Effects of exercise of different intensity on gut peptides, energy intake and appetite in young males.

UNLABELLED: INTRODUCTION AND RESEARCH AIMS: The aim of the work was an evaluation of the impact of physical exertion on the regulating of food intake and digestive system hormone release as well as the partly connected phenomenon of evaluating the subjective sensation of hunger and the amount of food consumed at various time following physical exercise. MATERIALS AND METHODS: The tests covered 12 young, healthy men, for whom the effects of physical exertion of a moderate and high intensity on the subjective sensation of hunger/satiety, evaluated by means of visual analogue scales, on food intake as well as on the metabolic and hormonal parameters were tested. RESULTS: Physical exertion resulted in a fall in the subjective sensation of hunger, but only following intensive exertion was this statistically significant. The intake of food was greater after exertion when compared to the control group. Moderate exertion resulted in a statistically significant but short-lived increase in the ghrelin level. This effect was not observed after intensive exertion, while in those tests during the post-meal period there occurred a fall in the concentration of ghrelin in the plasma. After exertion a physical fall was observed in the concentration of insulin in the plasma, for the intake of food resulted in a notable increase in its level. CONCLUSIONS: Physical highly intensive exertion, results in a temporary reduction in the subjective sensation of hunger but leads to an increased food intake. The current research suggests that moderate but not intensive physical exertion stimulates the secretion of ghrelin.

Lipoxins, the novel mediators of gastroprotection and gastric adaptation to ulcerogenic action of aspirin.

Previous studies revealed that prostaglandins contribute to the mechanism of maintenance of gastrointestinal integrity and mediate various physiological aspects of mucosal defense. The suppression of prostaglandin synthesis in the stomach is a critical event in terms of the development of mucosal injury after administration of various NSAID including aspirin (ASA). A worldwide use of ASA is now accepted due to its remarkable analgesic, antipyretic and anti-thrombotic prophylactics against myocardial infarct and coronary disorders despite the fact that the use of NSAIDs is associated with the risk of gastrointestinal bleedings, haemorrhagic lesions and ulcerations. It has become clear that other mediators besides prostaglandins can similarly act to protect the gastrointestinal mucosa of experimental animals and humans from injury induced by ASA. For instance, nitric oxide (NO) released from vascular epithelium, epithelial cells of gastrointestinal tract and sensory nerves can influence many of the same components of mucosal defense as do prostaglandins. This review was designed to provide an updated overview based on the experimental and clinical evidence on the involvement COX-2 derived products, lipoxins in the mechanism of gastric defense, gastroprotection and gastric adaptation to ASA. Lipoxins were recently considered as another group of lipid mediators that can protect the stomach similarly as NO-donors known to exert protective influence on the stomach from the injury under condition where the mucosal prostaglandin levels are suppressed. The new class of NO-releasing NSAIDs, including NO-aspirin or NO-naproxen, represent a very promising approach to reducing the toxicity of their parent NSAIDs. Aspirin-triggered lipoxin (ATL) synthesis, via COX-2, acts to reduce the severity of damage induced by this NSAID. Lipoxin analogues may prove to be useful for preventing mucosal injury and for modulating mucosal inflammation. Evidence presented in this review documents that ATL also play in important role in gastric adaptation during chronic ASA administration. Suppression of COX-2 activity by selective COX-2 inhibitors such as rofecoxib or celecoxib was shown to abolish the production of ATL and to diminish the gastric tolerability of ASA and gastric adaptation developed in response to repetitive administration of this NSAID. Synthetic analogues of lipoxins as well as newer class of NSAIDs releasing NO may be used in the future as the therapeutic approach to counteract adverse effects in the stomach associated with NSAIDs ingestion.

Involvement of orexigenic peptides in the mechanism of gastric mucosal integrity and healing of chronic gastric ulcers.

Orexigenic peptides are group of endocrine hormones exerting a pleiotropic influence on many physiological functions including regulation of the feeding behaviour and energy expenditure, release of growth hormone (GH) and inotropic effects on the heart. Some of these peptides such as ghrelin, originally identified in the gastric mucosa, has been involved not only in control of food intake and growth hormone release but also exerts the immunomodulatory and anti-inflammatory properties. This review summarizes the recent attempts to prove the concept that orexigenic peptides such as ghrelin, orexin-A and obestatin besides playing an important role in the mechanism of food intake, exhibit a potent gastroprotective action against the formation of acute gastric mucosal injury induced by various ulcerogens. This protective effect depends upon vagal activity and hyperemia mediated by NOS/NO and COX/PG systems and CGRP released from sensory afferent nerves. In addition, the appetite peptides such as ghrelin and orexin-A are implicated in the mechanism of the healing of preexisting gastric ulcers due to an activation of specific GHS-R1a and OX-R1 receptors and PG/COX system.

Involvement of sensory nerves in the protective effect of growth hormone on acute pancreatitis.

UNLABELLED: Growth hormone (GH) has been shown to protect the intestinal barrier integrity and to stimulate the production of insulin-like growth factor 1 (IGF-1), which inhibits the development of acute pancreatitis. Sensory nerves are implicated in the protection of pancreatic tissue against acute inflammation. The aim of this study was to investigate the influence of exogenous GH on acute pancreatitis (AP) and to assess the involvement of sensory nerves and IGF-1 in above effect. Studies were performed on Wistar rats. AP was induced by subcutaneous administration of caerulein (25mug/kg) to the conscious animals. GH (1 or 2mg/kg) was administered to the rats as an intraperitoneal injection 30min prior to the start of AP. To deactivate sensory nerves capsaicin was given at total dose of 100mg/kg 10days before the experiments. AP was confirmed by histological examination and manifested by the significant rises of pancreatic weight, and serum activities of lipase, TNFalpha and IL-10 (by 550%, 300% and 50%, respectively), whereas IGF-1 blood concentration was markedly reduced. Administration of GH prior to the caerulein infusion significantly increased GH, IGF-1 and IL-10 blood levels, attenuated harmful effects of AP and reduced histological manifestations of pancreatitis in the rats with intact sensory nerves. This was accompanied by the reduction of serum lipase, and TNFalpha activities. In the AP rats with capsaicin-deactivated sensory nerves GH failed to protect the pancreas against acute damage and, as a consequence of above deactivation, IGF-1 was low. CONCLUSION: GH modulates the development of acute pancreatitis in the presence of active sensory nerves probably via stimulation of IGF-1 release.

Dual, time-dependent deleterious and protective effect of anandamide on the course of cerulein-induced acute pancreatitis. Role of sensory nerves.

Some recent studies indicate that cannabis may induce acute pancreatitis in humans and administration of anandamide increases the severity of acute pancreatitis; whereas another study exhibits some therapeutic effects in acute pancreatitis. Aim of the present study was to discover what is the reason for these opposite confusing results and to determine the role of sensory nerves in this effect. Acute pancreatitis was induced in rats by cerulein. Anandamide, an endogenous cannabinoid, was administered i.p. (1.5 micromol/kg) before or 2 h after cerulein administration. Stimulation of sensory nerves was performed by capsaicin (0.5 mg/kg s.c.). In rats treated with combination of anandamide plus capsaicin, capsaicin was given 10 min after each dose of anandamide. After the last injection of cerulein or 4 h later, the study was terminated. In our study we observed that stimulation of sensory nerves by capsaicin, before administration of cerulein, reduced the severity of acute pancreatitis. Anandamide, administered alone before cerulein, increased pancreatic damage in acute pancreatitis. Anandamide administered in combination with capsaicin, before cerulein, abolished the capsaicin-induced protective effect on the pancreas. Opposite effects were observed when capsaicin and anandamide were administered after injection of cerulein. Capsaicin increased the severity of acute pancreatitis, whereas anandamide reduced pancreatic damage and reversed the deleterious effect of capsaicin. We conclude that the effect of anandamide on the severity of acute pancreatitis depends on the phase of this disease. Administration of anandamide, before induction of pancreatitis, aggravates pancreatic damage; whereas anandamide administered after induction of pancreatitis, reduces the severity of acute pancreatitis. Sensory nerves are involved in the mechanism of this biphasic effect of anandamide.

Gastroprotective action of orexin-A against stress-induced gastric damage is mediated by endogenous prostaglandins, sensory afferent neuropeptides and nitric oxide.

Orexin-A, identified in the neurons and endocrine cells in the gut, has been implicated in control of food intake and sleep behavior but little is known about its influence on gastric secretion and mucosal integrity. The effects of orexin-A on gastric secretion and gastric lesions induced in rats by 3.5 h of water immersion and restraint stress (WRS) or 75% ethanol were determined. Orexin-A (5-80 microg/kg i.p.) increased gastric acid secretion and attenuated gastric lesions induced by WRS and this was accompanied by the significant rise in plasma orexin-A, CGRP and gastrin levels, the gastric mucosal blood flow (GBF), luminal NO concentration and an increase in mRNA for CGRP and overexpression of COX-2 protein and the generation of PGE(2) in the gastric mucosa. Orexin-A-induced protection was abolished by selective OX-1 receptor antagonist, vagotomy and attenuated by suppression of COX-1 and COX-2, deactivation of afferent nerves with neurotoxic dose of capsaicin, pretreatment with CCK(2)/gastrin antagonist, CGRP(8-37) or capsazepine and by inhibition of NOS with L-NNA. This study shows for the first time that orexin-A exerts a potent protective action on the stomach of rats exposed to non-topical ulcerogens such as WRS or topical noxious agents such as ethanol and these effects depend upon hyperemia mediated by COX-PG and NOS-NO systems, activation of vagal nerves and sensory neuropeptides such as CGRP released from sensory nerves probably triggered by an increase in gastric acid secretion induced by this peptide.

Therapeutic potential of 1-methylnicotinamide against acute gastric lesions induced by stress: role of endogenous prostacyclin and sensory nerves.

1-Methylnicotinamide (MNA) is one of the major derivatives of nicotinamide, which was recently shown to exhibit antithrombotic and antiinflammatory actions. However, it is not yet known whether MNA affects gastric mucosal defense. The effects of exogenous MNA were studied on gastric secretion and gastric lesions induced in rats by 3.5 h of water immersion and water restraint stress (WRS) or in rats administered 75% ethanol. MNA [6.25-100 mg/kg intragastrically (i.g.)] led to a dose-dependent rise in the plasma MNA level, inhibited gastric acid secretion, and attenuated these gastric lesions induced by WRS or ethanol. The gastroprotective effect of MNA was accompanied by an increase in the gastric mucosal blood flow and plasma calcitonin gene-related peptide (CGRP) levels, the preservation of prostacyclin (PGI(2)) generation (measured as 6-keto-PGF1alpha), and an overexpression of mRNAs for cyclooxygenase (COX)-2 and CGRP in the gastric mucosa. R-3-(4-Fluoro-phenyl)-2-[5-(4-fluoro-phenyl)-benzofuran-2-ylmethoxycarbonylamino]-propionic acid (RO 324479), which is the selective antagonist of IP/PGI(2) receptors, reversed the effects of MNA on gastric lesions and GBF. MNA-induced gastroprotection was attenuated by suppression of COX-1 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole; SC-560] and COX-2 [4-(4-methylsulfonylphenyl)-3-phenyl-5H-furan-2-one; rofecoxib] activity, capsaicin denervation, and by the pretreatment with CGRP(8-37) or capsazepine. Addition of exogenous PGI(2) or CGRP restored the MNA-induced gastroprotection in rats treated with COX-1 and COX-2 inhibitors or in those with capsaicin denervation. WRS enhanced MDA content while decreasing superoxide dismutase (SOD) activity in the gastric mucosa, but pretreatment with MNA reversed these changes. MNA exerts potent gastroprotection against WRS damage via mechanisms involving cooperative action of PGI(2) and CGRP in preservation of microvascular flow, antioxidizing enzyme SOD activity, and reduction in lipid peroxidation.

[Protective role of leptin in acute gastric ulcers]. / Ochronna rola leptyny w ostrych wrzodach zoladka.

There are few data concerning protective effects of leptin on gastric epithelium treated with necrotic factors: ethanol, bile salts and hiperosmotic solutions. Further investigations are needed to establish the role of hormone leptin in gastroprotection and in the process of chronic gastric ulcers healing in animals. Exogenous leptin administration plays protective effects against 75% ethanol damage in gastric epithelium. Nitric oxide is involved in gastroprotective effects of leptin and CCK.

[Studies on the influence of Candida fungal colonization on the healing process of inflammatory lesions in the colon in rat animal model]. / Wplyw kolonizacji grzybów Candida na gojenie zmian zapalnych blony sluzowej jelita grubego w modelu zwierzecym colitis ulcerosa.

Present-day methods of successful treatment of inflammatory bowel diseases (IBD) result from a better understanding of their pathophysiology due to advances in preclinical studies in this area of knowledge. Until recently microbiological studies have been focused on the bacterial aspects in pathogenesis of GI disorders, however in the last years an interest in the presence of fungi in the gastrointestinal tract has also increased. In this study using an animal model of ulcerative colitis, the impact of fungal colonization of the colon on the intensity of inflammatory changes in the colonic mucosa and the course of their healing was carried out. The macroscopic and microscopic criteria relating to the changes of weight of examined fragments of the colon were evaluated while assessing differences between groups tested. The intensity of intestinal inflammatory changes was determined by assessment of such parameters, as colonic blood flow (CBF), the level of MPO as a marker of colonic neutrophil infiltration intensity and the plasma levels of IL-1beta; and TNF-alpha concentrations. Results at the 3rd day after TNBS rectal administration revealed an increase of weight of isolated segments of inflammed colon, a decrease of CBF and the 4-5 fold increase of plasma MPO activity. Candida colonization of colon mucosa of rats delayed healing of colonic ulcers, induced by TNBS and this was associated with the increased expression of plasma IL-1beta and TNF-alpha levels. Administration of antifungal (fluconazole) or probiotic (Lacidofil) treatment to C. albicans infected rats exerted favorable effect on healing of inflammatory changes in the colon because the area of ulcerations in groups of rats treated with fluconazole or Lacidofil was significantly smaller in comparison with those inoculated with Candida solution only. Administration of fluconazole or Lacidofil significantly decreased the weight of colon segments, the MPO activity and the plasma IL-1beta and TNF-alpha levels, as compared with respective values in the group receiving Candida only. The results of our studies indicate the deteriorating influence of Candida on the healing process of inflamed colon in the animal model of ulcerative colitis. Concomitant therapy with probiotic or antifungal treatment improved healing of colonic lesions, decreased the weight of inflamed colonic tissue and also attenuated the MPO activity and plasma proinflammatory cytokines IL-1beta and TNF-alpha levels.

The effect of luminal ghrelin on pancreatic enzyme secretion in the rat.

Ghrelin, a 28-amino-acid peptide produced predominantly by oxyntic mucosa has been reported to affect the pancreatic exocrine function but the mechanism of its secretory action is not clear. The effects of intraduodenal (i.d.) infusion of ghrelin on pancreatic amylase outputs under basal conditions and following the stimulation of pancreatic secretion with diversion of pancreato-biliary juice (DPBJ) as well as the role of vagal nerve, sensory fibers and CCK in this process were determined. Ghrelin given into the duodenum of healthy rats at doses of 1.0 or 10.0 microg/kg increased pancreatic amylase outputs under basal conditions or following the stimulation of pancreatic secretion with DPBJ. Bilateral vagotomy as well as capsaicin deactivation of sensory fibers completely abolished all stimulatory effects of luminal ghrelin on pancreatic exocrine function. Pretreatment with lorglumide, a CCK(1) receptor blocker, reversed the stimulation of amylase release produced by intraduodenal application of ghrelin. Intraduodenal ghrelin at doses of 1.0 or 10.0 microg/kg increased plasma concentrations of CCK and ghrelin. In conclusion, ghrelin given into the duodenum stimulates pancreatic enzyme secretion. Activation of vagal reflexes and CCK release as well as central mechanisms could be implicated in the stimulatory effect of luminal ghrelin on the pancreatic exocrine functions.

[Candidiasis in the experimental model of ulcerative colitis]. / Kandydiaza w doswiadczalnym modelu zapalenia jelita grubego.

In the present study on animal model of ulcerative colitis the influence of fungal colonization on the severity of inflammatory lesions in the colon and the course of their healing was evaluated. The results of our studies revealed, that significant fungal colonization (over 10(4) CFU/ml) delayed ulcer healing in the colon. It corresponded with the decrease of colonic blood flow (CBF) in the region of lesions and increase of interleukin (IL)-1beta, tumor necrosis factor(TNF)-alpha level in the serum. Introduction of antifungal therapy (fluconazole) or probiotic in rats inoculated with Candida accelerated the process of ulcer healing in the colon, expressed through the reduction of macro- and microscopic lesions in the colon and decrease of MPO, IL-beta TNF-alpha serum level.

Role of growth hormone and insulin-like growth factor-1 in the protective effect of ghrelin in ischemia/reperfusion-induced acute pancreatitis.

Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, has been shown to exhibit gastroprotective properties. The aim of present study was to determine whether ghrelin administration protects the pancreas against ischemia/reperfusion-induced pancreatitis and, if so, what is the role of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in this effect. In sham-operated or hypophysectomized rats, acute pancreatitis was induced by pancreatic ischemia followed by reperfusion. Ghrelin (4, 8 or 16 nmol/kg/dose) or IGF-1 (20 nmol/kg/dose) were administered intraperitoneally twice before and during induction of acute pancreatitis. In pituitary-intact rats, treatment with ghrelin attenuated the development of ischemia/reperfusion-induced pancreatitis and this effect was associated with partial reversion of the pancreatitis-evoked decrease in serum concentration of GH and IGF-1. Hypophysectomy eliminated GH from the serum, reduced serum IGF-1 concentration by 90% and increased in the severity of ischemia/reperfusion-induced pancreatitis. Administration of ghrelin was without any beneficial effect in this group of rats. In contrast, administration of IGF-1 in hypophysectomized rats reduced the severity of ischemia/reperfusion-induced pancreatitis in hypophysectomized rats. We conclude that administration of ghrelin inhibits the development of ischemia/reperfusion-induced pancreatitis and this effect is mediated by its influence on the release of GH and IGF-1.

Prostaglandin/cyclooxygenase pathway in ghrelin-induced gastroprotection against ischemia-reperfusion injury.

Ghrelin is involved in the control of food intake, but its role in gastroprotection against the formation of gastric mucosal injury has been little elucidated. We studied the effects of peripheral (i.p.) and central (i.c.v.) administration of ghrelin on gastric secretion and gastric mucosal lesions induced by 3 h of ischemia/reperfusion (I/R) with or without inhibition of ghrelin growth hormone secretagogue type 1a receptor (GHS-R1a) by using ghrelin antagonist, d-Lys(3)-GHRP-6; blockade of cyclooxygenase (COX)-1 (indomethacin, SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole]) and COX-2 (rofecoxib); and bilateral vagotomy or capsaicin denervation. I/R produced typical gastric erosions, a significant fall in the gastric blood flow (GBF), an increase in gastric myeloperoxidase (MPO) activity and malonyldialdehyde (MDA) content, and the up-regulation of mucosal ghrelin mRNA. Ghrelin dose-dependently increased gastric acid secretion and significantly reduced I/R-induced gastric erosions, while producing a significant rise in the GBF and mucosal PGE(2) generation and a significant fall in MPO activity and MDA content. The protective and hyperemic activities of ghrelin were significantly attenuated in rats pretreated with d-Lys(3)-GHRP-6 and capsaicin denervation and completely abolished by vagotomy. Indomethacin, SC560, and rofecoxib, selective COX-1 and COX-2 inhibitors, attenuated ghrelin-induced protection that was restored by supplying the methyl analog of prostaglandin (PG) E(2). The expression of mRNA for COX-1 was unaffected by ghrelin, but COX-2 mRNA and COX-2 protein were detectable in I/R injured mucosa and further up-regulated by exogenous ghrelin. We conclude that ghrelin exhibits gastroprotective and hyperemic activities against I/R-induced erosions, the effects that are mediated by hormone activation of GHS-R1a receptors, COX-PG system, and vagal-sensory nerves.

Ghrelin inhibits vascular superoxide production in spontaneously hypertensive rats.

BACKGROUND: Ghrelin is a novel peptide involved in the control of appetite, but its role in vascular pathologies remains to be elucidated. Ghrelin was shown to decrease blood pressure (BP) and improve endothelial function. Its plasma levels are correlated with BP in humans. Mechanisms of these effects are unknown. Because oxidative stress and increased superoxide production by NAD(P)H oxidases (Nox) are critical in the pathogenesis of hypertension, we aimed to study the effects of ghrelin on vascular superoxide production and NAD(P)H oxidase activity in spontaneously hypertensive rats (SHR). METHODS: Aortic superoxide production and NAD(P)H oxidase activity were measured using lucigenin (5 micromol/L) chemiluminescence. Aortas from Wistar-Kyoto rats (WKY) were used as control. Direct superoxide scavenging properties of ghrelin were tested using xanthine-xanthine oxidase system. RESULTS: Both basal superoxide production and vascular NADPH oxidase activity were significantly higher in aortas from SHR, than from WKY. Preincubation of aortic segments from SHR or WKY with ghrelin caused concentration-dependent (from 50 pg/mL to 5 ng/mL) decrease of basal superoxide production. Vascular NAD(P)H oxidase activity was inhibited by ghrelin, abolishing the difference between SHR and basal WKY. Ghrelin did not affect superoxide release from the in vitro xanthine-xanthine oxidase system, indicating lack of direct superoxide scavenging properties or inhibitory effects on xanthine oxidase in vitro. Nitric oxide synthase (NOS) inhibition, using N(omega)-nitro-L-arginine methyl ester (L-NAME), partially blunted the effects of ghrelin on NADPH oxidase activity indicating potential role of nitric oxide. CONCLUSIONS: Ghrelin inhibits vascular oxidative stress in SHR. This effect is likely related to the inhibition of vascular NAD(P)H oxidases.

The mechanism of heat-shock protein 70 gene expression abolition in gastric epithelium caused by Helicobacter pylori infection.

BACKGROUND: The members of the family of heat shock factors coordinate the inducible transcription of heat shock genes in response to diverse stimuli. Any disturbances in signal transduction may lead to the attenuation of heat shock proteins synthesis and to cell death due to apoptosis. It has been shown by others that different nuclear factors, such as nuclear factor interleukin 6 or signal transducer and activator of transcription 3, co-operate with heat shock factors, mostly enhancing their activator effect on heat shock proteins genes expression. Therefore, we sought to determine whether apoptosis induced in the gastric epithelium exposed to live Helicobacter pylori might occur due to the elimination of HSP70 expression and deregulation of the heat shock response of the cell. MATERIALS AND METHODS: Experiments were performed on KATO III gastric epithelial cells exposed to live cagA, vacA expressing Hp over different periods of time. Total cellular RNA, cytoplasmic and nuclear proteins were isolated for polymerase chain reaction, western-blot, electrophoretic mobility shift assay, decoy and co-immunoprecipitation studies. RESULTS: We found that in human gastric epithelium exposed to Helicobacter pylori, heat shock factor 1 is bound and restrained in complexes by phosphorylated signal transducer and activator of transcription 3 protein. In consequence, heat shock factor 1 bound up with phosphorylated signal transducer and activator of transcription 3 protein is unable to activate HSP70 protein synthesis in KATO III cells under stress conditions. Helicobacter pylori also causes changes in bax/bcl-2 cellular equilibrium, leading to the induction of apoptosis. CONCLUSIONS: The observed phenomenon might be the mechanism whereby gastric epithelium adapts to the infection of Helicobacter pylori, eliminating cells which are damaged or altered by bacterial cytotoxic products from the tissue.

Effect of probiotics and triple eradication therapy on the cyclooxygenase (COX)-2 expression, apoptosis, and functional gastric mucosal impairment in Helicobacter pylori-infected Mongolian gerbils.

BACKGROUND: Helicobacter pylori infection in Mongolian gerbils is an established experimental model of gastric carcinogenesis that mimics H. pylori-positive patients developing gastric ulcer and gastric cancer, but the effect of probiotic therapy on functional aspects of this infection remains unknown. METHODS: We compared the effects of intragastric inoculation of gerbils with H. pylori strain (cagA+ vacA+, 5 x 10(6) colony forming units/ml) with or without triple therapy including omeprazole, amoxicillin, and tinidazol or probiotic bacteria Lacidofil. Histology of glandular mucosa, the viable H. pylori, and density of H. pylori colonization were evaluated. The gastric blood flow was measured by H2-gas clearance method; the plasma gastrin and gastric luminal somatostatin were determined by RIA and expression of cyclooxygenase (COX)-2 and apoptotic Bax and Bcl-2 proteins were evaluated by Western blot. RESULTS: The gastric H. pylori infection was detected in all animals by histology and H. pylori culture. Basal gastric acid was significantly reduced in H. pylori-infected animals but not in those with triple therapy or Lacidofil. Early lesions were seen already 4 weeks upon H. pylori inoculation and consisted of chronic gastritis and glandular atypia associated with typical regenerative hyperplasia and increased mitotic activity and formation of apoptotic bodies. The H. pylori infection was accompanied by the fall in gastric blood flow, the marked increase in plasma gastrin, the significant fall in gastric somatostatin levels and Bcl-2 protein expression, and the rise in expression of COX-2 and Bax proteins. These mucosal changes were counteracted by the triple therapy and Lacidofil. CONCLUSIONS: H. pylori infection in gerbils, associated with regenerative hyperplasia of glandular structure, results in the suppression of gastric secretion, overexpression of COX-2, and enhancement in apoptosis and impairment of both, gastric blood flow and gastrin-somatostatin link that were reversed by anti-H. pylori triple therapy and attenuated by probiotics.

Dual age-dependent effect of ghrelin administration on serum level of insulin-like growth factor-1 and gastric growth in young rats.

UNLABELLED: Ghrelin is a circulating growth hormone-releasing peptide primarily isolated from human and rat stomach. The aim of present study was to investigate the effect of ghrelin administration on gastric growth in suckling, and young peripubertal 7-week-old rats. Rats were treated for 7 days with saline or ghrelin (4, 8 or 16 nmol/kg/dose) intraperitoneally twice a day. Suckling rats were treated from the fist postnatal day. RESULTS: Treatment with ghrelin did not affect animal weight in suckling rats; whereas in 7-week-old animals, administration of ghrelin caused a significant increase in body weight. In suckling rats, ghrelin decreased the gastric weight, DNA synthesis and DNA content. In young 7-week-old peripubertal rats, treatment with ghrelin increased food intake and animal body weight. This effect was accompanied with a significant increase in gastric mucosa weight, DNA synthesis and DNA content. Treatment with ghrelin increased serum level of growth hormone in all rats tested, but this result was much higher in 7-week-old peripubertal rats than in suckling rats. Serum level of insulin-like growth factor-1 was not affected by ghrelin administration in suckling rats. In contrast, ghrelin caused a significant increase in serum level of insulin-like growth factor-1 in 7-week-old peripubertal rats. We conclude that administration of ghrelin exhibits biphasic effect on gastric growth in young rats: in suckling rats, ghrelin reduces gastric growth, whereas in young 7-week-old animals, treatment with ghrelin stimulates gastric growth. The growth-promoting effect of ghrelin in the stomach seems to depend on the stimulation of food intake and the release of insulin-like growth factor-1.

Ischemic preconditioning inhibits development of edematous cerulein-induced pancreatitis: involvement of cyclooxygenases and heat shock protein 70.

AIM: To determine whether ischemic preconditioning (IP) affects the development of edematous cerulein-induced pancreatitis and to assess the role of cyclooxygenase-1 (COX-1), COX-2, and heat shock protein 70 (HSP 70) in this process. METHODS: In male Wistar rats, IP was performed by clamping of celiac artery (twice for 5 min at 5-min intervals). Thirty minutes after IP or sham operation, acute pancreatitis was induced by cerulein. Activity of COX-1 or COX-2 was inhibited by resveratrol or rofecoxib, respectively (10 mg/kg). RESULTS: IP significantly reduced pancreatic damage in cerulein-induced pancreatitis as demonstrated by the improvement of pancreas histology, reduction in serum lipase and poly-C ribonuclease activity, and serum concentration of pro-inflammatory interleukin (IL)-1beta. Also, IP attenuated the pancreatitis-evoked fall in pancreatic blood flow and pancreatic DNA synthesis. Serum level of anti-inflammatory IL-10 was not affected by IP. Cerulein-induced pancreatitis and IP increased the content of HSP 70 in the pancreas. Maximal increase in HSP 70 was observed when IP was combined with cerulein-induced pancreatitis. Inhibition of COXs, especially COX-2, reduced the protective effect of IP in edematous pancreatitis. CONCLUSION: Our results indicate that IP reduces pancreatic damage in cerulein-induced pancreatitis and this effect, at least in part, depends on the activity of COXs and pancreatic production of HSP 70.

Role of central and peripheral ghrelin in the mechanism of gastric mucosal defence.

Ghrelin, identified in the gastric mucosa, has been involved in the control of food intake and growth hormone (GH) release, but whether this hormone influences the gastric secretion and gastric mucosal integrity has been little elucidated. We compared the effects of intraperitoneal (i.p.) and intracerebroventricular (i.c.v.) administration of ghrelin on gastric secretion and gastric lesions induced in rats by 75% ethanol or 3.5 h of water immersion and restraint stress (WRS) with or without suppression of nitric oxide (NO)-synthase or functional ablation of afferent sensory nerves by capsaicin. The number and the area of gastric lesions was measured by planimetry, the GBF was assessed by the H2-gas clearance method and blood was withdrawn for the determination of the plasma ghrelin and gastrin levels. In addition, the gastric mucosal expression of mRNA for CGRP, the most potent neuropeptide released from the sensory afferent nerves, was analyzed in rats exposed to WRS with or without ghrelin pre-treatment. Ghrelin (5-80 microg/kg i.p. or 0.6-5 microg/kg i.c.v.) increased gastric acid secretion and attenuated gastric lesions induced by ethanol and WRS. This protective effect was accompanied by a significant rise in the gastric mucosal blood flow (GBF), luminal NO concentration and plasma ghrelin and gastrin levels. Ghrelin-induced protection was abolished by vagotomy and significantly attenuated by L-NNA and deactivation of afferent nerves with neurotoxic dose of capsaicin. The signal for CGRP mRNA was significantly increased in gastric mucosa exposed to WRS as compared to that in the intact gastric mucosa and this was further enhanced in animals treated with ghrelin. We conclude that central and peripheral ghrelin exerts a potent protective action on the stomach of rats exposed to ethanol or WRS, and these effects depend upon vagal activity and hyperemia mediated by the NOS-NO system and CGRP released from sensory afferent nerves.

Agonist of peroxisome proliferator-activated receptor gamma (PPAR-gamma): a new compound with potent gastroprotective and ulcer healing properties.

Pioglitazone, a specific ligand for peroxisome proliferator-activated receptor gamma (PPAR-gamma), was recently implicated in the control of inflammatory processes and in the modulation of the expression of various cytokines such as tumor necrosis factor alpha (TNF-alpha), but its role in the mechanism of gastric mucosal integrity has not been studied extensively. This study was designed to determine the effect of pioglitazone on gastric mucosal lesions induced in rats by topical application of 100% ethanol and by 3.5 h of water immersion and restraint stress (WRS) with or without pretreatment with indomethacin (5 mg/kg i.p.) to inhibit cyclooxygenase-1 (COX-1) and COX-2 enzyme activities and L-NNA (20 mg/kg i.p.) to suppress nitric oxide (NO)-synthase. In addition, the effect of pioglitazone on ulcer healing in rats with chronic acetic acid ulcers (ulcer area 28 mm2) was determined. Rats were killed 1 h and 3.5 h after ethanol administration or WRS exposure or at day 9 upon ulcer induction, and the number and area of gastric lesions were measured by planimetry, the gastric blood flow (GBF) was determined by H2-gas clearance technique and the mucosal PGE2 generation and gene expression and plasma concentration of TNF-alpha and IL-1beta were also evaluated. Pre-treatment with pioglitazone dose-dependently attenuated gastric lesions induced by 100% ethanol and WRS; the dose reducing these lesions by 50% (ID50) being 10 mg/kg and 7 mg/kg, respectively. The protective effect of pioglitazone was accompanied by the significant rise in the GBF, an increase in PGE2 generation and the significant fall in the plasma TNF-alpha and IL-1beta levels. Strong signals for IL-1beta- and TNF-alpha mRNA were recorded in gastric mucosa exposed to ethanol or WRS, and these effects were significantly decreased by pioglitazone. Indomethacin which suppressed PG generation by about 90%, while augmenting WRS damage, and L-NNA, that suppressed NO-synthase activity, significantly attenuated the protective and hyperaemic activity of this PPAR-gamma ligand. In the chronic study, pioglitazone significantly reduced the area of gastric ulcers on day 9 and significantly raised the GBF at the ulcer margin. The acceleration of ulcer healing by PPAR-gamma ligand was accompanied by a significant increase in the expression of PECAM-1 protein, a marker of angiogenesis. We conclude that (1) pioglitazone exerts a potent gastroprotective and hyperaemic actions on the stomach involving endogenous PG and NO and attenuation of the expression and release of proinflammatory cytokines TNF-alpha and IL-1beta, and (2) PPAR-gamma ligand accelerates ulcer healing, possibly due to the enhancement in angiogenesis at ulcer margin.