Mechanisms of gastric defence under conditions of combined influence of acute stress and non-steroidal anti-inflammatory drugs (NSAIDs) are still poorly studied. The aim of this study was to explore the effects of different types of NSAIDs (naproxen, celecoxib and ATB-346) in producing experimental gastric lesions (induced by water-restraint stress (WRS) or by epinephrine (EPN) injection) and to determine the role of lipid peroxidation and the nitric oxide (NO) system in the pathogenesis of the damage. Male rats were used (eight per group) in this work. The NSAIDs were all administered at a dose 10 mg kg(-1) 30 min prior to WRS or EPN injection. Administration of naproxen to the control rats caused development of gastric lesions, whereas administration of a hydrogen sulfide (H2S)-releasing NSAID (ATB-346) or a selective cyclooxygenase-2 inhibitor (celecoxib) did not cause gastric damage. In contrast, lipid peroxidation processes were enhanced in all groups as was the activity of NO synthase (NOS). Pretreatment with naproxen in the WRS model caused an increase in severity of damage and a decrease in NOS activity. ATB-346 displayed beneficial effects, manifested by a decrease in the area of gastric damage, but parameters of lipid peroxidation and the NOS system did not differ substantially from those in the group treated with naproxen. Administration of different NSAIDs under conditions of EPN-induced gastric damage resulted in the decrease in NOS activity and lipid peroxidation. None of the tested NSAIDs exacerbated EPN-induced gastric mucosal injury; indeed, they all reduced the extent of damage.
The use of nonsteroidal anti-inflammatory drugs (NSAIDs) in combination with being physiologically stressed often occurs in in the course of different pathologies. This situation may result in the alteration of digestive system functioning. The effect of stress brings about changes in the activity of nitric oxide synthase (NOS), arginase, cyclooxygenase (COX) and lipid peroxidation, whereas the use of NSAIDs interrupts the multiple functions of the cell via the inhibition of prostaglandins (PGs) synthesis. Taking into account that NOS and COX-systems are connected in their regulation, the aim of the study was to determine the role played by NOS and lipid peroxidation under conditions of the combined action of NSAIDs and stress. In our study, male rats were used. The NSAIDs (naproxen - a non-selective COX inhibitor, celecoxib - a selective COX-2 blocker, and the compound 2A5DHT (which is the active substance of dual COX, and the lipoxygenase (LOX) inhibitor, darbufelone) were all administered at a dose 10 mg/kg, prior to water restraint stress (WRS). WRS brought about an increase of inducible NOS (iNOS) activity in the intestinal mucosal and muscular membranes, as well as in the pancreas. Because of this, constitutive NOS izoform (cNOS) and arginase activities decreased. Moreover, the MDA concentration increased, indicating the development of oxidative stress. In our work, pretreatment with naproxen, as in the WRS model, engendered a decrease in iNOS activity. What is more, administration of Celecoxib did not change iNOS activity, as compared to WRS alone, and it showed a tendency to reduce lipid peroxidation. In addition, 2A5DHT prior WRS brought about a decrease of iNOS activity, with the subsequent rise of cNOS activity. Of note, MDA concentration decreased in all studied organs, indicating the reduction of lipid peroxidation under the action of the darbufelone active substance.
Influence of vitamins (Vit) C and E on the lipid peroxidation processes and activity of NO-synthase system in the pancreas of rats with the epinephrine-induced stress was studied. It was ascertained that Vit C decreased TBA-active products content as well as superdismutase activity more than Vit E under the same conditions. However the decrease of general NOS, eNOS activities and the content of NO2 - was more considerable in group with Vit E as compared to the action of Vit C. Both vitamins decreased the activity of iNOS equally. Combined action of Vit C and E under condition of epinephrine-induced stress reduced activity of general NOS and iNOS and the content of NO2 - more substantially from those treated with Vit independently, however there was no summation of their effects on studied processes.
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