Adult Rat Stomach Research Articles

Age-related changes in NG2-expressing telocytes of rat stomach.

NG2 immunoreactive cells (NG2 cells) are found in the brain and peripheral tissues including the skin, intestinal tracts, and bladder. In a previous study, we observed the presence of NG2 cells in the stomach using bioluminescence imaging techniques in NG2-firefly luciferase (fLuc) transgenic (Tg) rats. Here, we aimed to identify and characterize NG2 cells in the adult rat stomach. Immunohistochemical studies showed that NG2 cells were mainly present in the lamina propria and most of the cells were gastric telocytes, co-expressing CD34, and platelet-derived growth factor receptor alpha (PDGFRα), with a small oval-shaped cell body and extremely long and thin cellular prolongations. In the rat stomach, NG2-expressing telocytes comprised two subpopulations: NG2+/CD34+/PDGFRα+ and NG2+/CD34+/PDGFRα-. Furthermore, we showed that the expression of NG2 gene in the aged rat stomach decreased relative to that of the young rat stomach and the decline of NG2 expression in aged rats was mainly observed in NG2+/CD34+/PDGFRα+ telocytes. These findings suggested age-related alterations in NG2+/CD34+/PDGFRα+ telocytes of rat stomach.

Effect of sodium metabisulfite on lipid peroxidation and enzyme activities in adult rat stomach and spleen

Sodium metabisulfite (NaMBS) has been used as an antioxidant and antimicrobial agent in a variety of drugs and foods. The aim of our study was to evaluate the effect of subchronic ingestion of NaMBS on lipid peroxidation, protein and enzymatic antioxidants in the gastric tissue and splenic Wistar rat. The rats were divided into four groups (n = 06 rats/group) as follows; Control (C), rats treated with 0.25% NaMBS (S0.25%), rats treated with 1% NaMBS (S1%) and rats treated with 4% NaMBS (S4%). NaMBS was administered to animals via drinking water. At the end of the experimental period, Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxi-dase (GPx), catalase (CAT) and thiols were determined. Redox status assess-ment revealed that 1% and 4% NaMBS doses induced gastric and spleen lipid peroxidation in animals compared to the control group. On the other hand, activities of SOD, GPx, CAT and thiols were reduced in the S1% and S4% groups in the stomach and spleen compared to the controls. Slight changes were detected in the GPx and CAT in the stomach of S0.25% group compared to the control group. In conclusion, the subchronic consumption of NaMBS has an adverse effect on the spleen and stomach by inducing oxidative damage leading to an increase in lipid peroxidation, protein oxidation and alteration of enzyme activity antioxidant.

Protective role of curcumin against 2,3,7,8-tetrachlorodibenzo-dioxin-induced histological and biochemical changes in fundic mucosa of the adult rat stomach

Introduction 2,3,7,8-Tetrachlorodibenzo-dioxin (TCDD) is released into the environment from different activities and industrial sources, with a higher incidence of gastric exposure. This work aimed to study the histological and biochemical changes induced by TCDD in the fundic mucosa and the possible protective role of curcumin against these changes. Materials and methods Thirty adult female albino rats were classified into three groups: the control group (group I); the TCDD group (group II), in which rats received 100 μg/kg TCDD orally for 3 months; and the curcumin+TCDD group (group III), in which rats received an oral dose of 80 mg/kg curcumin in concurrence with TCDD for 3 months. The serum level of the gastrin hormone was measured. Samples from the fundus of the stomach were stained with H&E, Van Gieson, and PAS/alcian blue and for immunohistochemical detection of aryl hydrocarbon receptors (AHR) and chromogranin A. Morphometric and electron microscopic studies were also carried out. Results Hyperplasia and metaplastic mucosal changes, together with enteroendocrine cell hyperplasia, were evident. Moreover, glandular degeneration, areas of atrophic gastritis, cellular apoptosis, and gastric ulcers were detected. The previous results could be explained by both TCDD-induced hypergastrinemia and increased AHR expression. In contrast, curcumin appeared to have a propitious protective effect against TCDD-induced gastric affection. Most of the TCDD-induced gastric changes were not observed in group III. Conclusions It was concluded that the gastric mucosa is sensitive to the toxic effects of TCDD and curcumin can be used to avoid TCDD-induced gastric complications.

Plasticity of nodose ganglion neurons after capsaicin- and vagotomy-induced nerve damage in adult rats

Previous reports show that vagal afferent innervation of the stomach eventually regenerates from surviving nodose ganglion (NG) neurons after subdiaphragmatic vagotomy. Systemic capsaicin treatment destroys gastric vagal afferent neurons expressing vanilloid receptor 1 (VR1). However, it is not known whether gastric innervation lost after neuronal destruction can be restored. Here, we report that capsaicin-induced damage of NG neurons innervating the stomach in adult rats is followed by restoration of vagal afferent projections. Specifically, we compared measures of neuronal plasticity in NG and vagi after subdiaphragmatic vagotomy or capsaicin treatment. The numbers of VR1-immunoreactive neurons projecting to the stomach were significantly reduced 10 days after either capsaicin treatment or vagotomy. However, the VR1-immunoreactive afferent innervation of the stomach was restored to levels exceeding those of vagotomized rats by 37 days after capsaicin, whereas neither total afferent innervation nor VR1-immunoreactive innervation reached control levels, even by 67 days after vagotomy. Capsaicin treatment significantly increased NG neuronal nitric oxide synthase (nNOS) immunoreactivity at 10 days after capsaicin, and this increase was sustained for the duration of the study, indicating higher nNOS demand in restoration of vagal projections. Vagotomy was associated with a much smaller increase in the number of nNOS-immunoreactive NG neurons, detectable only at 10 days after surgery. The number of nNOS-immunopositive gastric-projecting neurons was dramatically reduced 10 days after either capsaicin treatment or vagotomy but returned to the control level in both groups at 67 days. We found a significantly higher number of growth cones in capsaicin-treated animals compared with controls. Capsaicin significantly increased the number of nNOS-immunopositive and nNOS-immunonegative growth cones in NG at all time points. Vagotomy did not increase the number of nNOS− growth cones in NG. We conclude that capsaicin treatment may result in more significant restorative capacities than vagotomy, mainly because of sprouting of capsaicin-insensitive nerve fibers.

Long-term dietary restriction influences plasma ghrelin and GOAT mRNA level in rats

The objective of this study was to examine the effect of chronic dietary restriction on the physical characteristics of the intestine and gut-derived satiety hormone production. Male Wistar rats (8 weeks) were randomized to ad libitum (AL) or 35% dietary restriction (DR) for 5 months. At the end of the study, physical measurements were made on the intestine and satiety hormone secretion and mRNA expression determined. A comparison group of young, growing AL rats (5 weeks) was also examined. The adult DR rats gained less weight over 5 months and had lower fat mass than adult AL rats ( p < 0.05). The weight of the small intestine as a percentage of total body weight was greater in adult DR compared to adult AL but lower than young AL rats. Compared to AL, DR down-regulated proglucagon and cholecystokinin mRNA in the duodenum and ghrelin mRNA in the stomach of adult rats but was not different from young AL. Ghrelin-O-acyltransferase (GOAT) mRNA in the stomach was up-regulated 21-fold in adult AL rats compared to young AL and 14-fold compared to adult DR rats. Total and des-acyl ghrelin was approximately 50% higher in adult DR and young AL rats compared to adult AL. Plasma leptin and insulin were lower in adult DR and young AL rats compared to adult AL. Our findings suggest that long-term energy deficits continue to drive up ghrelin levels which may have profound implications for practical implementation of DR as an anti-aging or anti-obesity strategy in humans.

Glucocorticoids Inhibit the Proliferation of Mucosal Cells and Enhance the Expression of a Gene for Pepsinogen and Other Markers of Differentiation in the Stomach Mucosa of the Adult Rat

Adrenalectomy caused a significant decrease in the mucosal level of pepsinogen in the adult rat stomach. This decrease was mainly due to a reduction in the level of the main component of rat pepsinogen isozymogens, namely, Pgl and in the level of expression of Pgl mRNA, with a maximal effect being evident 48 hours after operation. Immunohistochemical analysis revealed that the level of expression of Pgl in the pepsinogen-producing cells was decreased throughout the stomach mucosa and this decrease was especially marked in the immature chief cells located in the glandular neck of the fundic mucosa. Adrenalectomy also increased the proliferation of mucosal cells and suppressed the expression of cathepsin E and class III mucin, markers of differentiated stomach mucosa. All these changes were reversed by hydrocortisone replacement and the extent of the recovery of the level of Pgl mRNA was dependent on the dose of hydrocortisone, indicating the transcriptional control of the Pgl gene by hydrocortisone. The observed results suggest that the continuous presence of glucocorticoids is necessary for active transcription of Pgl gene in fully differentiated stomach mucosa and that glucocorticoids are important regulators of both the function and the morphology of stomach mucosal cells.

Identification of Protein-Tyrosine Kinase Genes Preferentially Expressed in Embryo Stomach and Gastric Cancer

For identification of the protein-tyrosine kinases that are expressed in embryo stomach and gastric cancer, a 16-day rat embryo stomach and two human gastric cancer cDNA expression libraries were screened with an anti-phosphotyrosine antibody. Eight cDNAs encoding protein-tyrosine kinase were isolated, and Northern blot analysis revealed that five out of eight clones were highly expressed in rat embryo stomach, but not in adult rat stomach. From nucleotide sequence analysis, these five cDNAs were identified as elk, erk, esk, TTK and fyn, respectively. We report here that the expression levels of two families of receptor type tyrosine kinase genes, elk/erk and esk/TTK are developmentally regulated in rat stomach and highly expressed in human gastric cancer tissues. These findings suggest that elk/erk and esk/TTK genes play important roles in embryonic development and carcinogenesis of the stomach.

Growth Hormone Receptor Expression in the Rat Gastrointestinal Tract*

We have used immunohistochemistry to define the cellular distribution of GH receptors in the gastrointestinal tract (GIT) and its derivatives. Immunohistochemistry was performed in the adult rat GIT with a panel of characterized monoclonal antibodies to the GH receptor. The most intense and heterogeneous immunoreactivity was observed in epithelial cell subpopulations of GIT mucosa. Mesenchymal elements of the GIT were homogenously and moderately immunoreactive. Intense immunoreactivity was observed in the ductal epithelium of the sublingual gland, scattered basal epidermal cells of the esophageal mucosa, zymogen cells of the gastric glands, scattered surface epithelial cells of the stomach, and scattered peripheral pancreatic acinar groups. Scattered enteroendocrine cells and parietal cells, crypt and villous columnar cells of the small intestine, surface columnar cells of the cecum/colon, crypt base columnar cells of the colon, and contiguous peripheral cords of pancreatic islet cells displayed strong immunoreactivity. No immunoreactivity was detectable in the mucous and serous acini of the sublingual and submandibular gland, respectively, mucous-secreting cells of the base of the cardiac and pyloric glands, surface epithelial cells of the fundus, paneth cells, goblet cells of cecum/colon, or mucous cells at the base of the cecal crypt. Other elements of the GIT were moderately or weakly immunoreactive. In support of our localization we can detect high affinity binding (Ka = 3 x 10(9] of [125I]human GH with ovine GH as displacing ligand to crude homogenates of adult rat stomach and intestine. We conclude that discrete epithelial cell subpopulations of the GIT and its derivatives are directly responsive to GH action. GH may, therefore, act independently of or synergistically with hepatic insulin-like growth factor-I in executing its physiological and/or growth-promoting role in the GIT.

Effect of prostaglandins on the adult rat stomach and intestine.

BACKGROUND--This study was designed to investigate the contribution of inhaled salbutamol to the increase in resting metabolic rate found in patients with chronic airflow limitation who were receiving bronchodilator therapy. METHODS--The resting metabolic rate of 10 normal subjects (age 20-47 years, weight 42-105 kg, seven men) was studied after inhalations of salbutamol or placebo. An open canopy method of indirect calorimetry was used to measure resting oxygen consumption (VO2) and resting carbon dioxide production (VCO2). Subjects inhaled two, four, eight, or 12 puffs (100 micrograms/puff) of salbutamol or placebo in a double blind manner. Recordings of VO2 and VCO2 were made after inhalation of the four doses of salbutamol or placebo, integrated over one hour, and compared. RESULTS--VO2 and VCO2 increased in a dose dependent manner after inhaled salbutamol with a maximum effect at five minutes after inhalation. After four puffs, VO2 was 203 and 188 ml/kg/h for salbutamol and placebo respectively. After eight puffs, VO2 was 207 and 185 and VCO2 was 167 and 155 ml/kg/h. After 12 puffs, VO2 was 220 and 190 with a VCO2 of 181 and 168 ml/kg/h. Twelve puffs of salbutamol increased the mean (SE) respiratory quotient from 0.85 (0.01) to 0.93 (0.04) at five minutes indicating an increase in ventilation in excess of metabolic demand. Mean heart rate increased in parallel with VO2. CONCLUSION--Inhaled salbutamol significantly increases resting metabolic rate in a dose dependent manner.

Mechanism of inactivation of mammalian L-histidine decarboxylase by ( S)- α-fluoromethylhistidine

The mechanism of inactivation by ( S)- α-fluoromethylhistidine (FMH) of L-histidine decarboxylase (HDC, L-histidine carboxy-lyase, EC 4.1.1.22) purified from whole bodies of fetal rat was studied. FMH inhibited the activities of HDC purified from fetal HDC as well as HDCs from the brain and stomach of adult rats. The activity was not restored by extensive dialysis, indicating that the inhibition was irreversible. The inactivation of HDC was time and concentration dependent and followed pseudo first-order kinetics. L-Histidine, a substrate, protected HDC against inactivation, but D-histidine did not. Apo-HDC was not inactivated by FMH. On labeling of HDC with [ 3H]FMH, a correlation was found between the extent of incorporation of radioactivity into the enzyme and the degree of inactivation. Two moles of the inhibitor were incorporated into one mole of HDC (108,000 daltons). Experiments with [ carboxyl- 14C]FMH and [ ring 2- 14C]FMH showed that decarboxylation was necessary for the inactivation and that one molecule of FMH moiety was incorporated into an HDC monomer during every three decarboxylations of FMH.

Cells intermediate between mucous neck cells and chief cells in rat stomach.

Morphological and histochemical methods revealed cells intermediate between mucous neck cells and chief cells in rat stomach. The secretory granules of mucous neck cells and chief cells were homogeneous. However, some cells resembling mucous neck cells in shape and size yet contained heterogeneous granules. One type of cell contained mucous granules showing a bipartite structure. The inner cores of these granules resembled the granules of mucous neck cells morphologically and after staining by the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) procedure and lectin-ferritin methods. The outer layer of these granules, however, resembled the granules of chief cells and failed to stain by these methods. Another type of cell also contained bipartite granules, but these showed a dense cap and lucent matrix. The cap of the granules did not stain with the PA-TCH-SP and lectin methods, but the remaining matrix was reactive. These presumed transitional cells were located in a layer between the mucous neck cells and the chief cells. Immature chief cells with sparse granular reticulum were found near these intermediate cells in some cases. Many similar intermediate type cells were also found in early developmental stages of the gastric mucosa in rat. These results suggest a close relationship between chief cells and mucous neck cells; chief cells may develop from undifferentiated stem cells via mucous neck cells in adult rat stomach.

The development of pancreatic and gastrointestinal somatostatin-like immunoreactivity and its relationship to feeding in neonatal rats.

Using a specific RIA technique, we have determined the somatostatin-like immunoreactivity (SLI) concentrations in acid extracts of pancreatic and gastrointestinal tissues and studied their relationships to feeding in fed and 15-h-fasted immature (less than 24 days old) rats. Mean pancreatic SLI concentrations per unit of protein were low before and immediately after birth before the initiation of feeding. They increased 7-fold during the first 3 days and remained high for the next 2 weeks. Gastric SLI concentrations were also low before and immediately after birth and increased progressively with age up to day 21 (time of weaning), followed by an abrupt increase at day 24, especially in 15-h-fasted rats. The mean SLI concentrations in the duodenum and jejunum were 4.9-6.3 times higher than that in the gastric antrum 1 day before birth and were also significantly higher than those in the gastric antrum for the first 3-7 days. No significant difference was found by age in the gel filtration patterns of tissue extracts from the pancreas, gastric antrum, and duodenum in fetal and fasted 3- and 24-day-old rats. I conclude from these findings that: 1) the developmental patterns of pancreatic and gastrointestinal SLI show a close relationship with feeding, suggesting the important role of somatostatin in the digestive functions and nutrition in immature rats, and 2) the quantitative distribution of somatostatin in the gastrointestinal tract markedly differs so that there is intestinal predominance in fetal or neonatal rats, and predominance in the stomach in adult rats.

An isolated vascularly perfused stomach for studying drug distribution, metabolism and action in the stomach: acid secretion in response to secretagogues.

Experimental utilization of isolated vascularly perfused rat stomach with retention of the exocrine response to various stimulants was studied. By the inclusion of bovine erythrocytes in the vascular perfusate and by the use of luminal perfusate possessing a suitable buffer capacity, it was found that acid secretion was significantly stimulated by the perfusion of histamine, pilocarpine, cyclic adenosine monophosphate (AMP), dibutyryl cyclic AMP or theophylline. In addition, cimetidine, a histamine H2-receptor antagonist, inhibited histamine-induced acid secretion in a reversible manner. Although tetragastrin stimulated acid secretion in immature rat or guinea pig stomach, it caused little secretory response in adult rat stomach. On the addition of pepstatin, a pepsin inhibitor, to the vascular perfusate, an acid secretion induced by tetragastrin in adult rat stomach was observed. These findings indicate that some changes in gastrin receptors may develop during the maturation process and that gastrin-induced acid secretion is easily altered by peptic activity in the gastric glands of the perfused stomach. The proposed perfusion system should be useful for studying drug distribution, metabolism and action in the stomach.

Irradiation Effect on Bioelectric Activity in Isolated Rat Stomach

Certain changes occurring in gastrointestinal tissue as a result of irradiation of the animal seem to involve the active transport mechanisms concerned with secretion or absorption of electrolytes (1), and at lower doses these changes occur in the absence of gross disturbances in diffusional transfer fluxes (2). The present study employing bioelectric parameters arose in the attempt to study irradiation effects on these active transport mechanisms by a more general approach than that employing singleand double-label tracers. Although this aim is achieved at the expense of information on the specific source of bioelectric activity, the approach seemed desirable for several reasons: Ion flux measurements can be obtained by in vivo tracer techniques of tested validity, but flux values show an inherently high biological variability (2, 3), unlike potential measurements. Also, similar measurements in isolated rat stomach have been hampered by necessary experimental com-promises related to tissue thickness, which may render a tracer analysis by itself equivocal (4). A more serious problem with flux measurements is that the ions metabolically transported may differ. In frog stomach active chloride secretion is believed to account primarily for the observed bioelectric potential (5), but in rat colon active sodium absorption is believed to account primarily for the observed potential (6), and in rat ileum both active sodium and active chloride movements are reported (7). The existence of a gastric sodium pump has been demonstrated in fetal and term rabbits (8), and in this connection we recently reported the specificity and quantitative dependence of all gastric bioelectric parameters on sodium ion in adult rat stomach maintained in vitro (9, 10). Despite these differences, bioelectric parameters should monitor the relative rate at which ions metabolically pumped precede counter ions moving by other means. The potential would measure the summated effects