Intestinal Ischemia-reperfusion Injury In Rats Research Articles

Outcomes of oxytocin treatment on intestinal ischemia-reperfusion injury in rats

Ischemia-reperfusion injury is a clinical condition that poses life-threatening risks and can be caused by diseases or operations such as trauma, shock, and gastric dilatation volvulus. The objective of this study was to examine the effect of oxytocin on intestinal damage in rats induced by experimental ischemia-reperfusion injury. Three groups of Wistar albino rats were established: a control group (CTR, n=6), an intestinal ischemia-reperfusion group (I-IR, n=6), and an intestinal ischemia-reperfusion with oxytocin group (I-IR+Oxt, n=6). The I-IR+Oxt group received an intraperitoneal injection of 1 mg/kg oxytocin 30 minutes before anesthesia. In the I-IR and I-IR+Oxt groups, the superior mesenteric artery was ligated for 1 hour to induce ischemia-reperfusion injury, followed by one hour of reperfusion by opening the ligatures. At the end of the reperfusion period, the rats were euthanized, and blood and intestinal tissue samples were collected. From the blood samples, ALT, ALP, AST, LDH, BUN, creatinine, IL-1β, and TNF-α concentrations were evaluated. Tissue samples were analyzed for IL-1β, TNF-α, and MDA activity. Serum and tissue IL-1β and TNF-α concentrations were higher in both the I-IR and I-IR+Oxt groups compared to the CTR group. However, these levels were found to be lower in the I-IR+Oxt group compared to the I-IR group. The histopathological analysis showed that the I-IR+Oxt group had better epithelial regeneration and less inflammatory cell infiltration compared to the I-I/R group. In conclusion, oxytocin inhibited the release of IL-1β and TNF-α and the harmful effect of I/R on intestinal cells.

Bifidobacterium longum GL001 alleviates rat intestinal ischemia-reperfusion injury by modulating gut microbiota composition and intestinal tissue metabolism.

Intestinal ischemia-reperfusion (IIR) injury leads to inflammation and oxidative stress, resulting in intestinal barrier damage. Probiotics, due to their anti-inflammatory and antioxidant properties, are considered for potential intervention to protect the intestinal barrier during IIR injury. Bifidobacterium longum, a recognized probiotic, has targeted effects on IIR injury, but its mechanisms of action are not yet understood. To investigate the mechanism of Bifidobacterium longum intervention in IIR injury, we conducted a study using a rat IIR injury model. The results showed that Bifidobacterium longum could alleviate inflammation and oxidative stress induced by IIR injury by suppressing the NF-κB inflammatory pathway and activating the Keap1/Nrf2 signaling pathway. Bifidobacterium longum GL001 also increased the abundance of the gut microbiota such as Oscillospira, Ouminococcus, Corynebacterium, Lactobacillus, and Akkermansia, while decreasing the abundance of Allobaculum, [Prevotella], Bacteroidaceae, Bacteroides, Shigella, and Helicobacter. In addition, Bifidobacterium longum GL001 reversed the changes in amino acids and bile acids induced by IIR injury and reduced the levels of DL-cysteine, an oxidative stress marker, in intestinal tissue. Spearman correlation analysis showed that L-cystine was positively correlated with Lactobacillus and negatively correlated with Shigella, while DL-proline was positively correlated with Akkermansia. Moreover, bile acids, cholic acid and lithocholic acid, were negatively correlated with Lactobacillus and positively correlated with Shigella. Therefore, Bifidobacterium longum GL001 may alleviate IIR injury by regulating the gut microbiota to modulate intestinal lipid peroxidation and bile acid metabolism.

The Effects of L-Carnitine on Gastrointestinal Contractility and Histological Changes in Rat Intestinal Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) of the small intestine causes serious abdominal pathologies including tissue dysfunction and organ failure. L-carnitine (L-C), a powerful antioxidant, may help lessen the severity of these pathological effects since it plays a key role in energy metabolism. In this work we aimed to study the effects of L-C on the isolated ileal and duodenal contractility and histological changes in intestinal ischemia and reperfusion injury. Twenty eight Wistar rats were divided into four groups. The first group is the control group. Second group, I/R group, had rats submitted to 45-minutes of intestinal ischemia and to 45-minutes reperfusion. The third group, I/R+ L-C group, rats were treated with L-C 5 minutes before reperfusion and than submitted to ischemia. The fourth group, included rats that were treated with L-C without ischemia or reperfusion. Intestinal ischemia was conducted by obstructing superior mesentery arteries by silk loop. The ileal and duodenal segments were isolated and suspended in tissue bath. Contractile responses were induced by acetylcholine (Ach) and relaxation was achieved with phenylephrine. At the same time the terminal ileal and duodenal segments were examined for histological changes. Ach-induced contraction responses were higher in the I/R+L-C group, the L-C group, and the control group compared to the I/R group, in both ileal and duodenal segments. On the other hand, the phenylephrine-induced relaxations were higher in the I/R+L-C and L-C groups, especially in duodenal segments. In I/R group intestinal morphology was observed to be severely damaged whereas in I/R+L-C group the damage was noticeably lower possibly due to protective properties of L-C. I/R injury caused severe cellular damage response within the muscularis resulting in decreased gastrointestinal motility. Treatment with the L-C has significantly affected the gastrointestinal contractility. Also L-C treatment reduced the damage in intestinal morphology that occurs after IR injury.

The protective effect of α7-nACh receptor and its interaction with 5-HT1B/1D receptors in acute intestinal ischemia-reperfusion injury in rats.

Over the past decades, great attention has been given to the nervous system modulating effects on the immune response in inflammation-associated injuries, such as acute intestinal ischemia-reperfusion (IR). Recently, we proved the anti-inflammatory and antioxidant effects of 5-hydroxytryptamine (5-HT)1B/1D receptors in intestinal IR injury in rats. Also, the alpha7 nicotinic acetylcholine (α7-nACh) receptor has anti-inflammatory effects in different inflammation-associated injuries. Starting from these premises, we aimed to examine the function of the α7-nACh receptors and the functional interactions between the anti-inflammatory and antioxidant effects of α7-nACh and 5-HT1B/1D receptors in acute intestinal IR injury. To confirm the expression and localization of α7-nACh receptors on the ileum nerves, an immunofluorescence-based method was applied. Then, intestinal IR injury was induced by 30-min occlusion of superior mesenteric artery and reperfusion for 2h in rats. Acute systemic administration of α7-nACh receptor agonist PNU-282987 and antagonist methyllycaconitine, and 5-HT1B/1D receptors agonist (sumatriptan) and antagonist (GR127, 935) were used in the model of intestinal IR injury. Finally, biochemical and histological parameters were assessed. Α7-nACh receptors were expressed by 9% on the ileum nerves. Likewise, activation of the α7-nACh receptor showed anti-inflammatory and antioxidant effects in intestinal IR injury but not as well as 5-HT1B/1D receptors. Interestingly, 5-HT1B/1D receptors via attenuation of glutamate (Glu) release indirectly activated the α7-nACh receptor and its protective effects against inflammation and oxidative stress. The protective effect of the α7-nACh receptor on intestinal IR injury was activated indirectly through the 5-HT1B/1D receptors' modulatory impact on Glu release.

Anwulignan Ameliorates the Intestinal Ischemia/Reperfusion.

Anwulignan is one of the monomer compounds in the lignans from Schisandra sphenanthera In this study, we observed the effect of anwulignan on intestinal ischemia/reperfusion (II/R) injury in male Sprague-Dawley rats and explored the underlying mechanisms. The results showed that pretreatment with oral anwulignan could significantly increase the mesenteric blood microcirculatory flow velocity; relieve the congestion and pathologic injury of jejunum; enhance the autonomic tension of jejunum smooth muscle and its reactivity to acetylcholine; increase the activities of superoxide dismutase, catalase, glutathione S-transferase, and choline acetyltransferase; increase the contents of acetylcholine and glutathione in the serum or jejunal tissue; decrease the activities of myeloperoxidase, protein kinase C, and nicotinamide adenine dinucleotide phosphate oxidase; reduce the contents of malondialdehyde, 8-hydroxy-2-deoxyguanosine, nicotinamide adenine, reactive oxygen species, tumor necrosis factor-α, interleukin (IL)-6, and IL-1β; increase the expression levels of muscarinic receptor 3, PI3K, phosphorylation protein kinase B, p-GSK3β Ser9, Nrf2, p-Nrf2, heme oxygenase (decycling) 1, and b-cell lymphoma 2 in the jejunal tissue; and decrease the expression levels of p-GSK3β Tyr216, kelch-like ECH-associated protein 1, Bax, and cleaved caspase-3, suggesting that anwulignan can ameliorate II/R-induced jejunal tissue injury in rats and that the mechanism may be related to its activating the PI3K/protein kinase B pathway and then regulating the Nrf2/Anti-oxidative Response Element signaling pathway and the expression of apoptosis-related proteins to play antioxidant and antiapoptotic roles. SIGNIFICANCE STATEMENT: Anwulignan can significantly reduce jejunal tissue injury and the production of inflammatory factors in rats with intestinal ischemia-reperfusion injury, improve the antioxidant capacity, and reduce the apoptosis of jejunal tissue, and it has the effect of significantly improving intestinal ischemia-reperfusion injury in rats, suggesting that anwulignan may be used as a potential drug for the prevention and treatment of intestinal ischemia-reperfusion injury or a resource for the development of health food.

Propofol improves intestinal ischemia-reperfusion injury in rats through NF-κB pathway.

The aim of this study was to investigate the effects of propofol on intestinal ischemia-reperfusion injury in rats through the nuclear factor-kappa B (NF-κB) pathway. A total of 24 Sprague-Dawley rats were selected and randomly divided into three groups, including sham operation group, ischemia group and propofol group. Rats in sham operation group were only treated with isolation of superior mesenteric artery, which was clipped for 1 h and reperfused for 2 h in ischemia group. Meanwhile, propofol (60 mg/kg) was injected into the femoral vein 1 h before ischemia in propofol group. TUNEL assay was performed to detect cell apoptosis of intestinal tissues. Real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to measure the expression levels of malondialdehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO), caspase-3 and B-cell lymphoma-2 (Bcl-2) in rats of each group. Western blotting was utilized to detect the protein expression levels of NF-κB pathway related molecules, such as myeloid differential protein-88 (MyD88), v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) and NF-κB. Furthermore, changes in plasma cytokine levels were determined via enzyme-linked immunosorbent assay (ELISA). The number of apoptotic cells in ischemia group was remarkably higher than that in sham operation group (p<0.05). However, it decreased notably in propofol group compared with ischemia group (p<0.05). In comparison with sham operation group, significantly up-regulated expression of caspase-3 and down-regulated expression of Bcl-2 were observed in the intestinal tissues of rats in ischemia group (p<0.05). Caspase-3 was lowly expressed, while Bcl-2 was highly expressed in the intestinal tissues of rats in propofol group compared with ischemia group (p<0.05). In addition, no statistically significant differences were observed in the expression level of SOD among sham operation group, ischemia group and propofol group (p>0.05). The expression levels of MDA and MPO were overtly higher in the intestinal tissues of rats in ischemia group than those in sham operation group and propofol group (p<0.05). Besides, the protein expression levels of MyD88, RelA and NF-κB in the intestinal tissues of rats in ischemia group were remarkably higher than those in sham operation group and propofol group (p<0.05). The activity of the NF-κB pathway in the intestinal tissues of rats in propofol group significantly declined compared with ischemia group (p<0.05). Moreover, compared with sham operation group, plasma levels of TNF-α, interleukin (IL)-2, IL-6 and IL-4 increased significantly in rats of ischemia group (p<0.05). However, they were markedly lower in propofol group than those in ischemia group (p<0.05). Propofol protects rats from intestinal ischemia-reperfusion injury through the NF-κB pathway.

The effects of ozone on the acute phase of intestinal ischemia-reperfusion injury in rats.

In this study, we aimed to examine the therapeutic effects of ozone on the acute phase of intestinal ischemia-reperfusion (I/R) injury in rats to resemble clinical practice. Eighteen Wistar albino rats were assigned to control (CG, n=6), sham (SG, n=6) and ozone groups (OG, n=6). A midline laparotomy was performed and a superior mesenteric artery (SMA) in the SG and OG was occluded with a 0/0 catgut suture, but in the CG, the incision was closed without any intervention. Tissue oxygenation was monitored with a tissue oxygenation monitor to achieve the same grade during intestinal ischemia. The incision was closed and, in the OG, ozone/oxygen mixture (0.7 mg/kg) was injected intraperitoneally, 20 minutes before reperfusion. Surgical incision was reopened and reperfusion was achieved after 60 minutes of ischemia in the SG and OG. After 60 minutes of reperfusion, 2 cm small intestine segment was sampled for histopathological assessment of the intestinal mucosal damage (Chiu score) and biochemical assessment of oxidative stress markers (nitric oxide: NO, malondialdehyde: MDA, superoxide dismutase: SOD) in all groups. The Chiu scores of the SG and OG were statistically increased than that of the CG (p=0.002; and p=0.002, respectively). Chiu score in the OG was higher compared to that in the SG, but not statistically significant (p=0.175). MDA levels were statistically higher in the SG and OG than that of the CG (p=0.004; and p=0.010, respectively). However, the difference between the SG and OG was not statistically significant (p=0.522). SOD and NO levels were not significantly different between groups (p=0.451 and p=0.056, respectively). Contrary to the literature, single-dose ozone therapy did not reduce the oxidative stress or improve the ischemic damage in intestinal I/R injury in rats. Further evaluation with different doses in different time periods is needed for potential clinical use.

Role of PI3K/Akt signaling pathway in propofol-induced reduction of intestinal ischemia-reperfusion injury in rats

Objective To evaluate the role of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway in propofol-induced reduction of intestinal ischemia-reperfusion (I/R) injury in rats. Methods Thirty-two healthy male Sprague-Dawley rats, aged 2-3 months, weighing 225-275 g, were divided into 4 groups (n=8 each) using a random number table method: sham operation group (Sham group), intestinal I/R group (I/R group), propofol group (P group), and PI3K inhibitor wortmannin plus propofol group (W+ P group). Intestinal ischemia was induced by occluding the superior mesenteric artery for 45 min followed by 2 h of reperfusion to establish the model of intestinal I/R injury.Propofol was intravenously infused at a rate of 20 mg·kg-1·h-1 starting from the onset of reperfusion until the end of reperfusion in group P. Wortmannin 15 μg/kg was intravenously injected at 25 min before reperfusion, and propofol was intravenously infused at a rate of 20 mg·kg-1·h-1 starting from the onset of reperfusion until the end of reperfusion in group W+ P.Rats were sacrificed at 2 h of reperfusion, and small intestinal tissues were obtained for microscopic examination of pathologic changes of intestinal mucosa and for determination of wet/dry weight ratio (W/D ratio), malondialdehyde (MDA) content (by thiobarbituric acid colorimetric method), superoxide dismutase (SOD) activity (using xanthine oxidase method), myeloperoxidase (MPO) activity (by MPO assay), and phosphorylated Akt (p-Akt) expression (by Western blot). Intestinal damage was assessed and scored according to Chiu. Results Compared with group Sham, Chiu′s score, W/D ratio, MDA content and MPO activity were significantly increased, the SOD activity was decreased, and p-Akt expression was down-regulated in group I/R (P<0.05). Compared with group I/R, Chiu′s score, W/D ratio, MDA content and MPO activity were significantly decreased, the SOD activity was increased, and p-Akt expression was up-regulated in group P (P<0.05). Compared with group P, Chiu′s score, W/D ratio, MDA content and MPO activity were significantly increased, the SOD activity was decreased, and p-Akt expression was down-regulated in group W+ P (P<0.05). Conclusion The mechanism by which propofol reduces intestrnal I/R injury is related to activating PI3K/Akt signaling pathway and inhibiting inflammatory and oxidative stress responses in rats. Key words: Propofol; Reperfusion injury; Intestines; Phosphatidylinositol 3-kinase; Protein kinases

The Protective Effect of Orally Administered Amlodipine against Intestinal Ischemia-Reperfusion Injury in Rats

Objective- This study investigated the effect of amlodipine on intestinal ischemia-reperfusion injury in ratsDesign-Experimental studyAnimals-Fifteen male Sprague-Dawly rats weighing 200-220gProcedure- Rats were randomly divided into 3 groups: IR group (operation with clamping), sham group (operation without clamping), and IRA group (operation with clamping and 5mg/kg amlodipine pretreatment). Intestinal ischemia-reperfusion was performed by occlusion (clamping) of the arteria mesenterica anterior for 60 min, followed by 60 min reperfusion. Levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) were determined in intestinal tissue of rats. Intestinal tissues were also investigated histopathologically. Results- Pretreatment with amlodipine impeded the increase in lipid peroxidation and mitigated GPx and SOD levels. Amlodipine also prevented I/R cellular damage and histological alternations in intestinal tissue. The levels of MDA (P<0.006) was significantly increased in the intestine of IR group rats. Intestinal GPx and SOD levels were decreased significantly (p<0.001) after I/R. Conclusion and clinical relevance- The findings of this study suggest that amlodipine has a preventive activity on I/R-induced intestine injury. The observed preventive effects of amlodipine in the present study can possibly be mediated by means of its well-known antioxidant and anti-inflammatory potential. Therefore, we suggest that amlodipine may be a novel approach to therapy for protective intestinal I/R injury.

Effect of oxycodone on intestinal ischemia-reperfusion injury in rats and the role of autophagy

Objective To evaluate the effect of oxycodone on intestinal ischemia-reperfusion injury in rats and the role of autophagy. Methods Twenty-four healthy adult male Sprague-Dawley rats, aged 6-9 weeks, weighing 180-220 g, were divided into 4 groups(n=6 each)using a random number table method: sham group(group S), intestinal I/R group(group I/R), oxycodone group(group O)and oxycodone plus autophagy inhibitor 3-methyladenine(3-MA)group(group O+ 3-MA). Intestinal I/R was induced via clamping the superior mesenteric artery for 1 h, followed by 2-h reperfusion in all the groups except for group S. Oxycodone 0.5 mg/kg was injected via caudal vein at 15 min before ischemia in group O and group O+ 3-MA.3-MA 30 mg/kg was intraperitoneally injected at 10 min before ischemia in group O+ 3-MA.Rats were gavaged with fluorescein-isothiocyanate-conjugated dextran(FITC-dextran)immediately before ischemia.Blood samples were collected from the cardiac apex at 2 h of reperfusion to detect the level of serum FITC-dextran.Blood samples were collected from the cardiac apex at 2 h of reperfusion to measure the concentrations of tumor necrosis factor-alpha(TNF-α)and interleukin-1beta(IL-1β)in serum by enzyme-linked immunosorbent assay.Small intestinal tissues were obtained at 2 h of reperfusion for examination of the pathological changes and for determination of the expression of occludin, Beclin-1 and microtubule-associated protein 1 light chain 3(LC3)(by Western blot). Intestinal damage was assessed and scored according to Chiu.The ratio of LC3Ⅱ expression to LC3Ⅰ expression(LC3Ⅱ/Ⅰ)was calculated. Results Compared with group S, the Chiu′s score, levels of serum FITC-dextran, TNF-α and IL-1β and LC3Ⅱ/Ⅰ ratio were significantly increased, the expression of Beclin-1 was up-regulated, and the expression of occludin was down-regulated in group I/R(P 0.05). Compared with group O, the Chiu′s score and levels of serum FITC-dextran, TNF-α and IL-1β were significantly increased, LC3Ⅱ/Ⅰ ratio was decreased, and the expression of occludin and Beclin-1 was down-regulated in group O+ 3-MA(P<0.05). Conclusion Oxycodone can ameliorate intestinal I/R injury, and the mechanism may be related to enhancing autophagy in intestinal tissues of rats. Key words: Oxycodone; Reperfusion injury; Intestine; Autophagy

Villin-1 Is a Novel Serological Biomarker for Intestinal Ischemia and Reperfusion Injury in Rats and Humans

Introduction: Intestinal ischemia remains a frequent pathology with a mortality rate up to 80%, due to delayed diagnosis and lack of efficient therapy. Intestinal reperfusion enhances the catastrophic effect of ischemia, known as ischemia-reperfusion injury (IRI). In contrast to other organs, serological markers for intestinal IRI are missing. We have accumulated evidence that villin-1 -a protein anchoring the actin filaments at the epithelial brush border- is a valuable candidate.The aim was to analyze villin-1 as a serological biomarker in a rodent and human model of intestinal ischemia reperfusion injury (IRI). Methods: In a rat model of intestinal IRI (temporary mesenteric artery clamping), 4 conditions were tested: (i) laparotomy only (sham); (ii) 30min ischemia + 5 reperfusion periods (0min/30min/60min/120min/24hours); (iii) 45min ischemia + 5 reperfusion periods; (iv) 60min ischemia + 5 reperfusion periods; (n=6/group). For survival analysis, 7-day reperfusion was included in each condition (n=10/group). Other end-points that were analyzed: histology (Park-Chiu/villus length); intestinal permeability (Ussing chamber); villin-1 (Western-Blot). In a validated human model of intestinal IRI (6cm jejunal-clamping during pancreaticoduodenectomy; 45min ischemia + 0min/30min/120min reperfusion) villin-1 was analyzed by immunoprecipitation (n=6). Results: In rat, increasing ischemia resulted in decreased survival (30min: 90%; 45min: 50%; 60min: 10%) and loss of intestinal integrity (histology/permeability). From 45min ischemia, villin-1 appeared in the plasma at 0min reperfusion and remained detectable until 120min reperfusion (Figure 1). At 0min reperfusion, villin-1 could differentiate between 45min or 60min ischemia corresponding to the different survival. Overall, villin-1 had a strong correlation with Park-Chiu score (r=0.7954;p<0.0001); villus length (r=−0.6585;p<0.0001); and permeability (r=−0.6127;p=0.0019). In human, villin-1 was released with ischemia and remained detectable until 120min reperfusion (Figure 2). Conclusion: For the first time, we showed that villin-1 is a serological biomarker of intestinal IRI in rat and human. These findings open new perspectives in the diagnosis of intestinal ischemia and warrant further clinical investigations.FIGURE 1: Rat model.FIGURE 2: Human model.

Fenofibrate reduces intestinal damage and improves intestinal recovery following intestinal ischemia-reperfusion injury in a rat.

Fenofibrate (FEN) is known as a nuclear receptor activator which regulates many pathophysiological processes, such as oxidative stress, inflammation, and leukocyte endothelium interactions. Recent studies have demonstrated an anti-oxidant, anti-inflammatory, and anti-ischemic role of FEN in the attenuation of ischemia-reperfusion (IR) injury in the kidney, liver, brain, and heart. The purpose of the present study was to examine the effect of FEN on intestinal recovery and enterocyte turnover after intestinal IR injury in rats. Male Sprague-Dawley rats were divided into four experimental groups: (1) sham rats underwent laparotomy, (2) sham-FEN rats underwent laparotomy and were treated with intraperitoneal (IP) FEN (20mg/kg); (3) IR rats underwent occlusion of both the superior mesenteric artery and the portal vein for 30min followed by 24h of reperfusion, and (4) IR-FEN rats underwent IR and were treated with IP FEN immediately before abdominal closure. Intestinal structural changes, Park's injury score, enterocyte proliferation, and enterocyte apoptosis were determined 24h following IR. The expression of Bax, Bcl-2, p-ERK, and caspase-3 in the intestinal mucosa was determined using real-time PCR, Western blot, and immunohistochemistry. Treatment with FEN resulted in a significant decrease in Park's injury score in jejunum (32%) and ileum (33%) compared to IR animals. IR-FEN rats also demonstrated a significant increase in mucosal weight in jejunum (23%) and ileum (22%), mucosal DNA (38%) and protein (65%) in jejunum, villus height in jejunum (17%) and ileum (21%), and crypt depth in ileum (14%) compared to IR animals. IR-FEN rats also experienced significant proliferation rates as well as lower apoptotic indices in jejunum and ileum which was accompanied with higher Bcl-2 levels compared to IR animals. Treatment with fenofibrate prevents intestinal mucosal damage and stimulates intestinal epithelial cell turnover following intestinal IR in a rat model.

N-acetylcysteine ameliorates liver injury in a rat model of intestinal ischemia reperfusion

BackgroundN-acetylcysteine (NAC) is an antioxidant with direct and indirect antioxidant actions used in the clinical setting. Oxidative stress is known to play a pivotal role in the intestinal ischemia reperfusion (IIR). Therefore, we studied the effect of different pretreatment regimens with NAC on the IIR injury in rats. Materials and methodsThirty-five male Wistar rats were randomly assigned to five groups. In group sham, only laparotomy was performed. Group control underwent IIR without NAC. In the other groups, NAC was administered intraperitoneally with different regimens: 150 mg/kg before ischemia (NAC 150), 300 mg/kg before ischemia (NAC 300), and 150 mg/kg before ischemia plus 150 mg/kg 5 min before reperfusion (NAC 150 + 150). Measurements in tissues and blood were conducted at 4 h of reperfusion following exsanguination. ResultsHistological score of the liver was significantly improved in NAC 300 compared with control (1.7 ± 0.5 versus 2.9 ± 1.1, respectively, P = 0.05). In addition, NAC treatment significantly reduced liver transaminases in all groups of treatment, mostly in group NAC 300. Plasma malondialdehyde levels were lower with NAC treatment, although not statistically significant. Lung glutathione peroxidase was significantly increased in group NAC 300 (P = 0.04), while the other oxidation biomarkers showed no significant differences. ConclusionsNAC exerts a significant protective role in liver injury following IIR, which seems to be independent of an intestinal protective effect. Additional administration of NAC before reperfusion was of no further benefit. The most effective regimen among the compared regimens was that of 300 mg/kg before ischemia.

Ischemic Preconditioning-Induced SOCS-1 Protects Rat Intestinal Ischemia Reperfusion Injury via Degradation of TRAF6.

The inflammatory immune response plays an important role in mesenteric ischemia and ischemia-reperfusion injury. Toll-like receptor 4 (TLR4) is a critical receptor in transduction of the inflammatory response and plays an important role in intestinal homeostasis. Tumor necrosis factor receptor-associated factor 6 (TRAF6), known as a key adaptor protein downstream of TLR4, is involved in the inflammatory response by activating multiple apoptotic signaling pathways. However, mechanisms of the suppressor of cytokine signaling-1 (SOCS-1) in regulating cell inflammation and apoptosis are still obscure. To investigate the TLR4-TRAF6 signaling pathway in intestinal ischemia and reperfusion injury, as well as SOCS-1 expression after ischemic preconditioning in the rat intestine. The small bowel ischemia, ischemia-reperfusion, and preconditioning models were induced using ligation of the superior mesenteric artery in male Sprague-Dawley rats; then, the mRNA and protein levels of TLR4, TRAF6, and SOCS-1 were analyzed using real-time PCR, Western blot, and immunohistochemistry, respectively. The expression of TLR4 and TRAF6 was gradually increased with increasing intestinal ischemia duration, but increased substantially after ischemia-reperfusion injury. After ischemic preconditioning, TLR4 and TRAF6 expressions decreased; however, expression of SOCS-1 and the TLR4-TRAF6 pathway inhibitor was increased. These data show that ischemic preconditioning may induce the activation of SOCS-1 to inhibit the TLR4-TRAF6 signaling pathway, thereby playing a protective role in ischemia-reperfusion injury.

Effect of Chelerythrine on Intestinal Cell Turnover following Intestinal Ischemia-Reperfusion Injury in a Rat Model.

Background Chelerythrine (CHE) is a benzophenanthridine alkaloid that is a potent, selective, and cell-permeable protein kinase C inhibitor. The purpose of the present study was to examine the effect of CHE on intestinal recovery and enterocyte turnover after intestinal ischemia-reperfusion (IR) injury in rats. Methods Male Sprague-Dawley rats were divided into four experimental groups: (1) sham rats underwent laparotomy, (2) sham-CHE rats underwent laparotomy and were treated with intraperitoneal CHE; (3) IR-rats underwent occlusion of both superior mesenteric artery and portal vein for 30 minutes followed by 48 hours of reperfusion, and (4) IR-CHE rats underwent IR and were treated with intraperitoneal CHE immediately before abdominal closure. Intestinal structural changes, Park injury score, enterocyte proliferation, and enterocyte apoptosis were determined 24 hours following IR. The expression of Bax, Bcl-2, p-ERK, and caspase-3 in the intestinal mucosa was determined using real Western blot and immunohistochemistry. Results Treatment with CHE resulted in a significant decrease in Park injury score in jejunum (threefold decrease) and ileum (twofold decrease), and parallel increase in mucosal weight in jejunum and ileum, villus height in jejunum and ileum, and crypt depth in ileum compared with IR animals. IR-CHE rats also experienced a significantly lower apoptotic index in jejunum and ileum, which was accompanied by a lower Bax/Bcl2 ratio compared with IR animals. Conclusions Treatment with CHE inhibits programmed cell death and prevents intestinal mucosal damage following intestinal IR in a rat.

Effect of Candida albicans on Intestinal Ischemia-reperfusion Injury in Rats.

Background:Inflammation is supposed to play a key role in the pathophysiological processes of intestinal ischemia-reperfusion injury (IIRI), and Candida albicans in human gut commonly elevates inflammatory cytokines in intestinal mucosa. This study aimed to explore the effect of C. albicans on IIRI.Methods:Fifty female Wistar rats were divided into five groups according to the status of C. albicans infection and IIRI operation: group blank and sham; group blank and IIRI; group cefoperazone plus IIRI; group C. albicans plus cefoperazone and IIRI (CCI); and group C. albicans plus cefoperazone and sham. The levels of inflammatory factors tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and diamine oxidase (DAO) measured by enzyme-linked immunosorbent assay were used to evaluate the inflammation reactivity as well as the integrity of small intestine. Histological scores were used to assess the mucosal damage, and the C. albicans blood translocation was detected to judge the permeability of intestinal mucosal barrier.Results:The levels of inflammatory factors TNF-α, IL-6, and IL-1β in serum and intestine were higher in rats undergone both C. albicans infection and IIRI operation compared with rats in other groups. The levels of DAO (serum: 44.13 ± 4.30 pg/ml, intestine: 346.21 ± 37.03 pg/g) and Chiu scores (3.41 ± 1.09) which reflected intestinal mucosal disruption were highest in group CCI after the operation. The number of C. albicans translocated into blood was most in group CCI ([33.80 ± 6.60] ×102 colony forming unit (CFU)/ml).Conclusion:Intestinal C. albicans infection worsened the IIRI-induced disruption of intestinal mucosal barrier and facilitated the subsequent C. albicans translocation and dissemination.

Direct intraperitoneal resuscitation with lidocaine, methylene blue and pentoxiphylline combination does not decreases inflammation after intestinal ischemia-reperfusion injury in rats

To evaluate the effects of an intraperitoneal solution of methylene blue (MB), lidocaine and pentoxyphylline (PTX) on intestinal ischemic and reperfusion injury. Superior mesenteric artery was isolated and clamped in 36 adult male Sprague Dawley rats. After 60 minutes, clamp was removed and a group received intraperitoneally UNITO solution (PTX 25mg/kg + lidocaine 5mg/kg + MB 2mg/kg), while the other group was treated with warm 0.9% NaCl solution. Rats were euthanized 45 min after drug administration. Lung and bowel were collected for histological evaluation (using Park's score) and determination of myeloperoxidase (MPO) and malondialdehyde (MDA) levels. Control samples showed lymphoplasmocytic infiltrate and crypt necrosis of villi. MPO and MDA measurements shown no differences between treated and control groups. The combination of lidocaine, methylene blue and pentoxyphylline administered intraperitoneally at the studied dose, did not decreased histological lesion scores and biochemical markers levels in intestinal ischemia/reperfusion injury.

Effect of Pretreatment With Extract of Origanum vulgare Leaves on Experimental Intestinal Ischemia-Reperfusion Injury in Rats

Background: Origanum vulgare is used in traditional medicine for antimicrobial, anti-inflammatory and antioxidant activities. Objectives: The present study was designed to investigate the protective effects of O. vulgare leaves extract on experimentally induced intestinal ischemia/reperfusion (I/R) injury in rats. Materials and Methods: In this experimental study, 24 male Wistar albino rats randomly divided into four groups. Group I/R underwent ischemia-reperfusion of the intestine (45 minutes of ischemia followed by 1 hour of reperfusion). Treatment groups I and II were given O. vulgare extract (200 and 400 ppm) via oral gavages for 1 week before inducing I/R. Group sham was given normal saline orally without inducing I/R. After the experiments, the jejunum was removed and the tissues were processed for histomorphometric examination of mucosa. Results: The treatment with O. vulgare extract significantly decreased mucosal damages in the treatment groups compared to group I/R, while severe mucosal damages were observed in the group I/R. Also, there was significant difference between treatment groups I and II (P = 0.054). Group sham observed normal intestinal mucosa. Conclusions: According to the results of current study, administration of O. vulgare extract protects the intestinal mucosa from I/R injuries.

Effects of remifentanil preconditioning on intestinal ischemia-reperfusion injury in rats: the relationship with opioid receptors

Objective To evaluate the effect of remifentanil preconditioning (RP) on intestinal ischemia-reperfusion (I/R) injury in rats and its relationship with opioid receptors. Methods Seventy-two Sprague-Dawley rats, aged 6-7 weeks, weighing 250-280 g, were randomly divided to 9 groups (n=8 each): sham operation group (S), intestinal I/R group (group I/R), RP group, different opioid receptor antagonists groups (N, BNI and CTOP groups), and opioid receptor antagonists + RP groups (N+ RP, BNI+ RP and CTOP+ RP groups). Intestinal I/R was produced by clamping the superior mesenteric artery for 1 h followed by 2 h reperfusion in all the groups except group S. RP was induced by 3 cycles of 5 min infusion of remifentanil 0.2 μg·kg-1·min -1 followed by 5 min infusion of normal saline before ischemia.Naltrindole (δ-receptor antagonist, 5 mg/kg), nor-binaltorphimine (κ-receptor antagonist, 5 mg/kg) and CTOP (μ-receptor antagonist, 1 mg/kg) were administered before RP.At 2 h of reperfusion, blood samples were collected from the cardiac apex for determination of serum diamine oxidase (DAO) activity.Intestinal tissues were then removed for microscopic examination.Intestinal damage was assessed and scored according to Chiu.Apoptosis in intestinal mucosal epithelial cells was detected using TUNEL assay, and apoptosis index was calculated.The expression of activated caspase-3 in intestinal mucosal epithelial cells was measured by Western blot. Results Compared with group S, the serum DAO activity, Chiu's score, and apoptosis index were significantly increased, and the expression of activated caspase-3 was up-regulated in I/R and RP groups (P 0.05). Compared with group RP, the serum DAO activity, Chiu's score, and apoptosis index were significantly increased, and the expression of activated caspase-3 was up-regulated in N+ RP and CTOP+ RP groups (P 0.05). Conclusion RP can mitigate intestinal I/R injury in rats, and the mechanism is related to the anti-apoptotic effect mediated by activation of δ- and μ-opioid receptors, but not κ-opioid receptors. Key words: Piperidines; Intestine; Reperfusion injury; Receptors, opioid

Sevoflurane Preconditioning Reduces Intestinal Ischemia-Reperfusion Injury: Role of Protein Kinase C and Mitochondrial ATP-Sensitive Potassium Channel

Ischemic preconditioning (IPC) has been considered to be a potential therapy to reduce ischemia-reperfusion injury (IRI) since the 1980s. Our previous study indicated that sevoflurane preconditioning (SPC) also reduced intestinal IRI in rats. However, whether the protective effect of SPC is similar to IPC and the mechanisms of SPC are unclear. Thus, we compared the efficacy of SPC and IPC against intestinal IRI and the role of protein kinase C (PKC) and mitochondrial ATP-sensitive potassium channel (mKATP) in SPC. A rat model of intestinal IRI was used in this study. The superior mesenteric artery (SMA) was clamped for 60 min followed by 120 min of reperfusion. Rats with IPC underwent three cycles of SMA occlusion for 5 min and reperfusion for 5 min before intestinal ischemia. Rats with SPC inhaled sevoflurane at 0.5 minimum alveolar concentration (MAC) for 30 min before the intestinal ischemic insult. Additionally, the PKC inhibitor Chelerythrine (CHE) or mKATP inhibitor 5-Hydroxydecanoic (5-HD) was injected intraperitoneally before sevoflurane inhalation. Both SPC and IPC ameliorated intestinal IRI-induced histopathological changes, decreased Chiu’s scores, reduced terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) positive cells in the epithelium, and inhibited the expression of malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α). These protective effects of SPC were similar to those of IPC. Pretreatment with PKC or mKATP inhibitor abolished SPC—induced protective effects by increasing Chiu’s scores, down-regulated the expression of Bcl-2 and activated caspase-3. Our results suggest that pretreatment with 0.5 MAC sevoflurane is as effective as IPC against intestinal IRI. The activation of PKC and mKATP may be involved in the protective mechanisms of SPC.