Distribution of beta-human chorionic gonadotropin-positive cells in noncancerous gastric mucosa and in malignant gastric tumors

The authors examined the localization and behavior of beta-human chorionic gonadotropin (HCG)-positive cells in human gastric noncancerous mucosa and in gastric malignant tumors, using immunohistochemistry and the anti-beta-HCG antibody. The beta-HCG-positive cells were located mainly in the antral mucosa and were generally restricted to the neck portion of the pyloric glands, although a few were present in fundic glands of the gastric body. The beta-HCG-immunoreactive cells were found in gastric carcinomas in 53% of the 92 cases examined. These cells were observed more often in advanced carcinomas that were histologically poorly differentiated than in early carcinomas or in well-differentiated tumors, but this prevalence had no statistical significance. The presence of the beta-HCG-positive cells in the gastric carcinomas suggested no appreciable prognostic significance, even quantitatively. In the syncytiotrophoblast-like tumor cells seen in four gastric tumor samples with histologic features of a choriocarcinoma, immunoreactivity to the beta-HCG was striking. There was, however, no recognizable dominance in the number of beta-HCG-reactive cells in the noncancerous mucosa around the tumor.

Molecular forms of gastrin in antral mucosa of the horse

The predominant form of gastrin in the antral mucosa of the stomach of virtually all species previously examined is the 17 amino acid peptide little gastrin (G17). This report describes the occurrence in equine antral mucosa of an immunoreactive form of gastrin with elution properties on Sephadex G-50 superfine similar to human unsulfated big gastrin (G34-I). This putative equine big gastrin was a major component of the gastrin immunoreactivity present. A second peak of activity in equine antral mucosa eluted in an identical manner to human little gastrin (hG17-I). Inhibition curves of equine big and little gastrin, with the gastrin radioimmunoassay utilized in this study, were parallel. This observation indicates that there was no spurious increase in the apparent relative amount of big gastrin due to significant differences in the RIA antibody cross-reactivity to big and little equine gastrin. The equine big gastrin peak was resolved by ion exchange chromatography into unsulfated and sulfated forms in approximately equal amounts. This data implies that posttranslational processing of gastrin in horses may differ from that of species previously studied.

Characterization of the carboxyl terminal flanking peptide of rat progastrin

A peptide identical in structure to the carboxyl-terminal flanking nonapeptide of rat progastrin, predicted by cDNA sequence, was synthesized. The synthetic peptide was used for production of a rabbit antiserum. This antiserum was used to develop a radioimmunoassay specific for rat carboxyl terminal flanking peptide. This assay was used to monitor the purification of immunoreactivity from rat antral extracts. Gel permeation, anion exchange and reverse phase chromatography steps resulted in a single absorbance peak associated with the carboxyl terminal flanking peptide immunoreactivity. The purified peptide eluted in the same position as the synthetic peptide during all three types of chromatography. This material was shown to be identical in mass to Ser-Ala-Glu-Glu-Glu-Asp-Gln-Tyr-Asn, the predicted sequence of the carboxyl terminal nonapeptide of rat progastrin.

Influence of diet on the development of antral gastrin-like immunoreactivity in the stomach of rats

The effects of individual food constituents on antral gastrin-like immunoreactivity concentrations were studied in young rats. Rats aged 7 to 20 days were given only rat breast milk and then weaned by various nutrients (regular laboratory chow, protein (ovalbumin)-, fat- or carbohydrate (starch)-rich food). Rats receiving rat breast milk only until 27 days of age were also studied. In rats on regular laboratory chow, antral gastrin-like immunoreactivity increased and reached adult levels on day 25. In rats on ovalbumin, fat-rich food or starch, it increased on day 23 but dropped thereafter. The increment by laboratory chow was higher than that by the individual nutrients. No increase was observed during milk feeding alone. Gel filtration of antral gastrin-like immunoreactivity from 25-day-old rats on laboratory chow or three essential nutrients showed the same results.

Aging and gastrin production: changes in serum and antral gastrin concentrations in the rat

Serum gastrin concentration and antral gastrin content were measured in 4-5- and 26-28-mo rats under fed conditions, after 3 days of starvation, and after 1 day of refeeding after starvation, to determine whether gastrin homeostasis is altered during aging. Gastric weight was 29% greater, but antral weight and DNA were less in the older rats. Serum gastrin fell during starvation and rose during refeeding in both groups, but it was lower in aging rats only during refeeding. Antral gastrin content in older animals was 60% of that in young rats. Starvation reduced antral gastrin only in the young, whereas refeeding lowered antral gastrin in the older animals. We conclude that, in aging rats, the relationship of serum and antral gastrin is altered during changes in food intake.

Prosomatostatin-derived antrin is present in gastric D cells and in portal blood

The three widely distributed peptides derived from prosomatostatin are the original neurohormone somatostatin-14, somatostatin-28, and somatostatin-28(1-12), which are all derived from the COOH terminus of the precursor. Recently a decapeptide derived from the NH2 terminus of the prohormone has been identified in extracts of rat gastric antrum and named antrin. Data now show that in both rats and humans this new molecular form is concentrated in the D cell of the gastrointestinal mucosa together with somatostatin-28(1-12). The highest concentration of antrin immunofluorescent cells is located in the mucosa of the gastric antrum. Ultrastructural studies performed on pyloric D cells using the protein A-gold technique reveals that antrin is present in the same secretory granules as somatostatin-28(1-12) and detectable in one-third of all secretory granules. Acid extracts of rat hepatic portal plasma contain a peptide similar or identical to antrin, indicating that the antral decapeptide circulates in blood.

Delta sleep-inducing peptide (DSIP)-like immunoreactivity in gut: coexistence with known peptide hormones

Delta sleep-inducing peptide-like immunoreactivity (DSIP-LI) has previously been demonstrated in brain neurons and in endocrine cells of the pituitary and the adrenal medulla. By means of three different antisera against synthetic DSIP we now describe the occurrence and distribution of DSIP-LI in several gut endocrine cells. The human gut was the richest source, where DSIP-LI was located in gastrin/CCK, secretin and PYY/glicentin cells. The rat and pig gut harbour a moderate number of immunoreactive cells in the antral mucosa but in the intestines DSIP-LI-containing cells were very few. By radioimmunoassay, the concentration of DSIP-LI was determined in extracts of various gut regions from man, pig and rat. The highest concentrations were found in all human specimens compared with corresponding samples in the pig and rat. In all three species, high-performance liquid chromatography revealed a single peak of DSIP-like material with approximately the same retention time as DSIP 3-9. Taken together, the present results provide evidence for the presence of DSIP-LI in gut endocrine cells in man, pig and rat; the human gut seems to be the richest source of DSIP-like peptides.

GABA-immunoreactive cells in the rat gastrointestinal epithelium

Frozen sections of the corpus ventriculi, antrum pyloricum, duodenum, jejunum, ileum and colon from animals perfusion fixed with glutaraldehyde were treated with an antiserum specific for glutaraldehyde-fixed GABA and processed by the peroxidase antiperoxidase method. Semi-thin plastic sections from the antrum pyloricum were treated similarly. Stained cells appeared in the epithelium of all segments examined except the corpus ventriculi. The highest density of cells was observed along the major curvature of the antrum pyloricum. Here they were located in the bottom half of the gastric glands. Many of the cells showed a process extending towards the glandular lumen. No significant staining in the epithelium appeared when the antiserum was preincubated with glutaraldehyde-GABA complexes, nor when the anti-GABA serum was exchanged with anti-glycine or preimmune serum. The present findings and previous physiological data suggest that GABA may play a role in gut endocrine regulation.

Evaluation of staining methods for identifying Campylobacter pylori

Campylobacter pylori has been implicated in the pathogenesis of peptide ulcer disease. The rapid identification of this organism may depend upon histologic diagnosis, because culture methods are complex and require a minimum of seven days in order to identify a negative specimen. The purpose of this study was to determine which stain used to identify this organism was the most cost-effective and easiest to perform and interpret on a routine basis. Sixty-one consecutive gastric antral biopsies were stained with hematoxylin and eosin, Giemsa, Brown-Brenn, and Warthin-Starry, with 23 of the cases stained by Brown-Hopps. Of the stains tested, the Wright-Giemsa was the easiest to perform. The organisms on the Wright-Giemsa showed a smooth, uniform purple color, whereas the Warthin-Starry gave the organism a granular appearance that at times could be confused for silver precipitate. Both the Wright-Giemsa and Brown-Hopps stain had the highest degree of identification of the organism (defined by percent positivity). The routine use of the Wright-Giemsa stain for identification of C. pylori in antral biopsies is recommended.

Gastrin and somatostatin in the rat antrum. The effect of removal of acid-secreting mucosa

Female rats were subjected to operations aimed at reducing the amount of oxyntic gland mucosa draining its acid secretion to the antrum. The rats were provided either with Heidenhain or Pavlov pouches reducing the oxyntic mucosa draining its secretion to the antrum by about 50% or subjected to various degrees (75, 90 and 100%) of fundectomy. Ten weeks following surgery, plasma levels of gastrin and somatostatin were assayed. At the same time, antral mucosal content of gastrin and somatostatin was determined as well as the mucosal density of these hormone-producing cells. There was a relationship between the amount of acid-secreting mucosa removed and the ensuring plasma concentration of gastrin. Thus, a stepwise increase in plasma gastrin was found with the highest levels obtained in rats subjected to 90 or 100% fundectomy. The somatostatin concentration in plasma was reduced only in rats subjected to fundectomy with the most sustained decrease in animals in which all oxyntic gland mucosa had been removed. There was also a relationship between the amount of acid-secreting mucosa removed and the gastrin content of the antral mucosa. An inverse relationship seemed to exist between antral gastrin and somatostatin concentrations. However, a significant decrease in somatostatin concentration of the antral mucosa was seen only in rats subjected to a fundectomy. The number of gastrin cells in the antral mucosa was increased in fundectomized rats only, with the largest density seen in rats deprived of all oxyntic mucosa. A corresponding decrease in the number of somatostatin cells was noticed. Our results would suggest an apparent functional relationship between antral gastrin and somatostatin cells, where the antral acid load (or pH) appears to be the major factor of physiological significance.

Characterisation of N-terminally extended met-enkephalin Arg6Gly7Leu8 variants in the porcine upper digestive tract

Proenkephalin A-derived peptides are known to occur in the gut, but their precise identity is uncertain. We report here the isolation of N-terminally extended forms of Met-enkephalin Arg6Gly7Leu8 from porcine upper digestive tract monitored by radioimmunoassay. A single major form was identified in pyloric antral muscle and mucosa, but in the duodenum two major forms were detected. Microsequence analysis together with immunological data revealed that the antral mucosal peptide and the most acidic duodenal peptide had identical amino-acid sequences, corresponding to a 5.3 kDa peptide terminating in Met-enkephalin Arg6Gly7Leu8. The data indicate that high-molecular-weight peptides may constitute a major proportion of gut opioid peptide immunoactivity.

Two types of rat gastric mucus glycoprotein subunits

Gastric mucus glycoproteins were extracted with 2% Triton X-100 from rat gastric corpus and antrum and purified by CsCl equilibrium centrifugation. Corpus mucus glycoproteins were degraded into what appeared to be two "subunits" (Mw 4.4 x 10(5) and 6 x 10(6)) by the reduction of disulfide bonds. Papain digestion of the latter produced glycopeptides with a molecular weight of approximately 4.4 x 10(5). This type of subunit had carbohydrate chains with about 9 sugars attached to every 2 amino acid residues. Papain digestion of the former type of subunit revealed no change in the elution profile on Bio-Gel A-15m. This type of subunit had carbohydrate chains with 17-19 sugars attached to every 3 amino acid residues. The subunit of antral mucus glycoproteins was essentially the same as the former type of corpus subunits in molecular weight (Mw 4.4 x 10(5)) and average oligosaccharide chain length. These results suggest that there are two distinct types of mucus glycoprotein subunits in rat stomach.

Plasma gastrin responses to bombesin and antral gastrin concentrations in patients with the intestinal type of gastric cancer

Mucosal atrophy of the gastric antrum (type B atrophic gastritis) is generally accepted as predisposing to the development of the intestinal type of gastric cancer. Since bombesin stimulates gastrin release selectively from the antral mucosa, the response can be used as a marker for antral mucosal atrophy. In this study we have investigated bombesin-stimulated plasma gastrin responses in 21 patients with the intestinal type of gastric cancer and we have compared the results with 12 patients with the diffuse type of gastric cancer, 17 patients with benign gastric ulcer, and 30 dyspeptic patients without endoscopical or histological abnormalities. Gastrin concentrations were also measured in extracts of antral biopsies. Basal plasma gastrin concentrations were not significantly different. In contrast, patients with the intestinal type of gastric cancer had a significantly lower plasma gastrin response to bombesin than did the normal subjects (P less than 0.01) and patients with the diffuse type of gastric cancer (P less than 0.05), but the result was not significantly different from that of the gastric ulcer patients. The antral gastrin content of the patients with the intestinal type of gastric cancer was significantly lower than in controls (P less than 0.005), the patients with the diffuse type of gastric cancer (P less than 0.05), and those with gastric ulcer (P less than 0.05). It is concluded that patients with the intestinal type of gastric cancer have, in contrast to those with the diffuse type of gastric cancer, an abnormally low plasma gastrin response to bombesin. This low response is due to a reduced gastrin content of the antral mucosa.

Influence of pancreatic surgery on gastric ulcers and somatostatin-like immunoreactivity in portal and aortic blood, and in the gastrointestinal tissues of the rat

Two weeks after pancreatic duct occlusion (OCC) or pancreatic half-resection (RES) in rats, the development of gastric ulcers was assessed. Somatostatin-like immunoreactivity (SLI) was measured simultaneously in portal and aortic blood as well as in fundic, antral, duodenal and pancreatic tissue specimens. Extracts of antral, duodenal and pancreatic tissue were chromatographed on a Sephadex G25 superfine column (1.6 +/- 90 cm) under strongly dissociating conditions. As compared to sham-operated controls (SHAM) ulcer index in arbitrary units (AU) and ulcer severity were significantly increased in duct-occluded rats (ulcer index: 5.6 +/- 1.9 AU in SHAM, 42.6 +/- 7.9 AU in OCC; severity: 0.47 +/- 0.37 mm in SHAM, 9.76 +/- 2.37 mm in OCC; p less than 0.001 respectively). Aortic SLI was increased in both experimental groups (SHAM: 53.2 +/- 7.4 pg/ml; RES: 110.9 +/- 16.6 pg/ml, p less than 0.01 vs SHAM; OCC: 96.0 +/- 9.0 pg/ml, p less than 0.001 vs SHAM); portal SLI was decreased in duct-occluded rats (SHAM: 88.9 +/- 7.1 pg/ml; OCC: 65.7 +/- 9.9 pg/ml; p less than 0.05). Tissue SLI was raised in the gastric fundus of duct-occluded rats (SHAM: 6.4/1.3-36.1 micrograms/g; OCC: 8.2/5.1-14.9 micrograms/g; p less than 0.05) and in the duodenum of resected animals (SHAM: 0.7/0.2-1.6 micrograms/g; RES: 1.4/0.4-2.3 micrograms/g; p less than 0.05), but decreased in the duct-occluded pancreas (SHAM: 3.7/1.0-8.2 micrograms/g; OCC: 2.1/0.5-5.6 micrograms/g; p less than 0.05). In all three groups, the major part of total SLI in antrum, duodenum and pancreas was identical with somatostatin-14 at gel chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycoconjugate expression in normal, metaplastic, and neoplastic human upper gastrointestinal mucosa

Glycoconjugate structure in upper gastrointestinal epithelium was studied using five lectins to determine the relationship between aberrant differentiation and glycoconjugate expression. Specimens of normal esophagus, stomach, and duodenum were examined and compared with specimens of columnar metaplasia in the esophagus (Barrett's esophagus) and specimens of adenocarcinoma of the esophagus and stomach. Specific terminal glycoconjugate structures were found for the esophagus, stomach, and duodenum. Minor differences were found between the antral and fundic gland mucosae, reflecting their respective cell populations. In biopsies of Barrett's esophagus, gastric-type columnar metaplasia expressed glycoconjugates indistinguishable from those in the normal stomach. In specialized-type columnar metaplasia, a more restricted expression of glycoconjugates was seen resembling the normal duodenum. The presence of low grade dysplasia in Barrett's esophagus associated with adenocarcinoma had no impact on glycoconjugate expression. However, a distinctive difference in glycosylation was seen in high grade dysplasia of the columnar-lined esophagus and in adenocarcinoma of the esophagus and stomach. Barrett's esophagus is a morphological mosaic in which the glycoconjugate expression resembles that seen in the normal stomach and duodenum. However, in high grade dysplasia and carcinoma, variable deletion of glycoconjugate expression can be found.

Immunoreactive neuromedin B and neuromedin C: distribution and molecular heterogeneity in rat and human tissue extracts

Immunoreactive neuromedin B and neuromedin C were characterized and measured in rat and human tissue extracts, using radioimmunoassay combined with gel filtration and high performance liquid chromatography in order to clarify tissue distribution and molecular structure. There are two distinct systems of bombesin-like peptide found in rat and human tissue. The neuromedin B family, including neuromedin B and big neuromedin B, is a major bombesin-like peptide in the brain; the neuromedin C gastrin-releasing peptide family is found mainly in the alimentary tract. Neuromedin B is the major and big neuromedin B the minor constituent of central nervous neuromedin B immunoreactivity. Gastrointestinal neuromedin C immunoreactivity is composed chiefly of neuromedin C in rats, and two N-terminally extended forms of neuromedin C including gastrin-releasing peptide in man. It is probable that molecular heterogeneity reflects species variation.

Localization of G cells in the antral mucosa of Rana temporaria: immunocytochemical and electron microscopy study

G cells of the frog antral mucosa are described both in deplasticized semithin sections treated with antigastrin/CCK COOH terminal serum and in subsequent thin sections observed under the electron microscope. G cells are quite abundant in the antral mucosa, located between mucosecretory cells in the lateral aspects of glands. They bear irregular, occasionally round granules, with a 190-nm mean diameter.

Degradation of endogenous heptadecapeptide gastrin by endopeptidase 24.11 in the pig

Hydrolysis of heptadecapeptide gastrin (G-17) by endopeptidase 24.11 (EC 3.4.24.11) was studied in vivo and in vitro in the pig. Ion exchange chromatography and radioimmunoassay with three region-specific antisera were used to identify the products of porcine G-17 degradation. Incubation of antral extracts with pure endopeptidase 24.11 resulted in a substantial loss of intact G-17: 80% C-terminal immunoreactivity was lost in 60 min. This hydrolysis was completely inhibited by phosphoramidon, which is a specific inhibitor of endopeptidase 24.11. In antral extracts G-17 accounted for greater than 95% of total C-terminal immunoreactivity, compared with less than 60% C-terminal immunoreactivity in the gastric venous outflow; shorter C-terminal forms comprised the major part of the remaining immunoreactivity. After infusion of phosphoramidon, the concentration of intact G-17 was increased, and there was a corresponding reduction in the concentration of other C-terminal immunoreactive fragments. We conclude that endopeptidase 24.11 degrades G-17 in vitro and in vivo and may be responsible for the generation of C-terminal fragments from G-17 after secretion from the porcine antral mucosa.

Smooth-muscle endoplasmic reticulum contains a cardiac-like form of calsequestrin

It is proposed that smooth-muscle endoplasmic reticulum contains calsequestrin and that this protein in smooth muscle resembles cardiac calsequestrin more than the skeletal-muscle form. This proposal is based on seven similarities between the smooth-muscle protein and cardiac calsequestrin. Proteins with an Mr of 55,000 can be extracted from the membranes of smooth muscle and of cardiac muscle using 100 mM Na2CO3. The protein from smooth muscle binds to phenyl-Sepharose in the absence of Ca2+ and is released by 10 mM CaCl2, as has been observed for cardiac calsequestrin. The protein from smooth muscle comigrates with the cardiac calsequestrin on Laemmli-type SDS-polyacrylamide gel electrophoresis. The protein of Mr 55,000 from smooth muscle and cardiac calsequestrin both strain blue with the carbocyanine dye Stains-all. Both proteins present similar one-dimensional Cleveland peptide maps although minor differences might exist. From an analysis of subcellular membranes separated by sucrose gradient centrifugation it is concluded that the protein with Mr 55,000 from the smooth muscle is confined to the endoplasmic reticulum, the same subcellular structure from which, in heart muscle, calsequestrin can be isolated. Antibodies raised against canine cardiac calsequestrin bind to a protein of similar Mr in smooth-muscle endoplasmic reticulum. In addition to the calsequestrin, three other extrinsic proteins with an Mr of 130,000, 100,000 and 63,000, stain blue with Stains-all and occur in the endoplasmic reticulum of smooth muscle.

Duodenal gastrin concentration in upper gastrointestinal disorders

Duodenal gastrin concentration was measured in endoscopic forceps biopsy specimens of the juxta-pyloric duodenal mucosa in patients with various gastrointestinal disorders. Duodenal gastrin concentration was 5.9 +/- 1.2 ng/mg (mean +/- 1 SEM) in control patients. Duodenal gastrin concentration was similar to control values in patients with duodenal ulcer, pyloric channel ulcer, vagotomy and pyloroplasty, and gastric atrophy and hypergastrinemia. In gastric ulcer patients, duodenal gastrin concentration, 2.8 +/- 0.6 ng/mg, was significantly less than the control value (P less than 0.05). Duodenal gastrin concentration was approximately one third of antral gastrin concentration in control, duodenal ulcer, and gastric ulcer patients and was approximately one fifth of antral gastrin concentration in vagotomy and pyloroplasty patients and gastric atrophy patients. Duodenal and antral gastrin concentrations were significantly correlated in normal controls and in gastric ulcer patients. The finding of normal duodenal gastrin concentration in patients with vagotomy and pyloroplasty and patients with gastric atrophy suggests that, unlike antral gastrin concentration, duodenal gastrin concentration is unaffected by a decrease in acid secretion rate. The low duodenal gastrin concentration in gastric ulcer patients indicates that the duodenum may be involved in the pathophysiology of gastric ulcer disease.

Isolation from chicken antrum, and primary amino acid sequence of a novel 36-residue peptide of the gastrin/CCK family

A peptide that cross-reacted with C-terminal gastrin/CCK antisera was isolated from chicken antral extracts by a combination of gel filtration and reversed-phase HPLC. The sequence was: Phe-Leu-Pro-His- Val-Phe-Ala-Glu-Leu-Ser-Asp-Arg-Lys-Gly-Phe-Val-Gln-Gly-Asn-Gly-Ala- Val-Glu-Ala-Leu-His-Asp-His-Phe-Tyr-Pro-Asp-Trp-Met-Asp-Phe(NH2). Aside from the C-terminal tetrapeptide and the Tyr residue, the molecule does not resemble other known forms of gastrin or CCK. The peptide was a potent stimulus of avian gastric acid but not pancreatic secretion. The results have important implications for the structure-activity and evolutionary relationships of the gastrin/CCK family.

Chromatographic and immunochemical studies on postsecretory processing of gastrin in the pig

Immunoreactive forms of gastrin in antral mucosal extracts and in gastric venous plasma of the pig were compared using ion-exchange and gel-filtration chromatography and radioimmunoassay using three region-specific antiserums. In antral mucosal extracts, gastrin heptadecapeptide (G-17) accounted for over 90% of the total C-terminal immunoreactivity, but in gastric venous plasma it accounted for only 47% of total C-terminal immunoreactivity. The remaining C-terminal immunoreactivity was accounted for by shorter C-terminal forms. Unsulfated and sulfated G-17 contributed 44.1 and 49.2%, respectively, of C-terminal immunoreactivity in antral mucosa. In contrast, they contributed 14 and 30%, respectively, to total C-terminal immunoreactivity in gastric venous plasma. Incubation of antral extracts with plasma in vitro resulted in a slow loss of intact G-17 (32.3% in 60 min) that could not account for the production of C-terminal fragments in vivo. Moreover, when antral extracts were infused into the gastroepiploic artery, over 90% of the gastrin present in the antral venous outflow corresponded to G-17. These observations suggest that it is unlikely that enzymes involved in the generation of the C-terminal forms are located either in blood or on the luminal side of the endothelial membrane. It is proposed, then, that antral gastrin is converted into shorter C-terminal fragments at or before the time it enters the circulation and that the major storage forms of gastrin in tissue account for less than 50% of the material in the gastric venous outflow.

Immunocytochemical evidence for differential distribution of gastrin forms using region-specific monoclonal antibodies

Immunocytochemical identification of cellular origins of different forms of gastrin in canine and human antral mucosa has been carried out using region specific monoclonal antibodies. Three types of gastrin cells were identified. The first type of cell was stained with both the C-terminal specific antibody of G17 and the N-terminal specific antibody of G17. The second type of cell was stained only with the C-terminal specific antibody of G17 but not with the N-terminal specific antibody of G17. The third type of cell was stained only with the N-terminal specific antibody of G17. From these findings we propose that the first type of cell contains gastrins with the amidated C-terminus of G17 such as component 1, G34, G17, or G14 as well as the free N-terminus of G17 such as G17, or C-terminal extended gastrins, the second type of cell contains gastrins only with the C-terminus of G17 but not with the N-terminus of G17 such as G34, or component 1, and the third type of cell contains C-terminal extended gastrins with intact N-terminus G17.

Sequences of gastrins purified from a single antrum of dog and of goat

Heptadecapeptide gastrins (G17) have been purified and sequenced from a variety of species. However, progastrin (G34) sequences have been determined only for pig and human from purified peptides and for rat from cDNA. Since G34 in most species accounts for only approximately 5% of total antral gastrin, micropurification techniques must be employed to avoid the need for large quantities of antral tissue. Efficient purification methodology yielded 1.5 and 1.3 nmol of G34 from the antrum of a single goat and of a single dog, respectively. The N-terminal pyroglutamyl residues were enzymatically removed and the peptides were sequenced through to the proximity of their COOH-termini. The COOH-terminal sequences of goat and dog G34 were confirmed by sequencing the corresponding deblocked G17 from each animal. The previously published dog G17 sequence was shown to be incorrect. The sequences for dog and goat G34 are: Dog less than ELGLQGPPQLVADLSKKQGPWMEEEEAAYGWMDF# Goat less than ELGLQDPPHMVADLSKKQGPWVEEEEAAYGWMDF# Dog and goat gastrins differ in 3 sites in the 17 amino acid NH2-terminus and only a single site in G17 (the sites of differences are underlined). The ratio for sulfated to non-sulfated antral G17 is 9:1 for the goat and 1:9 for the dog.

The distribution of polypeptide YY-like immunoreactivity in rat tissues

The distribution of peptide YY (PYY)-like immunoreactivity (IR) in rat tissues was determined by specific RIA after extraction with boiled 1 N acetic acid. The high concentration of PYY-IR was observed in the gastrointestinal tract, with concentrations gradually increasing from the duodenum to the end of colon. The concentration of PYY-IR in the colon was 298.7-449.5 pmol/g tissue (approximately 100-200 times more than that in the duodenum). Pituitary and pancreas contained measurable amounts of PYY-IR (6.8 and 6.3 pmol/g tissue). The concentration of PYY-IR in the mucosa was higher than that in the muscular layer in the small intestine, cecum, colon, and rectum. The ratio of the mucosal PYY-IR to the muscular PYY-IR was highest in the distal small intestine (4.7-6.8). Sephadex G-50 gel chromatography of the colon extracts revealed the one PYY-IR peak which corresponds to [125I]PYY. The gradual increase of PYY-IR from the duodenum to the end of the colon is different from the distribution of other known gut peptides.

Potency of natural and synthetic canine gastrin-releasing decapeptide on canine antral muscle

The carboxyl terminal decapeptide of gastrin-releasing peptide (GRP-10), a small, naturally occurring bombesin-like peptide, has been isolated from canine antral muscle, synthesized, and its bioactivity compared with other synthetic and natural gastrin-releasing peptides on stimulation of spontaneously occurring contractions of canine circular antral muscle in vitro. Concentrations of peptides were verified by amino acid analysis and radioimmunoassay. In this system three forms of natural canine GRP, synthetic GRP-10, synthetic porcine gastrin-releasing heptacosapeptide (GRP-27), [Gln3]GRP-10, and [Arg3]GRP-10 all were similar in potency to synthetic amphibian bombesin. These results differ from the low activity of GRP-10 previously reported in rat brain. The full biological potency on canine antral motility and the presence of GRP-10 in nerve fibers in the gut and in the spinal cord suggest a possible role for this peptide as a neurotransmitter or neuromodulator in regulation of smooth muscle contraction.

Antral gastrin- and somatostatin-producing cells and intraluminal peptide secretion in normal subjects and duodenal ulcer patients with and without vagotomy

The behaviour of gastrin (G) cells and somatostatin (D) cells in endoscopic antral biopsies and that of intraluminal gastrin (ILG) and somatostatin (ILS) release in the gastric juice were investigated in three groups of patients: control subjects, duodenal ulcer (DU) patients and DU patients treated by a superselective vagotomy (SSV). G and D cell densities were correlated in the three groups of subjects. The G/D cell ratio was significantly increased in SSV patients (P less than 0.001) as compared to control and DU patients. No correlation was found between gastrin or somatostatin cell densities and basal intraluminal levels of the two peptides. ILG output was significantly higher in DU patients than in control or SSV patients (P less than 0.001). ILS output was also higher in DU patients than in controls (P less than 0.001) and in SSV patients (P less than 0.05). It was also significantly augmented in SSV (P less than 0.001) as compared to control patients. ILG and ILS concentrations were only correlated in controls. Within each of the three groups of subjects, ILG and ILS release varied in function of the gastric juice pH. Our results emphasize the necessity to consider the intragastric pH as well as the physiological or pathological state to study intraluminal peptides in man.

Effect of inhibition of acid secretion on the regulatory peptides in the rat stomach

The effect of inhibiting acid secretion by pharmacologic agents on the gastric content of regulatory peptides has been determined by radioimmunoassay and immunocytochemistry. Plasma, antral, and fundic concentrations of gastrin were elevated in rats rendered virtually achlorhydric by treatment with high-dose omeprazole (400 mumol/kg daily for 10 wk). This was associated with an increase in the number and staining intensity of gastrin immunoreactive cells. A clear reciprocal relationship was observed between antral gastrin and somatostatin as assessed by both quantitative and qualitative methods. These changes had disappeared 10 wk after treatment was stopped. No alteration was found in the concentrations of other regulatory peptides proposed as important in control of acid secretion. Plasma and antral gastrin concentrations were elevated in rats treated with high-dose ranitidine (700 mumol/kg daily), but to a lesser extent than during omeprazole therapy, and somatostatin concentrations were unchanged.

Mucus, gastrin and somatostatin cells in cultured rat antral mucosa: immunofluorescence, ultrastructural and radioimmunological studies

Cells were isolated from the gastric antrum of newborn rats (7 and 10 days old) with the intent of studying mucus, gastrin (G), and somatostatin (D) cells. These cells were maintained in culture for 20 days. Their secretory properties were studied in vitro by cytochemical, immunocytochemical and radioimmunological methods. In vitro, mucus cells as well as G and D cells synthesized their secretory products intensely for the first 48 h, but beyond this point, their activity decreased. Mucus cells had a high rate of multiplication and formed sheets of epithelial cells in vitro. Their PAS-positive secretions were synthesized up until the 7th day of culture. During the first 3 days of culture, gastrin cells secreted detectable amounts of the hormone in the culture medium, but afterwards their secretion decreased. Somatostatin cells remained active until at least the 7th day of culture. They displayed long cytoplasmic processes which may serve as a means of communication with neighboring cells. Using ultrastructural techniques, mucus and endocrine cells were found to persist in culture. From a morphological point of view, they appeared similar to the cells found in the original antral tissue and this is an argument for the persistence of the secretory properties in cultivated cells. This experimental model appears to be reproducible and may be useful in the study of secretions of somatostatin, gastrin and mucus in the gastric antrum of the rat.

Identification of progastrin in gastrinomas, antrum, and duodenum by a novel radioimmunoassay

Recent studies on the gene sequence encoding the human pyloric antral hormone, gastrin, indicate a precursor of 101 residues. We have now raised antibodies to a synthetic analogue corresponding to (Tyr)-human progastrin COOH-terminal pentapeptide. The antibodies could be used in radioimmunoassay to measure this peptide, but they did not react with corresponding fragments of procholecystokinin, porcine progastrin, or other human progastrin-derived peptides, notably heptadecapeptide gastrin (G17), and 34-residue gastrin (G34). Radioimmunoassay of human antral and duodenal extracts revealed a major peak of activity that corresponded to the native COOH-terminal fragment of progastrin, and occurred in approximately equimolar amounts with COOH-terminal G17 immunoreactivity. In addition, there was a minor peak of apparently higher molecular weight material. In some gastrinomas the latter material was the predominant immunoreactive form, and it occurred in higher molar concentrations than any other form of gastrin. Digestion of this material with trypsin liberated peptides that reacted with antibodies specific for the NH2-terminus of G34, and G17. On this basis the high molecular weight component was identified as a form of gastrin that extended from the COOH-terminus of the precursor to a point at least beyond the NH2-terminus of G34, and probably included the entire progastrin sequence. The results suggest differences in posttranslational processing pathways of progastrin in antrum, duodenum, and gastrinomas. They also indicate that the present experimental approach allows the identification of progastrin-like substances, which should open the way to studying the mechanisms of gastrin biosynthesis.

Ultrastructure and localization of substance P and met-enkephalin immunoreactivity in the human fetal gastric antrum

The ultrastructural localization and relations of substance P- and met-enkephalin-labeled neuronal structures were examined in the wall of the human gastric antrum during early fetal life. By 14-16 weeks of gestation, clearly discernable neural plexuses and a well developed external muscle coat were present. In the submucous coat, neural plexuses varied from immature forms consisting of 1-4 neurites partially enveloped by Schwann cell processes to more mature plexuses where neurons were completely enclosed by Schwann cell processes. Neuronal profiles with substance P- and met-enkephalin-like immunoreactivities were observed in the submucous plexus. In the myenteric plexus met-enkephalin-like immunoreactivity was seen within cell bodies and neurites. By contrast, although substance P-like immunoreactivity was observed in neurites in the myenteric plexus, no substance P-labeled somata could be identified. Unlabeled terminals were seen in contact with both unlabeled dendrites and met-enkephalinergic neurons. An increase in electron density was observed at the sites of contact. These structures probably represent early stages in the development of synaptic specializations. In addition, met-enkephalin-labeled varicosities were seen in apposition to smooth muscle cells of the circular muscle coat. This suggests that antral smooth muscle cells are directly innervated by met-enkephalin neurons.

Beta-endorphin is present in active and inactive forms in rat gastric antrum

Lipotropin, beta-endorphin and a series of peptides related to beta-endorphin were extracted from rat antrum and resolved by gel filtration, ion exchange chromatography and high pressure liquid chromatography; the concentrations of the peptides were determined by radioimmunoassay. The major peptide with beta-endorphin immunoreactivity present in the antrum was lipotropin but it was accompanied by substantial quantities of beta-endorphin in its biologically active form; in addition there were minor quantities of a number of inactive beta-endorphin related peptides. The experiments demonstrate that in rat antrum gastrin can be accompanied by both active and inactive forms of beta-endorphin. The implications of post-translational processing mechanisms common to gastrin and beta-endorphin are discussed.

Comparative study on mucus glycoproteins in rat stomach and duodenum

The density of mucus glycoprotein compared to that of the corpus, antrum and duodenum was; 1.52, 1.49 and 1.57 g/ml respectively. Carbohydrate composition of gastrointestinal mucus glycoprotein consisted of N-acetylgalactosamine, N-acetylglucosamine, galactose, fucose and sialic acid. Ratios of carbohydrate composition among corpus, antral and duodenal mucus glycoproteins differed. The average length of an oligosaccharide was found to be about 12-13, 14 and 10 sugars in the corpus, antrum and duodenum, respectively. In the corpus, the amino acid content was found to have the following quantitative order: Thr greater than Ser greater than Glx = Pro; in the antrum: Thr greater than Ser greater than Glx; and in the duodenum: Thr greater than Ser greater than Pro. Corpus, antral and duodenal mucus glycoproteins have the blood-group A antigen; antral mucus glycoprotein in particular exhibited strong blood-group A activity.

Guinea pig "little" gastrin is a hexadecapeptide

Gastrin heptadecapeptides (gastrins I and II which differ in the presence of sulfate on the tyrosine of the latter) have been purified and sequenced from several mammalian species including pig, dog, cat, sheep, cow, human and, more recently, rat. This report describes the purification of "little" gastrin from guinea pig (GP) antra. GP antra were defatted with acetone and the acetone cakes were extracted with 0.1M NH4HCO3. The extract was concentrated by adsorption to DE53 anion exchange cellulose and the peak eluates were fractionated on a Sephadex G50F column. The peptides were brought to final purity by 3 successive HPLC steps. The GP sequence compared to other species is shown: (formula: see text) Thus GP "little" gastrins I and II are hexadecapeptides due to a deletion of a glutamic acid in the region 6-9 from the N-terminus.

[The effect of antral branch on canine antral gastrin and somatostatin concentrations in gastric vagotomy]

Three types of vagotomy: selective proximal gastric vagotomy with (SPV + P) or without (SPV) pyloroplasty and selective gastric vagotomy with pyloroplasty (SV + P) were performed on mongrel dogs, and antral immunoreactive gastrin (IRG) concentration and somatostatin like immunoreactivity (SLI) concentration were measured before and after operations. In both SPV and SPV + P groups, significant (p less than 0.01) increase in IRG concentration at the 8th and 12th postoperative weeks were observed. IRG concentration at the 12th postoperative week was significantly high (p less than 0.01) in SPV + P group compared with that in SPV group. In SV + P group, no significant change in IRG concentration was observed up to the 12th postoperative week, however, after 6th postoperative month a significant (p less than 0.01) increase was observed. SLI concentration showed no significant increase in both SPV and SV + P groups. In SPV + P group, it showed a significant (p less than 0.05) increase at the 12th postoperative week, when IRG concentration was remarkably high compared with that in the other groups. Furthermore, a significant (p less than 0.01) correlation was observed between pre- and post-operative IRG concentrations and SLI concentrations in SPV and SPV + P groups. The above results suggested that the antral branch influenced the increase in antral IRG concentration early after vagotomy and that the IRG increase might affect the increase in SLI concentration.

Isolation of calelectrin-like proteins associated with smooth muscle plasma membranes

Plasma membranes prepared from pig stomach smooth muscle (antral part) were extracted with Triton X-100 to isolate insoluble cytoskeletal components. Reextraction of the insoluble material in EGTA yielded a protein complex which resembled the family of proteins that has been designated as 'mammalian calelectrins' [Südhof, T.C. et al. (1984) Biochemistry 23, 1103-1109]. Plasma membranes prepared in the presence and in the absence of 0.6 M KCl differed by the amount of these proteins, but in both preparations the EGTA-extractable proteins were quantitatively important constituents. Two of these proteins were further purified by means of ion exchange chromatography to apparent homogeneity as judged from sodium dodecyl sulfate gel electrophoresis.

Rapid, small-scale preparation of gastrointestinal hormones by high-performance liquid chromatography on a C18 column

A rapid reversed-phase high-performance liquid chromatography method was developed for the isolation of small quantities of biologically active gastrointestinal hormones, using a Varian MCH-10 C18 column. Biologically active secretin was isolated from contamination with other hormones, including cholecystokinin, gastrin, motilin, and vasoactive intestinal polypeptide, from samples of the acid perfusate of canine duodenum and from the crude acetic acid extract of canine antral mucosa containing less than 100 picomoles of secretin. The method also appeared to be suitable for the isolation of cholecystokinin octapeptide and motilin.

Deficiency of immunoreactive somatostatin in the median eminence of Snell dwarf mice

Snell dwarf mice (dw/dw) are characterized by a genetically determined, congenital lack of pituitary GH, TSH and prolactin. Given that hypothalamic somatostatin is involved in the regulation of pituitary GH and TSH release, it was decided to investigate the content of immunoreactive somatostatin (IRS) in the median eminence of dw/dw and phenotypically normal mice of the same strain. The content of IRS in the pyloric antrum and pineal gland of these animals was also examined. The effects of ovariectomy and of hyperprolactinemia (induced by a pituitary graft under the kidney capsule) on the median eminence content of IRS were also studied in both normal and dwarf mice. Median eminence IRS content was significantly lower in the dw/dw (23.6 +/- 1.8 ng) than in normal mice (57.4 +/- 7.1 ng); no difference was found in the pyloric IRS content of dw/dw (16.9 +/- 1.6 ng/mg of protein) and normal animals (13.8 +/- 1.9 ng/mg of protein), nor in the pineal content of IRS (639.4 +/- 64.4 pg/gland in the dw/dw; 732 +/- 265 pg/gland in normals). Neither ovariectomy nor hyperprolactinemia were found to affect the IRS content in the tissues studied in normal or dwarf mice. Treatment of an additional group of 9 dwarf mice with L-thyroxine (L-T4 2 micrograms/48 h. s.c. for 2 weeks) significantly increased the animals weight (10.2 +/- 0.4 g versus 7.4 +/- 0.3 g) and produced maturation of facial features; however, it did not change the IRS content in any of the tissues studied. It is concluded that the content of IRS in the median eminence of mice with a congenital lack of GH, TSH and prolactin is significantly reduced and that this is unlikely to be related to the deficiency of thyroid hormones in these animals.

Elevated serum and antral gastrin in obese (ob/ob) mice

Elevations in serum gastrin concentration of six to seven times were found in postabsorptive 5- and 10-wk-old, but not 30- and 40-wk-old, obese mice in comparison with the appropriate lean controls. At 10 wk of age a fourfold hypergastrinemia was also evident in (ob/ob) mice denied food for 48 h. In 10-wk-old (ob/ob) mice that had eaten the same amount of food as lean mice from weaning, serum gastrin was six times that of lean controls. Antral gastrin concentration was 54% higher in fed 10-wk-old (ob/ob) mice than in lean mice. No relationship was found between alterations in serum gastrin and measures of gastrointestinal size or proliferative status. Maximal gastric acid output, expressed with respect to oxyntic mucosal dry weight, was reduced by 52% in 10-wk-old (ob/ob) mice compared with lean controls. It is concluded that the hypergastrinemia of 10-wk-old (ob/ob) mice is not caused by hyperphagia, but may be a consequence of reduced acid inhibition of gastrin release.

Somatostatin binding sites in cytosolic fraction isolated from rabbit antral and fundic gastric mucosa

Specific binding sites for somatostatin have been identified and characterized in cytosolic fraction of rabbit gastric mucosa at both antrum and fundus levels. The binding depended on time, temperature and pH, and was reversible and saturable. The stoichiometric data suggested the presence of two classes of binding sites: a class with high affinity (Kd = 26.7 and 37.0 nM in antrum and fundus, respectively) and low capacity (2.1 and 4.1 pmol somatostatin/mg protein in antrum and fundus, respectively), and a class with low affinity (Kd = 246.4 and 162.5 nM in antrum and fundus, respectively) and high capacity (134.1 and 110.9 pmol somatostatin/mg protein in antrum and fundus, respectively) at 25 degrees C and pH 7.4. The binding sites were shown to be highly specific for somatostatin since neuropeptides such as Leu-enkephalin, neurotensin and substance P behaved as ligands with very low affinity.

Beta-endorphinlike immunoreactivity and somatostatinlike immunoreactivity in normal gastric mucosa, muscle layer, and adenocarcinoma

beta-Endorphinlike immunoreactivity and somatostatinlike immunoreactivity were detected in the mucosa and muscle layer of normal gastric antrum and corpus and in moderately differentiated adenocarcinoma derived from the antral mucosa. The concentration of beta-endorphinlike immunoreactivity in the normal gastric tissues was 4-15 pmol/g wet wt tissue; this value varied from 9.64 to 241.39 pmol/g wet wt tissue (81.38 +/- 37.82 pmol/g wet wt tissue) in adenocarcinomas. The concentration of somatostatinlike immunoreactivity was 18-25 pmol/g wet wt tissue in normal gastric mucosa, whereas it was 1-2 pmol/g wet wt tissue in adenocarcinomas. Gel exclusion chromatography of beta-endorphinlike immunoreactivity revealed two peaks corresponding to beta-endorphin and beta-lipotropin. In normal mucosa and in the whole layer of antrum, the major peak was eluted near the position of beta-lipotropin, and the minor broad peak was eluted near the position of beta-endorphin. In contrast, in adenocarcinoma, beta-endorphinlike immunoreactivity was eluted broadly at the position of beta-endorphin and the other smaller peak was at the position of beta-lipotropin. Gel exculsion chromatography of somatostatinlike immunoreactivity also showed different patterns between antral mucosa and adenocarcinoma. This study revealed the presence of the opioid peptide, beta-endorphinlike immunoreactivity, not only in normal gastric tissue but also in adenocarcinomas with highly increased concentration and different elution patterns in combination with decreased concentration of somatostatinlike immunoreactivity.

Distribution of neurotensin in the canine gastrointestinal tract

The distribution of immunoreactive neurotensin in the canine gastrointestinal tract from the esophagus to the rectum, as well as in the pancreas, was determined by a specific neurotensin radioimmunoassay. Immunoreactive neurotensin was found throughout the gastrointestinal tract and in the pancreas. The highest concentrations of immunoreactive neurotensin were found in the mucosal extracts of the jejunum (422 +/- 68 ng/gm) and ileum (3025 +/- 289 ng/gm). Small but substantial amounts of immunoreactive neurotensin were found in the esophagus, fundus (includes fundus and corpus), antrum, duodenum, colon, and pancreas. The concentrations of neurotensin in the mucosal extracts of the jejunum and ileum increased in a graded fashion from the proximal jejunum to the distal ileum. The neurotensin concentration in extracts of the seromuscular layers of jejunum (73 +/- 14 ng/gm) and ileum (187 +/- 38 ng/gm) were statistically higher in comparison with other gut loci.

Increased antral G-cell number and gastrin content in dogs after massive small bowel resection

The effects of massive small-bowel resection on antral gastrin tissue concentration and G-cell number have been investigated in the dog. Tissue gastrin concentrations increased significantly after resection from 16.8 +/- 2.6 ng/mg wet weight to 30.3 +/- 3.2 ng. Immunoreactive gastrin cell number also increased from 29.8 +/- 2.5 cell/mm2 to 43.1 +/- 3.0 cells/mm2. Immunocytochemistry demonstrated that the hyperplastic gastrin cells were found in small groups, with the majority of the immunoreactivity located at the luminal pole of the cells. This finding, linked to hypogastrinemia in the dogs after massive small bowel resection, suggests that some of the hyperplastic G cells may have an exocrine rather than endocrine function.

Measurement of immunoreactive gastrin in tissue

A method for measurement of gastrin in human antral mucosa or in extragastric tissue has been developed and validated. Tissue gastrin was extracted by boiling followed by homogenization at neutral pH. Extractable gastrin immunoreactivity was measured by radioimmunoassay using an antiserum with equal affinity towards G-17 I, G-17 II, G-34 I and G-34 II molecular forms. Almost all extractable gastrin immunoreactivity was recovered after a single extraction and no significant interference by other peptides and/or substances present in tissue was found. The mean gastrin concentration in antral mucosa of healthy subjects was similar to that observed in duodenal ulcer patients, while patients with type A chronic atrophic gastritis or with antral gastrin cell hyperplasia had mean values significantly higher. Gastrin concentration in all specimens from gastrinoma or its metastases was above the upper limit of the range of control tissue. Measurement of tissue gastrin seems to be a valuable tool in the diagnosis of antral gastrin cell hyperplasia and Zollinger-Ellison syndrome.

Immunohistochemical localization to pyloric antral G cells of peptides derived from porcine preprogastrin

Antibodies to the peptides (designated cryptic A and B) that flank the G34 region of pig progastrin were used in immunohistochemical studies of the gastrointestinal tract. In elution and restaining experiments, the same cells were revealed by the cryptic peptide antibodies, and by antibodies specific for C-terminus of G17 and N-terminus of G34. The cells reacting with the cryptic peptide antibodies were localized predominantly to antral mucosa. They were found in pig, ferret, dog and cat but not in man, guinea pig, rat or mouse; presumably in the latter species there are amino acid substitutions in the cryptic peptides that influence immunoreactivity with the present antibodies. The results indicate that progastrin production occurs only in G cells in the gut, and that a single population of cells produces all the predicted regions of progastrin.

[The effects of selective proximal gastric vagotomy on antral mucosal gastrin and somatostatin concentrations]

Antral mucosal immunoreactive gastrin (IRG) and somatostatin-like immunoreactivity (SLI) were measured in separate prepyloric mucosal canine specimens obtained before and after selective proximal vagotomy (SPV). No significant difference was recognized in the distribution of IRG concentration in the mucosa of the anterior and posterior walls and in the mucosa of the lesser and greater curvatures. The IRG concentration in the mucosa had no correlation to the distance from the pyloric ring. The IRG concentration of specimens obtained within about 3 cm from the pyloric ring could be regarded as that of the antral mucosa. The effects of surgery on antral mucosal IRG and SLI were studied in 13 dogs consisted of two groups: SPV and simple laparotomy. No significant postoperative change of IRG or SLI concentrations was noted in simple laparotomy group. In SPV group, however, the IRG concentration rose significantly in the 8th and 12th weeks postoperatively (p less than 0.01). There was no significant change in the SLI concentration in the SPV group, but two of the seven dogs showed the high elevations after the 12th week. These results suggested that SPV has a more marked effect on the production of antral gastrin than that of antral somatostatin.

Radioreceptor and biological characterization of cholecystokinin and gastrin in the chicken

Radioimmunoassay, radioreceptor assays, and bioassays were used to demonstrate that chicken brain and antrum extracts contain cholecystokinin (CCK)-like and gastrinlike peptides, respectively. C-terminal-specific radioimmunoassay of partially purified chicken CCK and gastrin gave dilution curves parallel to those of the mammalian peptides. Mouse cerebral cortical and rat pancreatic membrane radioreceptor assays were used to differentiate CCK- from gastrinlike peptides on the basis of the different CCK versus gastrin specificities of the two receptors. Confirmation of the biological activity of chicken brain CCK was obtained by stimulation of amylase secretion from rat pancreatic lobules in vitro. The specificity of this response was demonstrated by the inhibition of chicken CCK-stimulated amylase secretion by the specific CCK receptor antagonist dibutyryl cGMP. Chicken antral gastrin stimulated gastric acid secretion from the rat stomach in vivo. In contrast to previous hypotheses, it is proposed that chickens have significant amounts of an antral gastrinlike peptide and that therefore it is possible that gastrin is involved in the physiological regulation of gastric acid secretion in chickens.