Physiology and Pathology of Gastrin

Understanding the potential causes of gastrointestinal dysfunctions in multiple system atrophy

Multiple system atrophy (MSA) is a rare, progressive neurodegenerative disorder characterised by autonomic, pyramidal, parkinsonian and/or cerebellar dysfunction. Autonomic symptoms of MSA include deficits associated with the gastrointestinal (GI) system, such as difficulty swallowing, abdominal pain and bloating, nausea, delayed gastric emptying, and constipation. To date, studies assessing GI dysfunctions in MSA have primarily focused on alterations of the gut microbiome, however growing evidence indicates other structural components of the GI tract, such as the enteric nervous system, the intestinal barrier, GI hormones, and the GI-driven immune response may contribute to MSA-related GI symptoms. Here, we provide an in-depth exploration of the physiological, structural, and immunological changes theorised to underpin GI dysfunction in MSA patients and highlight areas for future research in order to identify more suitable pharmaceutical treatments for GI symptoms in patients with MSA.

Evolution of the restorative proctocolectomy and its effects on gastrointestinal hormones

Gastrointestinal (GI) peptide hormones are chemical messengers that regulate secretory, mechanical, metabolic, and trophic functions of the gut. Restorative proctocolectomy (RPC) or resection of the colon and rectum with maintenance of intestinal continuity through the construction of an ileal pouch reservoir and preservation of the anal sphincters has become the standard of care for the surgical treatment of ulcerative colitis and familial adenomatous polyposis. The manipulation of the digestive system to create the ileal pouch involves altering gut-associated lymphoid tissue among other anatomic changes that lead to changes in GI peptides. In addition, the ileal pouch epithelium responds to a wide variety of stimuli by adjusting its cellularity and function. These adaptive mechanisms involve systemic factors, such as humoral and neural stimuli, as well as local factors, such as changes in intestinal peristalsis and intraluminal nutrients. There have been conflicting reports as to whether the alterations in GI hormones after RPC have actual clinical implications. What the studies on alterations of GI peptides' response and behavior after RPC have contributed, however, is a window into the possible etiology of complications after pouch surgery, such as pouchitis and malabsorption. Given the possibility of pharmacologically modifying GI peptides or select components of adaptation as a therapeutic strategy for patients with ileal pouch dysfunction or pouchitis, a clear understanding of human pouch mucosal adaptation is of paramount importance. In this review, we summarize the evolution of the RPC and its effects on the GI hormones as well as their possible clinical implications.

Gastric body partition for giant perforated peptic ulcer in critically ill elderly patients

BACKGROUND

To prevent or minimize leakage after simple closure of giant perforated peptic ulcers in critically ill elderly patients, we conducted a clinical study using gastric body partition to prevent upstream gastric juice and food from passing through the sutured ulcer.

METHODS

Ten critically ill elderly patients with giant (> 2.5 m) perforated peptic ulcer were included in the study of gastric body partition.

RESULTS

The patients' mean age was 78.2 years and mean delay in treatment was 95.6 hours. None of the 10 patients had major complications after operation, although minor leakage of the sutured ulcer occurred in 4 patients. Only one patient presented with recurrent anastomotic ulcer and one patient died 28 days after surgery.

CONCLUSIONS

Gastric body partition and gastrojejunostomy, in addition to simple closure of a giant perforated peptic ulcer, could be a quick, easy, and potentially effective alternative to avoid or at least to minimize leakage of the sutured ulcer. Moreover, gastric body partition, unlike antral partition, might not necessarily increase risks of hypergastrinemia and marginal ulcer.

Phenotypic Analysis of Vertigo 2 Jackson Mice with a Kcnq1 Potassium Channel Mutation

The KCNQ1 gene encodes a voltage-dependent potassium ion channel, and mutations in this gene are the most common cause of congenital long QT syndrome (LQTS). In the present study, we investigated the various phenotypic characteristics of vertigo 2 Jackson (C3H/HeJCrl-Kcnq1(vtg-2J)/J) mice with a Kcnq1 mutation. Both heterozygotes (vtg-2J/+) and homozygotes (vtg-2J/vtg-2J) showed prolonged QT intervals in electrocardiograms (ECGs) compared to C3H/HeJ control (+/+) mice. Furthermore, vtg-2J/vtg-2J mice showed gastric achlorhydria associated with elevation of their serum gastrin levels. The serum corticosterone levels were also significantly increased in vtg-2J/vtg-2J mice. In addition, vtg-2J/vtg-2J mice exhibited significantly higher blood pressure. These findings indicate that the Kcnq1 mutation in vtg-2J mice alters various physiological functions in the cardiac, gastric and adrenocortical systems, and suggest that vtg-2J mice may represent a useful model for studying Kcnq1 functions.

Gastric body partition to avoid ulcerogenic risk and hypergastrinemia

BACKGROUND

For treatment of giant perforated peptic ulcers, we hypothesized that partitioning of the gastric body instead of the antrum would prevent hypergastrinemia and minimize ulcerogenic risk. By maintaining part of the acid-secreting gastric body in continuity with the excluded distal stomach, gastrin-secreting cells in the antrum would still be inhibited by gastric acid secretion from the gastric body.

METHODS

We studied (1) gastric body partition with gastrojejunostomy in 8 critically ill patients with giant perforated peptic ulcers and (2) the influence of gastric partition on serum gastrin in 18 dogs with gastric antral partition + gastrojejunostomy, or gastric body partition + gastrojejunostomy, or gastrotomy.

RESULTS

No patient developed major postoperative complications. Serum gastrin levels were normal in 6 patients but showed an abnormal increase in 2 patients 1 month after gastric body partition. Serum gastrin levels had returned to the normal range at postoperative follow-up after 2 years. In the animal study, serum gastrin levels and the number of G-cells in the excluded antrum and acid-secreting parietal cells in the gastric body were increased when evaluated on day 60 postoperatively or after antral partition, compared with preoperative data in the same group. These changes did not occur in the group undergoing partition of the gastric body and the group undergoing gastrostomy. Postoperative serum gastrin levels, and the number of G-cells and parietal cells also was significantly greater in the antral partition group than in the other 2 groups. No ulcer was found in any dog in the gastric body partition and gastrostomy groups, but ulcers occurred in 4 dogs in the antral partition group, all of whom died of ulcer perforation.

CONCLUSIONS

Gastric body partition + gastrojejunostomy is a simple, dependable procedure for patients with perforated giant peptic ulcers. This procedure does not require extreme expertise and can be performed in a very short time, even by a trainee general surgeon in emergency.

Effects of hypochlorhydria and hypergastrinemia on structure and function of gastrointestinal cells. A review and analysis

Since hypochlorhydria can induce hypergastrinemia, and gastrin has a trophic effect on some gastrointestinal cells, states that cause elevated plasma gastrin levels are of interest in terms of effects on cell growth and function. This article reviews the relationship between gastric mucosal cells during periods of acid stimulation and inhibition and analyses the effects of hypochlorhydria and hypergastrinemia on gastric and colonic cells and tumors. Hypochlorhydria releases the inhibitory effect of antral gastrin cells, inducing them to release gastrin in the presence of peptides or amino acids in the gastric lumen or in response to antral distension. Gastrin stimulates the oxyntic mucosa, which may lead to hyperplasia of enterochromaffin-like cells, resulting in enterochromaffin-like carcinoid tumors in aged rats and, rarely, in patients with chronic atrophic gastritis or gastrinomas. In addition to hypergastrinemia, other factors appear to be required for the progression of enterochromaffin-like hyperplasia to carcinoids; genetic factors may be involved. Gastrin elevations due to antisecretory drug therapy are indirectly proportional to the degree of acid inhibition and are reversible upon cessation of therapy. The gastrin levels during omeprazole therapy are similar to those caused by gastric vagotomy. Available evidence does not support a relationship between hypergastrinemia and the occurrence or growth of gastric carcinoma or colonic tumors.

Role of serum fasting gastrin in screening for hypergastrinemic syndromes in duodenal ulcer disease

Basal serum gastrin levels were measured in 237 patients with endoscopically confirmed duodenal ulcer and were higher than normal in 16 cases. Protein meal gastrin stimulation was performed on this group of 16 patients and on a control group of 48 patients with normal basal gastrin concentrations but high rates of either ulcer recurrence or of complications (e.g., bleeding or perforation); 21 patients from the two groups were also tested for serum gastrin inhibition with secretin. Four cases (25%) of antral G-cell hyperfunction were found in the first group, plus 1 case compatible with Zollinger-Ellison syndrome (6.2%). Only 1 case (2%) of antral G-cell hyperfunction was found among the 48 controls. These results suggest the clinical utility of routine basal gastrin measurement in screening for hypergastrinemic patients with duodenal ulcer disease.

Reducing meal-stimulated acid secretion versus reducing nocturnal acid secretion for healing of duodenal ulcer

Both meal-stimulated and nocturnal acid secretions have been shown to be abnormally increased in patients with duodenal ulcer. The relative efficacy of an acid-reducing regimen aimed specifically at controlling postprandial acid secretion compared with one that controls nocturnal acid secretion is, however, not known. The endoscopic healing rates at weeks 2, 4, 6, 8, 10, and 12 of three cimetidine regimens with identical total daily dose--bedtime (1200 mg), mealtime (400 mg three times a day with meals), and reference (200 mg three times a day with meals and 600 mg at bedtime)--were compared in a randomized study on 141 patients with endoscopically proven duodenal ulcer. Evaluating endoscopists were blinded to patients' form and duration of treatment and their clinical progress; patients were unaware of the comparative design of the study. Life-table analysis for the 12 weeks of observation revealed that the mealtime regimen resulted in significantly (P less than 0.05) better healing rates than either the bedtime or the reference regimen. The differences were accounted for largely by the significantly (P less than 0.04) better healing rate at two weeks with the mealtime regimen (68%) than with either the bedtime (47%) or the reference (45%) regimen. These findings indicate that a regimen that aims at controlling meal-stimulated acid secretion achieves a faster healing rate than one that aims at controlling nocturnal acid secretion in the treatment of duodenal ulcer, and they suggest that postprandial acid secretion plays a greater role than nocturnal acid secretion in the pathophysiology of this condition.

Studies of the release of gastrin from the human duodenum induced by gastrin-releasing peptide

In the present study the influence of duodenal exclusion and vagotomy on basal release of gastrin from extra-antral stores has been investigated in addition to the consequences of these procedures on the gastrin response to gastrin-releasing peptide (GRP) infusion. Basal gastrin concentrations and the response to GRP were measured in seven patients after a Whipple operation, in seven patients after antrectomy combined with selective gastric vagotomy and B I reconstruction, in seven patients operated on with antrectomy, selective gastric vagotomy, and Roux-en-Y reconstruction, and finally in seven patients after antrectomy, truncal vagotomy, and Roux-en-Y reconstruction. Gastrin was measured by a highly specific radioimmunoassay. Very low concentrations were obtained after a Whipple operation, and no increase followed GRP infusion. The basal gastrin concentrations were slightly higher in antrectomized patients, irrespective of whether a selective gastric vagotomy had been added. However, in these patients a significant gastrin response followed GRP infusion. Duodenal exclusion seemed not to influence the response to GRP. On the other hand, extragastric vagotomy was followed by low gastrin concentrations in the basal state and only a marginal response to GRP administration. These results strongly suggest that GRP releases gastrin from the human duodenal mucosa and that duodenal exclusion does not alter the response of the duodenal gastrin cells to GRP stimulation. Vagal denervation of the duodenal mucosa seems to suppress the gastrin response to GRP, indicating an excitatory influence of the vagus nerve.

Gut hormone release by intraduodenal stimulation in duodenal ulcer patients

After an overnight fast, plasma levels of gut peptide hormones were determined before and after intraduodenal stimulation (IDS) with glucose and citric acid in 8 patients with a recent endoscopically proved duodenal ulcer (DU) attack and in 8 healthy volunteers. The DU patients had a hyperacidic mean BAO of 6.6 and an average PAO of 41.8 mEq/h. In DU, basal secretin levels were similar to those in controls, and after IDS secretin release was not impaired. There was no defect of VIP liberation or of the neurotensin response (basal 21 +/- 7 vs 16 +/- 3, after IDS 68 +/- 28 vs 35 +/- 5 pmol/l) which could account for gastric acid hypersecretion. Although fasting GIP levels were significantly lower than in controls (16 +/- 2.5 vs 25 +/- 1.4 pmol/l), they did not correlate negatively with BAO. In contrast to former studies with oral test meals, integrated GIP release was rather reduced after IDS. Basal plasma levels of gastrin were significantly lower in DU (4.0 +/- 0.4 vs 12 +/- 2 pmol/l) and were inversely related to BAO (r = -0.82, p less than 0.02). From the present data, there is insufficient evidence for abnormal plasma levels of gut hormones as major etiologic factors for basal hyperchlorhydria in ordinary DU disease.

Comparison of adrenergic and cholinergic receptor-mediated stimulation of gastrin release from rat antral fragments

Rat antral mucosal fragments were maintained in short-term culture to examine the relative potencies and receptor specificity of the cholinergic agonist, carbachol, and adrenergic agents, norepinephrine, isoproterenol, clonidine and phenylephrine in stimulating gastrin release. Results of these studies indicate that norepinephrine and carbachol evoke pharmacologically and temporally distinctive patterns of antral gastrin release. Dose-response experiments indicate that norepinephrine is approximately 10,000 times more potent on a molar basis than carbachol in stimulating antral gastrin release. Adrenergic (norepinephrine, isoproterenol) stimulation of antral gastrin release was prevented by propranolol, and cholinergic- (carbachol) mediated peptide release was blocked by both atropine and pirenzepine. Phenylephrine and clonidine did not alter basal gastrin release. The pattern of peptide release as a function of time was quite different for each agent: norepinephrine exerted its stimulatory effect acutely during the initial 30 minutes of incubation, while carbachol exhibited a sustained stimulatory action throughout the 2-hour culture period. In conclusion, data from these studies suggests that there are marked differences between norepinephrine and carbachol in their pharmacological potency and time-dependent activation of the G cell.

Divergent effects of bombesin and bethanechol on stimulated gastric secretion in duodenal ulcer and in normal men

To further investigate differences in the responses of normals and patients with duodenal ulcer with respect to gastrin release and acid and pepsin secretion, we infused bombesin (1 microgram/kg X h) or bethanechol (40 micrograms/kg X h) during the middle hour of a 3-h infusion of pentagastrin and compared the results with a pentagastrin infusion without added drug. Pentagastrin dosage (0.1 microgram/kg X h) was set to give about half-maximal response, to detect either inhibition or further stimulation of gastric secretion, whereas the dose of bombesin was chosen to give maximal gastrin but less than maximal acid secretion. Serum gastrin and somatostatin were also measured. In all subjects tested, bethanechol produced no effects on acid, gastrin, or somatostatin release but increased pepsin output. By contrast, bombesin inhibited pentagastrin-stimulated acid output in all 6 normal men by an average of 55%, whereas it inhibited acid output in only 2 of the 9 men with duodenal ulcer. Serum gastrin increases after bombesin in duodenal ulcer were three to four times greater than in normals. Although bombesin stimulates acid only by releasing gastrin, we postulate that bombesin may also simultaneously limit acid and pepsin secretion and speculate that this effect could be mediated by bombesin-induced somatostatin release. The cause for differences between duodenal ulcer and normal remain speculative.

Nature of the gastric acid-gastrin feedback loop in the fetal sheep

1. The neonates of sheep and other species have a decreased gastric acid secretion but an elevated plasma gastrin concentration. 2. Since low gastric acid secretion is a stimulus for gastrin release in mature animals the present study examined whether the relative hypochlorhydria in the sheep fetus was sustaining the hypergastrinaemia. 3. Fetal plasma gastrin was measured following fetal gastric acidification (pentagastrin infusion) and gastric neutralization (parietal cell blockade with the proton pump inhibitor omeprazole) in chronically cannulated fetal sheep from 101 days until term (145 days). 4. Acutely raising gastric pH with omeprazole increased plasma gastrin in the mature sheep. However, in the fetus increasing the pH with omeprazole or decreasing pH with pentagastrin had no effect on fetal plasma gastrin. This was true for fetuses from all age groups. 5. The results indicate that the gastric acid-gastrin feedback loop is not functional in the fetus and that the hypergastrinaemia at birth is therefore not the result of the relative hypochlorhydria. 6. The time after birth when the gastric acid-gastrin feedback loop matures remains to be determined.

Duodenal G- and D-cell changes following corticosteroid administration. Immunocytochemical long-term study in guinea pigs

Prednisolone administration in guinea pigs for 20 days induces significant hypergastrinemia and duodenal G-cell hyperplasia. Hypergastrinemia and duodenal G-cell hyperplasia are less prominent following 40 days of prednisolone administration and this could be partly attributed to the duodenal D-cell increased activity, which represents an adaptive response to the alterations of gastric secretory functions induced by corticosteroids.

Cholecystokinetic and pancreozymic effect of O-sulfated gastrin compared with nonsulfated gastrin and cholecystokinin

To assess whether sulfated gastrin contributes to the cholecystokinetic and pancreozymic activity of plasma in humans, 8 healthy subjects on separate days received a mixed meal, graded i.v. infusions of synthetic human tyrosine-O-sulfated gastrin 17 (10.9, 32.7, and 98.1 pmol/kg X h), which was compared with nonsulfated gastrin 17 (12.2, 36.6, and 109.8 pmol/kg X h) and O-sulfated cholecystokinin-octapeptide (5.5, 16.5, and 49.5 pmol/kg X h). Gallbladder volumes were measured by ultrasonography, and the concentrations of gastrin and cholecystokinin in the circulation were determined by specific radioimmunoassays. Neither of the gastrins induced changes in gallbladder volume at serum concentrations occurring postprandially, whereas cholecystokinin-octapeptide produced a significant reduction in gallbladder volume even at a plasma cholecystokinin concentration lower than observed postprandially. Another 8 subjects received the same infusions in combination with a background infusion of synthetic secretin (0.3 CU/kg X h). Gastric and duodenal juice was continuously aspirated using a double-marker perfusion technique. Neither of the gastrins caused an increase in the output of amylase, lipase, trypsin, chymotrypsin, or bilirubin, but both induced a modest increase in the output of bicarbonate and duodenal juice, the former only significantly during infusion of sulfated gastrin 17. The output of all parameters was significantly elevated during all doses of cholecystokinin-octapeptide. The results indicate that neither of the gastrins stimulates gallbladder contraction and pancreatic enzyme secretion in humans under physiologic conditions. However, gastrin may, like cholecystokinin, potentiate the effect of secretin on pancreatic secretion of juice and bicarbonate.

Fasting and food-stimulated serum gastrin concentration in 151 duodenal ulcer patients and 41 non-dyspeptic volunteers. Significant sex differences

In 41 non-dyspeptic volunteers (18 females and 23 males) the fasting and food-stimulated serum gastrin concentration was investigated. No significant sex differences were found in the basal serum gastrin concentration. The integrated postprandial gastrin output, however, was significantly higher in females than in males. In 151 duodenal ulcer patients (31 women and 120 men) significant sex differences were found in both the fasting and the food-stimulated serum gastrin concentration. Women had values approximately 60% higher than men. In 116 of the patients (27 women and 89 men) the basal and pentagastrin-stimulated gastric acid concentrations were investigated. In the basal state no significant sex differences in acid output were found. After stimulation women had significantly lower gastric acidity and gastric acid output than men.

Basal and food-stimulated levels of gastrin and pancreatic polypeptide in non-ulcer dyspepsia and duodenal ulcer

Basal and food-stimulated levels of gastrin and pancreatic polypeptide (PP) were studied in 86 patients with non-ulcer dyspepsia (NUD), defined as chronic or recurrent epigastric pain without anatomical antecedents and without concomitant symptoms of irritable bowel. Thirteen patients with endoscopically confirmed duodenal ulcer disease (DU) and 13 healthy subjects constituted the reference groups. The mean basal gastrin concentration was moderately but significantly (p less than 0.05) higher in the NUD group than in the reference groups (24.3 +/- 1.6 (SEM) pmol/l in NUD, compared with 15.0 +/- 1.5 and 13.6 +/- 1.0 pmol/l among DU patients and healthy subjects, respectively). The well-established postprandial hypergastrinemia in duodenal ulcer patients could be confirmed in this study, and their gastrin response to food was significantly (p less than 0.01) greater than the responses observed both in healthy subjects and in NUD patients. The two latter groups did not differ significantly with regard to gastrin increments, but there was a tendency towards greater increases in the NUD group. A significantly (p less than 0.05) enhanced PP response to the test meal was observed among the DU patients, whereas the response pattern in NUD was closely similar to that in healthy subjects.

Decision analysis in evaluation of hypergastrinemia

Hypergastrinemia and gastric acid hypersecretion are the principal laboratory features of Zollinger-Ellison syndrome. Decision and cost-effectiveness analyses were employed in the present study to compare and contrast the diagnostic strategies of initial gastric analysis followed by secretin infusion test versus secretin infusion test alone in the evaluation of hypergastrinemia in patients suspected of having gastrinoma. The results of this study showed that 59 percent of patients with elevated serum gastrin values were either hypochlorhydric or achlorhydric. Application of decision analysis to either diagnostic strategy demonstrated that gastric analysis followed by secretin infusion test, if indicated, was superior in expected value than secretin infusion test alone. Likewise, in this group of patients, performance of gastric analysis in the outpatient setting prior to secretin infusion testing was financially more advantageous than performance of secretin infusion testing alone. These results also demonstrate the importance of performing gastric analysis prior to anticipated hospitalization for evaluation of suspected gastrinoma. Such testing would obviate unnecessary hospitalization and medical costs.

Increased serum pancreatic polypeptide and serum gastrin secretion in patients with functional dyspepsia: correlation to the shape of the duodenal loop

Simultaneous measurement of food-stimulated serum pancreatic polypeptide and serum gastrin was carried out in 18 patients with functional dyspepsia and correlated to the shape of the duodenal loop. Significantly higher serum concentrations of pancreatic polypeptide and gastrin were encountered in patients with an abnormal shape of the duodenal loop compared to patients with a normal shape. Although no cause could be given to the phenomenon it may be taken into account when evaluating hormone profiles in patients with functional dyspepsia.

Acid and gastrin responses during intragastric titration in normal subjects and duodenal ulcer patients with G-cell hyperfunction

Amino acid induced acid and gastrin responses during intragastric titration at pH 2.5 and 5.5 were compared in normal subjects and duodenal ulcer patients with G-cell hyperfunction. The latter were identified on the basis of raised basal or maximal acid outputs and increased gastrin responses to feeding. In normal subjects the mixed amino acid meal stimulated only modest increases in serum gastrin, and the highest observed increase was about 30% that after a standard meal. In contrast, in the G-cell hyperfunction group the highest gastrin concentrations were similar to those after a standard meal. In the G-cell hyperfunction group the increment in serum gastrin at pH 2.5 expressed as a proportion of that at pH 5.5 was 0.29 indicating that the capacity of acid to inhibit gastrin release was well established in these patients. Acid secretory rates were close to maximal at both pH 2.5 and 5.5 during intragastric titration in the ulcer patients, but in normal subjects acid output was about 50% maximal at 2.5 and close to maximal at 5.5. The results suggest that the enhanced gastrin response to feeding in G-cell hyperfunction patients is because of increased sensitivity to amino acid stimulation rather than to diminished acid-inhibitory mechanisms.

Presence and stability of gastrin in the gastric juice of the fetal sheep

Although gastrin is found in adult gastric juice, rapid enzymatic destruction by pepsin in the acid environment makes a physiological role in the adult unlikely. Gastric pH in the fetal sheep is neutral so that gastric juice gastrin could be present, and if present, have a physiological function. The aim of this study was to determine the presence, molecular forms and metabolism of gastrin in gastric juice. Gastrin was present in fetal gastric juice at significantly higher concentrations than in fetal plasma. The majority of gastric juice gastrin was present as the biologically active gastrin-17. Gastrin was stable in normal fetal gastric juice, but was rapidly metabolized to smaller C-terminal fragments when the gastric juice was acidified. With the known growth promoting effect of gastrin on gastrointestinal mucosa, gastrin in fetal juice could have a unique role in the in utero development of the gastrointestinal tract.

Release of gastrointestinal peptides in response to vagal activation induced by electrical stimulation, feeding and suckling

This paper contains a discussion and presentation of evidence concerning vagal control of the release of some gastrointestinal peptides, the secretion of gastrin and somatostatin in particular. Some aspects of the regulation of vasoactive intestinal peptide (VIP), substance P, bombesin and insulin release by the vagus nerve are also reviewed. Data were obtained not only by electrical stimulation of the vagi but also by monitoring effects of feeding and suckling. The involvement of vagal afferents, transmitters, neurohormones in release of other hormones and humorally carried activators and inhibitors is analyzed. Particular attention is paid to the chains of reactions induced by physiological stimuli: feeding and suckling.

Effects of gastrocystoplasty on serum gastrin levels and gastric acid secretion

Hypersecretion of gastric acid and hypergastrinaemia occur when the antrum of the stomach is transposed as a diverticulum to the colon. Thus, when an antral pouch is transposed to increase bladder capacity or to replace the bladder as a gastrocystoplasty, similar pathophysiological disturbances can be anticipated. However, previous studies in our laboratories in dogs have shown that acid overproduction and stomal ulcerations do not occur. This paper reports the results of gastrocystoplasty in 13 patients followed up from 1 to 6 years. Gastric acid hypersecretion and hypergastrinaemia did not occur.

Adrenergic control of rat gastric somatostatin and gastrin release

The effect of adrenergic agonists and antagonists on the secretion of gastric somatostatin-like immunoreactivity (SLI) and gastrin was investigated in an isolated, vascularly perfused rat stomach preparation. Two- to six-fold increases in SLI secretion induced by isoproterenol, epinephrine, and norepinephrine were completely abolished by propranolol but were not influenced by phentolamine. Propranolol did not alter glucagon- and DB-cAMP-induced stimulation of SLI release. Experiments in which the beta 2-agonist salbutamol and the beta 1- and beta 2-blockers practolol and H35/25 were used showed that both subtypes of beta receptors are involved. Gastrin secretion revealed only minor changes in dose-response studies with a wide range of isoproterenol concentrations (2 X 10(-8) to 1.5 X 10(-4) M). The results obtained in this study suggest that in rats 1) the SLI response to adrenergic agonism is predominantly mediated by beta receptors; 2) both beta 1- and beta 2-adrenergic receptors are involved; 3) under in vitro conditions, adrenergic agonism is a weak stimulus for gastrin secretion.

Fluorescence histochemical methods for the study of peptide hormone-producing cells

Fluorescence histochemical methods for the demonstration of specific residues in peptides and proteins are reviewed: Formaldehyde-ozone for NH2-terminal tryptophan, formaldehyde-HCl for tryptophan regardless of position in the peptide, OPT for NH2-terminal histidine, formaldehyde-fluorescamine for "protected" amino groups, nitroso-naphthol for tyrosine, and phenanthrenequinone for arginine residues. The methods are potent in demonstrating granule-stored material in peptide hormone-producing cells. Also quinacrine, the fluorescent anti-malaria agent, binds to granular components, as yet unidentified, in several endocrine cell types. In many cases the fluorescence histochemical methods seem to demonstrate peptides and proteins distinct from the known hormones.

Fasting blood levels of gastrin, somatostatin, and pancreatic polypeptide in peptic ulcer disease

Fasting plasma levels of immunoreactive gastrin, somatostatin, and pancreatic polypeptide (PP) were determined in 67 patients with an endoscopically proven duodenal, pyloric, or prepyloric ulcer. Pretreatment gastrin (45.6 +/- 53.6 pmol/l, mean +/- S.D.) and somatostatin (54.5 +/- 27.5 pg/ml) did not differ significantly from those in 22 healthy controls (21.8 +/- 20.2 pmol/l and 64.8 +/- 24.7 pg/ml, respectively). The gastrin and somatostatin levels were not changed by 3 weeks of treatment either with propantheline and antacids or with cimetidine and antacids. The mean PP value before treatment was significantly (p less than 0.01) higher in duodenal ulcer patients (0.76 +/- 0.55 ng/ml) than in healthy subjects of similar age (0.36 +/- 0.26 ng/ml). The increased PP level was not lowered significantly by medical treatment even when this resulted in healing of the ulcer.