Acute gastric ulcer formation in response to electrical vagal stimulation in rats

Bidirectional crosstalk between the peripheral nervous system and lymphoid tissues/organs

The central nervous system (CNS) influences the immune system generally by regulating the systemic concentration of humoral substances (e.g., cortisol and epinephrine), whereas the peripheral nervous system (PNS) communicates specifically with the immune system according to local interactions/connections. An imbalance between the components of the PNS might contribute to pathogenesis and the further development of certain diseases. In this review, we have explored the "thread" (hardwiring) of the connections between the immune system (e.g., primary/secondary/tertiary lymphoid tissues/organs) and PNS (e.g., sensory, sympathetic, parasympathetic, and enteric nervous systems (ENS)) in health and disease in vitro and in vivo. Neuroimmune cell units provide an anatomical and physiological basis for bidirectional crosstalk between the PNS and the immune system in peripheral tissues, including lymphoid tissues and organs. These neuroimmune interactions/modulation studies might greatly contribute to a better understanding of the mechanisms through which the PNS possibly affects cellular and humoral-mediated immune responses or vice versa in health and diseases. Physical, chemical, pharmacological, and other manipulations of these neuroimmune interactions should bring about the development of practical therapeutic applications for certain neurological, neuroimmunological, infectious, inflammatory, and immunological disorders/diseases.

Acid-reducing vagotomy is associated with reduced risk of subsequent ischemic heart disease in complicated peptic ulcer: An Asian population study

Persistent exacerbation of a peptic ulcer may lead to a complicated peptic ulcer (perforation or/and bleeding). The management of complicated peptic ulcers has shifted from acid-reducing vagotomy, drainage, and gastrectomy to simple local suture or non-operative (endoscopic/angiographic) hemostasis. We were interested in the long-term effects of this trend change. In this study, complicated peptic ulcer patients who received acid-reducing vagotomy were compared with those who received simple suture/hemostasis to determine the risk of ischemic heart disease (IHD).This retrospective cohort study analyzed 335,680 peptic ulcer patients recorded from 2000 to 2006 versus 335,680 age-, sex-, comorbidity-, and index-year matched comparisons. Patients with Helicobacter pylori (HP) infection were excluded. In order to identify the effect of vagus nerve severance, patients who received gastrectomy or antrectomy were also excluded. The incidence of IHD in both cohorts, and in the complicated peptic ulcer patients who received acid-reducing vagotomy versus those who received simple suture or hemostasis was evaluated.The overall incidence of IHD was higher in patients with peptic ulcer than those without peptic ulcer (17.00 vs 12.06 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.46 based on multivariable Cox proportional hazards regression analysis controlling for age, sex, Charlson's comorbidity index, and death (competing risk). While comparing peptic ulcer patients with acid-reducing vagotomy to those with simple suture/hemostasis or those without surgical treatment, the aHR (0.58) was the lowest in the acid-reducing vagotomy group.Patients with peptic ulcer have an elevated risk of IHD. However, complicated peptic ulcer patients who received acid-reducing vagotomy were associated with reduced risk of developing IHD.

Gastric antiulcerogenic and hypokinetic activities of Terminalia fagifolia Mart. & Zucc. (Combretaceae)

The acute toxicity, the antioxidant activity, and the pharmacological activity on the gastrointestinal tract of rodents of the ethanolic extract (TFEE) from the bark of Terminalia fagifolia Mart. & Zucc. (Combretaceae) and of its aqueous (TFAqF), hydroalcoholic (TFHAF), and hexanic (TFHEXF) partition fractions have been evaluated. TFEE presented low acute toxicity, antioxidant, and antiulcerogenic activity against ethanol-induced ulcers, which was partially blocked by pretreatment with L-NAME and indomethacin. It reduced the total acidity and raised the pH of gastric secretion. Additionally, TFEE delayed gastric emptying and slightly inhibited the small intestinal transit and also presented a weakly antidiarrheal activity. The antiulcerogenic and antioxidant activity were also detected in TFAqF and TFHAF but not in TFHEXF. The antisecretory and gastroprotective activity of TFEE partially involve the nitric oxide and prostaglandin participation. Nevertheless, TFEE, TFAqF, and TFHAF drastically reduced the mucus layer adhered to the gastric wall of rats treated with ethanol or indomethacin. Complementary studies are required in order to clarify the paradox of the presence of a gastroprotector activity in this plant that, at the same time, reduces the mucus layer adhered to the gastric wall.

Protective effect of standardized extract of Cleome viscosa against experimentally induced gastric lesions in the rat

CONTEXT

Cleome viscosa Linn. (Capparidaceae) is used traditionally in the Indian system of medicine as a carminative, anthelmintic, and diuretic, and used for healing wounds, ulcers and diarrhea.

OBJECTIVE

A 70% ethanol (EtOH) extract of the aerial parts of Cleome viscosa extract (CVE) was investigated for gastroprotective activity in different gastric ulcer models in order to validate ethnobotanical claims regarding the plant use in ulcers.

MATERIALS AND METHODS

CVE (100, 200 and 400 mg/kg body weight) was administered orally, twice daily for 5 d, for prevention from EtOH, pylorus ligation (PL) and cold restraint stress (CRS)-induced ulcers in rats. Estimation of H(+)K(+)ATPase activity and gastric wall mucous were performed in EtOH-induced ulcer, antioxidant enzyme activities in supernatant mitochondrial fraction of CRS-induced ulcer, and gastric secretion parameters were estimated in PL-induced ulcer model.

RESULTS

CVE showed significant (p < 0.01) dose-dependent inhibition of lesion index in EtOH 15.93-42.30%, PL 26.34-59.28% and CRS 22.58-54.03%, respectively. CVE prevents the oxidative damage of gastric mucosa by blocking lipid peroxidation and by a significant (p < 0.001) decrease in superoxide dismutase, and an increase in catalase activity. A significant (p < 0.01) decrease occurred in the level of H(+)K(+)ATPase, volume of gastric juice and total acidity. Simultaneously, the level of gastric wall mucus and pH were increased significantly (p < 0.05). High performance thin layer chromatography analysis showed the presence of quercetin and gallic acid (0.3% and 0.25% w/w, respectively) in CVE.

CONCLUSIONS

Results of our study showed that C. viscosa possesses significant gastroprotective activity, probably due to free radical scavenging activity, and validates the folklore claim.

Gastroprotective effect of standardized leaf extract from Argyreia speciosa on experimental gastric ulcers in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Argyreia speciosa (L.f), Sweet (Family Convolvulaceae) is used traditionally in Indian System of Medicine as aphrodisiac, rejuvenating agent, intellect promoting agent, brain tonic and in the therapy of hepatomegaly, diabetes and chronic ulcer.

AIM OF THE STUDY

To study the gastroprotective effect of standardized butanol fraction of Argyreia speciosa leaf (ASE).

MATERIALS AND METHODS

The butanol fraction of Argyreia speciosa leaf (ASE; 50, 100 and 200mg/kg body weight) was administered orally, twice daily for 5 days for prevention from Aspirin (ASP)-, ethanol (EtOH)-, cold-restraint stress (CRS) - and pylorus ligation (PL)-induced ulcers. Estimation of antioxidant enzymes activity was carried out in CRS-induced ulcer model, and various gastric secretion parameters like volume of gastric juice, acid output, and pH value were estimated in PL-induced ulcer model.

RESULT

ASE showed dose-dependent ulcer protective effect in ASP 23.64-58.76% (p<0.01 to p<0.001), EtOH 15.45-58.45% (p<0.001), CRS 19.39-78.36% (p<0.001) and PL 19.67-69.04% (p<0.05 to p<0.01), respectively. The percentage of protection by standard drug ranitidine was 77.77-84.32% (p<0.01 to p<0.001) in various gastric ulcer models. The gastric wall mucus was significantly (p<0.001) enhanced by ASE and is regarded as the first line of defence against EtOH-induced gastric ulcers showing cytoprotective property. ASE showed a marginal decrease in volume, acid pepsin concentration and acid pepsin output. However, ASE reduced the ulcer index with significant decrease in LPO level (p<0.001), and SOD level (p<0.01 to p<0.001) as compared with CRS-induced group. A gradual and significant increase in CAT values were observed at 100 and 200mg/kg dose levels (p<0.01 to p<0.001).

CONCLUSIONS

The results of our study revealed that Argyreia speciosa possess significant dose dependent gastroprotective activity, probably due to its free radical scavenging activity.

Gastroprotective effect of Benincasa hispida fruit extract

Objectives:

The antiulcer activity of Benincasa hispida (Thunb.) Cogn. fruit was evaluated in rats against ethanol-induced gastric mucosal damage, pylorus ligated (PL) gastric ulcers, and cold restraint-stress (CRS)-induced gastric ulcer models.

Methods:

Petroleum ether and methanol extracts were administrated orally at the dose of 300 mg/kg, and omeprazole (reference standard) at the dose of 20 mg/kg. Ulcer index was common parameter studied in all the models. Further, vascular permeability was evaluated in ethanol model, and effect on lipid peroxidation, viz. melondialdehyde (MDA) content, superoxide dismutase (SOD), and catalase (CAT) levels were studied in CRS model.

Results:

Both the extracts produced significant reduction in ulcer index (P < 0.05) in all the models and the results were comparable with that of omeprazole-treated group. Further, significant reduction in vascular permeability (P < 0.05) was observed. In CRS model, MDA content was significantly reduced along with increase in CAT levels as compared to control group.

Conclusions:

Petroleum ether and methanol extracts of B. hispida possess significant antiulcer as well as antioxidant property.

Evaluation of antiulcer and antisecretory potential of Linum usitatissimum fixed oil and possible mechanism of action

The aim of the study was to evaluate the antiulcer activity of Linum usitatissimum fixed oil against aspirin-, indomethacin-, ethanol-, reserpine-, serotonin- and stress-induced gastric ulceration in rats and histamine-induced gastric ulceration in guinea pigs. Attempts were also made to evaluate the in vitro anticholinergic and antihistaminic activity and in vivo antisecretary and antiulcer activity of oil following pylorus ligation in rats. L. usitatissimum fixed oil exhibited significant antiulcer activity against different ulcerogens in experimental animal models. The fixed oil significantly inhibited acetylcholine- and histamine-induced contraction of guinea pig and rat ileums, respectively, suggesting its anticholinergic and antihistaminic activity. The oil also exhibited significant inhibitory effect on gastric secretion/total acidity and aspirin-induced gastric ulceration in pylorus-ligated rats. The lipoxygenase inhibitory, histamine antagonistic and antisecretory (anticholinergic) effects of the oil could probably have contributed towards antiulcer activity. L. usitatissimum fixed oil may be considered to be a drug of natural origin which possesses significant antiulcer activity. The present observation is the first experimental data showing antiulcer activity of L. usitatissimum fixed oil.

Antiulcer and antimicrobial activity of Anogeissus latifolia

Ethnobotanically, the bark of Anogeissus latifolia (Roxb. ex DC.) Wall. ex Guill. and Perr.(Combretaceae) has been reported to be used in the treatment of various disorders including stomach and skin diseases. We studied the antiulcer potential and antimicrobial activity of the 50% aqueous alcoholic extract in order to validate ethnobotanical claims regarding the plant use in the above-mentioned disorders. Gastroprotective potential of the Anogeissus latifolia extract (ALE) (100 and 200mg/kg/body weight) was studied on aspirin, cold-resistant stress (CRS), pylorus ligated (PL) and ethanol-induced ulcers. Status of the antioxidant enzymes superoxide dismutase (SOD) and catalase along with lipid peroxidation (LPO) was also studied in CRS-induced ulcers. The results of the present study showed for the first time that the ALE possessed gastroprotective activity as evidenced by its significant inhibition in the formation of ulcers induced by physical and chemical agents with a maximum of 84.16% curation (200mg/kg body weight) in CRS-induced ulcers. ALE decreased LPO and SOD with concomitant increase in catalase activity in CRS-induced ulcers. Moderate antibacterial activity and antifungal activity was also observed. High performance thin layer chromatography (HPTLC) showed the presence of gallic acid and ellagic acid (0.95%, w/w, 0.25%, w/w, respectively) in the plant. These findings could justify, at least partially, the inclusion of this plant in the management of gastric disorders in traditional medicine.

Effect of fish oil on offensive and defensive factors in gastric ulceration in rats

The effect of fish oil (FO) derived from Scomberoides commersonianus containing omega-3 polyunsaturated fatty acids was studied on gastric ulcers and as well as on offensive and defensive factors in gastric mucosal damage, following experimental gastric ulceration. FO significantly reduced the severity of ulceration in gastric ulcers induced by aspirin, cold-restraint stress (CRS), alcohol, and pylorus ligation. The results also indicated the potentiality of FO in maintaining the integrity of gastric mucosa by virtue of its effect on both offensive and defensive gastric mucosal factors. It decreased the offensive acid-pepsin secretion and augmented the defensive factors like mucin secretion, cellular mucus and life span of mucosal cells following pylorus ligation. FO significantly increased activity of anti-oxidant enzymes (catalase and glutathione peroxidase) and decreased lipid peroxidation in gastric mucosa of CRS rats. The study indicates the beneficial role of FO in gastric ulceration by inhibition of offensive mucosal factors and oxidative stress, and augmentation of defensive mucosal factors.

Allophylus serratus: a plant with potential anti-ulcerogenic activity

Allophylus serratus is known to possess various therapeutic properties. We evaluated the anti-ulcerogenic property of crude ethanolic extract of Allophylus serratus (AS) in different ulcer models in Sprague-Dawley rats. The extract at 400 mg/kg body weight, once daily, orally has a significant effect in cold restraint (CRU, 2 h cold restraint stress), aspirin (ASA, 150 mg/kg body weight, orally), alcohol (AL, 1 ml/200 gm of absolute alcohol) and pyloric ligation (PL, 4h ligation) induced gastric ulcer models as it showed protection index of 71.28, 62.50, 90.84 and 64.29% protection, respectively whereas, standard drug omeprazole (OMZ, 10mg/kg body weight) has shown protection index of 85.70, 74.99 and 74.99 in CRU, ASA and PL model respectively. Sucralfate (SUC, 500 mg/kg body weight) as a standard drug in AL model has 93.20% protection. Furthermore, AS has significantly decreased the free acidity (72.41%), total acidity (47.97%) and peptic activity (24.59%), respectively as well as has significantly increased the mucus secretion (29.41%). Conclusively the ulcer protective effect of AS may be due to its anti-secretory along with cytoprotective mechanism.

Antiulcer activity of Utleria salicifolia rhizome extract

The effect of 50% ethanolic extract of Utleria salicifolia (USE) was assessed in different acute and chronic gastric ulcer models in rats. USE, 50-200 mg/kg administered orally, twice daily for 5 days showed dose-dependent ulcer protective effect in pylorus ligation (14.48-51.03% protection, P < 0.5 to P < 0.01), aspirin (28.80-56.52% protection, P < 0.5 to P < 0.001), ethanol (13.22-60.74% protection, P < 0.5 to P < 0.001), cold-restraint stress (21.22-77.14% protection, P < 0.05 to P < 0.001), and acetic acid (20.0-84.37% protection, P < 0.5 to P < 0.001)-induced acute and chronic ulcers. USE also significantly (P < 0.001) reduced the ulcer incidence (50 and 10%) and severity (67.83 and 91.34% protection) of duodenal ulcer, induced by cysteamine. Besides USE offered protection (53.52 and 60.58%) against ethanol-induced depletion of gastric wall mucus. However, USE reduced the ulcer index with significant decrease in plasma corticosterone (25.53 and 39.52% protection, P < 0.1 and P < 0.05), lipid peroxidation (18.75 and 47.92% protection, P < 0.01 and P < 0.001), superoxide dismutase (15.80 and 26.61% protection, P < 0.05 and P < 0.001) and increased in catalase (28.42 and 71.0% protection, P < 0.05 and P < 0.001) activity, respectively. Preliminary phytochemical screening of the USE gave the positive test for steroids, alkaloids, terpenoids, saponins and tannins. The HPTLC studies in the toluene: ethyl acetate: formic acid and the densitometric scanning at 254 nm gave three major spots with area corresponding to 28.16, 17.17, and 13.79% at 0.69, 0.78, and 0.88 R(f) values, respectively. The results indicate that USE possesses antiulcer activity.

Gastric Antiulcer Activity of Syngonanthus arthrotrichus SILVEIRA

Syngonanthus arthrotrichus SILVEIRA, popularly known as "sempre-vivas mini-saia," is found in mountains of the Espinhaço range in the Brazilian states of Bahia and Minas Gerais. Extracts of this species contain several constituents, including flavonoids which may have antiulcerogenic activity. An ethanolic extract (EEOH), and flavonoid-rich (FRF) and flavonoid-deficient (FDF) fractions obtained from the scapes of S. arthrotrichus were investigated for their ability to prevent ulceration of the gastric mucosa in mice and rats. In the ethanol/HCl-induced ulcer model, lansoprazole (30 mg/kg), EEOH (50, 100, 250 mg/kg) given orally protected the gastric mucosal against injury in mice by 79%, 78%, 73%, and 64% respectively. In the ethanol-induced gastric ulcer model in rats, the lansoprazole (30 mg/kg), FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of rats by 65%, 38% and 25% respectively when compared with the negative control group. In indomethacin/bethanechol-induced gastric ulcers, cimetidine (100 mg/kg) and the EEOH (100, 250 mg/kg) inhibited gastric ulcer formation by 73%, 55% and 32% respectively. In this exactly model other treatments as cimetidine, FRF and FDF (100 mg/kg) each caused 54%, 36% and 45% inhibition, respectively. In the stress-induced gastric ulcer model, cimetidine (100 mg/kg) and the EEOH (50, 100, 250 mg/kg), inhibited gastric ulcer formation by 63%, 73%, 68% and 69% respectively. In the same model, cimetidine, FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of the mice by 60%, 51% and 47% when compared to the control group. In pylorus-ligated mice, cimetidine (positive control) and FRF significantly decreased gastric acid secretion, increased gastric pH and reduced the acid output when compared to the negative control. FDF had no significant effect on these parameters. The protection provided by FRF probably involved an antisecretory mechanism mediated by flavonoids which were absent in FDF. The amount of adherent mucous in the stomach contents was also evaluated with the treatments carbenoxolone (200 mg/kg), FRF and FDF (100 mg/kg) treatment. Each treatments significantly increased the amount of adherent mucous in the gastric juice (8.67+/-1.73, 3.35+/-1.59, 2.1+/-0.41 mg/g of wet tissue, respectively) compared to the control group, indicating a cytoprotective action on the gastric mucosa. Treatment with FRF plus indomethacin and FDF plus indomethacin reduced the prostaglandin biosyntesis (13.6+/-6.5, 27+/-5.5 pg/well) by the mucosa, indicating that the cytoprotective action on the gastric mucosa was not related to the level of prostaglandins. Only FDF (38+/-17 pg/well) maintained the level of prostaglandins and guaranteed the integrity of the mucosa. The results indicate that the EEOH, FRF and FDF have antisecretory and cytoprotective actions, that may be related to the presence of luteoline in the extract and active fractions.

Protective effect of polyunsaturated phosphatidylcholine pretreatment on stress ulcer formation in rats

PURPOSE

The aim of this study was to investigate whether polyunsaturated phosphatidylcholine. (PPC) pretreatment has any protective effect on gastric mucosal damage induced by cold-restraint stress (CRS) in rats.

METHODS

Forty swiss albino rats were divided into 3 groups. Group 1 (n = 10) was control, group 2 (n = 15) was stress ulcer, and group 3 (n = 15) was PPC-treated rats with stress ulcer. Stress ulcer was induced by the cold-restraint method for 4 hours at 4 degrees C after a starvation period of 72 hours. In the group 3 rats, PPC treatment was started 10 days before stress at a dose of 100 mg/d by oral route. Rats were terminated, stomachs were excised. Macroscopic ulcer index (UI), gastric tissue malondialdehyde (MDA) and superoxide dismutase (SOD) activities, plasma total nitrite, and erythrocyte catalase (CAT) concentrations were assayed.

RESULTS

Histopathologic examination showed a stress ulcer index of 0.12 +/- 0.19 mm in the treatment group and 23.6 +/- 8.97 mm in the stress ulcer group (P <.001). Tissue MDA and SOD concentrations were higher in the stress ulcer group than in the treatment group, the differences were statistically significant (P <.001). Plasma NO3-+ NO2- levels were higher (P<.005) and CAT levels were lower (P <.001) in the nontreatment group. There were no significant differences with respect to Ul, MDA, and SOD levels among the control and treatment groups (P >.05).

CONCLUSIONS

These results suggest that pretreating rats with PPC inhibits cold-restraint stress-induced gastric mucosal injury and might be useful in preventing stress-induced stomach ulcers.

Lafutidine, a novel histamine H2-receptor antagonist, increases serum calcitonin gene-related peptide in rats after water immersion-restraint stress

Lafutidine is a novel histamine H(2)-receptor antagonist with a potent and long-lasting anti-acid secretory effect that has also been found to have a potent gastroprotective effect. We investigated the effect of lafutidine on gastric mucosal injury induced in rats with the use of water-immersion restraint stress (WRS) by examining serum calcitonin gene-related peptide (CGRP) concentrations, which we measured with the use of an enzyme immunometric assay. WRS-induced mucosal erosive injury in the stomach was reduced significantly by both lafutidine and famotidine pretreatment (from 7.79 +/- 2.02 mm(2) to 3.09 +/- 0.74 mm(2) and 4.05 +/- 1.18 mm(2), respectively). A single administration of lafutidine or famotidine did not change the serum CGRP concentration from the control value when these drugs were administered without WRS. Lafutidine pretreatment before WRS caused a significant increase in serum CGRP concentration compared with famotidine (lafutidine, 86.64 +/- 9.52 pg/mL; famotidine, 47.55 +/- 4.35 pg/mL; control, 58.43 +/- 6.07 pg/mL). Our results suggest that lafutidine augments CGRP release from the rat stomach when administered before the induction of WRS.

Marked suppression of gastric ulcerogenesis and intestinal responses to stress by a novel class of drugs

When exposed to prolonged stress, rats develop gastric ulceration, enhanced colon motility with depletion of its mucin content and signs of physiological and behavioral arousal. In this model, we tested whether antidepressants (fluoxetine and bupropion), anxiolytics (diazepam and buspirone) or the novel nonpeptide corticotropin-releasing hormone (CRH) type-1 receptor (CRH-R1) antagonist, antalarmin, modify these responses. Fluoxetine, bupropion, diazepam and antalarmin all suppressed stress-induced gastric ulceration in male Sprague-Dawley rats exposed to four hours of plain immobilization. Antalarmin produced the most pronounced anti-ulcer effect and additionally suppressed the stress-induced colonic hypermotility, mucin depletion, autonomic hyperarousal and struggling behavior. Intraperitoneal CRH administration reproduced the intestinal but not the gastric responses to stress while vagotomy antagonized the stress-induced gastric ulceration but not the intestinal responses. We conclude that brain CRH-R1 and vagal pathways are essential for gastric ulceration to occur in response to stress and that peripheral CRH-R1 mediates colonic hypermotility and mucin depletion in this model. Nonpeptide CRH-R1 antagonists may therefore be prophylactic against stress ulcer in the critically ill and therapeutic for other pathogenetically related gastrointestinal disorders such as peptic ulcer disease and irritable bowel syndrome.

Hydroxyl radical is the major causative factor in stress-induced gastric ulceration

The role of the metal-catalyzed production of hydroxyl radicals (OH.) on gastric ulceration caused by restraint-cold stress in rat was studied. Stress causes a 50% increase in the thiobarbituric acid reactive species (TBARS) as a measure of the lipid peroxidation, nearly 70% increase in protein oxidation as measured by its carbonyl content and about 40% decrease in the glutathione content of the fundic stomach, suggesting oxidative damage by stress. Stress also causes a time-dependent increase in the mitochondrial superoxide dismutase activity and a decrease in the peroxidase activity, both of which correlate well with the increase in the severity of ulceration as measured by the ulcer index. Specific OH. scavengers such as benzoate or dimethylsulfoxide (DMSO) and the free radical trap such as alpha-phenyl N-tert-butyl nitrone (PBN) significantly inhibit gastric ulceration suggesting the role of OH. in this oxidative damage. Desferrioxamine (DFO), a nontoxic transition metal ion chelator, protects the mucosa against stress-ulceration dose dependently. Increased level of TBARS and the inactivation of gastric peroxidase are also prevented by DFO or by antioxidants such as glutathione or vitamin E, suggesting the critical role of metal ion and OH. in the oxidative damage. A metal-catalyzed OH. generating system constituted by Cu2+, H2O2 and ascorbate (reducing equivalent of O2-) causes inactivation of the purified gastric peroxidase in vitro, which can be effectively prevented by DFO. The stress-induced activation of the superoxide dismutase is completely blocked by pretreatment with alpha-amanitin indicating an increased synthesis of the enzyme by increased transcription of its m-RNA. Quantitative measurement indicates that stress causes a fivefold increase in the generation of OH., which correlates well with the increase in ulcer index with the progress of stress. The results indicate that the stress-induced gastric ulceration is a consequence of the oxidative damage of the gastric mucosa. This is caused by the OH. generated through the metal-catalyzed Haber-Weiss reaction between O2- and H2O2, the latter being formed by the stimulation of the superoxide dismutase and inactivation of the gastric peroxidase.

Tungstic acid reduction of cold-resistant stress-induced ulceration in rats

Sprague-Dawley rats were restrained at 4 degrees C for 2 h (stress). Tungstic acid in a single dose of 0.01, 0.1, 1, 10, 100 or 300 mg/kg (dissolved in distilled water) was administered intragastrically to animals 30 min prior to stress. Stress induced significant gastric mucosal damage, whereas tungstic acid pretreatment dose-dependently reduced lesion formation. Doses of tungstic acid of 1 mg/kg and higher significantly (P < 0.05-0.001) decreased ulcers. The mucosal mast cell counts in rats pretreated with tungstic acid were significantly higher than those of control rats. In motility experiments using oral administration of amberlite pellets, pretreatment with tungstic acid dose-dependently reduced the gastric emptying rate during a 1 h period of stress. Gastric mucosal xanthine oxidase and superoxide dismutase (SOD) activities, after pretreatment with a single dose of tungstic acid, were not altered in stressed animals. It is suggested that tungstic acid effectively antagonizes stress-induced gastric ulcers, possibly by decreasing motility and mass cell degranulation. Xanthine oxidase and SOD activities and mucous content were not changed in the gastric mucosa by the present method of tungstic acid administration.

Intracerebroventricular CRF inhibits cold restraint-induced c-fos expression in the dorsal motor nucleus of the vagus and gastric erosions in rats

Acute exposure to cold-restraint induces vagal-dependent gastric erosions associated with activation of neurons in the dorsal motor nucleus of the vagus (DMN) in rats. The influence of intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF) (10 micrograms) on c-fos expression in the brain and gastric erosions induced by 3 h cold-restraint was investigated in conscious rats. In cold-restraint exposed rats, CRF injected i.c.v. inhibited gastric erosions and the number of Fos positive neurons in the DMN by 93 and 72%, respectively, while Fos labelling in the nucleus tractus solitarius (NTS) was increased by 5-fold compared with vehicle group. c-fos expression was also induced in the central amygdala by i.c.v. CRF, unlike the vehicle-injected group exposed to cold-restraint. c-fos expression induced by cold-restraint in the raphe pallidus (Rpa) and paraventricular nucleus of the hypothalamus was not altered by i.c.v. CRF. These data indicate that central CRF-induced gastric protection results from the inhibition of DMN neuronal activity enhanced by cold-restraint. CRF action on DMN neurons may be related to the increase in the NTS and central amygdala inputs leading to inhibition of DMN neurons rather than to the decrease in the excitatory input from the caudal raphe projections to the DMN.

Endogenous zinc concentrations in cysteamine-induced duodenal ulcers in the rat

Exogenously administered zinc compounds have been shown to possess anti-ulcer activity against a wide variety of ulcerogenic agents, both in laboratory animal models and in human peptic ulcer disease. However, a strong possibility exists that endogenous zinc may also play an important role during noxious events by various mechanisms. Therefore, the aim of this study was to focus on the changes of endogenous zinc serum and tissue concentrations in cysteamine-induced duodenal lesions. We used atomic absorption spectrophotometry to determine the tissue and serum concentrations of zinc in normal (control) rats and those with cysteamine-induced duodenal ulcers. The results obtained in this study indicated that the onset, development and spontaneous healing of ulcer lesions were associated with certain shifts in zinc serum and tissue concentrations. Prior to ulcer formation, a significant increase was noted in serum zinc values. With the onset of duodenal lesions, zinc serum concentrations significantly decreased, while there was a significant increase in duodenal tissue concentrations when compared to healthy control animals. Zinc tissue concentrations decreased and returned to starting values by the end of the first week of spontaneous healing. This decrease in zinc tissue concentration corresponded to the healing rate of the duodenal ulcers. Serum zinc concentrations also returned to starting values within the first week period. These observations indicate and confirm that zinc could play an important role in duodenal ulcer disease and represent a natural defense system in the body.

The mechanistic pathway of gastric adaptive cytoprotection: a study on different components of the autonomic nervous system

1. The involvement of different components of the autonomic nervous system in the pathogenesis of ethanol-induced damage and the adaptive cytoprotection of mild irritants were studied in the gastric mucosa of male rats. 2. Capsaicin, yohimbine, and domperidone aggravated the 100% ethanol-induced gastric mucosal damage and attenuated the cytoprotective action of 20% ethanol, but not of 5% NaCl and 0.3 M HCl. Butoxamine and prazosin blocked the adverse actions of yohimbine and domperidone respectively. 3. Atropine, pirenzepine, and lidocaine lessened the severity of 100% ethanol-induced mucosal injury and further increased the cytoprotective action of 5% NaCl and 0.3 M HCl, but not of 20% ethanol. 4. Our results demonstrated that sensory afferent neurones, alpha 2-adrenoceptors and D2-dopaminergic receptors all play a significant role in the defensive mechanism of the gastric mucosa and the adaptive cytoprotection of 20% ethanol, while the M1- and M2-muscarinic receptors and sensory chemoreceptors on the gastric mucosa contribute only to the former action. The adverse effect of yohimbine and domperidone on lesion formation is probably mediated through the release of catecholamines, which subsequently act on the beta 2- and alpha 1-adrenoceptors respectively.

The role of the neurotransmitters acetylcholine and noradrenaline in the pathogenesis of stress ulcers

1. Adrenergic and cholinergic mechanisms seem to be involved in the pathogenesis of stress ulcers. 2. In this study, gastric ulcers were induced in rats by immobilization and cold. Prior intraperitoneal administration of both anticholinergic (atropine) as well as alpha-blocking medication (phenoxybenzamine) produced a very significant decrease in stress ulcers. 3. Additionally, using the technique of continuous intravenous perfusion in rats, acetylcholine was shown to have a gastric ulcerogenic effect, in contrast to noradrenaline. 4. It is concluded that acetylcholine is the peripheral mediator in stress ulcers, while noradrenaline intervenes at the encephalic level in stress ulcer pathogenesis.

Effect of stress on the antioxidant enzymes and gastric ulceration

The effect of cold-restraint stress on the antioxidant enzymes of the rat gastric mucosa was studied with a view to finding out their role in stress induced gastric ulceration. Histological examination revealed stress induced extensive damage of the surface epithelial cell with lesions extending up to submucosa in some cases. Stress causes time-dependent increase in histamine and pepsin content but decrease in acid content of the gastric fluid with the progress of ulceration (ulcer index) for two hours. The tissue lipid peroxidation was significantly increased as evidenced by accumulation of malondialdehyde. Since lipid peroxidation results from the generation of reactive oxygen species, stress effect was studied on some antioxidant enzymes such as superoxide dismutase, peroxidases and prostaglandin synthetase as a function of time. The time dependent increase in stress ulcer correlates well with the concomitant increase in superoxide dismutase activity and decrease in peroxidase and prostaglandin synthetase activity. This creates a favourable condition for accumulation of endogenous H2O2 and more reactive hydroxyl radical (OH.). Administration of antioxidants such as reduced glutathione or sodium benzoate prior to stress causes significant decrease in ulcer index and lipid peroxidation and protection of gastric peroxidase activity suggesting the involvement of reactive oxygen species in stress induced gastric ulceration. This is supported by the in vitro observation that OH. can also inactivate peroxidase and induce lipid peroxidation. As prostaglandin is known to offer cytoprotection, stress-induced loss of prostaglandin synthetase activity appears to aggravate the oxidative damage caused by reactive oxygen species.

Nitric oxide inhibition intensifies cold-restraint induced gastric ulcers in rats

Treatment 20 min beforehand with an inhibitor of nitric oxide (NO) synthesis NW-nitro-1-arginine methyl ester (L-NAME) (12.5, 25, 50 or 100 mg/kg, s.c.), dose-dependently intensified gastric glandular mucosal ulceration produced by cold-restraint stress. Hexamethonium (20 mg/kg) or atropine (1 mg/kg) pretreatment s.c. 20 min before stress strongly antagonised stress-evoked ulceration, as well as the ulcer-potentiating effects of L-NAME when either cholinoceptor antagonist was given concurrently with the NO inhibitor. Stress-induced mast cell degranulation was not worsened by L-NAME pretreatment. The findings suggest that NO could confer partial protection against stress-induced gastric ulcer formation; its activity is triggered off by the ulcerogenic mechanism of stress.

Site-specific formation of gastric ulcers by the electric stimulation of the left or right gastric branch of the vagus nerve in the rat

The present study was conducted to investigate the role of the parasympathetic nervous system innervating the stomach in gastric ulcer formation, with special reference to its neuroanatomic characteristics in rats. First, the effects of electric vagal stimulation on the gastric mucosa were examined. The electric stimulation of the left or right gastric branch of the vagus nerve caused gastric mucosal lesions to develop. Interestingly, however, gastric lesions were found on the anterior wall in the rats that had received electric stimulation to the left gastric branch of the vagus nerve and on the posterior wall in the rats that had received stimulation to the right gastric branch. Next, the cells of origin projecting to the left or right gastric branch of the vagus nerve were identified by means of a horseradish peroxidase retrograde tracer method. The left and right gastric branches were found to be innervated by the left and right dorsal motor nuclei of the vagus nerve in the medulla oblongata, respectively. It has been reported that the left and right dorsal motor nuclei of the vagus nerve separately innervate the anterior or posterior gastric wall. The present results, therefore, suggest that the long-lasting excitation of neurons in the dorsal motor nucleus facilitates the site-specific formation of gastric ulcers through the left or right gastric branch of the vagus nerve.

The antiulcer effect of verapamil in relation to gastric calcium levels in stressed rats

The antiulcer effect of verapamil, and its relationship to stomach calcium levels, were examined in rats restrained at 4 degrees C (stress). Stress for 2 hr significantly increased muscle calcium and induced mucosal ulceration in the gastric glandular segment; calcium concentrations in the glandular mucosa and serum were unaffected. Verapamil or calcium gluconate given 30 min before stress prevented the rise in gastric muscle calcium, and attenuated ulcer severity. Bis(beta-aminoethylether)-NNN'N'-tetra-acetic acid (EGTA) pretreatment, however, further elevated stomach muscle calcium and markedly worsened lesion formation. These findings suggest that increased stomach muscle calcium could be a causal factor in stress-induced gastric glandular ulceration.

Gastric lesions induced by kainic acid injection into the dorsal motor nucleus of the vagus nerve in rats

Kainic acid injection into the dorsal motor nucleus of the vagus nerve (DMN) induced lesions in the glandular stomach of rats. A decrease in mucus production seemed to play an important role in the pathogenesis of the kainic acid-induced gastric lesions. On the other hand, by means of horseradish peroxidase tracing method, the original cells projecting to the DMN were identified in the central nucleus of the amygdala, several hypothalamic nuclei and the insular cortex. Considering that kainic acid is a long-acting neuronal excitant, it was suggested that the continual stimulation of DMN neurons facilitated gastric ulcer formation.

Gastric motility is stimulated but overall blood flow is unaffected during cold restraint in the rat

The relationship between cold restraint-induced lesion formation, gastric motility, and gastric mucosal blood flow was studied in rats. Both anesthetized and unanesthetized animals placed in cold restraint developed gastric mucosal lesions. Gastric (corpus) motility was measured using extraluminal force transducers. Animals placed in cold restraint developed persistent, high amplitude, prolonged duration contractions. Those rats in which such contractions lasted greater than 1 h developed gastric mucosal lesions, whereas those animals in which such contractions lasted less than or equal to 1 h had no lesions. Overall gastric mucosal blood flow was measured using the hydrogen gas clearance technique. There was no significant change in overall gastric mucosal blood flow measured after 1, 2, and 3 h of cold restraint. We conclude that (a) the physical effect of cold water immersion is by itself sufficient to cause cold "restraint" lesions and (b) such lesions are associated with high amplitude, prolonged duration contractions lasting greater than 1 h.

The influence of chronic or acute nicotine pretreatment on ethanol-induced gastric ulceration in the rat

The effects in rats of chronic or acute nicotine pretreatment were studied on three gastric parameters: ethanol-induced ulceration, gastric wall mucus content and gastric acid secretion, under basal or histamine-stimulated conditions. Oral administration of ethanol (40%, 10 ml kg-1) depleted gastric wall mucus and produced ulceration in the gastric glandular mucosa. Ten-day nicotine pretreatment (15 or 25 micrograms ml-1 drinking water) worsened the adverse effects of ethanol on mucosal ulceration and mucus content, potentiated the gastric secretory action of histamine, but did not affect basal acid secretion. Single oral doses of nicotine (2 or 4 mg kg-1, given 1 h beforehand) prevented ulceration and mucus depletion in ethanol-treated animals; however, they did not influence either basal or histamine-stimulated gastric acid output. It is concluded that chronic nicotine administration aggravates ethanol ulceration, possibly by decreasing gastric wall mucus content and sensitizing the stomach to the acid secretory action of histamine. On the other hand, an acute oral dose of nicotine preserves the mucus content and prevents ethanol-induced ulcer formation.

The influence of verapamil on the gastric effects of stress in rats

The influence of verapamil on stress- or bethanechol-induced gastric effects was investigated in rats. Intraperitoneally injected verapamil (1, 2 or 4 mg/kg), given 30 min beforehand, dose-dependently prevented gastric glandular ulceration, mast cell degranulation and the increased stomach wall contractions evoked by restraint at 4 degrees C for 1 h. Gastric acid secretion, as well as ulceration in both the forestomach and glandular segment, produced by subcutaneously-injected bethanechol (3.2 mg/kg) were also inhibited. It is concluded that decreased amine release from the mast cells, stomach wall relaxation and reduced gastric acid were responsible for the ulcer-antagonising effects of the calcium-entry blocker. The possible antiulcer actions of verapamil are discussed in the light of present knowledge regarding calcium involvement in the various mechanisms thought to contribute to the pathophysiology of stress ulceration in rat stomachs.

The aetiology of gastric ulceration induced by electrical vagal stimulation in rats

Histamine and serotonin levels in gastric secretion and the effects of pharmacological antagonists were studied in rats in which stomach ulceration was induced by electrical vagal stimulation. Electrical vagal stimulation (2 and 5 V) produced a graded increase in haemorrhagic glandular mucosal ulcers. NaHCO3 perfusion completely neutralised the increased acid output but failed to prevent ulceration. Atropine inhibited gastric mast cell degranulation as well as histamine and serotonin release. Diphenhydramine, atropine and sub-diaphragmatic vagotomy antagonised the increase in intragastric pressure. Diphenhydramine, cimetidine, atropine or vagotomy but not methysergide reduced ulcer severity. It is concluded that gastric acid and serotonin do not play an important role in glandular ulceration induced by electrical vagal stimulation. The lesions probably result from increased intragastric pressure and release of gastric histamine which stimulates H1 and H2 receptors in the stomach. The similarities between the aetiologies of glandular ulcers due to electrical vagal stimulation and to stress are also discussed.

The lack of effects of somatostatin on gastric responses induced by electrical vagal stimulation

The effects of somatostatin on ulcer formation, gastric acid secretion and histamine release were assessed during vagus nerve stimulation in rats. Direct electrical vagal stimulation significantly increased histamine release and acid output in gastric secretion but decreased mast cell counts in gastric glandular mucosa. Hemorrhagic ulceration on the gastric glandular mucosa was also observed. Somatostatin pretreatment (10 micrograms/kg) did not inhibit gastric ulcer formation, gastric acid secretion or histamine release induced by vagal stimulation. Cimetidine (an H2 blocker) pretreatment, however, significantly decreased gastric acid secretion as well as ulcer formation. The present study indicates the direct vagal stimulation increases gastric acid secretion and ulcer formation. These effects are partially histamine dependent. Somatostatin did not inhibit histamine release induced by vagal stimulation and reflects the inability of the drug to prevent ulcer formation and gastric output under these conditions in rats. However, the inhibition of basal gastric acid secretion produced by somatostatin might be useful clinically in humans.

Gastric antral ulcers produced by the combined administration of indomethacin with 2-deoxy-D-glucose in the rat

The influence of 2-deoxy-D-glucose (2DG) on indomethacin ulcers was studied in rats. 2DG (200 mg/kg i.v.) produced large round ulcers in the lesser curvature of the antrum and aggravated lesions of the corpus 6 h after treatments in indomethacin (40 mg/kg i.p.)-treated rats. Insulin (5 units/kg i.v.) also produced gastric antral ulcers similarly to 2DG. Antral ulcers were revealed rather clearly 48 h after the administration of indomethacin and 2DG when the corpus lesion index was reduced. 2DG or insulin had only a slight influence on the severity of other experimental gastric ulcers. Peripheral gastric secretagogues, bethanechol (1 mg/kg s.c. X 2) or histamine (10 mg/kg s.c. X 2) did not produce antral ulcers at the gastric secretory dose in the indomethacin-treated rats. High doses of atropine (1.0 and 10 mg/kg s.c.) prevented gastric antral ulcers. The combined administration of indomethacin with 2DG produced gastric antral ulcers similar to human gastric ulcers in rats. The combination of gastric acid secretion, vagus nerve stimulation and some other factors may be involved in gastric antral ulcers produced in rats.

Circadian variation in the distribution of Hymenolepis diminuta (Cestoda) and 5-hydroxytryptamine levels in the gastro-intestinal tract of the laboratory rat

The circadian migration of Hymenolepis diminuta in the small intestine of the rat may be correlated with a circadian variation in 5-hydroxytryptamine levels present in worm tissue, in the intestinal lumen, in the intestinal mucosa, with the amount of fold present in the small intestine and in arterial blood. 5-HT and food levels in uninfected animals were also determined. The 16.00 h stage in the circadian cycle marks both the commencement of host feeding, followed by rising 5-HT levels in both worm and host tissues, and initiation of an anteriad migration of worm biomass. It was found that 5-HT levels in the intestine of parasitized animals were significantly higher than in the intestine of uninfected controls. This is the first report of circadian variation in mucosal and luminal 5-HT levels. The similarity in the circadian patterns of worm migration and worm luminal, mucosal and blood 5-HT levels were striking. Fasting eliminated the circadian rise in intestinal 5-HT levels and the worms did not migrate. Luminal 5-HT levels were significantly lower in fasted animals than in the comparable rats fed ad libitum. When the intestine was ligatured at the pyloric sphincter, worm anteriad migration still occurred after feeding, indicating that the presence of exogenous food in the intestine is not a factor in the initial migration of the worms.

The influence of cimetidine, a histamine H2-receptor antagonist, on the gastric effects of reserpine in rats

The effects of graded doses of cimetidine on both resting and reserpine-evoked gastric acid secretion were examined in relation to their influence on reserpine-induced ulceration, mast cell degranulation and mucosal microcirculatory changes in rat stomachs. Cimetidine 10 mg/kg or above reduced resting or reserpine-provoked gastric acid secretion as well as rumenal and glandular ulceration. However, non-acid-inhibiting doses, 5 mg/kg or below, continued to prevent glandular ulceration. Reserpine-evoked gastric glandular mucosal mast cell degranulation was unaffected by both acid-inhibiting and non-acid-inhibiting doses of cimetidine which dose-dependently blocked the superficial glandular mucosal microcirculatory volume changes. These results suggest that cimetidine prevents reserpine-induced glandular ulceration largely by blocking the ulcerogenic effect of histamine H2-receptor-mediated mucosal microcirculatory congestion, in contrast to antagonising rumenal lesions through acid inhibition; they also support the idea tha reserpine may release histamine mainly from the glandular mucosal mast cells. The possibility of another antiulcer mechanism, due to cytoprotection, is discussed.

Effects of water-immersion stress on gastric secretion and mucosal blood flow in rats

The correlation between acid secretion and mucosal blood flow in the rat stomach during stress loading was determined to provide clues to the etiology of the gastric ulceration which thus occurs. The gastric acid output was increased remarkably by water-immersion stress at 23 degrees C, and this increase lasted while the stress was given, yet the mucosal blood flow did not show a corresponding increase. In rats stressed for 3 hr, ulcerative changes were observed in the glandular portion of the stomach. The stress-induced increase in acid output correlated well with the severity of erosions. Pretreatment of animals with atropine 10 microgram/kg, given subcutaneously, or vagotomy, inhibited the increase in acid output and also inhibited the ulcer formation caused by the stress: however, the mucosal blood flow in these animals decreased significantly. These results suggest that when there is an elevation of gastric acid secretion with no parallel increase in mucosal blood flow, gastric ulceration may occur under conditions of stress.

Cholinergic-mediated gastric mast cell degranulation with subsequent histamine H1-and H2-receptor activation in stress ulceration in rats

The effects of atropine, mepyramine, metiamide or NaHCO3 on gastric ulceration, gastric secretion and gastric mast cell degranulation were studied in stressed pylorus-occluded rats. The influence of dexamethasone pretreatment on stress ulcers in animals without pylorus occlusion (intact rats) was also examined. Stress produced a high glandular lesion incidence and ulcer index, and markedly lowered gastric secretion and glandular wall mast cell counts. Injected 0.5 h before stress, atropine, mepyramine or metiamide strongly antagonised ulceration. Atropine or metiamide, but not mepyramine, reduced gastric secretion. Only atropine prevented stress-induced mast cell changes. NaHCO3, given intragastrically before stress, did not prevent ulceration or mast cell degranulation despite complete neutralisation of gastric acid. Dexamethasone-induced gastric mucosal mast cell depletion could reduce stress ulceration. The findings show that stress degranulates stomach mast cells via a cholinergic pathway; released histamine from this source is largely responsbile for gastric ulceration through H1- and H2-receptor effects. Histamine H2-receptor-mediated gastric acid may play only a small contributory role in stress ulcers in rats. The antiulcer mechanisms of histamine H1- and H2-receptor blockade are discussed.

Role of gastric motility in development of stress-induced gastric lesions of rats

Gastric motility of stressed rats was studied to determine its role in producing stress-induced gastric lesions. Restraint and water immersion resulted in an increase in gastric motility which consisted of an increase in frequency and amplitude of contractions and a rise in gastric tone. This increase reached maximal levels 2 to 4 hr after stress, and persisted thereafter. Formation of gastric lesions was markedly accelerated after occurrence of the increased gastric motility. In contrast, restraint alone neither produced such a vigorous increase in gastric motility, nor were the gastric lesions severe. A continuous infusion of papaverine during restraint and water immersion inhibited increase in frequency and amplitude of gastric contractions and prevented formation of gastric lesions. It is concluded that increased gastric motility is closely associated with marked formation of gastric lesions under conditions of restraint and water immersion stress and is probably a main cause for their vigorous formation, although formation of lesions occurs to a small degree without involvement of gastric motility.

Effects of cimetidine, a histamine H2-receptor antagonist, on various experimental gastric and duodenal ulcers

The effects of cimetidine, a new histamine H2-receptor antagonist, on the development of experimental gastric and duodenal ulcers were studied. It was found that either by the oral, intraduodenal, or intraperitoneal route this agent had a marked inhibitory activity on stress-, aspirin-, indomethacin-, or histamine-induced gastric ulcers in rats and guinea pigs. The effects of cimetidine on stress-, aspirin-, and indomethacin-induced gastric ulcers were dose-dependent in many cases. Pylorus-ligation uclers, reserpine- or serotonin-induced gastric ulcers were little influenced by cimetidine. Duodenal ulcers induced by continuous infusion of carbachol-histamine were significantly inhibited by a simultaneous infusion of cimetidine. An analysis of gastric contents in pylorus-ligated rats after stressing indicated a decreased volume and acid output as the result of intraduodenal cimetidine treatment. In contrast, cimetidine exerted little influence on gastric secretion in rats treated with aspirin or in guinea pigs treated with histamine. Thus, the mechanism of action of cimetidine in preventing gastric or duodenal ulcers is likely to occur by suppression of gastric secretory function in a duodenal ulcer model but by suppression of other unknown ulcerogenic factors in gastric ulcer models.

The effects of zinc sulphate on vagal-induced mast cell changes and ulcers in the rat stomach

The effects of zinc sulphate pretreatment on the formation of gastric ulcers, changes in intragastric pressure and changes in the gastric mucosal mast cell count induced by electrical vagal stimulation were studied in anaesthetized rats. Vagal stimulation produced a high gastric glandular ulcer incidence and ulcer index, increased the intragastric pressure, and reduced the number of granulated mast cells in the gastric mucosa and submucosa. Pretreatment with zinc sulphate (22, 44 ot 88 mg/kg), injected i.p. 48 h beforehand, reversed the changes in these parameters in a dose-related manner. These observations suggest that the inhibitory effects of zinc sulphate on mucosal mast cell degranulation may account for its ability to antagonise vagal-induced gastric glandular ulceration. The mechanisms involved in the aetiology of this type of gastric ulcer are discussed in the light of these results.

Effects of zinc chloride on gastric secretion and ulcer formation in pylorus-occluded rats

The effects of 10-day pretreatment with i.p. injections of zinc chloride, 16 mg/kg, on gastric secretion and on gastric ulceration induced by stress or by acid accumulation were examined in pylorus-occluded rats. Zinc chloride pretreatment significantly reduced the volume of gastric secretion and the total acid output as well as the incidence of gastric ulcers induced either by stress or by acid accumulation. The findings support the idea zinc compounds may be useful in the treatment of gastric ulcers.

Intragastric NaHCO3 perfusion and vagal-induced ulcer formation in the rat stomach

The effects of electrical vagal stimulation on gastric acid output and ulcer formation were studied in rats intragastrically perfused with saline or NaHCO3 solutions. Vagal stimulation produced a 100% incidence of glandular lesions and a significant increase in total acid output in saline-perfused stomachs. Antacid perfusion failed to prevent ulcer formation despite complete neutralization of the increased acid output. It is considered that vagal-induced gastric glandular lesions are not acid dependent.