotoxic protein, CagA, in gastric ulcer patients with those in age- and gender-matched controls; 2) to determine the gene expression of gastrin and its receptors (CCK B-R) at the margin of gastric ulcer and in the mucosa of antrum and corpus before and after successful eradication of HP, 3) to assess the plasma levels and gastric luminal contents of gastrin before and after HP eradication and 4) to examine the mRNA and enzyme protein expression of COX-1 and COX-2 as well as the PGE 2 generation in ulcer margin tissue and gastric antral and fundic mucosa before and after the HP eradication. The trial material included 20 patients with gastric ulcer and 40 age- and gender-matched controls. Anti-HP and anti-CagA IgG seroprevalence was estimated by specific antisera using ELISA tests. Gene expressions of gastrin, CCK B-R, COX-1 and COX-2 were examined using RT-PCR with β-actin as a reference and employing Western blotting for COX-2 expression, while gastrin and PGE 2 were measured by RIA. All gastric ulcers were located at smaller curvature within the antral mucosal area. The seroprevalence of HP, especially that expressing CagA, was significantly higher in gastric ulcers (85%) than in controls (62.5%). Both gastrin and CCK B-R mRNA were detected by RT-PCR in ulcer margin and gastrin mRNA was overexpressed in remaining antral mucosa, while CCK B-R mRNA was overexpressed in fundic mucosa of HP infected patients. Similarly, COX-2 mRNA and protein were found in margin of gastric ulcer and in the HP infected antral and fundic mucosa but not in the mucosa of HP eradicated patients in whom ulcers completely healed and gastrin was expressed only in antrum, CCK B-R only in corpus, while COX-1 was detected both in antrum and corpus. HP positive gastric ulcer patients showed about three times higher levels of plasma immunoreactive gastrin and about 50% higher luminal gastrin contents than the HP negative controls and this increased plasma and luminal gastrin was normalized following the HP eradication. A significant fall in gastrin and CCK B-R mRNA expression was noticed six weeks after HP eradication in gastric antral and fundic mucosa, while COX-2 mRNA completely disappeared after this treatment. We conclude that 1) HP infected gastric ulcer margin coexpresses gastrin, its receptors (CCK B-R), and COX-2; 2) HP infection may be implicated in gastric ulceration via increased release of gastrin that could be responsible for the overexpression of COX-2 that in turn could help ulcer healing through the stimulation of mucosal cell growth, restoration of the glandular structure and angiogenesis in the ulcer area and 3) gastrin produced in HP infected antral mucosa seems to be involved in the induction of COX-2 and PG production by this enzyme and this may contribute to the ulcer healing.

Comparative study on the appearance of various bioactive peptides in foregut derivates during the ontogenesis

Bioactive peptides have an important multifunctional role in the gastrointestinal tract. In the present study we have investigated the dynamism of the appearance of PACAP (pituitary adenylate cyclase activating polypeptide), VIP (vasoactive intestinal polypeptide), gastrin, and secretin immunoreactivities in human foregut derivates during the ontogenesis using an immunohistochemical approach. None of these peptides were observed in the foregut derivates of an 8-week-old embryo. VIP immunoreactive nerve fibers appeared by the 11th week in the smooth muscle layers of the stomach. No other peptide immunoreactivities were observed of this stage. In 18- and 20-week old fetuses PACAP, secretin, and gastrin immunoreactive cells appeared in the developing glands of the stomach. In the duodenum gastrin immunoreactivity was present in the Lieberkühn's glands and secretin immunoreactive cells were seen between the surface epithelial cells. In the pancreas secretin immunoreactivity was found in the Langerhans islets; however, PACAP immunreactivity was observed in the exocrine portion. The distribution of VIP fibers did not change during the fetal life and it was similar to the adult pattern. According to our results the appearance of PACAP, secretin, and gastrin in the developing glands suggests their role in the proliferation and differentiation of the epithelial derivates.

Involvement of gastrin in gastric secretory and protective actions of N-alpha-methyl histamine

Nα-methylhistamine (Nα-MH) is one of an unusual metabolite of histamine that was found in Helicobacter pylori-infected stomachs and is believed to interact with specific histamine H 1, H 2 and H 3-receptors to stimulate gastric acid secretion and gastrin release from isolated G-cells but the effects of Nα-MH on gastric mucosal integrity have been little studied. This study was designed; (1) to compare the effect of exogenous Nα-MH with that of standard histamine on gastric secretion and plasma gastrin levels in rats equipped with gastric fistula (series A); and (2) to assess the action of Nα-MH on gastric lesions induced by 100% ethanol (series B) in rats with or without removal of antral portion of the stomach (antrectomy). Rats of series B were pretreated intragastrically (i.g.) or intraperitoneally (i.p.) with Nα-MH or histamine (0.1–2 mg/kg) 30 min prior to 100% ethanol (1.5 ml, i.g.) with or without: (1) vehicle (saline); (2) RPR 102681 (30 mg/kg i.p.), to block CCK-B/gastrin receptors; and (3) ranitidine (40 mg/kg s.c.) to inhibit histamine H 2-receptors. The area of gastric lesions was determined planimetrically, gastric blood flow (GBF) was assessed by H 2-gas clearance method and venous blood was collected for determination of plasma gastrin levels by radioimmunoassay (RIA). Nα-MH and histamine dose-dependently increased gastric acid output (series A); the dose increasing this secretion by 50% (ED 50) being 2 and 5 mg/kg i.g or i.p., respectively, and this effect was accompanied by a significant rise in plasma gastrin levels. Both, Nα-MH and histamine attenuated dose-dependently the area of gastric lesions induced by 100% ethanol (series B) while producing significant rise in the GBF and plasma immunoreactive gastrin increments. These secretory, protective, hipergastrinemic and hyperemic effects of Nα-MH and histamine were completely abolished by antrectomy, whereas pretreatment with RPR 102681 attenuated significantly the Nα-MH and histamine-induced protection against ethanol damage and accompanying hyperemia. Ranitidine, that produced achlorhydria and a further increase in plasma gastrin levels, failed to influence the Nα-MH- and histamine-induced protection and accompanying rise in the GBF. We conclude that (1) Nα-MH stimulates gastric acid secretion and exhibit gastroprotective activity against acid-independent noxious agents in the manner similar to that afforded by histamine; and (2) this protection involves an enhancement in the gastric microcirculation and release of gastrin acting via specific CCK-B/gastrin receptors but unexpectively, appears to be unrelated to histamine H 2-receptors.