Quantitative analysis of cyclooxygenase-2 gene expression on acute gastric injury induced by ischemia-reperfusion in rats

doi:10.1016/S0024-3205(96)00694-7

Life Sciences

Volume 60, Issue 8, 17 January 1997, Pages PL127-PL133

https://doi.org/10.1016/S0024-3205(96)00694-7 Get rights and content

Abstract

The rat model of acute gastric damage induced by ischemia-reperfusion (I-R) has been used to evaluate the protective effect of various drugs on gastric injury. However, the quantitative expression state of cyclooxygenase-2 (COX-2), a protein which induces cytoprotective prostaglandins during inflammation, is still unknown in acute gastric injuriy induced by I-R. Therefore, we have quantitatively investigated the level of expression of COX-2 mRNA in injured gastric tissue of this model using the reverse transcription-competitive polymerase chain reaction method. The mRNA for COX-2 was expressed at low or undetectable levels in the normal gastric tissues in control rats, which were fasted for 18 hrs without I-R. The mRNA levels of COX-2 in injured gastric tissues were higher than those of control tissues between 6 hrs and 48 hrs after I-R. The maximum expression of COX-2 mRNA was recorded at 24 hrs (approximately a 200-fold increase). The expression state of COX-2, which has been ascertained in this study, should be useful in evaluating the effect of various drugs on the expression of COX-2 in acute gastric damage.

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Gastrointestinal (GI) irritation and/or ulceration caused by nonsteroidal antiinflammatory drugs (NSAIDs), a major adverse event of these drugs, mainly occur due to the indirect pharmacological actions primarily associated with a deficiency in endogenous prostaglandins (PGs) due to the inhibition of cyclooxygenase (COX). The pathogenic mechanisms of these lesions involve a number of functional alterations that are causally associated with a PG deficiency but differ depending on the tissues affected. In the stomach, NSAIDs enhance gastric motility and increase mucosal permeability, neutrophil infiltration, and oxyradical production, which result in gastric lesions in the presence of luminal acid. In the small intestine, NSAIDs cause intestinal hypermotility and decrease mucus secretion, resulting in enterobacterial invasion and the upregulated expression of inducible nitric oxide (NO) synthase/NO production, ultimately leading to enteropathy. In both tissues, NSAIDs upregulate the expression of COX-2 due to the inhibition of COX-1, and PGs produced by COX-2 suppress the adverse events associated with the inhibition of COX-1. Therefore, the inhibition of COX-1 and COX-2 is required for the ulcerogenic properties of NSAIDs to occur in the GI mucosa. NSAIDs not only damage the GI mucosa but they also impair the healing of preexisting ulcers, and this is mainly due to the inhibition of COX-2 and angiogenic responses.
Expressions of Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in Gastric Ischemia-Reperfusion: Role of Angiotensin II
2010, Journal of Surgical Research
Citation Excerpt :
Recent studies showed that COX-2 has a role in limiting and recovery of lesions. While COX-1 is widespread in healthy mucosa and decreases evidently in I/R exposed to tissue, COX-2 only increases near the lesion area of inflammatory tissue [29, 30]. It has been demonstrated that COX-2 mRNA expression increases only in lesion area in gastric mucosa exposed to inflammatory mediators [28].
Angiotensin II contributes to the pathogenesis of inflammation induced by ischemia-reperfusion (I/R) in various organs. Angiotensin II increases vascular permeability that initiates the inflammatory process and leads to the migration of inflammatory cells into the tissue. The aim of the present study was to investigate the effect of angiotensin II on ischemia-reperfusion induced expressions of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in rat stomachs exposed to ischemia-reperfusion.
Wistar rats were randomly separated into five groups: sham operated, I/R, I/R plus candesartan (an AT1 receptor antagonist), I/R plus PD123319 (an AT2 receptor antagonist), and I/R plus captopril (an angiotensin-converting enzyme inhibitor). Candesartan (1mg/kg/d), PD123319 (3mg/kg/d), and captopril (20mg/kg/d) were given subcutaneously twice a day for 5 d before I/R. The rats were submitted to gastric ischemia by clamping the celiac artery for 30min followed by 24h reperfusion.
Candesartan decreased the neutrophil accumulation, iNOS expression, and increased NOx level, COX-2 expression in the gastric tissue exposed to I/R compared with I/R group. PD123319 did not change the neutrophil accumulation, iNOS expression, PGE₂, or NOx levels, but increased the expression of COX-2 in the gastric tissue exposed to I/R. However, captopril did not play any role in I/R induced change in gastric mucosa.
The results suggest that Angiotensin II via angiotensin II type 1 receptor increases the accumulation of neutrophils and iNOS expression and plays a significant role in mediating inflammation in gastric mucosa exposed to I/R.
Cellular and molecular mechanisms of 17β-estradiol postconditioning protection against gastric mucosal injury induced by ischemia/reperfusion in rats
2010, Life Sciences
To investigate the protective effects of 17β-estradiol postconditioning against ischemia/reperfusion (I–R)-induced gastric mucosal injury in rats.
The animal model of gastric ischemia/reperfusion was established by clamping of the celiac artery for 30 min and reperfusion for 30 min, 1 h, 3 h, 6 h, 12 h or 24 h. 17β-estradiol at doses of 5, 50 or 100 μg/kg (rat) was administered via peripheral veins 2 min before reperfusion. In a subgroup of rats, the estrogen receptor antagonist fulvestrant (Ful, 2 mg/kg) was intravenously injected prior to 17β-estradiol administration. Histological and immunohistochemical methods were employed to assess the gastric mucosal injury index and gastric mucosal cell apoptosis and proliferation. The malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, xanthine oxidase (XOD) activity and hydroxyl free radical (–OH) inhibitory ability were determined by colorimetric assays. Subsequently, the expression of Bcl-2 and Bax in rat gastric mucosa was examined by western blotting.
17β-estradiol dose-dependently inhibited gastric I–R (GI–R) injury, and 17β-estradiol (50 μg/kg) markedly attenuated GI–R injury 1 h after reperfusion. 17β-estradiol inhibited gastric mucosal cell apoptosis and promoted gastric mucosal cell proliferation in addition to increasing SOD activity and –OH inhibitory ability and decreasing the MDA content and XOD activity. The Bax protein level increased 1 h after GI–R and was markedly reduced by intravenous administration of 17β-estradiol. In contrast, the level of Bcl-2 protein decreased 1 h after GI–R and was restored to normal levels by intravenous administration of 17β-estradiol. These effects of 17β-estradiol were inhibited by pretreatment with fulvestrant.
17β-estradiol postconditioning should be investigated further as a possible strategy against gastric mucosal injury.
Administration of angiotensin II in the paraventricular nucleus protects gastric mucosa from ischemia-reperfusion injury
2008, Brain Research
Citation Excerpt :
At present, gastric ischemia-reperfusion (GI-R) injury is widely investigated for its pathogenic mechanisms, such as the increase of free oxygen radicals(Cabeza et al., 2001), endothelin levels (Hassan et al., 1997b), microvascular dysfunction, polymorphonuclear leukocyte infiltration (Andrews et al., 1994), nitric oxide release (Blebea et al., 1996, Kim and Hwan Kim, 2001, Tanaka et al., 2001), gastric acid secretion (Kitano et al., 1997, Brzozowski et al., 2000), and prostaglandin decrease (Kishimoto et al., 1997) during GI-R. Based on these investigations, a number of protective agents have been found, such as anti-acid drugs (Kitano et al., 1997, Brzozowski et al., 2000), the endothelin converting enzyme inhibitor phosphoramidon (Hassan et al., 1997a), the anti-reactive oxygen species agent tetrahydrobiopterin (Ishii et al., 2000), and anti-leukocyte adhesion molecules (Andrews et al., 1997).
Our previous study demonstrated that electrical stimulation of the hypothalamic paraventricular nucleus (PVN) protects against gastric ischemia-reperfusion (GI-R) injury, but it is still unknown whether angiotensin II (Ang II) in the PVN plays a role in the development of GI-R. The purpose of this study was to investigate the effect of Ang II in the PVN on GI-R injury. GI-R injury was induced in rats by clamping the celiac artery for 30 min, and then reperfusing for 30 min, 1 h, 3 h, 6 h or 24 h, respectively. A cannula was inserted into the unilateral PVN for microinjection of Ang II. The extent of gastric mucosal damage was determined by gross and histological methods. We found that microinjection of pharmacological doses of Ang II (3, 30, and 300 ng) into the PVN dose-dependently inhibited GI-R injury, and that Ang II (30 ng) markedly attenuated GI-R injury at 1 h and 3 h after reperfusion. The effect of Ang II was prevented by pretreatment with the Ang II AT1 receptor antagonist losartan (5 µg) into the lateral cerebral ventricle. Furthermore, the protective effect of Ang II on GI-R injury was abolished by propranolol (1 mg/kg, i.v.) or disconnection of the nerves innervating the adrenal glands, was augmented by sympathectomy or phentolamine (1 mg/kg, i.v.), and was not affected by subdiaphragmatic vagotomy or atropine (1 mg/kg, i.v.). These results indicate that the PVN is a responsive site for central Ang II-induced protection against GI-R injury. The central effects of Ang II are mediated by AT1 receptors in the PVN, and the peripheral effects by a sympathetic-adrenal gland/β-adrenoceptor pathway.
Neuroregulative mechanism of hypothalamic paraventricular nucleus on gastric ischemia-reperfusion injury in rats
2002, Life Sciences
A rat model of gastric ischemia–reperfusion injury (GI-RI) was established by clamping the celiac artery for 30 min and allowing reperfusion for 1 h, on which the regulatory effect of the paraventricular nucleus (PVN) and its neural mechanisms were investigated. The results were: 1. Electrical stimulation of the PVN obviously attenuated the GI-RI. Microinjection of L-glutamic acid into PVN produced an effect similar to that of PVN stimulation. 2. Electrolytic ablation of the PVN aggravated the GI-RI. 3. Nucleus tractus solitarius (NTS) ablation could eliminate the protective effect of electrical stimulation of PVN on GI-RI. 4. Hypophysectomy did not alter the effect of electrical stimulation of PVN. 5. Vagotomy or sympathectomy both could increase the effect of PVN stimulation on GI-RI. These results indicate that the PVN participates in the development of GI-RI as a specific area in the CNS, exerting protective effects on the GI-RI. The NTS and vagus and sympathetic nerve may be involved in the regulative mechanism of PVN on GI-RI, but the PVN mechanism here is independent of the PVN-hypophyseal pathway.
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Pharmacology letterQuantitative analysis of cyclooxygenase-2 gene expression on acute gastric injury induced by ischemia-reperfusion in rats

Abstract

J. Biol. Chem.

Eur. J. Pharmcol.

Life Science

J. Biol. Chem.

Biochim. Biophys. Acta

J. Biol. Chem.

FASEB J.

J. Clin. Invest.

Pharmacology letter
Quantitative analysis of cyclooxygenase-2 gene expression on acute gastric injury induced by ischemia-reperfusion in rats