Immunocytochemical localization of rabbit gastric lipase and pepsinogen

Lipase and pepsin activities were determined in rabbit gastric biopsy specimens. Lipase activity was found to be restricted to a small part of the fundic mucosa, near the cardia, whereas pepsin activity spread over about two thirds of the total fundic area, overlapping that of lipase. The cells producing these two enzymes were labeled by immunofluorescence using polyclonal antibodies against rabbit gastric lipase (RGL) or antibodies against rabbit pepsinogen. The immunocytochemical localization showed unequivocally that RGL and pepsinogen, which were both present in the cardial area, were in fact located in different gastric cells. The cells producing pepsinogen were in the lower base of the gastric fundic glands, whereas the cells producing RGL were in the upper base of the same glands. The cells producing pepsinogen and RGL showed no significant morphological differences. In the part of the fundic area, where only pepsin activity was detected, cells producing pepsinogen covered both the lower and the upper base of the gastric glands. No chief cells were observed in the antral mucosa. RGL and pepsinogen could represent useful gastric enzyme markers for cellular differentiation studies.     

Circannual and Circa-Hemiannual Rhythms of Basal and Stimulated Gastric Secretion in Conscious Cats

Conscious cats equipped with a gastric fistula and a denervated Heidenhain pouch were submitted to weekly measurements of the basal and pentagastrin-stimulated gastric secretion for 1 to 14 years. Rhythms of basal secretion were documented in 37 cats for the group studies, in 25 cats only for the individual studies which required at least whole year data. Twelve-month or 6-month rhythms were detected for each variable studied, i.e. volume, acid, pepsin, fucose and uronic acid outputs in the group studies, with peaks for volume, acid and pepsin in Winter, peaks for uronic acid in Spring and Fall indicating different rhythms for oxyntic, chief and mucous cells. Individual studies detected rhythms in 25% of the analyses, and demonstrated male and female and cat to cat differences. Spectral analysis in 3 cats confirmed the differences in the individual rhythms with prominent peaks differing from 365 days in 50% of the cases. Chronopharmacological responses to pentagastrin were documented for volume, acid and pepsin outputs in 5 male and 6 female cats. Group analysis detected a Winter acrophase for volume and acid secretion and a Summer acrophase for pepsin secretion. Analysis of the stimulated response data showed interindividual variation but a higher percentage of detection for rhythms, i.e. 38% for all variables and 50% for pepsin secretion. Different rhythms in acid and pepsin secretion documented in individual studies could provide the basis of a better understanding of the discrepancies reported in the literature concerning the seasonal incidence of peptic ulcer disease.     

Circannual and Circa-Hemiannual Rhythms of Basal and Stimulated Gastric Secretion in Conscious Cats

Conscious cats equipped with a gastric fistula and a denervated Heidenhain pouch were submitted to weekly measurements of the basal and pentagastrin-stimulated gastric secretion for 1 to 14 years. Rhythms of basal secretion were documented in 37 cats for the group studies, in 25 cats only for the individual studies which required at least whole year data. Twelve-month or 6-month rhythms were detected for each variable studied, i.e. volume, acid, pepsin, fucose and uronic acid outputs in the group studies, with peaks for volume, acid and pepsin in Winter, peaks for uronic acid in Spring and Fall indicating different rhythms for oxyntic, chief and mucous cells. Individual studies detected rhythms in 25% of the analyses, and demonstrated male and female and cat to cat differences. Spectral analysis in 3 cats confirmed the differences in the individual rhythms with prominent peaks differing from 365 days in 50% of the cases. Chronopharmacological responses to pentagastrin were documented for volume, acid and pepsin outputs in 5 male and 6 female cats. Group analysis detected a Winter acrophase for volume and acid secretion and a Summer acrophase for pepsin secretion. Analysis of the stimulated response data showed interindividual variation but a higher percentage of detection for rhythms, i.e. 38% for all variables and 50% for pepsin secretion. Different rhythms in acid and pepsin secretion documented in individual studies could provide the basis of a better understanding of the discrepancies reported in the literature concerning the seasonal incidence of peptic ulcer disease.     

Immunocytolocalization of human gastric lipase in chief cells of the fundic mucosa

Summary The presence in human gastric juice of a lipase secreted by the gastric mucosae has been reported previously, but its exact cellular origin has not yet been established. Polyclonal antibodies specific to human gastric lipase (HGL) were prepared, and used by an immunofluorescence technique to label cells producing HGL. This immunocytolocalization was correlated with that of pepsin (chief cells) and parietal cells using specific polyclonal or monoclonal antibodies.Our results clearly establish that HGL is exclusively located in the chief cells of fundic mucosa; furthermore, it was found to be always co-located with pepsin. No HGL was observed in the parietal or mucus cells. HGL was always detected intracellularly, either in secretory granules of the apical region of the chief cells, or revealed by more diffuse cytoplasmic labelling.Abbreviations HGL Human gastric lipase - SDS PAGE Sodium dodecyl sulfate-polyAcrylamid gel electrophoresis - PBS Phosphate buffer saline     

Immunocytolocalization of human gastric lipase in chief cells of the fundic mucosa

The presence in human gastric juice of a lipase secreted by the gastric mucosae has been reported previously, but its exact cellular origin has not yet been established. Polyclonal antibodies specific to human gastric lipase (HGL) were prepared, and used by an immunofluorescence technique to label cells producing HGL. This immunocytolocalization was correlated with that of pepsin (chief cells) and parietal cells using specific polyclonal or monoclonal antibodies. Our results clearly establish that HGL is exclusively located in the chief cells of fundic mucosa; furthermore, it was found to be always co-located with pepsin. No HGL was observed in the parietal or mucus cells. HGL was always detected intracellularly, either in secretory granules of the apical region of the chief cells, or revealed by more diffuse cytoplasmic labelling.     

Effect of somatostatin on the secretin-induced gastric secretions of pepsin and mucus in cats

The effect of somatostatin 14 on gastric stimulation produced by secretin was determined in 6 conscious cats equipped with a gastric fistula and a denervated fundic pouch. Somatostatin strongly inhibited the basal and secretin-induced pepsin secretion. It did not, however, inhibit the secretin-induced mucus secretion, even though it decreased the basal mucus secretion. During somatostatin administration, the secretagogue effect of secretin on mucus secretion might be dissociated from its stimulatory action on pepsin secretion.     

Effects of Gastric Freezing on the Isolated Denervated Gastric Pouch in Dogs

The purpose of this study was to investigate the effects of gastric freezing on the chief and parietal cells of the stomach. To carry this out six Heidenhain pouch dogs were prepared. The secretions of these pouches were studied, both for HCl levels and pepsin activity, for 30 days before and 30 days after the freezing of the pouch. Freezing was carried out for one hour at -17 to -20° C. The results show that no essential depression of either the HCl levels or the pepsin activity of the juice was effected by freezing. Therefore, it is deduced that freezing does not affect the functional activity of either the chief or the parietal cells. Complications such as ulceration and fistula formation into adjacent organs occurred as a result of freezing in certain pouch dogs.     

Visualization of the secretory canaliculi of human parietal cells with a peroxidase-labelled peanut lectin

Summary Peanut lectin reactivity was examined in normal fundic glands from human gastric samples, both at light- and electron-microscopic levels, using a peroxidase conjugate. Positive reaction was observed in the glycocalyx of parietal cell secretory canaliculi as well as in the mucous globules of mucous cells and in the luminal cell coat of chief cells. The presence of terminal galactose in the canalicular glycocalyx may be connected with the peculiar function of hydrochloric acid secretion. Peroxidase-labelled peanut lectin is proposed as a marker for visualizing the secretory canaliculus of parietal cells.     

Sonic hedgehog is associated with H+-K+-ATPase-containing membranes in gastric parietal cells and secreted with histamine stimulation

Sonic hedgehog (Shh) is found within gastric parietal cells and processed from a 45-kDa to a 19-kDa bioactive protein by an acid- and protease-dependent mechanism. To investigate whether Shh is associated with the parietal cell membrane compartment that becomes exposed to both acid and proteolytic enzymes during acid secretion, the cellular location of Shh within resting and stimulated gastric parietal cells was examined. Immunofluorescence microscopy of rabbit stomach sections showed that Shh colocalized predominantly with parietal and pit, not chief/zymogen or neck, cell markers. In resting and histamine-stimulated rabbit gastric glands Shh was expressed only in parietal cells close to H+-K+-ATPase-containing tubulovesicular and secretory membranes with some colocalizing with gamma-actin at the basolateral membrane. Gastric gland microsomal membranes were prepared by differential and sucrose gradient centrifugation and immunoisolation with an anti-H+-K+-ATPase-alpha subunit antibody. The 45- and 19-kDa Shh proteins were detected by immunoblot in immunopurified H+-K+-ATPase-containing membranes from resting and stimulated gastric glands, respectively. Incubating glands with a high KCl concentration removed Shh from the membranes. Histamine stimulated 19-kDa Shh secretion from gastric glands into the medium. In human gastric cancer 23132/87 cells cultured on permeable membranes, histamine increased 19-kDa Shh secretion into both apical and basolateral media. These findings show that Shh is a peripheral protein associated with resting and stimulated H+-K+-ATPase-expressing membranes. In addition, Shh appears to be expressed at or close to the basolateral membrane of parietal cells.     

Comparative morphology of the stomach of some laboratory mammals

Histomorphology of the stomach of mouse, rat, hamster, guineapig, gerbil, and rabbit was studied. Although a common structural basis existed in the stomach between these species, the occurrence and distribution of various cells in gastric glands differed considerably between them. In mice, rats, hamsters and gerbils, the lower one-third of the glandular lamina propria was seemingly occupied by a varying proportion of parietal and chief cells. In rabbits, the predominantly occurring chief cells were distributed in the lower three-quarters of the glands intermingling with parietal cells, but in guinea-pigs the chief cells were not discernible. In hamsters, there was, however, a gradual increase of chief cells from the junction between nonglandular-glandular stomach toward the pyloric region. In all these species, parietal cells were the predominant cell type in the upper half to upper one-third of the gastric glands, often extending up to the neck of the glands interspersing between mucus neck cells and occasionally between chief cells.     

VIP inhibits histamine-induced ultrastructural changes related to acid secretion by parietal cells

We have studied the in vitro effect of VIP and histamine on ultrastructure of the parietal cells in isolated guinea pig fundic glands. The morphological changes induced by histamine in the parietal cells can be compared to those observed after histamine stimulation in vivo or in vitro on gastric mucosa preparations. In contrast, VIP incubation did not produce the ultrastructural changes related to gastric acid secretion, in resting parietal cells. Pretreatment of the glands by VIP resulted in a remarkable suppression of the histamine effect, since the parietal cells assumed an almost resting state. The data (1) indicate that the parietal cells in isolated gastric glands of the guinea pig retain in vitro the capacity to undergo the ultrastructural changes that are related to acid secretion in vivo after histamine or cAMP and (2) suggest that VIP is an inhibitor of histamine-induced gastric acid secretion in the guinea pig. It is proposed that VIP could act directly on the parietal cell via cAMP-phosphodiesterase activation, or indirectly via gastric somatostatin and/or prostaglandin secretions, inhibiting the H2 receptor-cAMP system of the parietal cell.     

Gastric dysfunction in sheep infected with Trichostrongylus colubriformis, a nematode inhabiting the small intestine

Barker I. K. and Titchen D. A. 1982. Gastric dysfunction in sheep infected with Trichostrongylus colubriformis, a nematode inhabiting the small intestine. International Journal for Parasitology12: 345–356. Six of 12 lambs infected with Trichostrongylus colubriformis had reduced abomasal acidification (pH 4.0–8.1) in comparison with uninfected pair-fed and replete controls (pH <3.5), though less than 0.8% of the worm burden was in the abomasum. Loss of prominence of parietal cells and encroachment of mucous cells deep into fundic glands was seen by light microscopy. Under the electron microscope, parietal cells had little canalicular or tubulovesicular development, had large vacuoles, many polyribosomes and few mitochondria in comparison with those in controls. In a further 8 sheep prepared with abomasal fistulae and separated fundic pouches and inoculated orally with T. colubriformis, the volume of fundic pouch secretion declined as feed intake dropped and in 7 out of 8 animals H⁺ concentration in fundic pouch secretion also fell. Infection generally reduced volume and acidity of pouch secretion more than did a pre-inoculation fast. In 5 sheep, abomasal content exceeded pH 4. Inoculation of T. colubriformis by enterotomy and Ostertagia circumcincta per os, in a lamb with a separated fundic pouch, caused depression of volume and acidity of pouch secretion characteristic of T. colubriformis infection, rather than the hypersecretion typical of abomasal infection with Ostertagia. Factors inhibitory to parietal cell differentiation and gastric acid secretion may be released from the small intestine of some sheep in response to changes in the gut induced by the presence of T. colubriformis. Abomasal dysfunction is a manifestation of severe intestinal trichostrongylosis.     

Heterogeneity of acid secretion induced by carbachol and histamine along the gastric gland axis and its relationship to [Ca2+]i

The gastric glands of the mammalian fundic mucosa are constituted by different cell types. Gastric fluid is a mixture of acid, alkali, ions, enzymes, and mucins secreted by parietal, chief, and mucous cells. We studied activation of acid secretion using LysoSensor Yellow/Blue in conjunction with fluo 3 to measure changes in pH and Ca(2+) in isolated rabbit gastric glands. We evidenced a spatial heterogeneity in the amplitude of acid response along the gland axis under histamine and cholinergic stimulation. Carbachol induced a transitory pH increase before acidification. This relative alkalinization may be related to granule release from other cell types. Omeprazole inhibited the acid component but not the rise in pH. Histamine stimulated acid secretion without increase of lumen pH. We studied the relationship between Ca(2+) release and/or entry and H(+) secretion in glands stimulated by carbachol. Ca(2+) release was associated with a fast and transient components of H(+) secretion. We found a linear relationship between Ca(2+) release and H(+) secretion. Ca(2+) entry was associated with a second slow and larger component of acid secretion. The fast component may be the result of activation of Cl(-) and K(+) channels and hence H(+)/K(+) pumps already present in the membrane, whereas the slow component might be associated with translocation of H(+)/K(+) pumps to the canaliculi. In conclusion, with cholinergic stimulation, gastric glands secrete a mixture of acid and other product(s) with a pH above 4.2, both triggered by Ca(2+) release. Maintenance of acid secretion depends on Ca(2+) entry and perhaps membrane fusion.     

正常大鼠胃黏膜中肌球蛋白轻链激酶定性和定位观察

目的观察正常大鼠胃组织中肌球蛋白轻链激酶的表达及分布特点。方法取11只SD正常雄性大鼠,在饥饿状态下,处死后取胃组织。通过免疫组化染色,观察正常大鼠胃组织中MLCK的表达及分布。结果MLCK在黏膜肌层、肌层和黏膜下层血管壁平滑肌均有大量表达;在胃底腺中,MLCK主要表达于壁细胞和主细胞胞浆内。结论MLCK不仅存在于平滑肌细胞内,还分布于胃底腺壁细胞和主细胞内,可能参与胃底腺腺细胞的分泌活动。     

The influence of a new prostaglandin E2 analogue (FCE 20700) on gastric acid and pepsin secretion in the dog.

The effects of FCE 20700, a new prostaglandin E₂ analogue, on gastric acid and pepsin secretion stimulated by different secretagogues were studied in dogs. Intravenous FCE 20700 produced a significant inhibition of total acid output (TAO) induced by pentagastrin or histamine in gastric fistula (GF) dogs. This effect was short-lasting and mainly due to a reduction in the volume of gastric juice with little acid concentration change. TAO and pepsin output stimulated by 2-deoxy-D-glucose were simililarly inhibited by intravenous FCE 20700. In dogs chronically fitted with both GF and Heidenhain pouch (HP), intragastric FCE 20700 significantly inhibited TAO stimulated by pentagastrin or histamine from HP, while acid secretion from GF was not significantly affected. It is concluded that FCE 20700 possesses a weak antisecretory activity in dogs. Consequently the antiulcer effects of this prostaglandin derivative seem to be largely independent from its influence on gastric acid and pepsin secretion.     

Regulation of free cytosolic Ca2+ in the peptic and parietal cells of the rabbit gastric gland

Quin 2-loaded isolated rabbit gastric glands and purified peptic cells were used to measure free cytosolic Ca2+ ([Ca2+]i) during hormone stimulation. Rabbit gastric glands are composed of peptic and parietal cells with less than 1% endocrine cells. Although both cell types responded to the same hormones, they may be distinguished in terms of the source of Ca2+ bringing about the change in [Ca2+]i. Experiments were designed to assign changes in [Ca2+]i to either the peptic or parietal cells and to attempt to maintain these distinctions in the mixed cell population of gastric glands. It was shown that the peptide cholecystokinin octapeptide induced a rapid and transient increase in [Ca2+]i of isolated peptic cells. This signal was independent of medium Ca2+ and insensitive to the Ca2+ channel blockers La3+ and nifedipine. In gastric glands, the Ca2+ outdependent increase in (Ca2+)i (the secondary transient) was slower and dose dependently blocked by La3+ and nifedipine. This allowed [Ca2+]i levels in the physiologically more intact rabbit gastric glands to be dissected and correlated with fluorescence changes of quin 2 in either cell type. The transient increase in [Ca2+]i coincided with a burst of pepsin but not acid secretion. A subsequent slower phase of pepsin secretion took place while the cells restored near resting [Ca2+]i. Using a combination of the Ca2+ ionophore A23187 and the protein kinase C activating phorbol ester 12-O-tetra-decanoylphorbol 13-acetate, the hormone response pattern of pepsin secretion could be mimicked. The intracellular Ca2+ stores of the peptic cells in the gastric gland remained depleted of Ca2+ until specific antagonists were added. The reloading of intracellular stores required medium Ca2+ although [Ca2+]i was maintained at resting level during the entire reloading period. Hence, a specialized pathway of Ca2+ reloading is postulated.     

Porcine ileal polypeptide causes an increase in cytoplasmic Ca2+ in both parietal and chief cells resulting in acid and pepsinogen secretion

Porcine ileal polypeptide, an enterooxyntin isolated from distal small intestinal mucosal epithelium, has been observed to stimulate gastric acid secretion in vivo as well as in vitro (Wider, M.D. et al. (1984) Endocrinology 115, 1484-1491, Wider M.D. et al. (1986) Endocrinology 118, 1546-1550). We report here that porcine ileal polypeptide stimulates both acid (aminopyrine accumulation) and pepsinogen secretion in isolated, enriched populations of guinea pig parietal and chief cells in a dose-dependent manner. Further, 10(-9) M porcine ileal polypeptide caused an increase in cytoplasmic Ca2+ concentration in both parietal and chief cells similar in magnitude to that observed with gastrin-17 (10(-8) M) (as measured by both fura-2 and aequorin) and cholecystokinin octapeptide (CCK-OP) (10(-8) M), respectively. Porcine ileal polypeptide has been observed to cause no stimulation of cAMP production in gastric glands from guinea pigs (Gespach, C., personal communication) nor is there any effect of medium Ca2+ depletion on acid production observed with guinea pig gastric mucosal sections. It is concluded that porcine ileal polypeptide, at concentrations similar to circulating levels observed in plasma of normal pigs (5 x 10(-9) M), acts directly on the parietal and chief cells to cause the mobilization of intracellular Ca2+ from the stores resulting in acid and pepsinogen secretion. These experiments demonstrate that this peptide is a potent enterooxyntin and chief cell secretagogue which acts via the same signal transduction mechanisms as gastrin and cholecystokinin.     

Multiple effects of phorbol ester on secretory activity in rabbit gastric glands and parietal cells

Acid secretory activity and respiration in rabbit gastric glands are stimulated by cAMP-dependent and -independent agonists. Potentiation between agonists suggests interaction of the activation pathways. Regulation of secretory response by protein kinase C was investigated with 12-0-tetradecanoyl phorbol-13-acetate (TPA). TPA elevated basal respiration, pepsin release, and acid secretion but inhibited histamine and carbachol stimulation of acid secretion by gastric glands, as measured by [dimethylamino-14C]aminopyrine accumulation. The inhibition of histamine response was specific for protein kinase C activators, occurred after a 20-min lag, and was not reversed by removal of TPA after 3 min of preincubation. TPA pretreatment inhibited acid secretory responses to cholera toxin and forskolin but enhanced the response to cAMP analogues. Cholera toxin and pertussis toxin simulated ADP-ribosylation of 45 and 41 kDa proteins, respectively, in parietal cell membranes. Therefore, both stimulatory (Gs) and inhibitory (Gi) GTP binding proteins of adenylyl cyclase appear to be present in parietal cells. Pretreatment with pertussis toxin attenuated PGE2 but not TPA inhibition of histamine stimulation of aminopyrine accumulation. Thus, the inhibitory effect of TPA does not appear to be associated with an action on Gi. The results with histamine and carbachol suggest that protein kinase C may regulate both cAMP-dependent and -independent stimulation of parietal cell acid secretion.     

Effect of cortisone acetate on acid secretion induced by histamine, pentagastrin, gastrin and food in dogs]

The effects of long term treatment with cortisone on the gastric secretion induced by histamine, pentagastrin, porcine gastrin and a meal have been investigated in four dogs with both gastric fistula and Heidenhain pouch. Cortisone increased the postcibal acid output and the observed maximal acid response from the pouch to all three exogenous stimuli. The ED 50'S remained unchanged. The same effects although less marked were observed in the innervated stomach. These data indicate that the increased acid secretion observed after long term treatment with cortisone is largely due to an increased secretory capacity of the gastric mucosa. This latter could result from an increase in the number of secretory units or to partial removal of a non competitive inhibitor of gastric secretion.     

Gastric lipase and pepsinogen during the ontogenesis of rabbit gastric glands

In rabbit stomach, gastric lipase activity level was found to increase from birth to 30 days old (weaning), and then decreased. In contrast, pepsin activity only appeared between 30 to 45 days old, and increased till to the adult level. It was observed that maturation of gastric glands in cardial mucosa was a downward elongation process from the mitotic cell pool. These mitotic cells were always found in the neck of the gastric glands, corresponding to the bottom of the gland at 6 days old and to the mid-zone of the gland in adult. Location of rabbit gastric lipase (RGL) cells in cardial glands varied with age and was found along the pit of the gastric glands at 6 days old. The extent of this cellular location decreased with age, whereas a second RGL cell zone appeared below the mitotic cell area at 18 and 30 days old. At 45 days old, the pepsinogen cells appeared in the bottom of the gland, and consequently the RGL cells were located in the mid-zone of the gastric glands, between mitotic cells (neck of the gland) and pepsinogen cells (lower part of the gland). Ultrastructural study of cardial gastric glands revealed different morphologies of the secretion granules in the cells along the gastric glands. In 6-day-old rabbits, secretory granules were found uniformly electron dense in the bottom of the glands and were RGL-labeled by the immunogold technique. In the medium part of the glands, granules appeared biphasic, with a clear and a dense part, and RGL labeling was confined to the electron-dense part.(ABSTRACT TRUNCATED AT 250 WORDS)