Effects of oral administration of (L)-arginine, (L)-NAME and allopurinol on intestinal ischemia/reperfusion injury in rats

Microbiome and intestinal ischemia/reperfusion injury

Intestinal ischemia/reperfusion injury is a severe disease associated with a high mortality. The mechanisms that cause ischemia/reperfusion injury are complex and many factors are involved in the injury formation process; however, the only available treatment is surgical intervention. Recent studies demonstrated that the intestinal microbiome plays a key role in intestinal ischemia/reperfusion injury and there are many factors associated with intestinal bacteria during the formation of the intestinal ischemia/reperfusion injury. Among the Toll-like receptors (TLR), TLR2, TLR4, and their adaptor protein, myeloid differentiation primary-response 88 (MyD88), have been reported to be involved in intestinal ischemia/reperfusion injury. Oxidative stress and nitric oxide are also associated with intestinal bacteria during the formation of the intestinal ischemia/reperfusion injury. This review focuses on our current understanding of the impact of the microbiome, including the roles of the TLRs, oxidative stress, and nitric oxide, on intestinal ischemia/reperfusion injury.

The effects of S-nitrosoglutathione on intestinal ischemia reperfusion injury and acute lung injury in rats: Roles of oxidative stress and NF-κB

BACKGROUND

Intestinal ischemia and reperfusion (I/R) induces oxidative stress, inflammatory response, and acute lung injury. S-nitrosoglutathione (GSNO), a nitric oxide donor, has been documented to have protective effects on experimental ischemia models.

AIM

The aim of this study was to examine the effect of GSNO on I/R-induced intestine and lung damage and detect the potential mechanisms emphasizing the protective role of GSNO.

METHODS

Intestinal I/R was induced by occluding the superior mesenteric artery for 30 min followed by reperfusion for 180 min. GSNO was administered intravenously before reperfusion period (0.25 mg/kg). The levels of lipid peroxidation, reduced glutathione, and myeloperoxidase (MPO), histopathological evaluation and immunohistochemical expressions of both nuclear factor KappaB (NF-κB) and inducible nitric oxide (iNOS) in intestine and lung tissues were assessed.

RESULTS

Histolopathologic evaluation demonstrated that intestinal I/R induced severe damages in the intestine and the lung tissues. Histopathological scores decreased with GSNO treatment. GSNO treatment reduced lipid peroxidation and MPO levels and inhibited expression of NF-κB and iNOS in the intestine.

CONCLUSION

Our results suggest that GSNO treatment may ameliorate the intestinal and lung injury in rats, at least in part, by inhibiting inflammatory response and oxidative stress.

Effect of amlodipine, lisinopril and allopurinol on acetaminophen-induced hepatotoxicity in rats

Background

Exposure to chemotherapeutic agents such as acetaminophen may lead to serious liver injury. Calcium deregulation, angiotensin II production and xanthine oxidase activity are suggested to play mechanistic roles in such injury.

Objective

This study evaluates the possible protective effects of the calcium channel blocker amlodipine, the angiotensin converting enzyme inhibitor lisinopril, and the xanthine oxidase inhibitor allopurinol against experimental acetaminophen-induced hepatotoxicity, aiming to understand its underlying hepatotoxic mechanisms.

Material and methods

Animals were allocated into a normal control group, a acetaminophen hepatotoxicity control group (receiving a single oral dose of acetaminophen; 750 mg/kg/day), and four treatment groups receive N-acetylcysteine (300 mg/kg/day; a reference standard), amlodipine (10 mg/kg/day), lisinopril (20 mg/kg/day) and allopurinol (50 mg/kg/day) orally for 14 consecutive days prior to acetaminophen administration. Evaluation of hepatotoxicity was performed by the assessment of hepatocyte integrity markers (serum transaminases), oxidative stress markers (hepatic malondialdehyde, glutathione and catalase), and inflammatory markers (hepatic myeloperoxidase and nitrate/nitrite), in addition to a histopathological study.

Results

Rats pre-treated with amlodipine, lisinopril or allopurinol showed significantly lower serum transaminases, significantly lower hepatic malondialdehyde, myeloperoxidase and nitrate/nitrite, as well as significantly higher hepatic glutathione and catalase levels, compared with acetaminophen control rats. Serum transaminases were normalized in the lisinopril treatment group, while hepatic myeloperoxidase was normalized in the all treatment groups. Histopathological evaluation strongly supported the results of biochemical estimations.

Conclusion

Amlodipine, lisinopril or allopurinol can protect against acetaminophen-induced hepatotoxicity, showing mechanistic roles of calcium channels, angiotensin converting enzyme and xanthine oxidase enzyme in the pathogenesis of hepatotoxicity induced by acetaminophen.

The effect of colchicine and low-dose methotrexate on intestinal ischemia/reperfusion injury in an experimental model

AIM

Intestinal ischemia/reperfusion (I/R) injury is a serious clinical condition. Colchicine and low-dose methotrexate have anti-inflammatory features. An experimental model was conducted to investigate the effect of colchicine and methotrexate on intestinal I/R injury.

METHODS

Twenty-four rats were included. Only laparotomy was done in control group (CG, n=6). In experimental groups, superior mesenteric artery was occluded. After 1h ischemia, reperfusion (1h) was started by de-occlusion. 30min before reperfusion, saline in sham group (SG, n:6), colchicine (1mg/kg) in colchicine group (CNG, n:6), and methotrexate (0.1mg/kg) in methotrexate group (MTXG, n:6) were infused intraperitoneally. Small intestines were harvested for evaluation of intestinal mucosal injury (Chiu score) and oxidative stress markers (nitric oxide: NO, malondialdehyde: MDA, superoxide dismutase: SOD).

RESULTS

Biochemically, MDA levels were significantly low in CG compared to SG, CNG, and MTXG (p<0.05). NO levels were significantly low and SOD levels were significantly high in CG compared to MTXG (p<0.05). Histopathologically, Chiu score was significantly low in CG compared to SG, CNG, and MTXG (p<0.05), and significantly high in MTXG compared to SG and CNG (p<0.05).

CONCLUSION

The present experimental model caused I/R injury in rat intestines. Contrary to literature, it was found that methotrexate worsens and colchicine does not attenuate intestinal I/R injury.

Impact of alanyl-glutamine dipeptide on proliferative and inflammatory changes in jejunal mucosa after acute mesenteric ischemia

PURPOSE

The aim of our study was to determinate the impact of dipeptide (alanyl-glutamine) administration on inflammatory and proliferative changes in jejunal mucosa after acute mesenteric ischemia.

METHODS

Male Wistar rats (n=30) were divided into three groups: ischemia/reperfusion (IR) group which undergoes 60min of mesenteric ischemia and 1 or 24h of reperfusion (IR1, IR24, n=12). Groups with dipeptide administration (D+IR1, D+IR24, Dipeptiven con inf., i.v., 0.75 g/kg) prior to IR injury were followed by 1 and 24h of reperfusion. At the end of reperfusion period jejunal bioptic samples were obtained for histological (H&E), histochemical (Alcian blue) and immunohistochemical (anti-PCNA, anti-MPO) evaluations.

RESULTS

Our results pointed out a significant (p<0.001) increase of histopathological injury score in IR1 group compared to D+IR1 group. Immunohistochemical evaluation showed that MPO-positivity was significantly increased in IR groups after 1 (p<0.001) as well as 24h of reperfusion (p<0.01) compared to dipeptide pretreated groups. Proliferative/reparatory rate was assessed using anti-PCNA antibody and showed a significant increase (p<0.01) in PCNA cell positivity in lamina propria in dipeptide treated group compared to IR group.

CONCLUSION

In conclusion we may suggest that administration of alanyl-glutamine dipeptide prior to IR injury may help to protect small intestine and its mucous membrane integrity against insult such as intestinal ischemic/reperfusion injury presents.

Naringenin adds to the protective effect of L-arginine in monocrotaline-induced pulmonary hypertension in rats: favorable modulation of oxidative stress, inflammation and nitric oxide

The present study was directed to investigate the possible modulatory effect of naringenin when co-administered with L-arginine in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60 mg/kg). L-arginine (500 mg/kg) and naringenin (50 mg/kg) were orally administered daily, alone and in combination, for 3 weeks. Mean arterial blood pressure, electrocardiography and echocardiography were then recorded and rats were sacrificed and serum was separated for determination of total nitrate/nitrite level. Right ventricles and lungs were isolated for estimation of oxidative stress markers, tumor necrosis factor-alpha, total nitrate/nitrite and transforming growth factor-beta. Myeloperoxidase and caspase-3 activities in addition to endothelial and inducible nitric oxide synthase protein expression were also determined. Moreover, histological analysis of pulmonary arteries and cardiomyocyte cross-sectional area was performed. Combined therapy provided a significant improvement in L-arginine protective effect toward preserving hemodynamic changes and alleviating oxidative stress, inflammatory and apoptotic markers induced by monocrotaline treatment. Furthermore, combined therapy prevented monocrotaline-induced changes in endothelial and inducible nitric oxide synthase protein expression as well as histological analysis compared with either treatment alone. In conclusion, naringenin significantly adds to the protective effect of L-arginine in pulmonary hypertension induced by monocrotaline in rats.

Pretreatment with mineralocorticoid receptor blocker reduces intestinal injury induced by ischemia and reperfusion: involvement of inhibition of inflammatory response, oxidative stress, nuclear factor κB, and inducible nitric oxide synthase

BACKGROUND

Spironolactone (Sp), a mineralocorticoid receptor antagonist, protects against the ischemia reperfusion (IR) injury of retina, kidney, heart, and brain. We aimed to investigate the effects of Sp on intestinal IR injury.

METHODS

Male Wistar rats were randomly divided into: (1) a sham control group; (2) an IR control group, subjected to 30 min ischemia and 3 h reperfusion; (3) a group treated with Sp (20 mg/kg) for 3 d before the IR; and (4) a sham-operated control group treated with Sp (20 mg/kg). After the reperfusion, blood and intestinal tissue samples were collected to evaluate histopathologic state, neutrophil infiltration (by measuring myeloperoxidase activity), levels of the cytokines (tumor necrosis factor α, interleukin 1α [IL-1α], interferon γ, monocyte chemotactic protein-1, granulocyte macrophage-colony stimulating factor, and IL-4), malondialdehyde (MDA) and reduced glutathione contents, and immunohistochemical expressions of nuclear factor κB, inducible nitric oxide synthase (iNOS), and caspase-3.

RESULTS

MDA content, myeloperoxidase activity, and plasma levels of tumor necrosis factor α, IL-1α, and monocyte chemotactic protein-1 were all elevated in IR, indicating the oxidative stress and local and systemic inflammatory response. Sp administration markedly reduced the MDA content and the cytokine levels. The pretreatment alleviated intestinal injury, neutrophil infiltration, and the expressions of caspase-3, iNOS, and NFκB.

CONCLUSIONS

The results implicate that Sp may have a strong protective effect against the intestinal IR injury. The effect can be mediated via suppression of both systemic inflammatory response and apoptosis through amelioration of oxidative stress and generation of proinflammatory cytokines, iNOS, caspase-3, and nuclear factor κB. Therefore, mineralocorticoid receptor antagonism might be of potential therapeutic benefit in cases of intestinal IR damage.

Neuroprotective effect of tadalafil, a PDE-5 inhibitor, and its modulation by L-NAME in mouse model of ischemia-reperfusion injury

BACKGROUND

The present study investigates the neuroprotective effect of tadalafil, a selective phosphodiesterase-5 inhibitor, in a mouse model of ischemia-reperfusion injury.

MATERIALS AND METHODS

Bilateral carotid artery occlusion for 12 min followed by reperfusion for 24 h was employed to produce ischemia-reperfusion-induced cerebral injury in male Swiss mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using Morris water maze test. Degree of motor incoordination was evaluated using inclined beam walk test, rota-rod test, and lateral push test. Brain nitrite/nitrate, brain acetylcholinesterase activity, brain thiobarbituric acid reactive species, and glutathione levels were also estimated.

RESULTS

Bilateral carotid artery occlusion, followed by reperfusion, produced a significant rise in cerebral infarct size, brain nitrite/nitrate levels, acetylcholinesterase activity, and thiobarbituric acid reactive species level along with a fall in glutathione. A significant impairment of memory and motor coordination was also noted. Pretreatment of tadalafil significantly attenuated the above effects of ischemia-reperfusion injury. Tadalafil-induced neuroprotective effects were significantly attenuated by administration of L-NAME, a nonselective nitric oxide synthase inhibitor.

CONCLUSIONS

Results indicate that tadalafil exerts neuroprotective effects, probably through nitric oxide-dependent pathways. Therefore, phosphodiesterase-5 can be explored as an important target to contain ischemia-reperfusion injury.

Febuxostat improves the local and remote organ changes induced by intestinal ischemia/reperfusion in rats

BACKGROUND

Xanthine oxidase has been implicated in the pathogenesis of a wide spectrum of diseases, and is thought to be the most important source of oxygen-free radicals and cell damage during re-oxygenation of hypoxic tissues.

AIMS

The present study was undertaken to demonstrate whether febuxostat is superior to allopurinol in prevention of the local and remote harmful effects of small intestinal ischemia/reperfusion injury in rats.

METHODS

Intestinal ischemia was induced by superior mesenteric artery ligation. The rats were assigned to five groups: the sham control; the intestinal ischemia/reperfusion; the allopurinol; and the febuxostat 5 and 10 mg/kg pretreated ischemia/reperfusion groups. Treatment was administered from 7 days before ischemia induction. After the reperfusion, the serum and tissues were obtained for biochemical, pharmacological, and histological studies.

RESULTS

Intestinal reperfusion led to an elevation in the serum levels of alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor-α, malondialdehyde, and xanthine oxidase as well as intestinal myeloperoxidase, malonadialdehyde, and xanthine oxidase/xanthine dehydrogenase activity. Furthermore, the ischemia/reperfusion induced a reduction in the contractile responsiveness to acetylcholine. These changes were significantly regulated by the pretreatment with febuxostat compared to allopurinol. The degree of pathological impairment in the intestinal mucosa, liver, and lung tissues were lighter in the pretreated groups.

CONCLUSIONS

Febuxostat may offer advantages over allopurinol in lessening local intestinal injury as well as remote hepatic and lung injuries induced by small intestinal ischemia/reperfusion.

Protective effect of endogenous hydrogen sulfide against oxidative stress in gastric ischemia-reperfusion injury

Hydrogen sulfide (H₂S) is a gaseous signaling molecule, which plays a critical role in a number of physiological and pathological progresses. In order to determine the effect of endogenous H₂S on gastric ischemia-reperfusion (GI-R), we evaluated the gastric mucosal damage in rats intraperitoneally injected with DL-propargylglycine (PAG, 50 mg/kg/day) or L-cysteine (L-cys, 50 mg/kg/day) for 7 days before GI-R. GI-R injury was achieved by clamping the celiac artery for 30 min, followed by reperfusion for 60 min. Gastric mucosal damage was macroscopically assessed in the area of injury and deep damage was assessed by histopathological scoring. PAG increased the area of gastric mucosal injury and deep damage compared with that in untreated GI-R rats (P<0.05). While PAG decreased the H₂S concentration and cystathionine γ-lyase (CSE) expression in the gastric mucosa, L-cys significantly attenuated the effects of GI-R. Western blot analysis revealed that the increases of malondialdehyde (MDA) and xanthine oxidase (XOD), and decreases of glutathione (GSH), superoxide dismutase (SOD) and the restriction of superoxide (O₂⁻) production in the PAG group were inhibited by L-cys (P<0.05). Endogenous H₂S has a protective effect against GI-R in rats by inhibiting oxygen free radical overproduction.