B. Bódis

Modification of aspirin and ethanol-induced mucosal damage in rats by intragastric application of resiniferatoxin

The capsaicin analogue ‘resiniferatoxin’ (RTX) was used to investigate the role of capsaicin-sensitive sensory nerves in gastric mucosal injury caused by intragastric (ig) acidified aspirin (200 mg/kg in 2 ml of 0.15 N HCl) or ethanol (2 ml of 50% v/v or 96%) in pylorus-ligated rats. Animals were sacrificed 1, 2 and 4 h later, when gastric secretory responses, number and severity of mucosal lesions were calculated. Intragastric RTX (0.6–1.8 µg/kg) prevented mucosal injury in a dose-dependent manner induced by topical acidified aspirin. The protective effect lasted for 1h and was accompanied by inhibition of gastric acid secretion by RTX. RTX (0.6 and 1.0 µg/kg) co-administered with ethanol reduced mucosal injury caused by 50% ethanol; the protective effect of RTX being more apparent when the drug was given 15 min prior to 50% ethanol. Unexpectedly, RTX co-administered with absolute ethanol aggravated the ethanol-induced mucosal damage. It is concluded that capsaicin-sensitive sensory nerves mediated microcirculatory changes in gastroprotection and these involve inhibition of gastric acid secretion.

Stimulation of capsaicin-sensitive sensory peripheral nerves with topically applied resiniferatoxin decreases salicylate-induced gastric H+ back-diffusion in the rat

Capsaicin-sensitive sensory nerves (CSSN) exert local protective functions in the stomach and have been proposed to regulate gastric H+ back-diffusion. The present study aimed to evaluate the possible influence of stimulation of CSSN with the intragastrically (ig) applied capsaicin analogue, resiniferatoxin (RTX), on gastric H+ back-diffusion and mucosal injury caused by ig application of HCl (2 ml 0.15 mol/L) or acidified salicylate (200 mg/kg in 2 ml 0.15 mol/L HCl) after 1 or 2 h in the pylorus-ligated rat. Stimulation of CSSN with a low concentration (0.04 µg/ml) of RTX markedly decreased H+ back-diffusion caused by acidified salicylate. After acute bilateral truncal vagotomy or treatment with atropine sulphate, RTX did not inhibit gastric acid back-diffusion. Surgical vagotomy alone increased, while RTX or atropine markedly diminished, the development of gastric mucosal injury in these models. In saline-treated rats, RTX significantly reduced gastric secretory volume and acid output. The inhibitory effect lasted for 1 h. These data suggest an essential role for CSSN in regulation of gastric acid secretion and in maintaining the integrity of the gastric mucosa that appear to depend on intact vagal nerves.

Direct cellular effects of some mediators, hormones and growth factor-like agents on denervated (isolated) rat gastric mucosal cells

The brain-gut axis has an important role in the mechanism of gastric cytoprotection in vivo. The aim of this study was to evaluate the in vitro effect of protective agents without any central and peripheral innervation. A mixed population of rat gastric mucosal cells was isolated by the method of Nagy et al (Gastroenterology (1994) 77, 433-443). Cells were incubated for 60 min with cytoprotective drugs such as prostacyclin, histamine, pentagastrin and PL-10 substances (synthesized parts of BPC). At the end of this incubation cells were treated by 15% ethanol for 5 min. Cell viability was tested by trypan blue exclusion test and succinic dehydrogenase activity. The following results were obtained: 1) prostacyclin, histamine and pentagastrin had no direct cytoprotective effect on isolated cells; and 2) PL-10 substances significantly protected the cells against ethanol-induced cellular damage. This led to the following conclusions: 1) in the phenomenon of gastric cytoprotection only the growth factor-like agents have a direct cellular effect; and 2) the intact peripheral innervation is basically necessary for the development of mediators and hormone-induced gastric cytoprotection.

Active water selective channels in the stomach: investigation of aquaporins after ethanol and capsaicin treatment in rats.

UNLABELLED Recent studies discovered the existence of aquaporins (AQP), suggesting their roles in the active, ATP dependent water secretion or absorption. Our recent development of the monoclonal antibody family against aquaporins (Type 1 and 4) allowed us a good opportunity to investigate the mechanism of the gastric mucosal edema in a rat model. THE AIM OF OUR STUDY was to evaluate the changes in the tissue level of aquaporins (AQP1 and AQP4) after ethanol and capsaicin treatment in rat stomach. MATERIALS AND METHODS the experiments were carried out on Sprague-Dawley rats weighing 150-200 g. The animals were fasted for 24 h, after the 1 ml of ethanol (50% v/v) or capsaicin (2 mg/ml) was given intragastrically. Rats were sacrificed after 5, 30, 60, 120 and 240 min, the tissue level of AQP1 and AQP4 was investigated immunoserologically by ELISA and dot-blot methods using our monoclonal antibodies. The location of these aquaporins in the gastric tissue was demonstrated by immunohistochemistry. RESULTS (1) in ethanol-treated stomach, both AQP1 and AQP4 increased after 5 min simultaneously with gastritis, then decreased dramatically depending on time. (2) In the capsaicin-treated group there were no changes in the tissue level of aquaporins in the first hour. After 60 min both AQP1 and AQP4 increased in the stomach without any macroscopically detectable changes, then decreased depending on time. (3) The immunohistochemical investigations using our monoclonal antibodies seem to support our present quantitative results. CONCLUSION chemically induced gastric mucosal lesions are started by an extended edema. In the induction of the edema and the subsequent gastric injury, aquaporins (both AQP1 and AQP4) play an important role in the maintenance of mucosal integrity.

Gastrin and pentagastrin enhance the tumour proliferation of human stable cultured gastric adenocarcinoma cells.

The effect of gastrin on stimulating tumour proliferation has been evaluated on human pancreas cancer cells in culture and in tumours transplanted to nude mice. The presence of CCK-B/gastrin-like receptor responsible for that effect of gastrin has been proved in colonic (WiDr, HT-29, YAMC) and pancreatic (PANC-1, BON) cell lines. The aim of our study was to examine the stimulating effect of gastrin and pentagastrin on the growth of human gastric adenocarcinoma cell line. The human gastric adenocarcinoma cell line (AGS, CRL-1739) was purchased from ATCC (Rockville, MA, USA). Gastrin-17 was purchased from Sigma-Aldrich (Budapest, Hungary), pentagastrin was from Zeneca Limited (Macclasfield, UK). The cells were incubated in DMEM containing 10% FCS on 96-well culturing plate with 10(4) cells/well starting cell number at 37 degrees C with 5% CO2. The proliferation rates were detected: by the measurements of the metabolically active cells with Owens reagent and the determination of protein content, and by cell counting in a haemocytometer at several incubation times. As a result, we detected similar proliferation rates using gastrin-17 or pentagastrin in the incubation medium. The stimulating effect of gastrin/pentagastrin on cell line proliferation was in correlation with its concentration. Our results proved that pentagastrin is a 10 times less effective stimulator of proliferation of gastric cancer than gastrin-17, and that AGS human adenocarcinoma cell line might be CCK receptor positive.

Surgical vagotomy enhances the Indomethacin-Induced gastrointestinal mucosal damage in rats

Karádi O, Bódis B, Király Á, Abdel-Salam OME, Sütō G, Vincze Á, Mózsik Gy. Surgical vagotomy enhances the indomethacin-induced gastrointestinal mucosal damage in rats. Inflammopharmacology. 1994;2:389-399.Indomethacin (IND)-induced gastrointestinal mucosal lesions and changes of vascular permeability were studied in rats with and without acute bilateral surgical vagotomy.The aims of study were (a) to compare IND-induced mucosal lesions in the stomach, small intestine and large bowel of rats with intact vagus and acute surgical vagotomy and (b) to evaluate the changes of vascular permeability following these treatments.The gastrointestinal (GI) mucosal damage was produced by IND (20 mg/kg s.c.) at 24 and 48 h after IND administration. Sham operation (laparotomy alone) or surgical vagotomy alone was carried out in control animals. The number and severity of GI mucosal damage was determined. The changes of mucosal vascular permeability were determined by Evans Blue assays in the GI mucosa and in the contents of stomach, small intestine and colon. Evans Blue was given into the tail vein at 15 min before the killing of animals.It was found that (a) no ulceration and change in mucosal vascular permeability was found in any parts of GI tract after sham operation or surgical vagotomy (without IND); (b) IND caused mucosal injury coincidental with vascular permeability in the stomach and small intestine, but not in the large bowel; (c) surgical vagotomy aggravated the IND-induced mucosal damage and increased vascular permeability in the stomach and small intestine, but not in the colon. In conclusion, the intact vagal nerve is required for the prevention of gastric and small intestinal mucosa to protect against IND injury.

Atropine-induced gastrointestinal cytoprotection dependences to the intact of vagal nerve against indomethacin-induced gastrointestinal mucosal and microvascular damage in rats.

UNLABELLED The non-steroidal antiinflammatory drugs, such as an indomethacin (IND), cause mucosal ulceration and increase the mucosal vascular permeability in the gastrointestinal (GI) tract. Some exogenous agents, e.g. the atropine, can protect the GI mucosa against these ulcerogenic effects. The gastrointestinal functions and mucosal protection, however, are regulated by the vagal nerve. The aims of this study was to examine the dependence of atropine-induced GI cytoprotection to the vagal innervation against the development of IND-caused ulcers and microvascular damage in the mucosa of stomach and small intestine in rats. METHODS the observations were carried out on CFY-strain rats. The mucosal damage was produced by subcutaneous administration of IND in a 20 mg/kg dose 24 h prior to the killing of animals at the same time as the start of atropine-application, which was given in a small dose (0.1 mg/kg) every 5 h. The subdiaphragmatic bilateral surgical vagotomy was done 24 h before the experiment. The vascular permeability, indicated by the microvascular endothel damage, was measured by the appearance and concentration of intravenously administered Evans blue into the GI mucosa. The number and severity of mucosal lesions and the Evans blue content of mucosa were determined in the stomach and small intestine. RESULTS (1) The IND caused mucosal ulcers and Evans blue extravasation into the mucosa of the stomach and small intestine. (2) The IND-induced mucosal ulceration and vascular permeability significantly decreased after atropine-administration in the same parts of GI tract. (3) The extent of cytoprotective effect of atropine against the IND was decreased after bilateral surgical vagotomy. CONCLUSIONS (1) The IND causes microvascular endothel damage in the stomach and small intestinal. (2) The atropine has a cytoprotective effect in the stomach and small intestine against the aggressive effects of IND without decrease of gastric acid secretion. (3) The intact vagal nerve is necessary to the function of cytoprotective mechanisms of atropine against the IND.

Evidence for direct cellular protective effect of PL-10 substances (synthesized parts of body protection compound, BPC) and their specificity to gastric mucosal cells

The direct gastric mucosal cellular effect of four PL-10 substances (a synthesized part of human body protection compound, BPC containing 14 or 15 amino acids) was studied on freshly isolated rat gastric mucosal cells and on a mouse myeloma cell line (Sp2/0-Ag14) in an ethanol-induced cell injury model. The examined substances were not toxic for the cells. Two of them proved to be significantly protective against the direct cellular damaging effect of ethanol (PL 10.1.15AK-3 in 5 microg/ml dose and PL 10.1.AK14-2 dose-dependently, ED50=50 ng/ml) on gastric mucosal cells. This cytoprotective effect was failured on mouse myeloma cells. Based on these results a part of the in vivo protection induced by BPC seems to be a direct cellular protective effect to gastric mucosal cells.

Role of the Vagal Nerve in the Development of Gastric Mucosal Injury and its Prevention by Atropine, Cimetidine, β-Carotene and Prostacyclin in Rats

Peptic ulceration including acute erosions is a multifactorial disease involving well-known factors such as trauma, stress, sepsis, hemorrhagic shock, burns, pulmonary and liver diseases1–9 and drugs such as reserpine10, epinephrine11–13, nonsteroidal antiinflammatory drugs7, steroids and other chemicals14.

Role of Vagal Nerve in Defence Mechanisms against NSAID-Induced Gastrointestinal Mucosal Damage

Many papers suggested only an aggressive role of the vagus nerve on the gastrointestinal (GI) mucosa; however, the essential role of the vagus nerve was proven in GI mucosal defence against different chemicals, e.g., ethanol, HCl, non-steroidal anti-inflammatory drugs (NSAIDs). In order to evaluate the role of the vagus nerve in the development of GI mucosal damage evoked in the rat by the administration of NSAIDs, the present studies were designed to: (1) compare the changes in the NSAID-induced GI mucosal damage after acute surgical and chemical (atropine treatment) vagotomy; (2) investigate the effect of sensory nerve stimulation and chemical deafferentation on the NSAID-induced gastric mucosal damage; (3) evaluate the cytoprotective action of prostacyclin under the above experimental conditions; (4) study the effect of surgical vagotomy on the gastroprotection induced by different drugs.Gastric mucosal damage was produced by intragastrically (acidified salicylates) or systemically (indomethacin) applied NSAIDs, while the small intestinal and large bowel mucosal injury was produced by systemic indomethacin application.Results(1) acute surgical vagotomy aggravated, whereas, chemical vagotomy prevented the GI mucosal damage produced by topically and systemically applied NSAIDs; (2) indomethacin produced significantly more damage in the small intestine than in the large bowel and stomach (order is small intestine > stomach > proximal colon) which is aggravated by acute surgical vagotomy in all these areas of the GI tract; (3) stimulation of capsaicin-sensitive sensory nerves with the capsaicin analogue resiniferatoxin protected against gastric mucosal damage by acidified salicylates and indomethacin; (4) chemical deafferentation enhanced the aspirin-induced gastric mucosal injury, while it did not interfere with the prostacyclin-induced gastric cytoprotection; (5) the mucosal protective effects of PGI2, atropine, cimetidine, sucralfate and scavengers (β-carotene) disappeared after acute surgical vagotomy.