Effects of lysine clonixinate on cyclooxygenase I and II in rat lung and stomach preparations

Store-operated Ca2+ Entry Facilitates the Lipopolysaccharide-induced Cyclooxygenase-2 Expression in Gastric Cancer Cells

Helicobacter pylori has been identified as one of the major causes of chronic gastritis, gastric and duodenal ulcers, and gastric cancer. Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria, and H. pylori LPS might play an exclusively important role in activating inflammatory pathways in monocytes and macrophages. To study the role of LPS in the underlying mechanism of inflammatory responses, we established an in vitro model using the human AGS gastric cancer cell line. We found that LPS mediates inflammation through setting off a cascade of events: activation of the store-operated calcium (SOC) channel, initiation of downstream NF-κB signaling, and phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). Phosphorylated ERK1/2 promotes the nuclear translocation of NF-κB, and eventually elevates the expression level of COX-2, a major inflammatory gene.

Ex vivo effects of lysine clonixinate on cyclooxygenases in rat lung and stomach preparations

Lysine clonixinate (LC) is an anti-inflammatory, anti-pyretic and analgesic drug with minor digestive side effects, which might suggest a weak COX-1 inhibitor. The aim of this study focused on ex vivo effects of LC 40 mg/kg ip and indomethacin (INDO) 10 mg/kg ip in lung and stomach preparations of control rats and LPS-treated rats (5 mg/kg ip). The non-steroidal antiinflammatory drugs were administered concomitantly, following three hours and before one, two or three hours of LPS treatment. Tissues were weighed and incubated in 2 ml of Kress Ringer Bicarbonate buffer containing glucose (11 mM) under an atmosphere of 95% oxygen and 5% CO(2). Approximately 200 mg of tissue were used for each determination; 0.25 microCi of (14)C-arachidonic acid was added to each tube and the tissues were incubated for 60 min. Prostanoids were extracted from the incubation medium and separated by TLC. Results were expressed as a percentage of the total radioactivity of the plates (% of cpm on plate/100 mg ww). It was found that LC animals that were not given LPS did not modify the synthesis of PGE(2); in lung and stomach tissues showing that did not inhibit COX-1 activity. However, LC inhibited clearly the synthesis of PGE(2) in both preparations obtained from LPS-treated animals. The inhibition was shown when the rats were treated concomitantly, 3 h after or 1 or 2 h before the injection of LPS.

In vivo and in vitro effects of lysine clonixinate on nitric oxide synthase in LPS-treated and untreated rat lung preparations

Recent studies have shown that some nonsteroidal antiinflammatory drugs (NSAIDS) inhibited the inducible NO synthase (iNOS) without direct effect on the catalytic activity of this enzyme. This study was conducted to investigate the in vitro and in vivo effects of lysine clonixinate (LC) and indomethacin (INDO) on NOS activity in rat lung preparation. LC is a drug with antiinflammatory, antipyretic, and analgesic action. In the in vitro experiments, rats were injected with saline or lipopolysaccharide (LPS) and killed 6 h after treatment. Lung preparations were incubated with LC at 2.3 x 10(-5) M or 3.8 x 10(-5) M. The minimum concentration did not modify NOS activity in control or LPS-treated rats but the maximum dose inhibited increased NO production induced by LPS. Furthermore, INDO at 10(-6) M had no effect on enzymatic activity in control or LPS-treated rats. In the in vivo experiments, 40 mg/kg of LC were injected ip. Such a dose did not affect basal production of NO. When LC and LPS were injected simultaneously 6 h before sacrifice, a significant decrease in LPS-induced NOS activity was observed. INDO 10 mg/kg injected in control animals had no effect on NOS activity and did not block LPS induced stimulation of NO production when injected simultaneously. Finally, when LC (40 mg/kg) was injected 3 h after LPS, the enzymatic activity remained unchanged. Expression of iNOS was detected by Western blotting in rats treated with LPS plus 4, 10, 20, and 40 mg/kg of LC. The lowest dose was the only one showing no effect on LPS-induced increase of iNOS. In short, LC is a NSAID with inhibitory action on the expression of LPS-induced NOS, effect that was not seen with INDO in our experimental conditions.