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.

In experimental epinephrine-induced gastric lesions in rats it was shown that olygopeptide Arg-α-Asp-Lys-Val-Tyr-Arg exerts cytoprotective effect, evaluated by the decrease of the area and severity of the damage of gastric mucosa as well as decrease of NOS activity, mainly due to the decrease of iNOS and NO production in gastric mucosa. Selective COX-2 blockade enhanced the cytoprotective action of AALVTA. Nonselective blockade by COX-1 caused significant decrease of the gastroprotective properties of AALVTA, showing involvement of COX-1 isoform in the mechanisms of cytoprotection of GM under the action of this hexapeptide.

Small intestinal injury is known to be one of the most commonly appearing pathologies, resulting in the use of medications such as: nonsteroidal anti-inflammatory drugs (NSAIDs), antitumor drugs and angiotensin-converting enzyme (ACE) inhibitors. The principal objective of this study is to evaluate the action of a novel mercaptoacrylic acid derivative able to release H2S on parameters of NO-synthase system and oxidative stress. Inducing enteropathy, three types of medications were used: indomethacin, an NSAID (35 mg/kg); methotrexate, an antitumor drug (10 mg/kg); and enalapril, an ACE inhibitor (2 mg/kg/day). 2-[(4-chlorophenyl-carbamoyl)-methyl]-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-acrylic acid (2C3DHTA) was introduced based on the background of medication-induced enteropathy (10 mg/kg/day). The survey showed that malondialdehyde (MDA) concentration, myeloperoxidase (MPO) activity, superoxide dismutase (SOD), catalase, and NO-synthases (NOS) were determined in the small intestinal mucosa. The increase in inducible NO-synthase (iNOS) activity was due to indomethacin and methotrexate administration. Constitutive NO-synthase (cNOS) activity was decreased by an ACE-inhibitor. The cytoprotective effect was demonstrated by 2C3DHTA, which returned iNOS activity to its control level and increased cNOS activity. The enterotoxic action of studied medication was accompanied by the development of oxidative stress manifested, activity of MPO was increased. MPO activity and manifestations of oxidative stress were decreased by 2C3DHTA. Effects of 2C3DHTA can be explained by the action of H2S, released from this compound in the gastrointestinal (GI) system.

Aim was to compare the action of 2A5DHT compound (dual COX-2/5-LOX inhibitor) and conventional non-steroidal anti-inflammatory drugs towards parameters of nitric oxide (NO) system and intensity of oxidative stress in the mucous membrane of the large intestine (MMLI) in rats with experimental ulcerative colitis. Methods. Ulcerative colitis was induced by administration of acetic acid. The activity of NO-synthases, content of NO, and parameters of lipoperoxidation processes were measured in MMLI. Results. COX-2/5-LOX inhibition by 2A5DHT compound did not cause considerable destructive changes of the MMLI of rats. The activity of inducible nitric oxide synthase (iNOS) declined more than 2 fold as compared to their activity in colitis. The intensity of lipoperoxidation processes was found to be much lower than under the separate effect of celecoxib or indomethacine. Conclusions. Dual COX-2/5-LOX inhibition by 2A5DHT has a significant cytoprotective effect in MMLI that is accompanied by reduction of oxidative stress and activity of NO-synthases. The substance 2A5DHT significantly overexceeds the cytoprotective effects of both selective and non-selective COX/LOX inhibitors and can be used in the treatment of inflammatory bowel diseas

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.