Antibody response against gastrointestinal antigens in demyelinating diseases of the central nervous system.

BACKGROUND: Antibodies against gastrointestinal antigens may indicate altered microbiota and immune responses in the gut. Recent experimental data suggest a connection between gastrointestinal immune responses and CNS autoimmunity. METHODS: Antibodies against gliadin, tissue transglutaminase (tTG), intrinsic factor (IF), parietal cells (PC) and Saccharomyces cerevisiae (ASCA) were screened in the sera of 45 patients with AQP4-seropositive neuromyelitis optica (NMO) and NMO spectrum diseases (NMO/NMO-SD), 17 patients with AQP4-seronegative NMO, 85 patients with clinically definite multiple sclerosis (MS), and 48 healthy controls (HC). RESULTS: Thirty-seven percentages of patients with AQP4-seropositive NMO/NMO-SD and 28% of patients with MS had at least one particular antibody in contrast to 8% of HC (P < 0.01, respectively). Antibodies were most common (46%) in AQP4-seropositive myelitis (P = 0.01 versus HS, P = 0.05 versus MS). Anti-gliadin and ASCA were more frequent in the AQP4-seropositive NMO-spectrum compared to controls (P = 0.01 and P < 0.05, respectively). CONCLUSION: Antibody responses against gastrointestinal antigens are common in MS and AQP4-seropositive NMO/NMO-SD, especially in longitudinally extensive myelitis.

Survey of Raynaud's phenomenon and systemic sclerosis based on a representative study of 10,000 south-Transdanubian Hungarian inhabitants.

OBJECTIVES: To assess the prevalence of Raynaud's phenomenon (RP) and of RP associated systemic sclerosis (SSc) in a large regional representative study. METHODS: Ten thousand individuals aged between 14-65 years participated in face-to-face interviews. The stratified sample of the South-West Hungarian population was representative for age, sex and urban or rural residence. Individuals reporting complaints suggesting the presence of "clinically significant" RP were asked to undergo a clinical investigation. Patients showing complaints provoked by taking something out of the freezer (-20 degrees C) compartment of the refrigerator and/or whether they had experienced digital ulcers were sorted into this category. RESULTS: The overall prevalence of RP was at least 578.9/10,000, and the prevalence of "clinically significant" RP could be calculated as at least 87.7/10,000 inhabitants. In this latter group 17.2% of the cases had either established SSc or anticentromere antibody or scleroderma capillary pattern on nailfold capillaroscopy. SSc with "clinically significant" RP and/or ulcers was identified in a prevalence of 9.1/10.000 individuals, whilst there was a prevalence of 14.7/10,000 of RP with either anticentromere antibody or scleroderma capillary pattern. CONCLUSIONS: "Clinically significant" RP affects almost 1% of the population. We identified cases with early stages of scleroderma spectrum disorder showing either anticentromere autoantibody or scleroderma capillary pattern. The prevalence of SSc was found to be higher than expected. It is reasonable to screen "clinically significant" RP cases for scleroderma-related symptoms because this approach makes it possible to identify patients with both SSc and early scleroderma related symptoms.

Otilonium bromide enhances sensory thresholds of volume and pressure in patients with irritable bowel syndrome.

UNLABELLED: Visceral hyperalgesia has been suggested to play a role in the development of symptoms presented by irritable bowel syndrome patients. Otilonium bromide was developed to block smooth muscle Ca release to control cramping pain of these patients. AIMS: to determine whether otilonium bromide can influence sensory thresholds of patients suffering from irritable bowel syndrome. METHODS: 15 patients with Rome-II positive IBS were tested by Synectics Visceral Stimulator Barostat using rapid phasic distension (870 ml/min). The sensory threshold for first sensation, stool, pain and maximum tolerable volume and pressure were measured. All of the parameters were tested before and 1 week after the initiation of otilonium bromide (Spasmomen, Berlin Chemie, 3x40 mg) therapy. RESULTS: The perceptual thresholds for first sensation, stool, pain and maximum tolerable distention were, 8.8+/-1.7 Hgmm, 19.2+/-2.1 Hgmm, 26.3+/-2.8 Hgmm, 28.7+/-2.8 Hgmm for pressure, 90+/-21 ml, 145+/-28 ml, 208+/-25 ml, 213+/-28 ml for volume, before treatment, respectively. Otilonium bromide treatment did not influence the thresholds for first sensation and stool, 7.4+/-1.4 Hgmm, 20.7+/-4.6 Hgmm and 83+/-21 ml, 178+/-35.8 ml, respectively. The pressure threshold of pain was significantly higher 1 week after treatment (26.3+/-2.8 Hgmm vs. 29.1+/-5.5 Hgmm, P<0.05), but the volume threshold of this sensation remained unchanged (208+/-25 ml vs. 234+/-39 ml, not significant). The pressure (28.7+/-2.8 Hgmm vs. 38.1+/-3.4 Hgmm, P<0.05) and volume (213+/-28 ml vs. 278+/-27 ml, P<0.05) thresholds for maximum tolerable volume were increased by 7 days otilonium bromide treatment. CONCLUSION: These data suggest that otilonium bromide enhances sensory thresholds to recto-sigmoideal distention.

Failure of capsaicin-containing red pepper sauce suspension to induce esophageal motility response in patients with Barrett's esophagus.

UNLABELLED: The physiologic importance of afferent sensory pathways in the esophageal motor functions has been recently recognised. Capsaicin-sensitive sensory afferents were shown to play a role in the maintenance of mucosal integrity of the GI tract, and regulation of human esophageal motility. The aim of this study was to investigate the effect of topical application of capsaicin-containing red pepper sauce (Tabasco, 25%v/v, pH:7.0) suspension on the phasic activity of the human esophagus of healthy volunteers and patients with Barrett's esophagus. METHODS: The diagnosis of Barrett's esophagus was based on the findings of esophagoscopy and histology taken from the squamocolumnar junction of the esophagus. Esophageal motility was measured by perfusion manometry before and after application of red pepper sauce. RESULTS: Capsaicin containing red pepper sauce increases the motility response (LES tone, contraction amplitude, propagation velocity) of the human esophagus in healthy volunteers. This response failed in patients with Barrett's esophagus. CONCLUSION: Impaired esophageal sensory motor function may serve as one etiologic role in the development of Barrett's esophagus.

The key-role of vagal nerve and adrenals in the cytoprotection and general gastric mucosal integrity.

BACKGROUND: Our laboratory group observed earlier that the gastric mucosal cytoprotective effect of prostacyclin (PGI(2)) disappeared after surgical vagotomy in rats. Similarly to this, the beta-carotene induced gastric cytoprotection disappeared in adrenalectomized rats too. AIMS: In these studies we aimed to investigate the possible role of vagal nerve and adrenals in the development of gastric mucosal lesions induced by exogenously administered chemicals (ethanol, HCl, NaOH, NaCl and indomethacin), and on the effects of cytoprotective and antisecretory drugs (atropine, cimetidine), and scavengers (vitamin A and beta-carotene). METHODS: The observations were carried out in fasted CFY strain rats. The gastric mucosal lesions were produced by intragastric (i.g.) administration of narcotising agents (96% ethanol; 0.6 M HCl; 0.2 M NaOH; 25% NaCl) or subcutaneously (s.c.) administered indomethacin (20 mg/kg) in intact, surgically bilaterally vagatomized, and adrenalectomized rats without or with glucocorticoid supplementation (Oradexon, 0.6 mg/kg given i.m. for 1 week). The gastric mucosal protective effect of antisecretory doses of atropine (0.1-0.5-1.0 mg/kg i.g.) and cimetidine (10-25-50 mg/kg i.g.), and vitamin A and beta-carotene (0.01-0.1-1.0-10 mg/kg i.g.) was studied. The number and severity of mucosal gastric lesions was numerically or semiquantitatively measured. In other series of observations the gastric acid secretion and mucosal damage were studied in 24 h pylorus-ligated rats without and with acute bilateral surgical vagotomy. RESULTS: It was found that: (1) the chemical-induced gastric mucosal damage was enhanced in vagotomized and adrenalectomized rats, meanwhile the endogenous secretion of gastric acid, and the development of mucosal damage can be prevented by surgical vagotomy; (2) the gastric cyto- and general protection produced by the drugs and scavengers disappeared in vagotomized and adrenalectomized rats; (3) the gastric mucosal protective effects of drugs and of scavengers returned after sufficient glucocorticoid supplementation of the rats. CONCLUSION: It has been concluded that the intact vagal nerve and adrenals have a key role in the gastric mucosal integrity, and in drugs- and scavengers-induced gastric cyto- and general mucosal protection.

One year follow-up of patients after successful helicobacter pylori eradication therapy.

UNLABELLED: The aim of this study was to investigate the Helicobacter pylori (Hp) status of patients who underwent successful eradication therapy 1 year prior to the study and to evaluate their current symptoms. METHODS: all of the patients were initially evaluated by oesophago-gastro-bulboscopy and the Hp status was determined by at least two different methods [rapid urease test, histology or urea breath test (UBT)]. The Hp infection was treated with a 1-week triple therapy protocol, and the UBT was repeated 4-6 weeks later. We invited back 110 patients who had negative post-eradication UBT results 12+/-3 months prior to the study period. UBT was repeated and a questionnaire was completed about the previous and present complaints and medication. RESULTS: 80 of the 110 patients (73%) came back for the follow-up. Twenty five patients had peptic ulcer disease, 36 patients had gastritis or duodenitis without erosive lesions, and 19 patients had erosive form of gastritis or duodenitis initially. All of the patients except one in the erosive gastritis group had negative control UBT 1 year after the eradication, which means 1.25% recurrence rate within 1 year. The eradication therapy completely revealed the symptoms of 16 patients in the ulcer group (64%), 13 patients in the gastroduodenitis group (36%, P=0.03 vs. ulcer patients), 10 patients with erosive gastroduodenitis (52%), but this was only temporary. One year after the eradication therapy seven of the ulcer patients (28%), 11 patients with gastroduodenitis (31%) and seven patients with erosive gastroduodenitis (37%) were symptom-free. Most of the patients had epigastric pain (44%), heartburn (43%) and/or abdominal distension (33%). Nine ulcer patients (36%), 10 patients with gastroduodenitis (28%) and five patients with erosive gastroduodenitis (26%) were taking H(2)-blockers regularly. CONCLUSION: the 1-month post-eradication UBT was probable true negative in all of the evaluated cases, since 79 patients (98.75%) were also negative after 1 year. The Hp recurrence rate is very low (1.25%) in a 1-year period. The symptoms were relieved shortly after eradication therapy in the majority of patients with ulcer disease or erosive lesions. However, significantly smaller portion of the patients with gastroduodenitis became symptom-free. Only about one third of the treated patients remained symptom-free 1 year after the eradication.

Prevalence of the factor V Leiden mutation in human inflammatory bowel disease with different activity.

BACKGROUND: the developmental mechanism of inflammatory bowel disease (IBD) in patients is unknown, but it may be influenced by different environmental and genetical factors. AIMS of this study were: (1) to classify the IBD patients according the disease activity; and (2) to determine the presence of factor V Leiden mutation in IBD patients. PATIENTS AND METHODS: the observation was carried out in 49 patients with Crohn's disease (CD) and 29 patients with ulcerative colitis (UC). None of them had a history of thrombotic episodes. IBD was diagnosed by conventional clinical, endoscopic, radiological and histological criteria. The factor V Leiden mutation was detected by the polymerase chain reaction (PCR) method. Crohn's disease activity index (CDAI) was evaluated using the method of the National Cooperative Crohn's Disease Study. We determined the UC disease activity according to Truelove-Witts classification. RESULTS: The prevalence of factor V Leiden mutation was increased in both populations of the patients to compare it with healthy persons (14.28 and 27.58% vs. 5.26%, n=7/49 and 8/29 vs. 3/57). The statistical analysis did not show a significant relationship between the CDAI or the Truelove-Witts grade in UC and the presence of Leiden mutation. CONCLUSION: the presence of factor V Leiden mutation probably has a role in the development of IBD. Our results suggest a higher prevalence of this mutation in Central European patients than in Southern, Northern Europe or America, may be due to the genetical differences of these populations.

Mechanisms of action of retinoids in gastrointestinal mucosal protection in animals, human healthy subjects and patients.

UNLABELLED: Retinoids prevent chemically induced gastric mucosal damage without inhibiting gastric acid secretion ("nutritional gastric cytoprotection"). The gastroprotective effects of retinoids do not depend on 1) vitamin A activity; 2) number of unsaturated double bonds; 3) the presence of a characteristic chemical structure of their terminal components; however, they depend on 1) intact vagal nerve and 2) adrenals in experimental animals. The gastric cytoprotective effect of retinoids produces a dose-dependent inhibition of ATP-transformation into ADP. It also increases the transformation of ATP into cAMP. Other features of these gastric cytoprotective effects of retinoids include: 1) The retinoid-induced gastric mucosal protection differs from that of PGs; 2) The cAMP is an intracellular signal in the development of gastric mucosal damage produced by chemicals (e.g., ethanol, HCl, indomethacin) and in the protection of gastric mucosa induced by retinoids (but not by PGs); 3) The gastric mucosal protection induced by retinoids and gastric mucosal permeability can be separated in time. The existence of gastric mucosal protection can be demonstrated in healthy persons (against indomethacin treatment), in patients with gastric ulcer (GU) and duodenal ulcer (DU) without any inhibition of gastric acid secretion. The serum levels of vitamin A and zeaxanthin were significantly decreased in patients with chronic gastrointestinal (GI) inflammatory diseases (e.g., terminal ileitis, ulcerative colitis), colorectal polyposis, and different (e.g., esophageal, gastric, pancreatic, hepatocellular and colorectal) malignant diseases. The serum levels of vitamin A provitamins were unchanged and their GI mucosal protective effects do not depend on vitamin A activity. CONCLUSIONS: 1) Abundant experimental and human observations clearly proved the defensive role of retinoids in the GI tract; 2) There is a correlation between the a) scavenger properties of retinoids vs. intact vagal nerve; b) scavenging properties vs. intact adrenals. 3) The GI mucosal protective effect of retinoids is correlated with biochemical changes in the GI mucosa.

Vagus-mediated activation of mucosal mast cells in the stomach: effect of ketotifen on gastric mucosal lesion formation and acid secretion induced by a high dose of intracisternal TRH analogue.

TRH analogue, RX 77368, injected intracisternally (i.c.) at high dose (3 microg/rat) produces gastric mucosal lesion formation through vagal-dependent pathway. The gastric mucosal hyperemia induced by i.c. RX 77368 was shown to be mediated by muscarinic vagal efferent fibres and mast cells. Furthermore, electrical vagal stimulation was observed to induce gastric mucosal mast cell degranulation. The aim of the study was to assess the influence of ketotifen, a mast cell stabilizer, on RX 77368-induced gastric lesion formation and gastric acid secretion. RX 77368 (3 microg, i.c.) or vehicle (10 microL, i.c.) was delivered 240 min prior to the sacrifice of the animals. Ketotifen or vehicle (0.9% NaCl, 0.5 mL) was injected intraperitoneally (i.p.) at a dose of 10 mg x kg(-1) 30 min before RX 77368 injection. The extent of mucosal damage was planimetrically measured by a video image analyzer (ASK Ltd., Budapest) device. In the gastric acid secretion studies, the rats were pretreated with ketotifen (10 mg x kg(-1), i.p.) or vehicle (0.9% NaCl, 0.5 mL, i.p.), 30 min later pylorus-ligation was performed and RX 77368 (3 microg, i.c.) or vehicle (0.9% NaCl, 10 microL, i.c.) was injected. The rats were killed 240 min after i.c. injection, and the gastric acid secretion was measured through the titration of gastric contents with 0.1 N NaOH to pH 7.0. RX 77368 (3 microg, i.c.) resulted in a gastric mucosal lesion formation involving 8.2% of the corpus mucosa (n = 7). Ketotifen elicited an 85% inhibition on the development of mucosal lesions (n = 7, P < 0.001) whereas ketotifen alone had no effect on the lesion formation in the mucosa (n = 7). The RX 77368 induced increase of gastric acid secretion was not influenced by ketotifen pretreatment in 4-h pylorus-ligated animals. Central vagal activation induced mucosal lesion formation is mediated by the activation of mucosal mast cells in the stomach. Mast cell inhibition by ketotifen does not influence gastric acid secretion induced by i.c. TRH analogue in 4-h pylorus-ligated rats.

13C-Urea breath test is superior in sensitivity to detect Helicobacter pylori infection than either antral histology or rapid urease test.

There is no single technique which fulfils the criterion for a reference method to detect Helicobacter pylori (Hp) infection. The aim was to compare the results of antral histology (H), rapid urease test (U) and urea breath test (UBT) from antral biopsy samples in patients having gastric or duodenal lesions during upper GI endoscopy. We used the following methods: 1) biopsy specimens for histology (Warthin-Starry staining); 2) rapid urease test; and 3) 13C-urea breath test with infrared spectrometry. The total number of patients was 166 examined by H, U, and UBT. H, U and UBT were negative (-) in 64 patients and positive (+) in 51. The true positivity and false negativity (%, number of patients in parentheses) of each method based upon the positivity of the other two tests were: H+, U+ (54): UBT+, 94.4% (51) and UBT-, 5.6% (3); H+, UBT+ (57): U+, 89.5% (51) and U-, 10.5% (6); U+, UBT+ (65): H+, 78.5% (51) and H-, 21.5% (14). If Hp infection is considered to be positive when at least two tests detect the presence of Hp, UBT shows the highest sensitivity in comparison to histology of biopsy specimens and urease test. UBT is highly recommended as a screening test for Hp infection in patients presenting upper GI endoscopic alterations.

Effects of indomethacin, with vitamin A or beta-carotene, on the rat gastric mucosa: extra-and intracellular membrane-bound ATP mechanisms.

BACKGROUND: Indomethacin (IND) is a widely used non-steroidal anti-inflammatory agent in the treatment of various inflammatory disorders, which causes gastrointestinal injury in humans and animal experiments. Vitamin A and beta-carotene prevent the IND-induced gastric mucosal injury. These compounds modify the membrane-bound ATP-dependent energy systems. The aims of this investigation were: (1) To study the IND-induced gastric mucosal damage and its prevention by vitamin A and beta-carotene; (2) to measure the biochemical compounds of the gastric mucosa ATP, ADP, ATP/ADP, AMP, ATP+ADP+AMP, 'energy charge' (ATP + 0.5 ADP)/(ATP+ADP+AMP), cAMP, lactate under the circumstances mentioned above; (3) to analyze the extra- and intracellular regulatory mechanisms between the membrane-bound ATP-dependent energy systems. METHODS: The observations were carried out with CFY (Sprague-Dawstrein rats, weighing 180-210 g). The gastric mucosal damage was produced by IND (20 mg/kg sc. administration) and it was prevented by vitamin A (or beta-carotene), given in doses of 0.01-0.1 to 1.0-10.0 mg/kg ig. Different biochemical compounds (ATP, ADP, AMP, cAMP, lactate) and parameters (ATP/ADP, adenylate pool, 'energy charge') were measured and calculated. RESULTS: (1) Vitamin A and beta-carotene prevented dose-dependently the IND-induced gastric mucosal damage; (2) the extent of ATP-ADP transformation was increased significantly, while the ATP-cAMP decreased in the gastric mucosa after IND-treatment; (3) vitamin A and beta-carotene enhanced the extent of ATP-cAMP transformation, while the ATP-ADP transformation was inhibited (the actions were dose-dependent responses); (4) No change was found in 'energy charge' by IND, while its value decreased significantly with vitamin A and beta-carotene. CONCLUSIONS: (1) A very complex extra- and intracellular feedback mechanism system exists in the gastric mucosa during IND, IND + vitamin A, and IND + beta-carotene treatments; (2) The gastric mucosal preventive effect of vitamin A and beta-carotene only partly depend on their scavenger properties.

Leiden mutation in patients with Crohn's disease.

BACKGROUND: Inherited resistance to activated protein C is a common risk factor of venous thrombosis. In a majority of patients the defect is caused by single-point mutation in the gene for factor V. This mutated form of factor Va is more stable against proteolytic attack by activated protein C. The prevalence of this inherited defect in the European population is at least 5%. The risk of thrombosis is increased in the case of heterozygosity 5- to 10-fold, in homozygous subjects 50- to 100-fold, but even homozygous individuals will not necessarily suffer from thrombosis. The aim of our study was to determine whether the presence of Leiden mutation might play a role in the pathophysiology and clinical manifestation of Crohn's disease. MATERIALS AND METHODS: Thirty-four patients with Crohn's disease (mean age 34 years, range 21-72 years) were studied. None of them had a history of thrombotic episodes. We examined the case history for risk factors: use of oral contraceptive, steroids, cigarette smoking. Levels of fibrinogen, APTT, lupus anticoagulant and levels of IgG and IgM class anticardiolipin (ACL) antibodies were determined. The Leiden mutation was detected by PCR method (Denninger et al., 1995). RESULTS: Fibrinogen was elevated in five cases, lupus anticoagulant in one case, but none of the patients had ACL antibodies in the serum. Molecular analyses showed heterozygosity for the Leiden factor V gene mutation in the case of 30 patients (25%). CONCLUSION: Thromboembolic events frequently complicate the clinical course of patients with Crohn's disease; however, we do not have enough knowledge about its role in manifestation of the disease. These results suggested the high frequency of Leiden mutation among our patients and suggest a new genetic background of Crohn's disease.

Peripheral mediators involved in gastric hyperemia to vagal activation by central TRH analog in rats.

Mechanisms mediating the increase in gastric mucosal blood flow (GMBF) induced by the stable thyrotropin-releasing hormone (TRH) analog RX-77368 injected intracisternally at a gastric acid secretory dose (30 ng) were investigated using hydrogen gas clearance in urethan-anesthetized rats. The histamine H1 receptor antagonist pyrilamine (intravenously), capsaicin (subcutaneously, 10 days), and NG-nitro-L-arginine methyl ester (L-NAME, intracisternally) failed to impair the 150% rise in GMBF induced by intracisternal injection of RX-77368. By contrast, atropine (subcutaneously) and NG-monomethyl-L-arginine (intravenously) completely inhibited the increase in GMBF evoked by intracisternal RX-77368. L-NAME (intravenously) blocked the intracisternal RX-77368-induced increase in GMBF in capsaicin-pretreated rats, and the L-NAME effect was reversed by intravenous L- but not D-arginine. These findings indicate that vagal efferent activation induced by TRH analog injected intracisternally at a gastric acid secretory dose increases GMBF through atropine-sensitive mechanisms stimulating L-arginine-nitric oxide pathways, whereas H1 receptors and capsaicin-sensitive afferent fibers do not play a role.

Cellular mechanisms of beta-carotene-induced gastric cytoprotection in indomethacin-treated rats.

Indomethacin (IND) is a non-steroidal anti-inflammatory agent which is widely used in the treatment of various inflammatory disorders. The drug causes gastrointestinal injury in humans and experimental animals. The aim of these studies was to examine the time course correlation between the macroscopic appearance of mucosal damage, tissue level of PGE(2) and adenosine nucleotide metabolism during the development of indomethacin (IND)-induced mucosal damage and its prevention by beta-carotene.The observations were carried out on both sexes of CFY-strain rats, weighing 180-200 g. Gastric mucosal damage was produced by subcutaneous administration of IND (20 mg/kg). beta-Carotene (Hoffman-La Roche, Switzerland) was given intragastrically at the time of IND administration at doses of 0.01, 0.1, 1 and 10 mg/kg. The animals were sacrificed at 0, 1, 2, 3 and 4 h after IND administration when the number and severity of mucosal lesions were noted and the tissue levels of ATP, ADP, AMP, cAMP, lactate and PGE(2) were measured from the total homogenate of gastric mucosa. The ratio of ADP/ATP, the values of the adenylate pool (ATP+ADP+AMP), and 'energy charge' [(ATP+0.5ADP)/(ATP+ADP+AMP)] were calculated.It was found that: (a) gastric mucosal lesions appear macroscopically 2 h after IND administration; (b) the tissue level of ATP decreased, while ADP was increased 1 h after administration; (c) the most significant decrease in cAMP was found 1 h after IND administration, and thereafter its level returned to baseline; (d) beta-carotene dose-dependently prevented the IND-induced mucosal damage and elevated the cAMP level, but it did not alter the mucosal PGE(2) level 3 or 4 h after IND administration; (e) beta-carotene produced an elevation in ATP and a decrease in ADP level; (f) no significant changes were found in 'energy charge' of the gastric mucosa in IND-treated animals.The development of gastric mucosal damage due to IND was associated with increased energy liberation, i.e. transformation of ATP into ADP, and decreased ATP-cAMP transformation. The significant decrease in cAMP preceded the macroscopic appearance of mucosal damage. The increase in ATP-cAMP transformation is involved in the development of beta-carotene-induced gastric cytoprotection.

Ketotifen prevents gastric hyperemia induced by intracisternal thyrotropin-releasing hormone at a low dose.

The thyrotropin-releasing hormone (TRH) analog, RX 77368, (p-Glu-His-(3,3'-dimethyl)-Pro-NH2) injected intracisternally (i.c.) at low doses increases gastric mucosal blood flow through vagal cholinergic and calcitonin gene-related peptide dependent pathways. The influence of the mast cell stabilizer, ketotifen, on i.c. injection of RX 77368 (1.5 ng)-induced changes in gastric mucosal blood flow (hydrogen gas-clearance technique), gastric acid secretion and mean arterial pressure was studied in urethane-anesthetized rats. RX 77368 increased gastric blood flow by 131% and systemic arterial pressure by 11 mm Hg and decreased gastric mucosal vascular resistance by 54% whereas acid secretion was not altered within the 30 min period post injection. Ketotifen had no effect on these basal parameters but abolished i.c. RX 77368-induced increased gastric mucosal blood flow and decreased gastric vascular resistance. These data suggest that mast cells may be part of the peripheral mechanisms involved in vagal gastric hyperemia induced by TRH analog injected i.c. at a low dose.

Mechanisms mediating gastric hyperemic and acid responses to central TRH analog at a cytoprotective dose.

Gastric hyperemic and acid responses to the stable thyrotropin-releasing hormone (TRH) analog RX-77368 injected intracisternally at a cytoprotective dose were investigated, as well as the underlying mechanisms of the responses. Gastric acid secretion (GAS), mucosal blood flow (GMBF; measured by the hydrogen gas clearance technique), and mucosal vascular resistance (GMVR) and mean arterial pressure (MAP) were assessed simultaneously for 30 min before and after RX-77368 (1.5 ng) administration in urethan-anesthetized rats. RX-77368 increased GMBF from 46.8 +/- 5.3 to 100.6 +/- 20.9 ml.min-1.100 g-1 and MAP from 70.3 +/- 2.1 to 84.3 +/- 5.9 mmHg and decreased GMVR from 1.50 +/- 0.33 to 0.84 +/- 0.08 mmHg.ml-1.min.100 g, whereas GAS was not significantly altered (1.8 +/- 0.4 vs. 4.7 +/- 1.7 mumol/30 min) in vehicle-pretreated rats. The GMBF, MAP, and GMVR responses to RX-77368 were not modified by indomethacin (5 mg/kg ip), whereas GAS was increased. In rats pretreated with capsaicin (125 mg/kg sc) or calcitonin gene-related peptide (CGRP) antagonist hCGRP-(8-37), intracisternal RX-77368 did not increase GMBF or decrease GMVR but did stimulate GAS. These data show that vagal stimulation by the TRH analog RX-77368 injected intracisternally at a nonacid secretory dose increases GMBF. Gastric hyperemia is mediated by CGRP contained in capsaicin-sensitive afferent fibers, whereas acid secretion is under the inhibitory influence of prostaglandins and CGRP.

Influence of [4Cl-D-Phe6,Leu17]VIP on VIP- and central TRH-induced gastric hyperemia.

The specific VIP receptor antagonist, [4Cl-D-Phe6,Leu17]VIP, infused i.v. blocked close-intra-arterial infusion of VIP-induced increase in gastric mucosal blood flow (GMBF, measured by the hydrogen gas clearance), and decrease in mean arterial blood pressure while not influencing basal levels in urethane-anesthetized rats. The thyrotropin-releasing hormone (TRH) stable analog, RX 77368, injected intracisternally (IC, 30 ng) increased GMBF and blood pressure. The VIP antagonist did not significantly reduce the GMBF response to IC RX 77368 while enhancing the rise in blood pressure. These findings indicate that [4Cl-D-Phe6,Leu17]VIP is an antagonist for exogenous VIP-induced gastric hyperemia and hypotension and that VIP modulates the systemic blood pressure response to IC RX 77368 at 30 ng while not playing a primary role in the increase of GMBF.

Intravenous interleukin-1-beta-induced inhibition of gastric emptying: involvement of central corticotrophin-releasing factor and prostaglandin pathways in rats.

The role of corticotrophin-releasing factor (CRF) and prostaglandin in interleukin-1 beta (IL-1 beta)-induced delayed gastric emptying was investigated. Gastric emptying was monitored 20 min after orogastric delivery of a methylcellulose phenol red solution in fasted rats injected intravenously with IL-1 beta at the ED50 dose (3 ng/rat) 30 min before the non-caloric solution. The IL-1 receptor antagonist (IL-1ra) injected intravenously (3 micrograms/rat) or intracisternally (100 ng/rat) reversed the IL-1 beta-induced 47% inhibition of gastric emptying by 100% and 62%, respectively. The new CRF antagonist [DPhe12, Nle21,38, C alpha MeLeu37]-CRF12-41 (20 micrograms/rat), injected intracisternally, or indomethacin (5 mg/kg i.p.) completely abolished IL-1 beta (3 ng/rat i.v.)-induced gastric stasis. The CRF antagonist injected intravenously (20 micrograms/rat) did not influence the IL-1 beta inhibitory action. None of the pretreatments given alone influenced basal gastric emptying. These data suggest that peripheral IL-1 beta-induced inhibition of gastric emptying is mediated by specific IL-1 receptor interactions and brain CRF pathways requiring the integrity of eicosanoid-cyclooxygenase pathways.

Central vagal activation by TRH induces gastric hyperemia: role of CGRP in capsaicin-sensitive afferents in rats.

The role of calcitonin gene-related peptide (CGRP) in the vagal cholinergic-mediated increase in gastric mucosal blood flow (GMBF) induced by the stable thyrotropin-releasing hormone (TRH) analogue RX-77368 injected intracisternally (ic, 30 ng) was investigated in urethan-anesthetized rats using the hydrogen gas clearance technique. alpha-CGRP (14 micrograms.kg-1.h-1) or bethanechol (150 micrograms.kg-1.h-1) infused close intra-arterially to the stomach or RX-77368 injected intracisternally increased GMBF by 76, 102, and 131%, respectively, 30 min after administration. The CGRP antagonist, human CGRP-(8-37) [hCGRP-(8-37)], injected intravenously (15 micrograms/kg bolus and 3 micrograms.kg-1.h-1) inhibited by 100, 97, and 73% the gastric hyperemic response to alpha-CGRP, TRH analogue, and bethanechol, respectively, whereas the substance P antagonist CP-96,345 (3 mg/kg iv) had no effect. In capsaicin-pretreated rats, hCGRP-(8-37) no longer blocked the increase in GMBF induced by intracisternal RX-77368. These results suggest that the gastric hyperemic response to central vagal activation induced by intracisternal TRH analogue at 30 ng is mediated by local effector function of capsaicin-sensitive afferent fibers releasing CGRP.