Phosphodiesterase Type IV Inhibitors Prevent Ischemia-Reperfusion-Induced Gastric Injury in Rats

Anti-ulcerogenic effect of methanolic extract of Elaeagnus conferta Roxb. seeds in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Elaeagnus conferta Roxb. (Elaeagnaceae) is a subtropical shrub mainly native to India, Vietnam, Malaysia and South China, whose various parts are used for treatment of diabetes, gastric ulcers, pain, oxidative stress and pulmonary disorders. Though the other parts of the plant have been reported for their ethnic use i.e. fruits as astringent locally and for cancer systemically, leaves for body pain and flowers for pain in chest and the seeds are mentioned as edible, there is no report per se on the medicinal use of seeds. Based on the fact that seeds of closely resembling species i.e. Elaeagnus rhamnoides has demonstrated significant anti-gastroulcerative property, the probability of the seeds of E. conferta possessing similar activity seemed quite significant.

AIM OF THE STUDY

Phytochemical investigation and assessment of pharmacological mechanism(s) involved in anti-ulcer effect of methanolic extract of the seeds of E. conferta.

MATERIALS AND METHODS

Bioactive phytoconstituents were isolated by column chromatography. These were identified by spectroscopic techniques including infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) and mass spectrometry. Methanolic extract (MEC) of the seeds was prepared by cold maceration and its anti-ulcerogenic potential was evaluated using indomethacin (50 mg/kg) and water immersion stress models in male rats. The animals were pre-treated with different doses of MEC (400 and 800 mg/kg) and the therapeutic effect was compared with standard drug i.e. ranitidine (RANT; 50 mg/kg). The ameliorative effects of MEC were investigated on gastric juice pH, total acidity, free acidity and ulcer index. The assays of malionaldehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH) and pro-inflammatory cytokines i.e. interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were carried out to find out the possible mechanism(s) of protection. Further, histopathological changes were also studied.

RESULTS

Chromatography studies and further confirmation by spectroscopic techniques revealed the presence of four different compounds in MEC i.e oleic acid (1), stearic acid (2), ascorbic acid (3) and quercetin (4). MEC exhibited anti-ulcerogenic effect in dose dependent manner which may be attributed to suppression of pro-inflammatory cytokines (IL-6, TNF-α) and MDA (112.7%), and up-regulation of protective factors such as CAT (90.48%), SOD (92.77%) and GSH (90.01%). Ulcer inhibition, reduction in total and free acidity and increase in gastric juice pH were observed in MEC treated rats as compared to disease control animals. Histopathological findings confirmed decreased cell infiltration, less epithelial cell damage and regeneration of gastric mucosa in dose dependent manner.

CONCLUSIONS

The anti-ulcer effect of MEC may be attributed to its ability to scavenge free radicals and anti-inflammatory property via suppression of TNF-α and IL-6, thus offers a complete and holistic approach for management of peptic ulcer.

Possible protective effect of TNF-α inhibition and triad NO/cGMP/VEGF activation on gastric ulcer in rats

Peptic ulcers are one of the world's major gastrointestinal disorders, embracing both gastric and duodenal ulcers, and affecting 10% of the world population. The current study aimed to investigate the possible protective effect of tadalafil and pentoxifylline (PTX) on indomethacin-induced peptic ulcers. Male albino rats were divided into five groups: control group; ulcerated group; Indomethacin + Tadalafil, in which animals were pretreated with tadalafil orally before indomethacin; Indomethacin+ PTX, in which animals were pretreated with PTX orally before indomethacin; and Indomethacin + Tadafil + PTX. Indomethacin treatment revealed histopathological changes and ulcer scoring and ulcer index were markedly increased. Serum levels of prostaglandin and heme oxygenase-1 were significantly decreased. The ulcerogenic also induced marked oxidative stress as evident from the increased malondialdehyde, decreased in gastric glutathione content and superoxide dismutase activity, while the gastric myeloperoxidase was increased. Gastric nitric oxide content was decreased and the expression of vascular endothelial growth factor was downregulated while the tumor necrosis factor α (TNF-α) level was dramatically increased. Pretreatment of the ulcerative group by either tadalafil or PTX or their combination improved all these pathological changes. Tadalafil or PTX may have a role in protecting gastric mucosa damage caused by indomethacin which may be useful in the future for the treatment of gastric ulceration.

Methanolic Extract of Distemonanthus benthamianus (Caesalpiniaceae) Stem Bark Suppresses Ethanol/Indomethacin-Induced Chronic Gastric Injury in Rats

Distemonanthus benthamianus (Caesalpiniaceae) is a plant from the Cameroon pharmacopoeia very widely used in the treatment of many pathologies among which are gastrointestinal disorders. The main purpose of this study was to assess the healing properties of gastric ulcer from the methanolic extract of Distemonanthus benthamianus and its mechanisms of action. The healing properties of gastric ulcers (chronic ulcer model induced by ethanol and indomethacin) were evaluated in vivo in adult male rats, while the mechanisms of action were evaluated in vitro by anti-inflammatory assay (protein denaturation, cyclooxygenase, and lipoxygenase assays) and immunomodulatory assay (ROS production (using technical chemiluminescence), cytokine (TNF-α, IL-1β, IL-6) production (using ELISA), proliferation of T cells (using liquid scintillation counter), and cytotoxicity (using MTT assay)). The methanolic extract of Distemonanthus benthamianus inhibited protein denaturation (75.63%) and the activities of cyclooxygenase (78.92%) and 5-lipoxygenase (81.54%). The extract also significantly (p < 0.001) inhibited intracellular and extracellular ROS production and T cell proliferation and reduced significantly (p < 0.01, p < 0.001) TNF-α, IL-1β, IL-6, and PGE2 production. At all doses (125, 250, and 500 mg/kg), the extract significantly reduces the ulceration index and the area of ulceration and significantly increases the mass of gastric mucus. In addition, the extract significantly decreases the level of MDA, significantly increases the activities of catalase and glutathione, and then improves the hematological parameters in sick animals. Histological micrographs show that in the presence of the extract, there is advanced reepithelialization with recovery of the ulcerated epithelium. Thus, the extract of Distemonanthus benthamianus has healing properties against gastric ulcers which are associated with its anti-inflammatory, immunomodulatory, and antioxidant effects.

Description of a Novel Phosphodiesterase (PDE)-3 Inhibitor Protecting Mice From Ischemic Stroke Independent From Platelet Function

Supplemental Digital Content is available in the text.

Background and Purpose—

Acetylsalicylic acid and clopidogrel are the 2 main antithrombotic drugs for secondary prevention in patients with ischemic stroke (IS) without indication for anticoagulation. Because of their limited efficacy and potential side effects, novel antiplatelet agents are urgently needed. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, protected from IS in clinical studies comprising mainly Asian populations. Nevertheless, the detailed mechanistic role of PDE-3 inhibitors in IS pathophysiology is hardly understood. In this project, we analyzed the efficacy and pathophysiologic mechanisms of a novel and only recently described PDE-3 inhibitor (substance V) in a mouse model of focal cerebral ischemia.

Methods—

Focal cerebral ischemia was induced by transient middle cerebral artery occlusion in 6- to 8-week-old male C57Bl/6 wild-type mice receiving substance V or vehicle 1 hour after ischemia induction. Infarct volumes and functional outcomes were assessed between day 1 and day 7, and findings were validated by magnetic resonance imaging. Blood-brain barrier damage, as well as the extent of local inflammatory response and cell death, was determined.

Results—

Inhibition of PDE-3 by pharmacological blockade with substance V significantly reduced infarct volumes and improved neurological outcome on day 1 and 7 after experimental cerebral ischemia. Reduced blood-brain barrier damage, attenuated brain tissue inflammation, and decreased local cell death could be identified as potential mechanisms. PDE-3 inhibitor treatment did neither increase the number of intracerebral hemorrhages nor affect platelet function.

Conclusions—

The novel PDE-3 inhibitor substance V protected mice from IS independent from platelet function. Pharmaceutical inactivation of PDE-3 might become a promising therapeutic approach to combat IS via inhibition of thromboinflammatory mechanisms and stabilization of the blood-brain barrier.

Protective effects of phosphodiesterase-4-specific inhibitor rolipram on acute ischemia-reperfusion injury in rat kidney

OBJECTIVE

To investigate the effect of Rolipram, a phosphodiesterase-4-inhibitor, on renal ischemia-reperfusion injury (IRI) in rats.

METHODS

Thirty rats were divided into 5 different groups of 6 rats. Nothing was done to the control group. In the second group, the renal pedicle was clamped for 30 minutes. In the third group, 1 mg/kg of Rolipram was given by intraperitoneal injection 30 minutes before clamping. The fourth group received the same injection when the clamp was placed, as did the fifth group 30 minutes after the clamp was opened. Clamping time was set at 30 minutes. Twenty-four hours later, nephrectomy was performed in all the groups. Half of each kidney was examined histopathologically. Levels of biochemical agents, such as malondialdehyde, superoxide dismutase, and catalase, were measured in the other half.

RESULTS

The malondialdehyde (MDA) levels significantly decreased and reached control levels in the group in which Rolipram was administered 30 minutes after reperfusion (P = .07). The catalase and superoxide dismutase activities obtained from renal homogentisates of the ischemia groups were evaluated; there were striking increases in tissue levels of these 2 enzymes in the groups in which Rolipram was administered during ischemia and 30 minutes after ischemia (P < .001). Histopathologically, there was no significant difference in inflammation between the Rolipram-administrated groups compared with group 1 (control) and group 2 (IRI). Tubular necrosis and apoptosis was significantly lower in group 5 than the other groups, except group 1 (P < .001).

CONCLUSION

We suggest that in surgical procedures that can lead to renal IRI, the administration of Rolipram can decrease oxidative renal tissue damage and the severe deterioration of renal function.

Irsogladine maleate ameliorates inflammation and fibrosis in mice with chronic colitis induced by dextran sulfate sodium

Intestinal fibrosis is a common and severe complication of inflammatory bowel disease (IBD), especially Crohn's disease (CD). To investigate the therapeutic approach to intestinal fibrosis, we have developed a mouse model of intestinal fibrosis by administering dextran sulfate sodium (DSS) and examining the effects of irsogladine maleate (IM) [2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate], which has been widely used as an antiulcer drug for gastric mucosa in Japan, on DDS-induced chronic colitis. In this experimental colitis lesion, several pathognomonic changes were found: increased deposition of collagen, increased number of profibrogenic mesenchymal cells such as fibroblasts (vimentin(+), α-SMA(-)) and myofibroblasts (vimentin(+), α-SMA(+)) in both mucosa and submucosa of the colon with infiltrating inflammatory cells, and increased mRNA expressions of collagen type I, transforming growth factor (TGF)-β, matrix metalloproteinase (MMP)-2, and tissue inhibitor of matrix metalloproteinase (TIMP)-1. When IM was administered intrarectally to this colitis, all these pathological changes were significantly decreased or suppressed, suggesting a potential adjunctive therapy for intestinal fibrosis. IM could consequently reduce fibrosis in DSS colitis by direct or indirect effect on profibrogenic factors or fibroblasts. Therefore, the precise effect of IM on intestinal fibrosis should be investigated further.

Pharmacological mechanisms underlying the anti-ulcer activity of methanol extract and canthin-6-one of Simaba ferruginea A. St-Hil. in animal models

RELEVANCE

Simaba ferruginea A. St-Hil. (Simaroubaceae) is a subshrub typical of the Brazilian Cerrado, whose rhizomes are popularly used as infusion or decoction for the treatment of gastric ulcers, diarrhea and fever.

AIM OF THE STUDY

To evaluate the pharmacological mechanism(s) of action of the antiulcer effects of the methanol extract of Simaba ferruginea and its alkaloid canthin-6-one.

MATERIALS AND METHODS

Rhizome of Simaba ferruginea was macerated with methanol to obtain the methanol extract (MESf) from which was obtained, the chloroform fraction. Canthin-6-one alkaloid (Cant) was purified and then isolated from the chloroform fraction (CFSf). The isolated Cant was identified by HPLC. Anti-ulcer assays were determined using ethanol and indomethacin-induced ulcer models in mice and rats respectively. In order to determine the probable mechanisms of actions of MESf and Cant animals were pretreated with l-NAME prior to anti-ulcer agent treatments and ulcer induction and nitric oxide (NO) level determined in order to assess NO involvement in the gastroprotective effects. Assays of malondialdehyde (MDA), myeloperoxidase (MPO), pro-inflammatory cytokines: interleukin 8 (IL-8) and tumor necrosis factor-alpha (TNF-α) and prostaglandin E(2) (PGE(2)) were also carried out according to previously described methods.

RESULTS

The results indicate that the antiulcerogenic effects of MESf and Cant in ethanol-induced ulcer is mediated in part through increase in the production of protective endogenous NO as the antiulcerogenic activity of MESf and Cant was reduced in animals pre-treated with l-NAME. In indomethacin-induced ulcer pre-treatment with MESf and Cant showed reduction in the levels of MPO and MDA in the gastric tissue, thus indicating the participation of the antioxidant mechanisms on the gastroprotective effects. The plasma levels of IL-8 in ulcerated rats with indomethacin were also reduced by Cant, but not by MESf, indicating that inhibition of this cytokine contributes to the gastroprotective effect of Cant. However MESf and Cant had no effect on the mucosal membrane levels of PGE(2), indicating that the gastroprotective effects of these agents is independent of PGE(2) modulation.

CONCLUSION

The results obtained in this study with MESf and Cant added insights into the pharmacological mechanisms involved in their mode of antiulcer action. The results indicate that Cant is one of the compounds responsible for these effects. Such findings are of extreme importance in the strive for future development of potent, safer and effective antiulcer agent. The efficacy of MESf and Cant in gastroprotection shows that Simaba ferruginea might be a promising antiulcer herbal medicine, in addition to confirming the popular use of this plant against gastric ulcer models utilised in this study.

Comparison of the efficacy of irsogladine maleate and famotidine for the healing of gastric ulcers after Helicobacter pylori eradication therapy: a randomized, controlled, prospective study

OBJECTIVE

Helicobacter pylori eradication therapy alone cannot heal gastric ulcers in Japanese patients. Irsogladine has previously been shown to accelerate the healing of gastric ulcers after H. pylori eradication therapy. And we previously reported that histamine H(2) receptor antagonists inhibit gastric ulcer relapse after H. pylori eradication therapy. We therefore compared the efficacy of irsogladine with famotidine as appropriate treatments for ulcers after eradication therapy.

METHODS

Gastric ulcer patients with H. pylori infection (n = 119) were randomized to treatment with irsogladine 4 mg/day (n = 60) or famotidine 40 mg/day (n = 59) following 1-week H. pylori eradication therapy. After treatment, assessments of gastric ulcer healing were performed.

RESULTS

The ulcer healing rates in patients receiving irsogladine and famotidine were 85.2% (46/54) and 79.6% (43/54), respectively, and were not significantly different (p = 0.4484). In the famotidine group, the healing rate was significantly lower in patients who drink alcohol than in those who do not (60.0% vs. 91.2%; p = 0.0119). However, in the irsogladine group the healing rate did not differ between patients who drink alcohol and those who do not. Furthermore, the healing rate in smokers was significantly higher in the irsogladine group (88.0%) than in the famotidine group (59.1%) (p = 0.0233).

CONCLUSIONS

Irsogladine and famotidine are both acceptable in treatment after H. pylori eradication therapy in gastric ulcer patients. Findings also suggest that irsogladine is more beneficial than famotidine in patients who drink alcohol and smoke.

Gastric submucosal microdialysis in the detection of rat stomach ischemia--a comparison of the 3H2O efflux technique with metabolic monitoring

Microdialysis has been utilized for nutritive blood flow measurements, but both the advantages and disadvantages of various approaches have not been evaluated in parallel in the stomach yet. Our aim was to compare the (3)H(2)O efflux technique with biochemical monitoring during temporary celiac artery occlusion in anesthetized rats. Microdialysis probes were implanted in the gastric submucosa and perfused with (3)H(2)O; samples were analyzed for β-activity, glucose, lactate, pyruvate and glycerol. Gastric mucosa and plasma were subjected to morphometry and analysis of myeloperoxidase, total thiols and lactatdehydrogenase. The most dramatic responses to ischemia were observed in lactate/pyruvate and lactate/glucose (%) ratios (6.1-9.3×, p < 0.0001); the changes in (3)H(2)O efflux and glycerol were less pronounced (1.1-1.7×, p < 0.0001 and < 0.01, respectively). (3)H(2)O efflux correlated best with the lactate/glucose ratio and glucose alone (r = 0.693 and -0.681, respectively, p < 0.0001). A correlation was also found between plasma lactatdehydrogenase and relative glycerol release (r = 0.600, p < 0.05). Myeloperoxidase, lactatdehydrogenase and histology score were increased by ischemia/reperfusion (0.06-0.12 nkat g(-1), p < 0.05, 0.26-0.44 nkat g(-1), p < 0.05 and 1.79-2.33, p < 0.05, respectively), macroscopy and plasma thiols remained unchanged. Microdialysis is useful in monitoring gastric ischemia, metabolic monitoring being superior to the (3)H(2)O efflux technique. The results question the efficacy of the utilized model to produce standardized major gastric damage.

Irsogladine maleate suppresses indomethacin-induced elevation of proinflammatory cytokines and gastric injury in rats

AIM: To investigate the mucosal protective effect and the mechanisms of action of the anti-ulcer drug irsogladine maleate in gastric injury induced by indomethacin in rats.

METHODS: Gastric mucosal injury was induced in male Hos:Donryu rats by oral administration of indomethacin at a dose of 48 mg/kg. One hour before indomethacin treatment, animals were orally pretreated with irsogladine maleate at doses of 1 mg/kg, 3 mg/kg or 10 mg/kg. Four hours after indomethacin administration, the animals were sacrificed and their stomachs were rapidly removed and processed for the evaluation of gastric mucosal damage and the determination of the concentrations of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-8 and myeloperoxidase (MPO) in mucosal tissues.

RESULTS: Linear hemorrhagic mucosal lesions were observed primarily in the glandular stomach 4 h after oral administration of indomethacin. Pretreatment with irsogladine maleate markedly reduced the number and severity of these lesions in a dose-dependent manner. The mucosal concentrations of proinflammatory cytokines (TNF-α, IL-1β, and IL-8) and MPO, which indicates the degree of mucosal infiltration by neutrophils, increased concomitantly with the occurrence of gastric injury in the indomethacin-treated rats. Pretreatment with irsogladine maleate significantly decreased the levels of these inflammatory factors in gastric tissue elicited by indomethacin.

CONCLUSION: The mucosal protective effects afforded by irsogladine maleate on gastric injury induced by indomethacin are mediated by inhibition of mucosal proinflammatory cytokine production and neutrophil infiltration, leading to suppression of mucosal inflammation and subsequent tissue destruction.

Irsogladine, an anti-ulcer drug, suppresses superoxide production by inhibiting phosphodiesterase type 4 in human neutrophils

Neutrophil superoxide production is implicated in the pathogenesis of gastric mucosal damage induced by various ulcerative agents and Helicobacter pylori infection. We investigated here the effects of an anti-ulcer drug irsogladine [2, 4-diamino-6-(2, 5-dichlorophenyl)-s-triazine maleate] on cAMP formation in isolated human neutrophils. The cAMP level in human neutrophils was elevated by a phosphodiesterase (PDE) type 4 selective inhibitor rolipram, but not by any inhibitors of PDE1, PDE2 and PDE3. Irsogladine also increased cAMP formation in a concentration-dependent manner in neutrophils. A non-selective PDE inhibitor 3-isobutyl-1-methylxanthine (IBMX) alone significantly increased cAMP level, whereas irsogladine was unable to further increase cAMP level in the presence of IBMX. Irsogladine inhibited concentration-dependently the superoxide (O(2)(-)) production induced by various stimuli including formyl-methionyl-leucyl-phenylalanine, opsonized zymosan, guanosine 5'-[gamma-thio] triphosphate, A23187 and phorbol 12-myristate 13-acetate. These effects of irsogladine were mimicked by rolipram, IBMX and dibutyryl cAMP. The inhibitory effects of irsogladine and rolipram on the O(2)(-) production were reversed by a protein kinase A inhibitor H-89. These results indicate that irsogladine inhibits the superoxide production in human neutrophils by the increase of cAMP content by PDE 4 inhibition, which in turn contributing to the anti-ulcer effects of irsogladine on gastric mucosal lesions associated with oxidative stress.