G-cell Population Research Articles

Complex morphology of gastrin-releasing G-cells in the antral region of the mouse stomach.

Gastrin-releasing enteroendocrine cells (G-cells) are usually described as flask-shaped cells with a large base and a small apical pole, integrated in the epithelium lining the basal region of the antral invaginations in the stomach. By means of a transgenic mouse line in which the enhanced version of GFP is endogenously expressed under the control of a gastrin promoter, we have analyzed the spatial distribution and morphological features of G-cells. We found that G-cells were not only located at the basal region of the invagination but to a lesser extent also at the upper region. Visualization of the entire cellular morphology revealed that G-cells show complex morphologies. Basally located G-cells are roundish-shaped cells which project a prominent apical process towards the lumen and extend basal protrusions containing the hormone gastrin that were frequently found in close proximity to blood vessels and occasionally in the vicinity of nerve fibers. Inspection of G-cells in the upper region of antral invaginations disclosed a novel population of G-cells. These cells have a spindle-like contour and long apical and basal processes which extend vertically along the antral invagination, parallel to the lumen. This G-cell population seems to be in contact with a network of nerve fibers. While the functional role of these untypical G-cells is still elusive, the results of this study provide some useful indications to possible roles of these G-cells.

Concomitant onset of hypergastrinemia, intragastric alkalinity and gastric hyperplasia, and numbers of antral G cells in Taenia taeniaeformis-infected rats

Infection of hepatic larvae of Taenia taeniaeformis is associated with gastropathy in rats. The sequence of occurrence of the prominent changes, i.e. gastric hyperplasia, intragastric alkalinity and hypergastrinemia, could provide an insight on the pathogenetic mechanism(s) involved in the induction of gastric changes. Density of gastrin producing antral G cells was also examined to determine the cause of hypergastrinemia. Five-week-old, male Wistar rats were orally infected with approximately 4000 Taenia taeniaeformis eggs and examined for changes of stomach morphology, intragastric pH, and serum gastrin every 2 weeks post-infection. Numbers of antral G cells were determined by quantitative immunohistochemistry. Gastric hyperplasia, hypergastrinemia, and rise of intragastric pH occurred concomitantly 56 days post-infection. Mean number of G cells per 100 μm 2 antral mucosa in infected rats was comparable to uninfected controls, although there was an apparent increase in width of antral mucosal sections in hyperplastic stomachs. The concomitant onset of gastric hyperplasia, intragastric alkalinity and hypergastrinemia, most likely indicate that chemical mediators are involved which primarily mediate rapid hyperplasia of mucus-secreting cells. Hypergastrinemia associated with this condition could be due to antral G-cell hyperfunction. However, an increase in total antral G-cell population should be considered because of gross enlargement of hyperplastic stomachs.

The effect of total parenteral nutrition (TPN) on gastrin release in the rat

The effect of short-term (7 days) total parenteral nutrition (TPN) on gastrin release was studied in vivo and in the isolated vascularly perfused rat stomach. The daily plasma gastrin concentration of parenterally fed rats was significantly lower than in ad lib fed control animals (53 ± 17 pg/ml vs 159 ± 32 pg/ml, P < 0.05) as early as day 2 and a similar pattern was observed on days 4 and 6. The fasting plasma gastrin concentration of control animals was 2-fold greater than of the parenterally fed group ( P < 0.05). Following oral peptone, the gastrin response of TPN and control animals doubled although peak gastrin levels were greatly reduced in TPN rats. Basal gastrin release from the perfused stomachs of control rats was 2-fold greater than from TPN rats ( P < 0.05). Electrical stimulation of the vagal trunks resulted in a significantly greater elevation in gastrin secretion from control stomachs compared to TPN animals (4-fold vs. 2.4-fold increase, P < 0.05). Quantification of the antral G-cell population revealed a significant reduction in the number of G-cell of TPN rats compared to controls (97 ± 8 cells/mm vs 76 ± 6 cells/mm, P < 0.05). These results indicate that luminal nutrient stimulation is necessary for the maintenance of normal G-cell secretory activity in vivo and from the in vitro stomach. G-cell hypoplasia appears to be partially responsible for reduced gastrin output to basal and stimulated conditions after TPN.

Alterations in serum gastrin levels and antral G- and D-cell population following corticosteroid administration. RIA and immunocytochemical long-term study in guinea pigs.

Fourteen guinea pigs were given prednisolone daily for 20 days and 11 for 40 days. Another 20 formed the two control groups. Short-term prednisolone treatment significantly increased serum gastrin levels and antral G-cell population as compared to the control group. The same parameters significantly decreased following 40 days of prednisolone treatment as compared to the group of short-term prednisolone treatment. Forty days of prednisolone treatment significantly increased antral D-cell population as compared to the control and short-term prednisolone treatment groups. It is concluded that hypergastrinaemia and antral G-cell hyperplasia following corticosteroid administration is temporary and is accompanied by antral D-cell hyperplasia.

Influence of sex-hormones on serum gastrin and antral G-cell population in guinea pigs.

Influence of sex-hormones on serum gastrin and antral G-cell population in guinea pigs.

Behavior of somatostatin-immunoreactive cells in the gastric mucosa before and after selective proximal vagotomy and pyloroplasty in treatment of gastric and duodenal ulcers

Antral somatostatin-immunoreactive cells (D cells) were counted pre- and postoperatively in 20 patients with duodenal ulcer and in 8 patients with gastric ulcer. Counts were obtained either over a 2-yr postoperative period (duodenal ulcer patients) at intervals of 0.5, 1, and 2 yr or over a ⩾4-yr postoperative period (gastric ulcer patients) at intervals of 1–2 yr. In patients with a normal population of gastrinimmunoreactive cells (G cells), the D cells were within the normal range (mean value 0.53% in duodenal ulcer patients and 0.67% in gastric ulcer patients). High G-cell values were accompanied by high D-cell values (e.g., in gastrin-cell hyperplasia) and low G-cell values were accompanied by low D-cell values. The G-cell to D-cell ratio was 8:1 and 6.6:1 in duodenal and gastric ulcer patients, respectively. After selective proximal vagotomy and pyloroplasty, the following observations were made: (a) the relation of number of G cells to number of D cells remained unchanged; (b) the postoperative rise in G-cell population was accompanied by a rise in D-cell population; (c) hypertrophy of the D cells was apparent as was postoperative hyperplasia, with a postoperative increase in D-cell size. Morphologic coupling of the gastrin-somatostatin system in the antrum is assumed. This is constant in ulcer disease both before and after vagotomy.

Total Counts of Antral Gastrin Cells: A Simple Direct Method

A simple technique has been developed to quantitate the gastrin cells (G-cells) from the pyloric antrum of the rat. The antrum was digested in pronase to suspend the epithelial cells. This cell suspension was counted and pelleted. The pellet was embedded in paraffin, sectioned, then labeled using the indirect immunofluorescence technique specific for gastrin. The percentage of G-cells was determined from photographs of fluorescing sections and total G-cell numbers were determined by relating these data to total epithelial cell counts. In 14 rats the average G-cell population totaled 1.03 +/- 0.21 X 10(5) G-cells/antrum. The technique is simple, time-saving and avoids the uncertainties inherent in previous procedures for the estimation of G-cell numbers.

Gastrin release from isolated perfused rat stomach after vagotomy.

Postvagotomy hypergastrinemia persists in the isolated perfused rat stomach, but its cause is unknown. The possible role of cholinergic nervous pathways was investigated in the isolated vascularly perfused rat stomach after vagotomy. Atropine and hexamethonium, but not propranolol, inhibited postvagotomy hypergastrinemia. A nervous mechanism involving acetylcholine was further suggested by the inhibitory action of methionine-enkephalin on gastrin release after vagal section. Methacholine, a muscarinic receptor agonist, only weakly stimulated gastrin release from vagotomized stomachs when compared with shamoperated controls, indicating that a cholinergic drive was already in place. Immunocytochemical studies of antral tissue following vagotomy indicated that numbers of gastrin-containing cells (G-cells) were not increased after vagotomy but exhibited reduced intensity of gastrin staining when compared with control stomachs. It was concluded that basal hypergastrinemia may result from increased stimulation of a normal G-cell population by a cholinergic mechanism at the ganglionic level.

The Antrum in Duodenal Ulcer Patients

Estimates of the border between antral and fundic mucosa, antral size, antral G-cell density, G-cell population, and total G-cell volume were made from multiple biopsies taken from the gastric curves during parietal cell vagotomy for duodenal ulcer in 33 patients. No relation was found between the landmarks of Latarjet's nerve and the border. The fundic mucosa was underdenervated in 20% of the patients, and the postoperative acid response to sham feeding in these was higher than in patients with an overdenervated or optimally denervated border. No relation was found between antral size, defined as antral mucosal volume containing G-cells, and preoperative acid secretion. However, an inverse relation was found between antral size, defined as antral mucosal volume containing no parietal cells, and preoperative maximum acid secretion, suggesting an inverse relation between areas with and without parietal cells. No relation was found between acid secretion and G-cell densities, G-cell population, or total G-cell volume.

Quantitative studies of the gastrin-producing cells of the human antrum. A methodological study.

The antral gastrin-producing cells (G-cells) have been identified by the indirect immunoperoxidase technique in two antrum preparations removed due to a recurrent duodenal and gastric ulcer. Morphometric principles were applied to the G-cells with determination of their volume density, numerical density, and mean cell volume. The study showed that within-observer variation, between-observer variation and within-patient variation were negligible, provided at least 200 G-cells were counted. A biopsy material can be used, as well as larger tissue blocks, when this minimum sample size is respected. A method for estimating the total G-cell population and the total G-cell volume in the antrum was developed. In the antrum removed due to a gastric ulcer the number of G-cells was 190 x 10(6) and their total volume 176 mm3.

G-cell population and serum gastrin response to cimetidine-OXO test meal in relation to histopathological alterations in resected stomachs from patients with peptic ulcer disease.

The relationship between histopathological alterations and G-cell population in the stomach was studied in l4 resected stomachs from patients with chronic peptic ulcer disease (6 with duodenal ulcer and 8 with gastric ulcer). G-cells were identified by indirect immunoperoxidase method. When atrophy was graded three steps (0, 1, 2), the average grade of DU and GU was 0.23 and 0.89, respectively. There was a significant correlation (r=0.871, p less than 0.005) between atropic grade and G-cell population in each stomach. The mean occupation rate with intestinal metaplasia was 0.9% in DU and 35.8% in GU. There was no correlation between total pyloric area and G-cell population, however residual pyloric area excluding intestinal metaplasia correlated significantly with G-cell population (r=0.557, p less than 0.05). There was a significant difference in the mean G-cell population which were 26.5 millions in DU and 8.9 millions in GU. The mean integrated gastrin response to Cimetidine-OXO test meal were 559+/-236 pg/ml in DU and 216+/-124 pg/ml in GU, and there was significant correlation (r=0.889, p less than 0.005) between G-cell population and integrated gastrin response. The average age of both groups, however, was 27.7 in DU and 52.8 in GU, so that these differences of G-cell population and functional G-cell mass in both groups might originate in the histopathological alterations accompanying with the aging.

G-cell populations in resected stomachs from gastric and duodenal ulcer patients

The G-cell population in the pyloric antrum and proximal duodenum was studied quantitatively by immunofluorescence in specimens from 10 gastric and 12 duodenal ulcer patients. In both groups, G-cell density was highest in the pyloric antrum and much lower in the intermediate zone and proximal duodenum, and G-cell counts were statistically higher at the greater than the lesser curvature. The estimated total number of G cells in the whole pyloric antrum including the intermediate zone in the duodenal ulcer group was (1.806 ± 0.347) × 107, this value was significantly greater (P < 0.05) than that of (0.872 ± 0.207) × 107 in the gastric ulcer group. This difference was due to a higher incidence of intestinal metaplasia and a decrease in the thickness of the antral mucosa in the latter group. The estimated total number of G cells showed a significant negative correlation not only with the patient age (P < 0.01) but also with the degree of intestinal metaplasia of the antral mucosa (P < 0.01) in both duodenal and gastric ulcer patients.

G-cell population in antral mucosa of the dog

The gastrin-cell (G-cell) population in the pyloric antrum of 8 dogs was studied quantitatively by immunofluorescence. The G-cell population was dense in the pyloric antrum and very few cells were seen in the antrocorporal junction. The estimated total number of G cells was (1.66 +/- 0.12) X 10(7) in the pyloric antrum and the greatest number of G cells per unit mucosal surface area was along the greater curvature of the pyloric antrum. Except along the greater curvature, G cells per unit musocal volume were significantly greater in number (P less than 0.05) in the proximal antrum adjacent to the antrocorporal junction that in any other regions distal to it. Differences in mucosal thickness were considered as a causative factor for these differences.

Studies of isolated and enriched rat antral mucosa gastrin cells.

A technique has been developed to obtain viable, isolated and enriched populations of gastrin cells (G-cells) from the rat stomach. Restricted tissue samples from a small area of the pyloric antrum known to be particularly rich in G-cells, were sequentially digested with pronase followed by mechanical agitation, to remove the epithelial cells. This technique resulted in a significant enrichment of G-cells (3-4 fold) since the surface epithelial cells and upper portions of the glands were discarded before the initial G-cell fraction was collected. These cells in suspension were then isolated from each other by gentle pipetting in a DNase containing solution and designated the crude preparation (CP). The G-cells were then purified further by separating the cells according to size by velocity sedimentation. The greatest concentration of G-cells (15-25%) was found in the fraction containing cells with diameters of 10 to 12 micrometer. The effectiveness of the technique was evaluated by counting G-cells as identified by electron microscopy and immunofluorescence and assessing gastrin activity by radioimmunoassay. All three methods indicated that cell separation by gravity velocity sedimentation enriched the G-cell population 15-20 fold over their concentration in the CP. The combined techniques of selective pronase digestion followed by gravity velocity sedimentation resulted in an isolated cell preparation containing a 50-100 fold increase of G-cells over their normal distribution in the intact gastric mucosa. Since these isolated G-cells retain features indicating viability, their usefulness for in vitro studies is suggested.

Effects of Prolonged Administration of Metiamide on Serum Gastrin, Gastrin Content of the Antrum and Gastric Corpus, and G-Cell Population in the Rat

The effect of prolonged metiamide administration on serum gastrin, gastrin content of the antrum and gastric corpus, and G-cell population was studied in the rat. A single subcutaneous injection of metiamide (200 mg/kg) at the onset of 16 days of continous treatment with three daily injections was followed by a fivefold increase in serum gastrin level at 4 hr in fasted and at 4 and 6 hr in fed rats. After 16 days of metiamide, the fed rats showed a peak in serum gastrin level of the same magnitude as on day 1, but only at 4 hr. Two hours later, the levels decreased rapidly to basal values. In the fasted animals, the response to metiamide was reduced to a threefold increase at 2 hr. There was no difference in gastrin content of the antrum and gastric corpus nor in volume density of the G-cells after the prolonged treatment compared with the controls. It is concluded that in spite of rises in serum gastrin, prolonged metiamide medication has no effect on the gastrin content of the antrum and gastric corpus nor on the G-cell population in the rat. Furthermore, after prolonged treatment, metiamide-induced gastrin release is diminished.

Fasting and food-stimulated serum gastrin concentrations in relation to the antral G-cell population. A study in patients with peptic ulcer disease.

The fasting serum concentration and the first-hour serum gastric response to a protein-rich meal were related to the antral G-cell population in 14 patients with peptic ulcer. They were divided into a uremic (n=5) and non-uremic group (n=9). Fasting serum gastrin correlated significantly with the total antral G-cell mass only in the non-uremic patients who showed a relatively narrow transitional body-antrum zone. Conversely, the integrated serum gastric response was inversely related to the size of this zone in both groups of patients. A presumptive endocrine G-cell mass was estimated by subtracting the G cells in the transitional zone from the total antral G-cell population. Total gastrin output correlated positively with this estimated mass in the non-uremic group and in the material as a whole. Also, the integrated gastrin response was positively correlated with the presumptive endocrine G-cell mass in the whole material. It was concluded that G cells in the transitional body-antrum zone, where also parietal cells are present, do not release gastrin into the circulation during meal stimulation like G cells in the remaining part of the pyloric antrum. On the basis of these results and our previous morphological observations (19), we propose that the G cells in the transitional zone are involved in a paracrine interrelationship with the surrounding parietal cells rather than contributing to the circulating pool of gastrin.

Quantitative studies of gastrin cells (G cells) and parietal cells in relation to gastric acid secretion in patients with peptic ulcer disease.

The distribution of parietal cells in the body mucosa, and of G cells in the antral mucosa, was quantitatively mapped in resected stomachs from 42 patients (12 with gastric ulcer, 11 with duodenal ucler, 14 with duodenal ulcer and uremia, and 5 with gastric cancer) who preoperatively had had their gastric acid secretion measured. In the material as a whole there was a significant positive correlation between the parietal-cell density and maximal acid output (MAO), and a significant negative correlation between the parietal-cell density and patient age. A significant positive correlation was found between the antral G-cell mass and basal acid output (BAO). When the individual patient categories were analyzed, the correlation between parietal-cell density and MAO were significant in the group with duodenal ulcer and uremia, and in the group with gastric cancer. Correlation between parietal-cell density and age was found only in the group with duodenal ulcer and uremia. There was no correlation between the parietal-cell density and various parameters of the antral G-cell population in the material as a whole or in any of the individual groups.