Ghrelin and leptin did not improve meiotic maturation of porcine oocytes cultured in vitro.

To improve culture system for in vitro maturation (IVM) of porcine oocytes, ghrelin, leptin or growth hormone (GH), at concentration of 0, 0.5, 5, 50 and 500 ng/ml were added to the porcine follicular fluid (pFF)-supplemented medium NCSU23, and their effects on the maturation and cytoskeletal distribution of the oocytes with or without cumulus cells were compared. In the cumulus-denuded oocytes, no significant changes were noted in the maturation rate by different hormone treatments due to a marked decline in the controls. Maturation of the cumulus intact oocytes was moderately interfered by ghrelin (0.5-50 ng/ml, p < 0.01), but not significantly affected by leptin and GH. Distribution density of the cytoplasmic microtubules was decreased significantly by addition of ghrelin (by approximately 30% in 50-500 ng/ml, p < 0.01), whereas no remarkable effect was noted by leptin supplementation. High concentration (500 ng/ml) of ghrelin or leptin decreased significantly the cytoplasmic microfilaments in density (by 43% and 38%, p < 0.01, respectively). GH did not affect cytoskeletal distribution. The results suggest, in the culture system using pFF-supplemented medium that (i) ghrelin may have some inhibitory effect on the organization of microtubules and microfilaments, probably being a factor in lowered maturation rate and (ii) the addition of higher concentration of leptin may decrease microfilaments in density with no effect on meiotic maturation of the porcine oocytes.

Non-chemotactic Dictyostelium discoideum mutants with altered cGMP signal transduction.

Folic acid and cAMP are chemoattractants in Dictyostelium discoideum, which bind to different surface receptors. The signal is transduced from the receptors via different G proteins into a common pathway which includes guanylyl cyclase and acto-myosin. To investigate this common pathway, ten mutants which do not react chemotactically to both cAMP and folic acid were isolated with a simple new chemotactic assay. Genetic analysis shows that one of these mutants (KI-10) was dominant; the other nine mutants were recessive, and comprise nine complementation groups. In wild-type cells, the chemoattractants activate adenylyl cyclase, phospholipase C, and guanylyl cyclase in a transient manner. In mutant cells the formation of cAMP and IP3 were generally normal, whereas the cGMP response was altered in most of the ten mutants. Particularly, mutant KI-8 has strongly reduced basal guanylyl cyclase activity; the enzyme is present in mutant KI-10, but can not be activated by cAMP or folic acid. The cGMP response of five other mutants is altered in either magnitude, dose dependency, or kinetics. These observations suggest that the second messenger cGMP plays a key role in chemotaxis in Dictyostelium.

Protection against osmotic stress by cGMP-mediated myosin phosphorylation.

Conventional myosin functions universally as a generator of motive force in eukaryotic cells. Analysis of mutants of the microorganism Dictyostelium discoideum revealed that myosin also provides resistance against high external osmolarities. An osmo-induced increase of intracellular guanosine 3',5'-monophosphate was shown to mediate phosphorylation of three threonine residues on the myosin tail, which caused a relocalization of myosin required to resist osmotic stress. This redistribution of myosin allowed cells to adopt a spherical shape and may provide physical strength to withstand extensive cell shrinkage in high osmolarities.

Interaction between salsolinol (SAL) and thyrotropin-releasing hormone (TRH) or dopamine (DA) on the secretion of prolactin in ruminants.

We have recently demonstrated that salsolinol (SAL), a dopamine (DA)-derived compound, is present in the posterior pituitary gland and is able to stimulate the release of prolactin (PRL) in ruminants. The aim of the present study was to clarify the effect that the interaction of SAL with thyrotropin-releasing hormone (TRH) or DA has on the secretion of PRL in ruminants. A single intravenous (i.v.) injection of SAL (5mg/kg body weight (b.w.)), TRH (1microg/kg b.w.), and SAL plus TRH significantly stimulated the release of PRL in goats (P<0.05). The cumulative response curve (area under the curve: AUC) during 120min was 1.53 and 1.47 times greater after the injection of SAL plus TRH than either SAL or TRH alone, respectively (P<0.05). A single i.v. injection of sulpiride (a DA receptor antagonist, 0.1mg/kg b.w.), sulpiride plus SAL (5mg/kg b.w.), and sulpiride plus TRH (1microg/kg b.w.) significantly stimulated the release of PRL in goats (P<0.05). The AUC of PRL during 120min was 2.12 and 1.78 times greater after the injection of sulpiride plus TRH than either sulpiride alone or sulpiride plus SAL, respectively (P<0.05). In cultured bovine anterior pituitary (AP) cells, SAL (10(-6)M), TRH (10(-8)M), and SAL plus TRH significantly increased the release of PRL (P<0.05), but the additive effect of SAL and TRH detected in vivo was not observed in vitro. In contrast, DA (10(-6)M) inhibited the TRH-, as well as SAL-induced PRL release in vitro. All together, these results clearly show that SAL can stimulate the release of PRL in ruminants. Furthermore, they also demonstrate that the additive effect of SAL and TRH on the release of PRL detected in vivo may not be mediated at the level of the AP, but that DA can overcome their releasing activity both in vivo and in vitro, confirming the dominant role of DA in the inhibitory regulation of PRL secretion in ruminants.

Rabeprazole-based eradication therapy for Helicobacter pylori: a large-scale study in Japan.

BACKGROUND: Large-scale studies of rabeprazole-based Helicobacter pylori eradication therapy have not been reported in Japan. AIMS: To evaluate H. pylori eradication by rabeprazole-based therapy with reference to antibiotic susceptibility, CYP2C19 genotype, and rabeprazole and clarithromycin dosages. METHODS: From 35 centres 479 H. pylori-positive patients with gastric or duodenal ulcer were randomized to four treatment groups: Group 1 (10 mg rabeprazole + 750 mg amoxicillin + 200 mg clarithromycin twice daily for 7 days); Group 2 (10 mg, 750 mg, 400 mg); Group 3 (20 mg, 750 mg, 200 mg) and Group 4 (20 mg, 750 mg, 400 mg). RESULTS: Eradication rates were 86% (102 of 119), 89% (97 of 109), 91% (106 of 116) and 90% (104 of 115) for Groups 1-4, respectively. The eradication rate was 95% (360 of 379) for clarithromycin-susceptible strains, and 50% (30 of 60) for clarithromycin-resistant strains. The eradication rates were 88% (332 of 379) and 96% (77 of 80) in extensive metabolizers and poor metabolizers, respectively. CONCLUSIONS: Rabeprazole-based therapies achieved 50% eradication of clarithromycin-resistant H. pylori, and even achieved good rates in extensive metabolizers. Accordingly, rabeprazole can be recommended as part of a first-line proton pump inhibitor-based triple therapy for H. pylori.

Oxyntomodulin analog and exendin-4 derivative lower plasma glucose in cattle.

The present study was undertaken with the aim of examining whether and how exendin-4 (1-3) fragment, ie, Ex-4 (1-3) fragment, contributes to the regulation of glucose. An analog of oxyntomodulin (OXM) ([Gly2, Glu3]-OXM), a glucagon analog ([Gly2, Glu3]-glucagon), and two derivatives of Ex-4 (glucandin and [Gly2, Glu3]-glucandin) were synthesized by substituting with Gly2, Glu3 at the N-terminuses of OXM and glucagon and/or by attaching Ex-4 (30-39) amide at the C-terminus of glucagon. Effects of these peptides on plasma insulin and glucose concentrations were investigated in cattle by conducting 3 in vivo experiments. In all 3 experiments, 0.1% BSA saline was injected as a control. In experiment 1, glucandin (amino acid sequence was glucagon [1-29]-Ex-4 [30-39] amide) and [Gly2, Glu3]-glucandin were injected at the dose rates of 5 µg/kg BW in 4-mo-old Holstein steers. Results showed that glucoregulatory effects of glucandin were similar to those of glucagon. [Gly2, Glu3]-glucandin stimulated insulin secretion at 2 to 10 min and lowered glucose concentrations at 15 to 75 min. Experiment 2 was carried out to better understand the glucose-lowering potency of [Gly2, Glu3]-glucandin, in comparison with Ex-4 and glucagon-like peptide-1 (GLP-1), using 4.5-mo-old Holstein steers. [Gly2, Glu3]-glucandin was injected at dose rates of 0.3 µg/kg BW, 1.0 µg/kg BW, 3.2 µg/kg BW, and 6.4 µg/kg BW. Ex-4 and GLP-1 were injected at dose rates of 0.3 µg/kg BW. Results showed that the insulinotropic and glucose-lowering effects of [Gly2, Glu3]-glucandin were not as potent as for Ex-4 and GLP-1, and the minimum effective dose of [Gly2, Glu3]-glucandin to regulate plasma glucose concentrations was 3.2 µg/kg BW. In experiment 3, [Gly2, Glu3]-OXM and [Gly2, Glu3]-glucagon were injected at dose rates of 5 µg/kg BW in 5-mo-old Holstein steers. Both [Gly2, Glu3]-OXM and [Gly2, Glu3]-glucagon increased insulin concentration. [Gly2, Glu3]-OXM potently lowered plasma glucose, but [Gly2, Glu3]-glucagon did not change it. In summary, our findings clearly demonstrate that Ex-4 (1-3) fragment contributes to the regulation of glucose. [Gly2, Glu3]-OXM and [Gly2, Glu3]-glucandin are insulinotropic and glucose-lowering peptides. It was of interest that the substitution of the first 3 amino acids of OXM with Ex-4 (1-3) could reverse the upregulation of glucose by OXM into downregulation of glucose. In lowering glycemia, [Gly2, Glu3]-OXM seemed almost as effective as Ex-4, and [Gly2, Glu3]-glucandin was less profound than Ex-4. These findings contributed new insights into the hormonal regulation of glucose in ruminants. The action of [Gly2, Glu3]-OXM and [Gly2, Glu3]-glucandin might provide an advantage in glycemic control of insulin resistance in cattle and humans.

Effect of conjugated linoleic acid type, treatment period, and dosage on differentiation of 3T3 cells.

This study was conducted to determine effect of CLA and linoleic acid (LA) on cell differentiation, cellular glycerol-3-phosphate dehydrogenase (GPDH) activity, and FA accumulation in differentiating 3T3-L1 cells (3 isomers x 3 treatment periods x 4 doses). The cells were cultured in 24-well plates for proliferation until confluence. Then they were treated with media containing 0, 10, 35, or 70 mg/L (0, 35, 125, or 250 mmol/L, respectively) of LA, cis9,trans11- or trans10,cis12-CLA during early (day 0-2), intermediate and late (day 3-8), or overall (day 0-8) differentiation periods. Dexamethasone, methyl-isobutylxanthine, and insulin were supplemented to the media only for the early period to induce the differentiation. On day 8 of postconfluence the cells were harvested for Oil Red O staining, analysis of GPDH activity, and determination of the FA Concentration. Cellular LA or CLA was found to accumulate in a dose-response manner, mainly during the intermediate/late period. Treatment with trans10,cis12-CLA lowered (P < 0.05) GPDH activity and the concentration of FA including palmitic acid (16:0) and palmitoleic acid (16:1), especially during the intermediate/late and overall periods, or whenever a high dose of 70 mg/L was applied. This also resulted in a higher (P < 0.05) ratio of saturated FA to monounsaturated FA. Treatment with LA or cis9,trans11-CLA lowered cellular FA only when they applied during the early period at a dose of 70 mg/L. The results demonstrated that the inhibitory effects of CLA on differentiation, GPDH activity, and FA accumulation of 3T3-L1 cells are dependent on the isomer type, treatment period, and dose.

Insulinotropic action of bombesin-like peptides mediated by gastrin-releasing peptide receptors in steers.

The present study characterizes the receptor that mediates the insulinotropic action of bombesin-like peptides (BLP) in ruminants. Eight Holstein steers were randomly and intravenously injected with synthetic bovine gastrin-releasing peptide (GRP; 0.9 nmol/kg BW), neuromedin B (NMB; 0.9 nmol/kg BW), or neuromedin C (NMC; 0.9 nmol/kg BW), each alone or combined with the antagonist of GRP receptors N-acetyl-GRP-OCHCH (N-GRP-EE; 22.5 nmol/kg BW) or the antagonist of GH secretagogue receptor type 1a (GHS-R1a) [D-Lys]-GHRP-6 (21.5 nmol/kg BW). Blood samples were collected at -10, 0 (just before injection), 5, 10, 15, 20, 30, 45, 60, 75, and 90 min relative to injection time. Levels of injected peptides, insulin, and glucose in plasma were analyzed. Results showed that the peak of insulin levels was seen at 5 min after injection of NMC or GRP. Plasma glucose was observed in 2 phases; a significant rise followed a remarkable fall after NMC or GRP administration compared with injection of the vehicle ( < 0.05). On a same molar basis, effects of GRP on insulin and glucose were more potent than those of NMC ( < 0.05). The NMC-induced changes of insulin and glucose were completely blocked by N-GRP-EE, but [D-Lys]-GHRP-6 did not block any of these changes. Administration of NMB or N-GRP-EE alone did not change the circulating levels of insulin or glucose during any of the sampling time points ( > 0.05). These results indicated that the insulinotropic action of BLP is mediated by GRP receptors but not through a ghrelin/GHS-R1a pathway and that BLP may be involved in the regulation of glucose homeostasis in ruminants.

The membrane potential modulates the ATP-dependent Ca2+ pump of cardiac sarcolemma.

The effect of membrane potential on the activity of the ATP-dependent Ca2+ pump of isolated canine ventricular sarcolemmal vesicles was investigated. The membrane potential was controlled by the intravesicular and extravesicular concentration of K+, and the initial rates of Ca2+ uptake both in the presence and the absence of valinomycin were determined. The rate of Ca2+ uptake was stimulated by a inside-negative potential induced in the presence of valinomycin. The valinomycin-dependent stimulation was enhanced by the addition of K+ channel blocker, tetraethylammonium ion or Ba2+. The electrogenicity of cardiac sarcolemmal ATP-dependent Ca2+ pump is suggested from the increase of Ca2+ uptake by negative potential induced by valinomycin.

cGMP potentiates receptor-stimulated Ca2+ influx in Dictyostelium discoideum.

Binding of extracellular cAMP to surface receptors induces at least two responses in Dictyostelium discoideum, the G-protein-dependent activation of guanylyl cyclase, and the opening of a plasma membrane Ca2+ channel. Some experiments suggest that intracellular cGMP opens the Ca2+ channel, while others demonstrate that the channel can open in the absence of functional G-proteins (and thus in the absence of cGMP formation). We have analysed 45Ca2+ uptake in three mutants with altered cGMP formation. Mutant stmF shows a prolonged cGMP response due to deletion of an intracellular phosphodiesterase. Uptake of receptor-stimulated 45Ca2+ is enhanced about two-fold in this mutant if compared to wild-type cells, suggesting that cGMP regulates the opening of the channel. Mutant KI-7 has very low levels of surface cAMP receptors, but nevertheless an enhanced receptor-stimulated cGMP response due to a defect in the turn-off of guanylyl cyclase. This mutant shows poor receptor-stimulated 45Ca2+ uptake, suggesting that cGMP alone is not sufficient to open the Ca2+ channel. Finally, mutant KI-8 has no cGMP due to the absence of nearly all guanylyl cyclase activity. The mutant shows significant but reduced 45Ca2+ uptake (19% of wild-type; 60% if corrected for the reduced level of surface cAMP receptors), suggesting that the channel can open in the absence of cGMP. Taken together, the results demonstrate that receptor-stimulated Ca2+ influx is not directly induced by cGMP formation; it can occur in the absence of cGMP, but is potentiated two- to four-fold by cGMP.

Aberrant cGMP-binding activity in non-chemotactic Dictyostelium discoideum mutants.

The kinetics of cGMP-binding to the major cGMP-binding activity in Dictyostelium were investigated in 10 non-chemotactic mutants (KI mutants; KI-1 approximately 10). A wild-type cell contains about 3000 binding sites with a Kd of 1.5 nM. cGMP may dissociate from these binding sites with fast (F-type) or slow (S-type) kinetics, and DNA has been shown to promote the conversion of F- to S-type of cGMP-binding. The 10 mutants were placed in 4 classes, based on equilibrium and non-equilibrium binding properties and the effect of DNA. Class I mutants (KI-1, 3 and 8) have normal cGMP-binding properties. Class II mutants (KI-2, 6 and 7) show increased Kd values but nearly normal Bmax, normal F/S ratio and normal effects of DNA. Class III mutants (KI-4, 5 and 10) have a strongly decreased Kd and increased Bmax, nearly all binding sites are of the S-type and DNA does not affect the binding; apparently these mutants have a cGMP-binding protein locked in the S-form. cGMP-binding in class IV mutant (KI-9) is normal except that the number of binding sites is increased about 3-fold. The finding of seven mutants with altered cGMP-binding in 10 non-chemotactic mutants suggests that the cGMP-binding activity plays an important role in the chemotactic signal transduction pathway.

Effects of dietary protein and growth hormone-releasing peptide (GHRP-2) on plasma IGF-1 and IGFBPs in Holstein steers.

This study was conduct to determine the influence of dietary protein on the response of plasma insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding proteins (IGFBPs) to exogenous growth hormone releasing peptide-2 (GHRP-2 or KP 102) in Holstein steers. Eight 16-month-old Holstein steers were grouped by liveweight to two feeding treatments; high protein (HP; CP 1.38 kg/day and TDN 4.5 kg/day DM intake, n=4) or low protein (LP; CP 0.66 kg/day and TDN 4.42 kg/day DM intake, n=4). The experiment was a single reverse design whereby each group was injected twice daily with GHRP-2 (12.5 microg/kg body weight (BW)/day) or saline solution into the jugular vein for a 6-day period. Plasma IGF-1 in the HP group were higher than in the LP group (P<0.05), but plasma 34 kDa IGFBP-2 was lower in the HP than the LP group (P<0.05). The amplitude of the maximum growth hormone (GH) peaks responding to GHRP-2 injection were higher at day 1 than at day 6 of saline or GHRP-2 treatment in both LP and HP steers (P<0.05). The area under the GH response curve for 180 min after the GHRP-2 injection was not significantly different between the LP and the HP groups at days 1 and 6. A response in plasma IGF-1 concentration to GHRP-2 treatment in the HP group was observed at day 1 (198.9+/-18.1 ng/ml), day 2 (195.2+/-21.1 ng/ml) and day 6 (201.3+/-14.8 ng/ml) (P<0.05). No increase in plasma IGF-1 was observed from GHRP-2 administration in the LP group. Although the response of plasma IGF-1 concentration to GHRP-2 administration was increased in the HP group (P<0.05), there was no apparent effect of GHRP-2 treatment on plasma 38-43 kDa IGFBP-3 and 34 kDa IGFBP-2 at days 2 and 6 of treatment. In conclusion, it is proposed that the 34 kDa IGFBP-2 is sensitive to dietary protein level and may play an important role in the regulation of circulating IGF-1 in ruminant. In addition, increased plasma IGF-1 concentration observed in the HP group in response to the GHRP-2 treatment did not appear to affect plasma IGFBPs.

cGMP as second messenger during Dictyostelium chemotaxis.

The chemoattractant cAMP induces directed cell locomotion in Dictyostelium cells. Several second messenger pathways are activated upon binding of cAMP to G-protein-coupled receptors, including adenylyl cyclase, guanylyl cyclase, phospholipase C, and the opening of plasma membrane Ca2+ channels. These second messenger responses are unaltered in many chemotactic mutants, except for the cGMP response. Activation of guanylyl cyclase depends on G-proteins and is regulated by a cGMP-binding protein in a complex manner. This cGMP-binding protein also mediates intracellular functions of cGMP to activate a PKC-related kinase that phosphorylates myosin II heavy chain, thereby allowing myosin filaments to rearrange during cell movement.

Chemotactic and osmotic signals share a cGMP transduction pathway in Dictyostelium discoideum.

In the ameboid eukaryote Dictyostelium discoideum, chemotactic stimulation by cAMP induces an increase of intracellular cGMP and subsequently the phosphorylation of myosin heavy chain II. Resistance to high osmotic stress also requires transient increases of intracellular cGMP and phosphorylation of myosin heavy chain II, although the kinetics is much slower than for chemotaxis. To examine if chemotaxis and osmotic stress share common signaling components we systematically analyzed the osmotic cGMP response and survival in chemotactic mutants with altered cGMP signaling. Null mutants with deletions of cell surface cAMP receptors or the associated GTP-binding proteins Galpha2 and Gbeta show no cAMP-induced cGMP response and chemotaxis; in contrast, osmotic stress induces the normal cGMP accumulation and survival. The same result was obtained with the non-chemotactic mutant KI-10, which lacks the activation of guanylyl cyclase by cAMP. This indicates that these components are required for chemotaxis but not osmotic cGMP signaling and survival. The potential guanylyl cyclase null mutant KI-8 shows no chemotaxis, no osmotic cGMP increase and reduced survival in high osmolarity. Two types of cGMP-binding protein mutants, KI-4 and KI-7, also show reduced tolerance during high osmotic stress. Taken together, these observations clarify that chemotactic and osmotic signals are detected by different mechanisms, but share a cGMP signaling pathway.

The effect of the replacement of ADP with a photoaffinity ATP analogue, 2-azido-ADP, in F-actin on its function.

2-Azido-ATP, a photoaffinity ATP analogue, was incorporated into actin and the influence of the incorporation on the actin function was studied. The replacement of ADP with 2-azido-ADP in F-actin both before and after photocross-linking decreased appreciably the actin-activated S1-ATPase activity. Photocross-linked 2-azido-ADP-F-actin could be depolymerized by dialysis against a solution containing 0.1 mM CaCl2, 0.1 mM ATP and 1 mM Tris-HCl (pH 8.0). However, once it depolymerized, it lost very quickly the ability to polymerize even in the presence of a sufficient amount of ATP and Ca2+.

Effects of sucralfate, 15(R)15-methyl prostaglandin E2, and cimetidine on rat gastric mucosal damage induced by ethanol.

The efficacy of sucralfate, 15(R)15-methyl prostaglandin E2, and cimetidine in protecting against ethanol injury in rat stomachs was examined. Rats that had been fasted were pretreated intragastrically with either sucralfate 160 mg/kg, 15(R)15-methyl prostaglandin E2 16 micrograms/kg, cimetidine 100 mg/kg, or an equal amount of vehicle alone (control). One hour later, all rats received 1 ml of 99.5 percent ethanol orally and were killed 15 minutes or 24 hours later. Stomachs were removed, and mucosal damage was assessed macroscopically as well as by scanning electron microscopy. Pretreatment with either 15(R)15-methyl prostaglandin E2 or sucralfate significantly reduced the number and extent of ethanol-induced mucosal gastric lesions; pretreatment with cimetidine, however, failed to produce positive results. It is concluded that the abilities of 15(R)15-methyl prostaglandin E2 and sucralfate in protecting against ethanol injury are comparable.

Effects of sucralfate, lansoprazole, and cimetidine on the delayed healing by hydrocortisone sodium phosphate of chronic gastric ulcers in the rat.

We have previously shown that chronic sucralfate ingestion stimulates gastric epithelial proliferation in rats, which may explain one of the beneficial effects of sucralfate in healing of peptic ulcers. In a separate study, we have found that chronic steroid administration delays the healing of experimental gastric ulcers in rats. This study was designed to test the beneficial effects of sucralfate, cimetidine, and lansoprazole (AG-1749, a new proton pump inhibitor), on the delayed healing by steroids in rat chronic gastric ulcers. Chronic gastric ulcers were produced in male Wistar rats, weighing 180 g, by the application of 100% acetic acid. The rats were randomly divided into five groups; (1) control, (2) vehicle alone, (3) 10 mg/kg lansoprazole, (4) 500 mg/kg sucralfate, and (5) 100 mg/kg cimetidine. Except for controls, all rats received daily intraperitoneal injections of 2.5 mg/kg hydrocortisone sodium phosphate. Tested drugs were administered intragastrically (lansoprazole and sucralfate) or intraperitoneally (cimetidine) twice a day for 2 weeks. Rats were sacrificed 14 days later and ulcer size was measured. Chronic administration of hydrocortisone sodium phosphate resulted in a significant delay of ulcer healing induced by acetic acid. Treatment with either lansoprazole or sucralfate abolished the deleterious effect of steroids, whereas cimetidine had no effect. These results indicate that lansoprazole and sucralfate overcome the delayed healing by steroids of chronic gastric ulcers in the rat.

The effect of NSAIDs and a COX-2 specific inhibitor on Helicobacter pylori-induced PGE2 and HGF in human gastric fibroblasts.

BACKGROUND: There is compelling evidence for the pivotal role of Helicobacter pylori in the pathogenesis of gastrointestinal ulcer disease. However, despite the bacterium's toxicity, the majority of H. pylori infections are not accompanied by gastric ulcers. This implies the existence of a host mechanism offsetting H. pylori toxicity. AIMS: To evaluate gastric fibroblasts' expression of hepatocyte growth factor (HGF), which is known to facilitate gastric ulcer healing, in the presence of H. pylori; to compare the effect on H. pylori-induced HGF expression of a COX-2 selective inhibitor with that of nonselective nonsteroidal anti-inflammatory drugs METHODS: Human gastric fibroblasts were cultured from human gastric mucosa obtained at surgery. Prostaglandin E2 (PGE2) and HGF were measured by EIA. The expression of COX-2 mRNA was assessed by the TaqMan quantitative RT-PCR system. RESULTS: H. pylori increased PGE2 release in gastric fibroblasts. H. pylori induced expression of COX-2 mRNA, which indicates that PG induction by H. pylori is through COX-2. Sulindac sulphide, etodolac and NS 398 all inhibited H. pylori-induced PGE2 release to the same extent. These agents also inhibited H. pylori-induced HGF release. CONCLUSION: Gastric fibroblasts produce PG and HGF in response to the presence of H. pylori, which may be considered part of the human body's defensive reaction to H. pylori toxicity. This defensive mechanism is inhibited not only by COX-2 nonselective NSAIDs but also by a COX-2 selective inhibitor. These findings indicate the importance of COX-2 in chronic H. pylori infection.

Gastric restitution is inhibited by dexamethasone, which is reversed by hepatocyte growth factor and rebamipide.

BACKGROUND: Glucocorticoids have been shown to induce peptic ulcers, especially when co-administered with NSAIDs. Hepatocyte growth factor (HGF) plays a role in gastric ulcer repair, facilitating the restitution of gastric mucosal epithelial cells. HGF expression is induced by PGs in gastric fibroblasts. We hypothesized that dexamethasone (DEX) may inhibit PG production and HGF expression, thus inhibiting HGF-induced gastric epithelial restitution. AIM: To investigate the effect of DEX on gastric restitution, using cultured gastric cells, the role of HGF in the restitution inhibited by DEX, and the effect of rebamipide on DEX- inhibited restitution. METHODS: Human gastric fibroblasts were prepared from human stomach obtained at surgery; PGE2 and HGF is determined by ELISA; Restitution was assessed by the round wound restitution model, using coculture of gastric fibroblasts and epithelial cells; COX-2 and HGF mRNA were quantified by TaqMan RT-PCR system. RESULTS: 1. DEX inhibited HGF mRNA and COX-2 mRNA. Accordingly, it inhibited PGE2 and HGF release. 2. DEX inhibited the restitution of gastric cells. 3. The inhibition of restitution was reversed by HGF and rebamipide to the same extent. 4. Rebamipide induced PGE2 and HGF. CONCLUSION: DEX inhibits restitution via HGF depletion, and rebamipide reverses the inhibited restitution by HGF induction.