Protective effect of teprenone against acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

The protective effect of teprenone, an anti-ulcer drug, against acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (0.75 mg/kg). Teprenone (50, 100, or 200 mg/kg) was orally administered 0.5 h before compound 48/80 treatment. Administered teprenone prevented gastric mucosal lesion development found at 3 h after compound 48/80 treatment dose-dependently, although no dose of teprenone affected the decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 3 h after the treatment. Increases in the activities of myeloperoxdiase (an index of neutrophil infiltration) and xanthine oxidase and the content of thiobarbituric acid reactive substances (an index of lipid peroxidation) and decreases in the contents of hexosamine (a marker of gastric mucus) and adherent mucus occurred in gastric mucosal tissues at 3 h after compound 48/80 treatment. Administered teprenone dose-dependently attenuated all these changes found at 3 h after compound 48/80 treatment. These results indicate that orally administered teprenone protects against compound 48/80-induced acute gastric mucosal lesions in rats possibly through its stimulatory action on gastric mucus synthesis and secretion and its inhibitory action on neutrophil infiltration and enhanced lipid peroxidation in the gastric mucosal tissue.     

Protective effect of omeprazole against acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats.

Omeprazole, a proton pump inhibitor is known to function not only as a proton pump inhibitor but also as an anti-inflammatory agent, an antioxidant or a stimulator of gastric mucus secretion. We have shown that the pathogenesis of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats involves neutrophil infiltration, lipid peroxidation, and mucin depletion, but not acid secretion, in the gastric mucosal tissue. Therefore, we examined whether omeprazole protects against acute gastric mucosal lesions induced by compound 48/80 in rats. Rats were injected with omeprazole (10 or 50 mgkg(-1), i.p.) at 0.5h before injection of compound 48/80 (0.75 mgkg(-1), i.p.). Omeprazole prevented gastric mucosal lesion development at 0.5 and 3h after compound 48/80 injection. Omeprazole attenuated decreased nonprotein sulfhydryl content and increased myeloperoxidase and xanthine oxidase (XO) activities and lipid peroxide (LPO) content in the gastric mucosa at 0.5h after compound 48/80 injection and increased myeloperoxidase and XO activities and LPO content, but not decreased hexosamine and adherent mucus contents, in the gastric mucosa at 3h. These results indicate that omeprazole protects against compound 48/80-induced acute gastric mucosal lesions in rats possibly through its anti-inflammatory and antioxidant actions.     

Protective effect of ebselen,a seleno-organic compound,against the progression of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator,in rats

The protective effect of ebselen, which possesses glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties, against the progression of acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (0.75 mg/kg). Ebselen (50, 100 or 200 mg/kg) was orally administered 0.5 h after compound 48/80 treatment, at which time gastric mucosal lesions appeared. Post-administered ebselen suppressed gastric mucosal lesion progression at 3 h after compound 48/80 treatment dose-dependently, although no dose of ebselen affected the decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 3 h after the treatment. A decrease in Se-glutathione peroxidase activity and increases in myeloperoxidase and xanthine oxidase activities and the concentration of thiobarbituric acid reactive substances were found in gastric mucosal tissues at 0.5 h after compound 48/80 treatment, and these changes were further enhanced at 3 h. Post-administered ebselen attenuated all these changes found at 3 h after compound 48/80 treatment dose-dependently. The present results indicate that ebselen exerts a protective effect against the progression of compound 48/80-induced acute gastric mucosal lesions in rats, and they suggest that this protective effect of ebselen could be due to its glutathione peroxidase-like activity and its antioxidative and anti-inflammatory properties.     

Effect of oral vitamin E administration on acute gastric mucosal lesion progression in rats treated with compound 48/80, a mast cell degranulator

The effect of oral vitamin E administration on acute gastric mucosal lesion progression was examined in rats treated once with compound 48/80 (C48/80) (0.75 mg/kg, i.p.) in comparison with that of subcutaneously administered superoxide dismutase (SOD) plus catalase (CAT). Vitamin E (50, 100 or 250 mg/kg) administered at 0.5 h after C48/80 treatment reduced progressive gastric mucosal lesions at 3 h after the treatment dose-dependently, like SOD plus CAT administered at the same time point. The gastric mucosa of C48/80-treated rats had decreased Se-glutathione peroxidase activity and vitamin E, ascorbic acid, and hexosamine contents and increased myeloperoxidase and xanthine oxidase activities and thiobarbituric acid reactive substances content at 3 h after the treatment. Administered vitamin E attenuated all these changes found at 3 h after C48/80 treatment dose-dependently, like administered SOD plus CAT. C48/80-treated rats administered with vitamin E (100 or 250 mg/kg) had higher gastric mucosal vitamin E content than C48/80-untreated rats. Neither administered vitamin E nor SOD plus CAT had any effect on the increases in serum serotonin and histamine concentrations and the decrease in gastric mucosal blood flow found at 3 h after C48/80 treatment. In the gastric mucosa of C48/80-untreated rats administered with vitamin E, thiobarbituric acid reactive substances content decreased with an increase in vitamin E content. These results indicate that orally administered vitamin E prevents acute gastric mucosal lesion progression in C48/80-treated rats possibly by suppressing oxidative stress, neutrophil infiltration, and mucus depletion in the gastric mucosa like administered SOD plus CAT.     

Effect of gefarnate on acute gastric mucosal lesion progression in rats treated with compound 48/80, a mast cell degranulator, in comparison with that of teprenone

We have reported that teprenone (geranylgeranylacetone), an anti-ulcer drug, prevents acute gastric mucosal lesion progression in rats treated once with compound 48/80 (C48/80), a mast cell degranulator, possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa. Herein, we examined the preventive effect of gefarnate (geranyl farnesylacetate), an anti-ulcer drug, on acute gastric mucosal lesion progression in rats treated once with C48/80 (0.75 mg/kg, i.p.) in comparison with that of teprenone, because the chemical structure and anti-ulcer action of gefarnate are similar to those of teprenone. Gefarnate (50, 100 or 200 mg/kg) administered orally at 0.5 h after C48/80 treatment, at which time gastric mucosal lesions appeared, reduced progressive gastric mucosal lesions at 3 h dose-dependently. At 3 h after C48/80 treatment, the gastric mucosa had decreased adherent mucus and hexosamine contents and increased myeloperoxdiase (an index of neutrophil infiltration) and xanthine oxidase activities and thiobarbituric acid reactive substances (an index of lipid peroxidation) content. Post-administered gefarnate attenuated all these changes dose-dependently. These preventive effects of gefarnate were similar to those of teprenone at a dose of 200 mg/kg. Post-administered gefarnate did not affect the increases in serum serotonin and histamine concentrations and the decrease in gastric mucosal blood flow at 3 h after C48/80 treatment like teprenone. These results indicate that orally administered gefarnate prevents acute gastric mucosal lesion progression in C48/80-treated rats possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa like teprenone.     

Role of endogenous serotonin and histamine in the pathogenesis of gastric mucosal lesions in unanaesthetised rats with a single treatment of compound 48/80, a mast cell degranulator.

In unanaethetised rats with a single injection of compound 48/80, a mast cell degranulator (0.75 mg kg-1, i.p.), gastric lesions occurred with increased serum serotonin and histamine levels and reduced gastric mucosal blood flow at 0.5 h after the injection and developed at 3 h. Pretreatment with either cyproheptadine (a serotonin and histamine antagonist) or methysergide (a serotonin antagonist) prevented the formation of gastric mucosal lesions with attenuation of reduced gastric mucosal blood flow at 0.5 h after compound 48/80 injection, while pretreatment with either amitriptyline (a selective inhibitor of histamine release from mast cells), tripelennamine (a histamine H1-receptor antagonist), famotidine (a histamine H2-receptor antagonist) or cimetidine (a histamine H2-receptor antagonist) had no effect. Pretreatment with either cyproheptadine, methysergide, amitriptyline or tripelennamine prevented the development of gastric mucosal lesions at 3 h after compound 48/80 injection, while pretreatment with either famotidine or cimetidine had no effect. These results indicate that in unanaesthetised rats with a single compound 48/80 treatment, acutely released endogenous serotonin causes gastric mucosal lesions, while released endogenous histamine mainly contributes to the lesion development and that gastric acid plays little role in the pathogenesis of the compound 48/80-induced acute gastric lesions.     

Acute intracerebroventricular injections of the mast cell degranulator compound 48/80 and behavior in rats

The intracerebroventricular (ICV) injection of the mast cell degranulator Compound 48/80 (2.5-2.0 micrograms/kg) produced a marked behavioral syndrome in normotensive rats. The behaviors included head and body shakes, paw tremor, excessive grooming, unusual posture and gait, mild diarrhoea, piloerection, extreme agitation and irritability to touch, and a later phase of sedation. The highest doses (15 and 20 micrograms/kg) also produced catalepsy and episodes of "barrel rolling" (continuous rolling of 1-8 turns around the longitudinal axis). These behaviors were observed for approximately 15-30 min although the sedation and catalepsy were maintained for 90-120 min. A second ICV injection of the 10 micrograms/kg dose of Compound 48/80 given 2 hr after an initial injection of this dose, produced a much reduced response and the numbers of head and body shakes, and episodes of paw tremor and grooming were between 20-30% of those produced by the first injection. The reduced effect of the second injection indicates that the behavioral effects of Compound 48/80 may arise from the acute degranulation of mast cells rather than direct effects on neuronal populations or the cerebral vasculature.     

Preventive effect of teprenone on acute gastric mucosal lesion progression in compound 48/80-treated rats

The preventive effect of teprenone (6,10,14,18-teramethyl-5,9,13,17-nonadecatetaene-2-one), an anti-ulcer drug, on acute gastric mucosal lesion progression was examined in rats with a single intraperitoneal (i.p.) injection of compound 48/80 (0.75 mg/kg). Teprenone (20, 100 or 200 mg/kg), which was orally administered 0.5 h after compound 48/80 treatment at which time gastric mucosal lesions appeared, prevented gastric mucosal lesion development at 3 h after the treatment dose-dependently. Gastric mucosal tissues of compound 48/80-treated rats showed increases in myeloperoxidase (an index of neutrophil infiltration) and xanthine oxidase activities and thiobarbituric acid reactive substances (an index of lipid peroxidation) content and decreases in Se-glutathione peroxidase activity and hexosamine and vitamin E contents at 3 h after the treatment. Post-administered teprenone attenuated all these changes dose-dependently. These results indicate that teprenone prevents acute gastric mucosal lesion progression in compound 48/80-treated rats possibly by suppressing gastric mucus depletion, neutrophil infiltration and oxidative stress in the gastric mucosal tissue.     

The intracerebroventricularly administered mast cells degranulator compound 48/80 increases the pituitary-adrenocortical activity in rats

The effect of brain mast cells degranulation by compound 48/80 on the pituitary-adrenocortical activity, measured indirectly through corticosterone secretion, and the involvement of a histaminergic mechanism in that stimulation was investigated in conscious rats. All the drugs were given intracerebroventricularly (icv), histamine antagonists 15 min prior to compound 48/80. Compound 48/80 induced a significant dose- and time-related increase in the serum corticosterone levels. That increase, measured 1 h after administration of compound 48/80, was moderately diminished by icv pretreatment of rats with mepyramine and cimetidine, histamine H1- and H2-receptor antagonists. Three hours after administration of compound 48/80 mast cells of the thalamus and the hypothalamus were completely degranulated. At the same time the thalamus and the whole brain histamine levels were substantially higher than in the saline-treated control rats. The above results suggest that histamine liberated from the brain mast cells and central histamine receptors play a moderate role in increasing the pituitary-adrenocortical activity by compound 48/80.     

Effect of cimetidine on the mucosal hydroxyproline content of rat gastric lesions induced by compound 48/80.

Extensive gastric mucosal lesions developed in rats after the administration of compound 48/80 at a dose of 0.75 mg/kg daily for 3 days. The hydroxyproline content of gastric mucosa was significantly increased 4 h after the last injection of compound 48/80, and subsequently decreased as the lesions healed. Treatment with cimetidine (CAS 51481-61-9) at a dose of 50 mg/kg (twice a day for 3 days) did not affect either the development or the healing of the compound 48/80-induced gastric lesions. However, the increase in mucosal hydroxyproline content was significantly reduced by treatment with cimetidine. This fact suggests that cimetidine might have an inhibitory effect on the regeneration of collagen in gastric mucosa.     

Plaunotol prevents indomethacin-induced gastric mucosal injury in rats by inhibiting neutrophil activation

BACKGROUND: Activated neutrophils play a critical role in indomethacin-induced gastric mucosal injury. AIM: To investigate the effect of plaunotol, an anti-ulcer agent, on neutrophil activation in vitro and its effect on gastric mucosal injury and gastric accumulation of neutrophils in rats given indomethacin. METHODS: Human monocytes and neutrophils were isolated from the peripheral blood of healthy volunteers. We examined the effect of plaunotol on neutrophil elastase release, production of O2-, intracellular calcium concentration and expression of adhesion molecules CD11b and CD18 in activated neutrophils in vitro. The effect of plaunotol on TNF-alpha production by monocytes stimulated with endotoxin also was investigated in vitro. The effect of plaunotol (100 mg/kg, p.o.) on gastric mucosal injury and neutrophil accumulation was investigated in male Wistar rats given indomethacin (30 mg/kg, p.o.). RESULTS: Plaunotol inhibited the fMLP-induced release of neutrophil elastase from activated neutrophils, as well as the opsonized zymosan-induced production of O2- by neutrophils. Plaunotol significantly inhibited increased levels of intracellular calcium, a second messenger of neutrophil activation, in vitro. The fMLP-induced increases in CD11b and CD18 expression were also inhibited by plaunotol in vitro. Plaunotol inhibited monocytic production of TNF-alpha, a potent activator of neutrophils. Both gastric mucosal injury and gastric neutrophil infiltration in rats given indomethacin were significantly inhibited by the oral administration of plaunotol. CONCLUSIONS: Plaunotol inhibits indomethacin-induced gastric mucosal injury, at least in part by inhibiting neutrophil activation.     

Changes in membrane potential induced by compound 48/80 in the peritoneal mast cells of rats

The changes in membrane potential induced by compound 48/80 were studied using rat peritoneal mast cells. The mean resting membrane potential of rat mast cells was -12.3 +/- 0.7 mM. When compound 48/80 was added to the mast cells, the cells were degranulated approximately 120 sec after the addition of the drug, after which immediate depolarization occurred. Degranulation of mast cells was not observed, even under the depolarization or hyperpolarization conditions caused by the replacement of a high K+ medium or the removal of K+ from the medium, respectively. Under both conditions, when compound 48/80 was added to the mast cells, degranulation was observed. Abrupt and marked depolarization was induced 30-60 sec after compound 48/80 was added. In addition, repolarization followed by gradual depolarization was observed without degranulation in mast cells treated with cytochalasin D after the addition of compound 48/80. These results suggest that the mast cells were depolarized by compound 48/80 independently of degranulation. It is also feasible that the gradual depolarization and repolarization induced by compound 48/80 in mast cells pretreated with cytochalasin D participated in the extracellular Na+ and Na+/K(+)-pump, respectively.     

Tea catechins have dual effect on mast cell degranulation induced by compound 48/80

Green tea catechins are emerging as one of the most efficient and safest ingredient in health promoting food. We investigated catechin's effects on intracellular ROS generation in mast cell activation and degranulation. Compound 48/80, receptor mimetic basic secretagogues for mast cell, induced ROS generation dose-dependently with bell-shaped degranulation pattern in canine cutaneous mastocytoma cells (CM-MC). When intracellular ROS level was relatively low, catechins decreased both ROS and the degranulation. However, when intracellular ROS level was remarkably high, catechins decreased ROS level but increased the degranulation paradoxically. Gallocatechins showed the stronger effects than non-gallated catechins. Exogenous H(2)O(2) also shows dual effect on degranulation dose-dependently. EGCG shows the dual effect on the tyrosine and threonine phosphorylation depending on the concentration of compound 48/80. Particularly, 60 kDa protein tyrosine-phosphorylated by EGCG with 3 microg/ml of compound 48/80 might be a negative regulator for the degranulation. Taken together, there is an optimal level of ROS for the degranulation, and the catechins have a dual function by controlling ROS level.     

Histamine release induced from mast cells by active components of compound 48/80

Compound 48/80 and 14C-labeled compound 48/80 were synthesized, and fractionated by thin-layer chromatography into 14 components (A-N) with various histamine releasing activities and different Ca2+ requirements for their actions. The histamine release induced from rat mast cells in vitro by the most active component, fraction D (molecular weight = 2280, a tridecamer composed of 13 monomer units), was greatly enhanced by extracellular Ca2+, and was partially reduced by pretreatment of the cells with dinitrophenylated ascaris antiserum, an IgE. In contrast, the histamine release induced by fraction H (molecular weight = 1580, a nonamer composed of 9 monomer units), was higher in Ca2+ -free medium than in Ca2+-containing medium, and was partially reduced by pretreatment of mast cells with neurotensin or substance P, Ca2+-independent releasers. Apparently both fractions D and H are useful reagents for investigating the role of Ca2+ in histamine release and releaser binding in mast cells.     

Pharmacologic interference with mast cell degranulation induced by BW 48/80

Summary A number of therapeutically unrelated agents diminish mast cell degranulation induced by BW 48/80; phenylbutazone, acetylsalicylic acid, chlorpromazine, morphine, meperidine and etonitazine. The mechanisms by which these agents act is unknown. Administration of hydrocortisone, cortisone and ACTH has no effect on mast cell disruption. Hypophysectomy induces a greater resistance of mast cells against the disrupting effect of BW 48/80.With 4 Figures in the Text     

Role of gastric acid and bile acids in the pathogenesis of compound 48/80-induced gastric lesions in rats

We studied the effects of various agents, which influence gastric acidity and bile acids, on compound 48/80 (48/80)-induced gastric lesions in rats. 48/80-Induced gastric lesions were produced by repeated intraperitoneal administration of 48/80 at 0.75 mg/kg once daily for 4 days. Test agents were given orally twice daily (30 min before and 9 hr after 48/80 administration) for 4 days. AI(OH)3 and sucralfate at 2000 mg/kg/day, a weak antacid dose, significantly inhibited (about 50-60%) the development of 48/80-induced lesions. Propantheline at 60 mg/kg/day and omeprazole at 60 or 200 mg/kg/day, which reduced gastric secretion for more than 12 hr, also significantly inhibited (about 30-40%) these lesions. Cimetidine at 200 mg/kg/day, which reduced gastric secretion for only 5 hr, had little effect on the lesion formation. Cholestyramine, which is a potent bile acids binding agent, had no effect on 48/80-induced lesions in doses of 600 or 2000 mg/kg/day. These results suggest that gastric acid, but not bile acids, is partly involved in the pathogenesis of 48/80-induced gastric lesions.     

Circulatory depression and ventricular arrhythmias induced by compound 48/80 in anaesthetized rats.

The effects of graded doses of compound 48/80 on various cardiovascular and respiratory parameters were studied in pentobarbitone-anaesthetized rats. Following intravenous injections, this compound significantly depressed the mean blood pressure (MBP), left ventricular pressure (LVP) and dLVP/dtmax, and caused ventricular tachycardia (VT) or fibrillation (VF) and death. Heart rate (HR) response were variable, and there were no marked changes in airway resistance or blood gases. Pretreatment of the animals with either cimetidine or diphenhydramine significantly prolonged the time of onset of VT/VF but failed to alter the changes in other circulatory variables. A combination of cimetidine and diphenhydramine significantly alleviated the decreases in MBP and LVP and prevented the occurrence of VT/VF. It is suggested that the circulatory depression and the occurrence of ventricular arrhythmias following the administration of compound 48/80 result from activation of H1- and H2-receptors by elevated blood histamine levels due to release of the amine from tissues.     

ADP-ribosylation of rho proteins is inhibited by melittin, mast cell degranulating peptide and compound 48/80.

The amphiphilic agents melittin, mast cell degranulating peptide and compound 48/80 inhibit the ADP-ribosylation of the small GTP-binding proteins rho by Clostridium botulinum exoenzyme C3. Half-maximal and maximal inhibition (greater than 90%) of ADP-ribosylation occurred at about 8 and 25 micrograms/ml for compound 48/80, at 10 and 45 microM for mast cell degranulating peptide and at 15 and 50 microM for melittin, respectively. In addition, these compounds increase the steady state GTP hydrolysis and the association and dissociation rate of GTP-binding of rho proteins through an increase of GDP/GTP exchange. The data suggest that the amphiphilic agents tested interact with small GTP-binding proteins of the rho protein family.