Immunoreactive-FSH in human normal gastric mucosa.

Using indirect immuno-peroxidase staining technique, localization of immunoreactive follicle-stimulating hormone (IR-FSH) is demonstrated in the cytoplasm of the epithelial cells of normal human stomach. In view of their triangular shape and central nucleus and their predominance in the intermediate glands of the gastric mucosa, these cells are identified as parietal cells. The stromal tissue is devoid of staining reaction.

Purification and characterization of a fatty-acid-binding protein from the gastric mucosa of rats. Possible identity with heart fatty-acid-binding protein and its parietal cell localization.

Fatty acid-binding protein (FABP) was purified from rat gastric mucosa by successive Sephadex G-75 chromatography, DEAE-cellulose chromatography and HPLC on an RP-2 (Merck) reversed-phase column. The purified stomach FABP migrated as a single band corresponding to an apparent molecular mass of 15 kDa on SDS/PAGE. Stomach FABP appeared to be identical with rat heart FABP, as judged from its electrophoretic mobility, amino acid composition and tryptic peptide map. In addition, the amino acid sequences of two selected tryptic peptides coincided completely with the rat heart FABP sequence deduced from that of cDNA. Stomach FABP showed immunochemical identity with rat heart FABP when tested with an antiserum against rat heart FABP. Immunohistochemically, stomach FABP was specifically stained with anti-(rat heart FABP) serum in parietal cells of the gastric mucosa. The results suggested that the primary structure of stomach FABP is identical with that of rat heart FABP, and showed that stomach FABP is localized in parietal cells of the gastric mucosa.

Identification of a 185-kDa band 3-related polypeptide in oxyntic cells.

Polyclonal antibodies to the purified mouse erythrocyte anion exchange protein (band 3) and to a conserved COOH-terminal peptide of mouse band 3 (alpha-Ct) recognized a single major 185-kDa polypeptide in immunoblots of a membrane fraction prepared from rabbit gastric glands. Competition studies revealed that the epitopes shared between the rabbit gastric 185-kDa antigen and the approximately 100-kDa mouse erythrocyte band 3 protein are restricted to the COOH-terminal domain of band 3, which is known to contain the catalytic site for anion exchange activity. Immunofluorescence microscopy was used to demonstrate that this band 3-related polypeptide is associated with the plasma membrane in a subpopulation of gastric gland cells composed exclusively of oxyntic cells, as judged by the coincidence of immunofluorescence with alpha-Ct and with a monoclonal antibody to the gastric H+-K+-ATPase. This alpha-Ct-reactive antigen was further localized to the cytoplasmic face of the basolateral membrane of oxyntic cells, which correlates well with the physiologically determined site of anion exchange activity. These data demonstrate the presence in gastric oxyntic cells of a novel member of the family of proteins related to the erythrocyte anion exchanger. The possibility that the 185-kDa polypeptide is an anion exchanger is discussed.

Distribution of G-cells in the antrum and duodenum and D-cells in the fundus, antrum, duodenum and pancreas of the guinea pig.

Antral and duodenal G-cells and fundic, antral, duodenal and pancreatic D-cells were demonstrated immunocytochemically and their population size was estimated in guinea pigs of both sexes. The population of antral (210 + 18.03 SD cells/cm) and duodenal (13.20 + 3.12 SD cells/cm) G-cells is lower in guinea pigs than in dogs. Antral and duodenal G/D-cell ratios (1.6/1 and 1.2/1) are also lower in the guinea pig than in man. Antral G- and D-cell populations are greater in male (210 + 18.03 SD cells/cm and 128.2 + 17.63 SD cells/cm) than in female (176 + 13.8 SD cells/cm and 108.4 + 6.9 SD cells/cm) guinea pigs. The percentage of pancreatic D-cells is greater in the guinea pig (20-25%) than in man and rat. It is concluded that the differences in gastric and duodenal G- and D-cells between guinea pigs and other species possibly reflect different gastric secretory functions. Sex related differences in the endogenous sex hormones can explain differences in gastric secretion between the two sexes. Pancreatic D-cells possibly exert their action on neighbouring endocrine cells through different pathways from those seen in man and rat.

Identification and characterization of a cytosolic 30 kDa histamine stimulated phosphoprotein in parietal cell cytosol.

Histamine stimulated acid secretion is mediated by an increase in intracellular cAMP. Cytosolic protein phosphorylation stimulated by histamine was investigated in isolated rabbit parietal cells. Histamine stimulated the phosphorylation of a 30 kDa phosphoprotein with an isoelectric point of 5.6. Cimetidine completely inhibited histamine-stimulated pp30 phosphorylation. However, omeprazole had no effect on the phosphorylation of pp30. Forskolin and 8-bromo-cAMP also stimulated the phosphorylation of pp30. The results suggest that pp30 is a histamine-stimulated, cAMP-dependently phosphorylated protein substrate in parietal cell cytosol.

Developmental regulation of rat intrinsic factor mRNA.

Using a full-length rat intrinsic factor (IF) cDNA clone, we have examined gene expression of IF in selected tissues from the adult rat and during postnatal development in the rat stomach. IF mRNA was expressed only in the rat stomach, and in situ hybridization revealed that the expression was limited to the chief cells at the base of the oxyntic glands. IF mRNA concentration in the stomach increased with postnatal age and reached a peak at the 30th day. Postnatally the amount of IF mRNA hybridized increased in both individual cells and in total number of cells. Administration of cortisol to, or adrenalectomy of, rats between 5 and 12 days of age resulted in increase or decrease of IF mRNA levels, respectively. Other hormones tested (pentagastrin, thyroxine, and triiodothyronine) had no significant effect. During the suckling period, IF bound well to the ileal receptor, despite lower than adult levels of activity and different glycosylation, as assessed by binding to concanavalin A-Sepharose beads. These results show that developmental expression of IF activity in rat is closely related to the expression of its mRNA and that corticosteroids play an important role in such an expression.

Localization of phospholipid-rich zones in rat gastric mucosa: possible origin of a protective hydrophobic luminal lining.

Mammalian gastric mucosa is unusually hydrophobic or nonwettable, which may be an essential biophysical characteristic of the gastric mucosal barrier. Since this property may be attributable to an adsorbed layer of surface-active phospholipids (SAPL), we investigated the distribution of SAPL in rat oxyntic mucosa. Ferric hematoxylin (FH) and iodoplatinate (IP), selective histochemical stains for phospholipids (as confirmed by spot tests), were used to detect SAPL in frozen sections and aldehyde-fixed tissue, respectively. Using FH staining in conjunction with extraction procedures that either solvate or preserve SAPL, we determined that positive reactivity was the greatest in the apical third of the oxyntic mucosa between the glandular neck region and the surface. IP reactivity appeared to parallel the FH staining pattern. Mucous cells, especially the surface epithelial cells, were heavily stained. Electron microscopic examination revealed that these cells contain inclusion bodies associated with various subcellular organelles, e.g., nuclear envelope, endoplasmic reticulum, Golgi apparatus and its vesicles, and mucous secretory granules. Vesicles and myelin figures, which resembled those found in lung surfactant, were observed extracellularly in close association with the surface mucous cells. Our findings suggest that mucous cells are actively involved in synthesis and storage of SAPL, which may be an essential component of the stomach's protective hydrophobic lining.

Demonstration of specific E-type prostaglandin receptors using enriched preparations of canine parietal cells and [3H]misoprostol free acid.

High-affinity, E-type prostaglandin binding sites in enriched canine parietal cell preparations were identified with [3H] misoprostol free acid, a prostaglandin E1 analogue. Saturable, reversible, and highly stereospecific binding was identified, with approximately 8,000 binding sites per cell. Prostaglandin I and F bound weakly, and cimetidine and histamine did not bind. The results indicate that [3H] misoprostol free acid binds to E-type prostaglandin receptors, which suggests that the ulcer-healing inhibition of gastric acid secretion by misoprostol results from its interaction with a specific E-type prostaglandin receptor.

Solitary polypoid hamartoma of the oxyntic mucosa of the stomach.

A solitary pedunculated polyp of the oxyntic mucosa removed from a 66-year-old patient with atrophic gastritis and achlorhydria exhibited distinctive histological features consisting of submucosal, mostly oxyntic-type glands with a smooth muscular framework. Histochemical and immunohistochemical studies demonstrated that the glands were composed of well differentiated chief, parietal, and endocrine cells. Moreover, less frequent glands of the antro-pyloric type were also seen. The lesion was regarded as a previously unrecognized variety of gastric hamartoma.

Lectin binding to parietal cells of human gastric mucosa.

A light microscopic and ultrastructural analysis of lectin receptors on parietal cells from human gastric mucosa was performed utilizing 12 biotinylated lectins in conjunction with an avidin-biotin-peroxidase complex. Peanut agglutinin conjugated directly to peroxidase was also used. Several fixatives and fixation regimens were evaluated for optimal preservation of parietal cell saccharide moieties. Formalin proved to be the most practical fixative for light microscopic studies. A periodate-lysine-paraformaldehyde (PLP) combination provided good preservation of lectin binding capacity but yielded relatively poor ultrastructure. Conversely, glutaraldehyde provided excellent preservation of ultrastructure but a somewhat diminished lectin binding activity, which was overcome by using long incubation times and high concentrations of reagents. Parietal cells reacted strongly with Bandieraea simplicifolia, Dolichos biflorus, peanut agglutinin, and soybean agglutinin (all specific for galactosyl/galactosaminyl groups) and weakly with Ulex europaeus (specific for fucose). At the light microscopic level a beaded, perinuclear staining pattern was observed which, ultrastructurally, corresponded to an intense staining of intracytoplasmic canaliculi. The membranes of the intracytoplasmic canaliculi were characterized by an abundance of galactosyl residues, a paucity of fucosyl groups, and a lack of mannosyl and glucosyl residues. The biochemical and physiological significance of these findings is discussed.

Morphologically different biopsy specimens of the human gastric mucosa. I. The use of enzymatic cell isolation for quantitative determination of parietal cells.

Single biopsies of human gastric mucosa from controls and different groups of patients were used for enzymatic cell isolation by pronase and collagenase and subsequent count of parietal and nonparietal cells. This procedure was tested in regard to its validity and delivered the following cell numbers. Total gastric cells/mg wet weight gastric mucosa: normal gastric mucosa [controls (C), n = 95] 31,500 +/- (SEM) 1,490, chronic superficial gastritis (GI; n = 49) 36,300 +/- 2,770, chronic gastritis with beginning atrophy (GII; n = 36) 44,100 +/- 3,050 (p less than 0.025), chronic atrophic gastritis (GIII; n = 12) 40,100 +/- 5,760, duodenal ulcer (DU; n = 26) 29,340 +/- 2,280, gastric ulcer (GU; n = 23) 37,090 +/- 3,000, gastric resection according to Billroth I (BI; n = 7) 57,480 +/- 12,360 (p less than 0.005) and Billroth II (BII; n = 12) 52,560 +/- 6,730 (p less than 0.005). Parietal cells/mg wet weight gastric mucosa: 1,910 +/- 490 (C), 1,980 +/- 140 (GI), 1,700 +/- 200 (GII), 1,170 +/- 220 (GIII, p less than 0.025), 2,580 +/- 240 (DU, p less than 0.05), 1,690 +/- 150 (GU), 1,500 +/- 250 (BI), 1,360 +/- 320 (BII). Parietal cell concentration (density) did not differ in males and females and did not change with age. The method delivers relevant cell numbers, is suitable to detect qualitative differences and can be used for the interpretation of biochemical studies.

Intrinsic factor within parietal cells of patients with juvenile pernicious anemia. A retrospective immunohistochemical study.

One of the diverse group of disorders that cause pernicious anemia in childhood, juvenile pernicious anemia, has been characterized by normal acid secretion, normal gastric mucosal histology, adequate intestinal absorption of cobalamin in the presence of exogenous gastric intrinsic factor (IF), but the inadequate "production" of IF from birth. Inadequate production has been inferred from the absence of measured IF in stimulated gastric secretions. To assess whether immunogenic IF was commonly present within the parietal cells of subjects with juvenile pernicious anemia, we studied paraffin-embedded biopsy material from the largest reported series of childhood pernicious anemia, using a well-characterized indirect immunoperoxidase method. Preliminary studies were able to identify IF in fundic mucosal biopsy specimens that had been stored for as long as 27 yr. In a blinded evaluation, six of the nine fundic biopsy specimens from children with juvenile pernicious anemia demonstrated immunogenic IF. Two sets of siblings were concordant for the presence or absence of intracellular IF, and six gastric biopsy specimens from patients with Imerslund's syndrome were all positive for IF. These findings indicate that juvenile pernicious anemia is a heterogeneous group of disorders whose similar clinical expression might be caused by (a) inadequate synthesis of IF, (b) a block in IF secretion, (c) the secretion of an abnormal IF that does not bind to cobalamin, or (d) the secretion of other abnormal IFs that could contain a number of other functional defects.

Postnatal undernutrition: effect of epidermal growth factor on growth and function of the gastrointestinal tract in rats.

Rats were kept undernourished from birth to 24 days of age. At 17 days of age, the undernourished animals were divided into two groups and then injected with either saline or epidermal growth factor (EGF; 20 micrograms/kg) once a day for 7 days. They were killed 12-14 h after the last injection at which time the animals were 24 days old. During the experimental period the undernourished animals were prevented from weaning. A well-nourished group (weaned) which was injected with saline from 17 to 24 days of age, was also included. Undernutrition by itself significantly decreased body weight and the weight of the oxyntic gland area, antrum, and small intestine. This was also accompanied by a parallel reduction in DNA, RNA, and protein content in the oxyntic gland and small intestine. However, administration of EGF to undernourished rats resulted in a partial reversal of the situation. In undernourished rats, EGF caused significant enhancements in body weight as well as the weight of the gastrointestinal tissues and their protein and nucleic acid content when compared with the saline-treated undernourished controls. Furthermore, the magnitude of stimulation was found to be greater in the oxyntic gland than in the small intestine following EGF administration. The antral or serum gastrin levels were not affected by EGF. In both saline- and EGF-treated undernourished rats, lactase, sucrase, and alkaline phosphatase activities (expressed as total or specific activity) were found to be significantly higher than in the well-nourished animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The mammalian gastric parietal cell in vitro.

To summarize the metabolic status of the parietal cell: There does not seem to be a close relationship between cellular ATP levels and acid secretion. Acid secretion is absolutely dependent on oxygen, and oxygen consumption will increase in direct proportion to the rate of acid secretion. However, the absolute rate of respiration is not closely related to the formation of acid in the subtissue systems. Acid formation can be driven directly by addition of ATP in permeabilized glands, even under apparent anoxic conditions. This correlates well with the presence of the gastric (H+, K+)-ATPase in the parietal cell. If ATP is the main source of energy for the acid secretion, it is quite possible that the relevant ATP pool is compartmentalized and that the content in this pool has a high turnover rate, whereas the ATP used for other cellular functions would be spared. A pure redox mechanism in the gastric mucosa is not possible. However, it remains to be shown that a redox component is not involved in the secretory process. The acid formation measured by AP accumulation in the gastric glands is not an indication of secretory rate. Thus even though ATP appears to restore acid formation in permeabilized glands, this effect has been mainly studied in nonstimulated systems. A detailed study over the energy requirement in the permeabilized resting cell remains to be done. In the mammals we only have information so far about the piglet and the rabbit in terms of substrate preference. The differences between the two could either be due to species or age difference. In both mammals and amphibia, there is no evidence to suggest that acid secretion results in an increase in oxygen consumption purely due to a state IV to III transition of mitochondrial respiration. Rather, increased Krebs-cycle activity would appear to be the major metabolic result of stimulation.