Novel method for producing standard subacute gastric ulcer in rats and for the quantitative evaluation of the healing process. Effect of several drugs on healing

Polysaccharides of Dendrobium officinale Kimura & Migo Leaves Protect Against Ethanol-Induced Gastric Mucosal Injury via the AMPK/mTOR Signaling Pathway in Vitro and vivo

Ethanol-induced gastric mucosal injury is a common gastrointestinal disorder. Polysaccharides separated from herbs have been shown to be effective for ethanol-induced gastric mucosal injury, but whether the polysaccharides from Dendrobium officinale Kimura & Migo leaves (LDOP-1) protected mucosa from ethanol-induced injury remains unknown. Thus, the present study carried out gastric mucosal protection and the mechanism of LDOP-1 in vivo and vitro. The chemical composition of LDOP-1 was a heteropolysaccharide comprising mannose, galacturonic acid, glucose, galactose, and arabinose at a molar ratio of 2.0:1.1:0.7:0.5:0.4. Pharmacological results showed that LDOP-1 significantly reduced gastric mucosal injury score and pathological injury, improved antioxidant capacity, reduced the level of reactive oxygen species, and reversed the apoptosis of GES-1 in vivo and vitro. Research showed that LDOP-1 pretreatment upregulated the expression level of p-AMPK, LC3β, HO-1, and Beclin-1; downregulated the expression level of p-mTOR and p62; and reversed the expression level of caspase3, Bax, and Bcl-2. This study was the first to demonstrate that LDOP-1 could protect against ethanol-induced gastric mucosal injury via the AMPK/mTOR signaling pathway in vitro and vivo.

Antiulcer activity of ethanol leaf extract of Cassia fistula

The ethanol leaf extract (ELE) of Cassia fistula Linn. (Caesalpinaceae) was evaluated for antiulcer activity against pylorus ligation-induced gastric ulcer. Ranitidine (30 mg/kg b.w.) and ELE at doses of 250, 500, and 750 mg/kg b.w. were administered orally in different groups of rats (n = 6), 1 h prior to pyloric ligation. Four hours after pyloric ligation, the gastric juice was collected for evaluation of various parameters. The antiulcer activity of ELE was evidenced by the significant attenuation of gastric volume, pH, free acidity, and total acidity in the gastric juice of pyloric-ligated rats in a dose-dependent manner, and this protective effect could be due to strengthening of the mucosal defense mechanism. ELE pre-treatment significantly attenuated the fall in status of sialic acid and fucose accompanied by an increase in hexose, hexosamine, total non-amino polysaccharide, total carbohydrate, and C:P ratio in the gastric juice of pylorus-ligated rats, and this effect could be due to protection of the mucosal barrier system. ELE pre-treatment significantly prevented the increase in LPO and SOD accompanied by a fall in CAT, in the gastric juice of pyloric-ligated rats. This protective ability of ELE against pylorus ligation-induced gastric ulcer could be attributed to its free radical scavenging and antioxidant properties. Higher doses of ELE (750 mg/kg b.w.) produced maximum antiulcer activity comparable to ranitidine treatment. In essence, the antiulcer activity of ELE could be attributed to (i) a decrease in gastric acid secretion, (ii) protection of the mucosal barrier and restoration of mucosal secretions, (iii) inhibition of free radical generation or prevention of lipid peroxidation, and (iv) free radical scavenging or antioxidant properties.

Gastroprotective effect of Terminalia arjuna bark on diclofenac sodium induced gastric ulcer

AIM

The present study was aimed to evaluate the effect of methanolic extract of Terminalia arjuna (TA) on diclofenac sodium induced gastric ulcer in experimental rats.

METHODS

Animals were induced for gastric ulcer with diclofenac sodium (DIC) (80mg/kg bodyweight in water, orally) and treated orally with TA in various doses ranging from 100mg/kg bodyweight to 500mg/kg bodyweight. The effective dose was 400mg/kg bodyweight, since this dose elicited a maximum reduction in lesion index. The gastroprotective effect of TA was assessed from volume of gastric juice, pH, free and total acidity, pepsin concentration, acid output in gastric juice, the levels of non-protein sulfhydryls (NP-SH), lipid peroxide (LPO), reduced glutathione (GSH), and activities of enzymic antioxidants--super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and myeloperoxidase (MPO) in gastric mucosa. The levels of DNA, protein bound carbohydrate complexes--hexose, hexoseamine, sialic acid, fucose in gastric mucosa and gastric juice and the levels of RNA in gastric mucosa were assessed. The stomach tissues were used for adherent mucus content and also for the histological examination.

RESULTS

A significant reduction in lesion index was observed in ulcer induced animals treated with TA (DIC+TA) compared to ulcerated rats (DIC). A significant increase was observed in pH, NP-SH, GSH, enzymic antioxidants, protein bound carbohydrate complexes, adherent mucus content, nucleic acids with a significant decrease in volume of gastric juice, free and total acidity, pepsin concentration, acid output, LPO levels and MPO activities in DIC+TA rats compared to DIC rats. Histological studies confirmed the gastroprotective activity of TA.

CONCLUSION

From the data presented in this study it could be concluded that T. arjuna acts as an gastroprotective agent probably due to its free radical scavenging activity and cytoprotective nature.

Biochemical studies on the anti-ulcerogenic potential of Hemidesmus indicus R.Br. var. indicus

Roots of Hemidesmus indicus var. indicus are used for various ailments in Indian traditional medicines. The present study evaluated the antiulcerogenic property of aqueous ethanolic extracts of the roots in animal models. Modified pyloric ligated (Shay) rat model and aspirin-induced ulcerogenesis in pylorus ligated rat models were used for this study and analysed for gastric volume, ulcer score, pH, free and total acidity and sodium and potassium ion output. Bio-chemical estimations like total proteins, total hexoses, hexosamine, fucose, sialic acid and pepsin were also made. Ulcer score was calculated for cysteamine-induced duodenal ulcer model. Roots collected during flowering season were found to be more effective than that collected during vegetative seasons.

Prevention of topical and ocular oxidative stress by positively charged submicron emulsion

A positively charged submicron emulsion with zeta potential values ranging from 35 to 45 mV and mean droplet size around 150-250 nm has recently been developed and characterized. This formulation is based on three surface-active agents, an egg yolk phospholipid mixture, poloxamer 188, and stearylamine, a cationic lipid with a pKa of 10.6. The emulsion toxicity was evaluated in three animal studies. The results of the ocular tolerance study in the rabbit eye indicated that hourly administration of one droplet of the positively charged emulsion vehicle was well tolerated without any toxic or inflammatory response to the ocular surface during the five days of the study. No marked acute toxicity was observed when 0.6 mL of positively charged emulsion was injected intravenously to BALB/c mice. Furthermore, no difference was noted between this group of animals and the group injected with the marketed and clinically well accepted negatively charged Intralipid emulsion. These observations were further confirmed in a four week toxicity study following intravenous administration to rats of 1 mL/kg of the positively charged emulsion as compared to Intralipid. No toxic effect was noted in any of the various organs examined, whereas the results of the hematological and blood chemistry tests remained in the normal range for both emulsions, confirming the preliminary safety study findings. In addition, it was demonstrated by means of a non-invasive technique that alpha-tocopherol positively charged emulsions prevented oxidative damage in rat skin subjected to UVA irradiation. The intrinsic ability of positively charged emulsified oil droplets to protect against reactive oxygen species cannot be excluded, and could act synergistically with the antioxidant alpha-tocopherol itself. The effect of blank and piroxicam positively charged emulsions on rabbit eye following alkali burn was also evaluated. The blank emulsion showed a very rapid healing rate during the first three days with a breakdown in day 14. Complete re-epithelialization was observed in day 28. The same behavior (albeit less pronounced), was noted in piroxicam emulsion, although piroxicam is known to inhibit the epithelial healing process. It can therefore be deduced that the positively charged emulsion vehicle prevented piroxicam from interfering with the epithelial healing process due to the intrinsic free radical scavenger ability of the positively charged submicron emulsion previously demonstrated. Finally, the efficacy of this promising emulsion vehicle containing effective cosmetic ingredients in preventing skin damage and aging following oxidative stress is evaluated.

Evaluation of a positively charged submicron emulsion of piroxicam on the rabbit corneum healing process following alkali burn

The effect of piroxicam in three different formulations was tested on rabbits for 28 days in an alkali burn model. The ulceration healing process was determined by evaluating the severity of the burn (scored from 0 to 5), and the re-epithelization healing process was measured by the area of the defects. The results indicated that the piroxicam positively charged submicron emulsion was the most effective formulation in lowering the ulcerative cornea score while the piroxicam positively charged emulsion and the blank emulsion were more effective in promoting the re-epithelization healing process. The piroxicam solution elicited the slowest healing re-epithelization rate after 28 days and was unable to complete the entire healing process. The new positively charged submicron emulsion formulation of piroxicam had a pronounced effect on both the ulceration rate and epithelial defects in the management of corneal alkali-burning.

Computer-based quantitative morphometric analysis of the dynamic characteristics of indomethacin and ethanol-induced gastric lesions in the rat

A computerized morphometric analysis was used to measure the gastric lesions in rats induced by oral administration of 2 mL of 100% EtOH or indomethacin 80 mg/kg. In both cases, the lesions were followed over a period of several days to determine their time course characteristics. Indomethacin lesions were present 1 hr after the administration of the drug and reached a peak after 6 hr. Ethanol lesions appeared as early as 1 min after administration and were fully expressed after 1 hr. Recovery of the gastric mucosa was observed after 2 and 6 days, respectively. The use of this computerized systems allows precise measurements of gastric lesions and facilitates the evaluation of the effect of drugs in the gastrointestinal tract.