Prostaglandins and the protection of the gastroduodenal mucosa in humans: a critical review

Antiulcerogenic activity of Zizyphus lotus (L.) extracts

Oral administration of aqueous extracts of Zizyphus lotus root barks (50-200 mg/kg) leaves (50-200 mg/kg) and fruits (200-400 mg/kg) produced a significant (p<0.01) and dose dependent inhibition to the acute ulcer induced by HCl/ethanol solution. The methanolic (MeOH), ethyl acetate (EtOAc) and chloroformic (CHCl(3)) leaves extracts when administered orally at the dose of 200 mg/kg, exhibited a significant (p<0.01) inhibition of gastric lesions by 45%, 76% and 33%, respectively. Indeed, methanolic and ethyl acetate root barks extracts significantly reduced the gastric lesions by 47% and 41%, respectively. While the chloroformic root barks extract had no significant activity (19%). The effect of all extracts was compared with cimetidine (100 mg/kg, 62%) and omeprazole (30 mg/kg, 93%). Volume, pH and acidity of gastric juice were studied in pylorus-ligated rats. Root barks (200 mg/kg, p<0.01), leaves (200 mg/kg, p<0.01) and fruits (400 mg/kg, p<0.05) aqueous extracts showed significant reduction of gastric juice secretion in pylorus ligated rats, whereas the other extracts did not show any significance. Thus, Zizyphus lotus extracts act essentially as cytoprotective agents, which support the antiulcer effect of this plant in the traditional medicine.

Upper gastrointestinal bleeding in relation to previous use of analgesics and non-steroidal anti-inflammatory drugs. Catalan Countries Study on Upper Gastrointestinal Bleeding

To assess the risk of upper gastrointestinal bleeding associated with the use of individual non-narcotic analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), a multicentre study of 875 cases of upper gastrointestinal bleeding and 2682 hospital controls was done. With control for confounding factors, the overall odds ratio estimate for aspirin taken at least once during the week before the first symptom was 7.2 (95% confidence interval 5.4-9.6). Non-aspirin NSAIDs associated with upper gastrointestinal bleeding were diclofenac (7.9 [4.3-14.6]), indomethacin (4.9 [2.0-12.2]), naproxen (6.5 [2.2-19.6]), and piroxicam (19.1 [8.2-44.3]). Paracetamol, propyphenazone, and dipyrone did not increase the risk. A previous history of gastrointestinal bleeding or peptic ulcer did not greatly affect odds ratio estimates, which differed according to sex and were higher for younger than for older patients. However, the incidence of upper gastrointestinal bleeding was higher among the elderly.

16,16-Dimethyl prostaglandin E2 and/or syngeneic bone marrow transplantation increase mouse survival after supra-lethal total body irradiation

We evaluated the effects of 16,16-dimethyl prostaglandin E2 (dm-PGE2), with and without syngeneic bone marrow transplantation (BMT) on the survival and hematopoietic recovery of mice given 14-20 Gy total body irradiation (TBI). Survival of mice given combined dm-PGE2 and BMT was improved significantly over that of mice given either treatment alone. The 30-day survival after 14, 15, 16 or 18 Gy TBI for combined treatment was 97, 90, 20 or 10 percent, respectively. The corresponding 30-day survival rates for mice given BMT alone were 69, 60, 7 or 0 percent, respectively. For dm-PGE2 alone, 30-day survival was 63, 20, 10 or 0 percent, respectively. Deaths in both dm-PGE2 treated groups generally occurred after day 10 whereas deaths in the BMT group occurred before day 10. All irradiated controls were dead on or before day 10; after larger doses, deaths clustered around day 5. After 20 Gy TBI, all mice in all groups were dead by day 7. Studies of white blood cell recovery 1-9 days after 14 Gy TBI showed improvement with BMT, whereas dm-PGE2 did not enhance recovery. Nucleated cells per humerus, spleen weight, and spleen iron uptake (erythropoiesis) were also improved by BMT but not dm-PGE2.

Rioprostil and ranitidine in the prevention of duodenal ulcer relapse

One hundred and ninety duodenal ulcer patients who had relief of pain and endoscopically proven ulcer healing after a short treatment period are allocated at random to double-blind maintenance treatment with a synthetic dehydroprostaglandin-E1, rioprostil, 300 micrograms, or ranitidine, 150 mg, at bedtime for 6 months. Patients are monitored every two months and examined by endoscopy after six months of treatment, or more often if warranted. The cumulative relapse rate in the rioprostil group at six months is 32% (25/78) vs. 28% (20/72) in the ranitidine group. This difference is not significant. The percentage of side effects observed is 17% in the rioprostil group vs. 5% in the ranitidine group, but discontinuation of treatment is observed with the same frequency in the two groups.

Rioprostil vs. ranitidine in duodenal ulcer healing: a double-blind multicentre trial

A total of 156 patients with endoscopically proven duodenal ulcers are randomized in a double-blind, multicentre trial comparing rioprostil, 300 micrograms b.d., with ranitidine, 150 mg b.d. With rioprostil, the cumulative healing rate by endoscopy is 73% at 4 weeks, and 87% at 6 weeks. With ranitidine it is 79% and 92%, respectively. There is no difference in the occurrence of pain after the two types of treatment, and the side effects are comparable in the two groups. These results show that rioprostil is probably as effective and safe as ranitidine in the treatment of duodenal ulcer.

Mucosal prostaglandin levels of the gastric stump

The endogenous mucosal PG levels (PGE2, PGF2 alpha, PGI2, TXB2) of the gastric stump were investigated from biopsy materials, after partial gastrectomy made for ulcer disease. The mucosa of the stomach remnant were found to contain mainly PGE2 and PGI2. The PG contents of the mucosa of gastric stump were not influenced by the type of resection. Mucosal PG concentrations on the greater curvature were not dependent on the patients' age, the indication of the gastrectomy, the duration of postoperative interval, or the sex of the patient. There was no relation between the secretion capacity of the resected stomach and the mucosal PG contents of the greater curvature. After Billroth I and II gastrectomy procedures equivalently fair correlations have been established between the mucosal levels of PGE2 and PGF2 alpha, PGE2 and TXB2, PGF2 alpha and TXB2, PGI2 and TXB2 on the greater curvature, respectively. After both types of gastrectomy the mean PGI2 mucosal concentration of the greater curvature was significantly lower than those of the gastroenteroanastomosis and lesser curvature below the cardia, which in turn did not differ from each other. Biliary reflux does not cause characteristic alterations of the mucosal PG levels on the greater curvature. No definite relation between the histological findings of the mucosa and the PG concentrations was observed, which suggests a secondary role of the endogenous PGs in the pathogenesis of light microscopic mucosal alterations of the resected stomach.

Profiles of eicosanoid production from 14C-arachidonic acid and prostaglandin metabolism by rabbit esophageal mucosa and muscularis

In an attempt to elucidate the possible involvements of eicosanoids in esophageal functions and disorders, we have investigated the formation of both cyclooxygenase and lipoxygenase metabolites from 14C-arachidonic acid by rabbit esophageal tissues. Homogenates of rabbit esophageal mucosa and muscularis were incubated with 14C-arachidonic acid and after ether extraction eicosanoids were separated and quantified by reverse phase high performance liquid chromatography. The predominant cyclooxygenase products were 6-keto-PGF1 alpha, PGF2 alpha, and PGE2 for mucosa and 6-keto-PGF1 alpha, and PGE2 for muscularis. The formation of these products was inhibited both by indomethacin and the dual pathway inhibitor, nordihydrogualaretic acid (NDGA). In mucosa the major eicosanoid was 12-HETE (12-hydroxyeicosatetraenoic acid) which was inhibited by NDGA but not by indomethacin which on the contrary enhanced its formation. Additionally four polar products were synthesized which appeared to be lipoxygenase-dependent as their formation was inhibited by NDGA but not by indomethacin. Muscularis produced as a minor lipoxygenase product only 12-HETE, which was inhibited by NDGA but unchanged in the presence of indomethacin. In addition, both tissues, but mucosa more than muscularis, possessed large prostaglandin catabolizing capacity. The present findings indicate that rabbit esophageal tissues can convert 14C-arachidonic acid into lipoxygenase as well cyclo-oxygenase products which may have a role in esophageal physiology and pathophysiology.

Gastric prostaglandin E2 release induced by aluminium hydroxide and aluminium hydroxide-containing antacids in rats. Effect of low doses and citric acid

Suspensions of aluminium hydroxide or a commercial antacid containing aluminium hydroxide (Trigastril) was instilled intragastrically in rats in doses comparable to high and low human therapeutic doses (aluminium hydroxide, 125 mg and 12.5 mg/kg, respectively). Corresponding experiments were carried out with 0.6% citric acid added to the antacid suspensions. Prostaglandin E2 (PGE2) in the gastric content was analysed by radioimmunoassay 6 h after drug administration. Both high and low doses of aluminium hydroxide and Trigastril increased the concentration of PGE2 significantly. Citric acid did not significantly affect the antacid-induced PGE2 release except in combination with a low dose of aluminium hydroxide, with which a significant increase was seen. Release of PGE2 by low doses of antacids implies the possibility that enhanced cytoprotection may be involved in the mechanism by which antacids promote the healing of peptic ulcers.