The Protective Role of Carbon Monoxide (CO) Produced by Heme Oxygenases and Derived from the CO-Releasing Molecule CORM-2 in the Pathogenesis of Stress-Induced Gastric Lesions: Evidence for Non-Involvement of Nitric Oxide (NO)

Abstract

Carbon monoxide (CO) produced by heme oxygenase (HO)-1 and HO-2 or released from the CO-donor, tricarbonyldichlororuthenium (II) dimer (CORM-2) causes vasodilation, with unknown efficacy against stress-induced gastric lesions. We studied whether pretreatment with CORM-2 (0.1–10 mg/kg oral gavage (i.g.)), RuCl3 (1 mg/kg i.g.), zinc protoporphyrin IX (ZnPP) (10 mg/kg intraperitoneally (i.p.)), hemin (1–10 mg/kg i.g.) and CORM-2 (1 mg/kg i.g.) combined with NG-nitro-l-arginine (l-NNA, 20 mg/kg i.p.), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 mg/kg i.p.), indomethacin (5 mg/kg i.p.), SC-560 (5 mg/kg i.g.), and celecoxib (10 mg/kg i.g.) affects gastric lesions following 3.5 h of water immersion and restraint stress (WRS). Gastric blood flow (GBF), the number of gastric lesions and gastric CO and nitric oxide (NO) contents, blood carboxyhemoglobin (COHb) level and the gastric expression of HO-1, HO-2, hypoxia inducible factor 1α (HIF-1α), tumor necrosis factor α (TNF-α), cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) were determined. CORM-2 (1 mg/kg i.g.) and hemin (10 mg/kg i.g.) significantly decreased WRS lesions while increasing GBF, however, RuCl3 was ineffective. The impact of CORM-2 was reversed by ZnPP, ODQ, indomethacin, SC-560 and celecoxib, but not by l-NNA. CORM-2 decreased NO and increased HO-1 expression and CO and COHb content, downregulated HIF-1α, as well as WRS-elevated COX-2 and iNOS mRNAs. Gastroprotection by CORM-2 and HO depends upon CO’s hyperemic and anti-inflammatory properties, but is independent of NO.

Nitric oxide, afferent sensory nerves, and antioxidative enzymes in the mechanism of protection mediated by tricarbonyldichlororuthenium(II) dimer and sodium hydrosulfide against aspirin-induced gastric damage

“…Moreover, the upregulation of gastric mucosal iNOS protein expression induced by aspirin was decreased in rats pretreated with CORM-2 but not with NaHS. This finding is in keeping with our previous observation that CO released from CORM-2 decreased NO content that was possibly elevated because of an increase in iNOS activity in gastric mucosa of rats compromised by stress and that L-NNA had no effect on the gastroprotective action of this compound [26]. Regarding the effect of L-NNA on NaHS-induced gastroprotection, there is convincing evidence that H 2 S can interact with NO in the regulation of mucus secretion, GBF, and gastric mucosal defense in experimental models and in regulation of vascular tone in animals and humans [36,37].…”

“…Previous studies have documented that the mechanism of aspirin-induced gastric damage involves an inhibition of cytoprotective prostaglandin E 2 production via COX-1/ COX-2 enzymatic activity and the prominent fall in GBF leading to the formation of severe hemorrhagic lesions of gastric mucosa [5,[29][30][31][32][33]. On the other hand, recent studies reported that the endogenous gaseous mediators H 2 S, CO, and NO contribute to the maintenance of gastric mucosal integrity and prevent the formation of gastric mucosal lesions induced by various noxious stimuli, such as exposure to stress or administration of ethanol, bisphosphonates, and NSAIDs, including aspirin [5,17,19,21,22,26,34].…”

“…Their abdomens were opened for the GBF measurement by a laser Doppler flowmeter (Laserflo blood perfusion monitor, model BPM 403A, Vasamedics, St Paul, MN, USA), as described elsewhere [25]. The stomach was excised and opened along the greater curvature to determine the area of aspirin-induced gastric lesions by means of computerized planimetry (Morphomat, Carl Zeiss, Berlin, Germany) [26,27]. Next, the gastric mucosal samples from oxyntic mucosa were scraped off on ice, snap-frozen in liquid nitrogen, and stored at -80°C until further analysis [21].…”

Carbon monoxide released from its pharmacological donor, tricarbonyldichlororuthenium (II) dimer, accelerates the healing of pre‐existing gastric ulcers

“…One day after the induction of a gastric ulcer, animals were randomly divided into appropriate experimental groups consisting of five animals in each ( n = 5) and were treated daily, intragastrically (i.g. ), throughout the period of 9 days with (i) vehicle (saline or DMSO/saline solution 1/10); (ii) CORM‐2 (0.1–10 mg·kg −1 ); (iii) RuCl 3 (2.5 mg·kg −1 ), as a negative control for CORM‐2, which does not release CO (Takasuka et al ., ; Magierowska et al ., ); (iv) haemin, an HO1 inducer (Park et al ., ; Magierowska et al ., ), at a dose of 5 mg·kg −1 , which has been previously reported to protect the gastric mucosa against ethanol‐induced damage (Magierowska et al ., ); and (v) ZnPP, an HOs inhibitor (Hirai et al ., ), at a dose of 10 mg·kg −1 , previously reported to decrease CO content in gastric mucosa (Magierowska et al ., ). In the majority of experiments, CORM‐2 was administered at a dose of 2.5 mg·kg −1 , which decreased the ulcer area by more than 50% compared with the vehicle control group.…”

“…The expression of mRNA for EGF, HO1, HO2, COX‐2, iNOS, HIF‐1α, TNF‐α, IL‐1β and β‐actin (as housekeeping gene) in gastric mucosa was determined by semi‐quantitative real‐time PCR, as described previously (Magierowska et al ., ; ). Briefly, RNA was isolated from gastric mucosal samples using GeneMATRIX Universal RNA Purification Kit (EURx, Gdansk, Poland).…”