Protective effects of L-carnitine on intestinal ischemia/reperfusion injury in a rat model

Synbiotics Alleviate Hepatic Damage, Intestinal Injury and Muscular Beclin-1 Elevation in Rats after Chronic Ethanol Administration

The purpose of this study was to investigate the beneficial effects of synbiotics on liver damage, intestinal health, and muscle loss, and their relevance in rats with chronic ethanol feeding. Thirty Wistar rats fed with a control liquid diet were divided into control and synbiotics groups, which were respectively provided with water or synbiotics solution (1.5 g/kg body weight/day) for 2 weeks. From the 3rd to 8th week, the control group was divided into a C group (control liquid diet + water) and an E group (ethanol liquid diet + water). The synbiotics group was separated in to three groups, SC, ASE, and PSE. The SC group was given a control liquid diet with synbiotics solution; the ASE group was given ethanol liquid diet with synbiotics solution, and the PSE group was given ethanol liquid diet and water. As the results, the E group exhibited liver damage, including increased AST and ALT activities, hepatic fatty changes, and higher CYP2E1 expression. Intestinal mRNA expressions of occludin and claudin-1 were significantly decreased and the plasma endotoxin level was significantly higher in the E group. In muscles, beclin-1 was significantly increased in the E group. Compared to the E group, the PSE and ASE groups had lower plasma ALT activities, hepatic fatty changes, and CYP2E1 expression. The PSE and ASE groups had significantly higher intestinal occludin and claudin-1 mRNA expressions and lower muscular beclin-1 expression when compared to the E group. In conclusion, synbiotics supplementation might reduce protein expression of muscle protein degradation biomarkers such as beclin-1 in rats with chronic ethanol feeding, which is speculated to be linked to the improvement of intestinal tight junction and the reduction of liver damage.

Effects of Lipoic Acid on Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury often occurred in some pathologies and surgeries. I/R injury not only harmed to physiological functions of corresponding organ and tissue but also induced multiple tissue or organ dysfunctions (even these in distant locations). Although the reperfusion of blood attenuated I/R injury to a certain degree, the risk of secondary damages was difficult to be controlled and it even caused failures of these tissues and organs. Lipoic acid (LA), as an endogenous active substance and a functional agent in food, owns better safety and effects in our body (e.g., enhancing antioxidant activity, improving cognition and dementia, controlling weight, and preventing multiple sclerosis, diabetes complication, and cancer). The literature searching was conducted in PubMed, Embase, Cochrane Library, Web of Science, and SCOPUS from inception to 20 May 2021. It had showed that endogenous LA was exhausted in the process of I/R, which further aggravated I/R injury. Thus, supplements with LA timely (especially pretreatments) may be the prospective way to prevent I/R injury. Recently, studies had demonstrated that LA supplements significantly attenuated I/R injuries of many organs, though clinic investigations were short at present. Hence, it was urgent to summarize these progresses about the effects of LA on different I/R organs as well as the potential mechanisms, which would enlighten further investigations and prepare for clinic applications in the future.

Sesamin Protects against and Ameliorates Rat Intestinal Ischemia/Reperfusion Injury with Involvement of Activating Nrf2/HO-1/NQO1 Signaling Pathway

Intestinal ischemia-reperfusion (I/R) may induce cell/tissue injuries, leading to multiple organ failure. Based on our preexperiments, we proposed that sesamin could protect against and ameliorate intestinal I/R injuries and related disorders with involvement of activating Nrf2 signaling pathway. This proposal was evaluated using SD intestinal I/R injury rats in vivo and hypoxia/reoxygenation- (H/R-) injured rat small intestinal crypt epithelial cell line (IEC-6 cells) in vitro. Sesamin significantly alleviated I/R-induced intestinal histopathological injuries and significantly reduced serum biochemical indicators ALT and AST, alleviating I/R-induced intestinal injury in rats. Sesamin also significantly reversed I/R-increased TNF-α, IL-6, IL-1β, and MPO activity in serum and MDA in tissues and I/R-decreased GSH in tissues and SOD in both tissues and IEC-6 cells, indicating its anti-inflammatory and antioxidative stress effects. Further, sesamin significantly decreased TUNEL-positive cells, downregulated the increased Bax and caspase-3 protein expression, upregulated the decreased protein expression of Bcl-2 in I/R-injured intestinal tissues, and significantly reversed H/R-reduced IEC-6 cell viability as well as reduced the number of apoptotic cells among H/R-injured IEC-6 cell, showing antiapoptotic effects. Activation of Nrf2 is known to ameliorate tissue/cell injuries. Consistent with sesamin-induced ameliorations of both intestinal I/R injuries and H/R injuries, transfection of Nrf2 cDNA significantly upregulated the expression of Nrf2, HO-1, and NQO1, respectively. On the contrary, either Nrf2 inhibitor (ML385) or Nrf2 siRNA transfection significantly decreased the expression of these proteins. Our results suggest that activation of the Nrf2/HO-1/NQO1 signaling pathway is involved in sesamin-induced anti-inflammatory, antioxidative, and antiapoptotic effects in protection against and amelioration of intestinal I/R injuries.

Effect of Genistein and L-carnitine and Their Combination on Lipid Profile and Inflammatory Cytokines in Experimental Nephrotic Syndrome

BACKGROUND

Nephrotic syndrome is a disorder caused by kidney damage that results in severe leakage of protein from blood into urine. Hyperlipidemia is one complication of nephrotic syndrome. L-carnitine and genistein can control cardiovascular diseases by causing changes in lipid metabolism and cytokine production. This study was designed to examine the effects of genistein and L-carnitine on serum lipid and cytokine profiles in experimental nephrotic syndrome.

METHODS

In this study, 50 male Sprague-Dawley rats were randomly divided into five groups of 10 animals each with similar mean body weights (300±50 g). The five groups were NC (normal-control), PC (patient-control), LC (L-carnitine), G (genistein), and LCG (L-carnitine-genistein). Serum HDL-cholesterol (HDL) LDL-cholesterol (LDL), triglyceride, cholesterol, IL-6, and TNF-α were measured. Statistics were analyzed using SPSS 18.0.

RESULTS

At the end of the study, of the patient groups, HDL was significantly greater in the LC than in the PC or G groups (P<0.001). LDL was significantly less in the G than in the PC, LC, or LCG groups (P<0.001). Interleukin-6 was significantly greater in the PC than in the LC, G, or LCG groups, and significantly greater in the LC than in the G group. (P<0.001), but no significant differences were found for triglyceride, cholesterol, or TNF-α between the patient groups.

CONCLUSION

Genistein had less effect on HDL and triglyceride levels than LC or LCG. Regarding inflammatory cytokines, genistein and L-carnitine had less effect on TNF-α than on IL-6.

Chlorogenic acid in the oxidative stress injury triggered by Shuang-Huang-Lian injection

Injections of Chinese herbs are a novel approach to prepare traditional Chinese medicines. However, as injections of Chinese herbs have been extensively used, adverse drug reactions (ADRs) have been on the increase. Additionally, the mechanism for injections of Chinese herbs remains unclear. This study explored the potential role played by chlorogenic acid (CGA) in initiating oxidative stress injury triggered by the utilization of injections of Chinese herbs and the underlying mechanism. A total of 90 male Wistar rats were raised for varying periods by using Shuang-Huang-Lian (SHL) injection or CGA in diverse dosages. Western blot analysis examined the expression of nicotinamide adenine dinucleotide phosphate oxidase subunits, spectrophotometry was used to examine the activity taken by catalase, ELISA was used to examine the concentrations of inflammatory factors in serum, and intravital microscopy was employed to examine the microcirculation. The results showed that the excessive peroxide production induced by CGA in high-dose or SHL in the venule walls may well be through nicotinamide adenine dinucleotide phosphate oxidase along with a decline in the activity of catalase, and led to imbalance of basal levels of pro-(TNF-α) and anti-(IL-10) inflammatory cytokines. On the basis of the aforementioned results, the mechanism hidden behind the adverse effects of CGA induced by irrational use of Chinese herbal injection can be identified from a deeper perspective.

Different Dietary Proportions of Fish Oil Regulate Inflammatory Factors but Do Not Change Intestinal Tight Junction ZO-1 Expression in Ethanol-Fed Rats

Sixty male Wistar rats were fed a control or an ethanol-containing diet in groups C or E. The fat compositions were adjusted with 25% or 57% fish oil substituted for olive oil in groups CF25, CF57, EF25, and EF57. Hepatic thiobarbituric acid-reactive substance (TBARS) levels, cytochrome P450 2E1 protein expression, and tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and IL-10 levels, as well as intracellular adhesion molecule (ICAM)-1 levels were significantly elevated, whereas plasma adiponectin level was significantly reduced in group E (p < 0.05). Hepatic histopathological scores of fatty change and inflammation, in group E were significantly higher than those of group C (p < 0.05). Hepatic TBARS, plasma ICAM-1, and hepatic TNF-α, IL-1β, and IL-10 levels were significantly lower, and plasma adiponectin levels were significantly higher in groups EF25 and EF57 than those in group E (p < 0.05). The immunoreactive area of the intestinal tight junction protein, ZO-1, showed no change between groups C and E. Only group CF57 displayed a significantly higher ZO-1 immunoreactive area compared to group C (p = 0.0415). 25% or 57% fish oil substituted for dietary olive oil could prevent ethanol-induced liver damage in rats, but the mechanism might not be related to intestinal tight junction ZO-1 expression.

The effect of antioxidant supplementation on bacterial translocation after intestinal ischemia and reperfusion

The intestine is highly sensitive to ischemia/reperfusion (I/R) injury. Intestinal I/R may cause local tissue injury and disruption of the intestinal mucosal barrier, allowing the passage of viable bacteria and endotoxins from the gastrointestinal lumen to distant organs. This phenomenon, known as bacterial translocation (BT), may lead to systemic disorders with high morbidity and mortality. Oxidative stress mediators such as reactive oxygen species, polymorphonuclear neutrophils and nitric oxide are believed to contribute to the intestinal I/R injury. Many antioxidants have shown protective effects against I/R injury of various organs. The present article provides an overview of studies investigating the effect of antioxidant supplementation on BT after intestinal I/R.

The preventive effects of dexmedetomidine against intestinal ischemia-reperfusion injury in Wistar rats

OBJECTIVES

Intestinal ischemia-reperfusion is a major problem, which may lead to multiorgan failure and death. The aim of this study was to evaluate the protective effects of dexmedetomidine on cell proliferation, antioxidant system, cell death, and structural integrity in intestinal injury induced by ischemia-reperfusion in rats.

MATERIALS AND METHODS

Animals were randomized into three groups: group A, sham-operated or control; group B, intestinal ischemia/reperfusion (IR); and group C, intestinal IR pretreated with 50 μg of dexmedetomidine. Intestine tissue was collected from all rats 30 min after desufflation, and fresh frozen for histological and biochemical evaluation.

RESULTS

The intestinal tissue of group B rats showed a significant decrease in the antioxidant enzyme activities. However, these enzyme activities were improved by the administration of dexmedetomidine. Inhibiting the protein expression of MCP7, PAR2, P-JAK, P-STAT1, and P-STAT3 proved the protective effect of dexmedetomidine. The immunohistochemical staining revealed its protective effect by maintaining the normal structural integrity, less caspase-3 immuno reactivity, and increased cell proliferation count in the intestinal tissues.

CONCLUSIONS

Intraperitoneal injection of dexmedetomidine significantly protected intestine IR injury in rats by inhibiting the inflammatory response, intestinal epithelial apoptosis, and maintaining structural integrity of intestinal cells.

Impaired intestinal mucosal barrier upon ischemia-reperfusion: "patching holes in the shield with a simple surgical method"

Mesenteric ischemia-reperfusion (IR) is associated with impairment of the gut barrier function and the initiation of a proinflammatory cascade with life-threatening results. Therefore methods directed to ameliorate IR injury are of great importance. We aimed at describing the effects of postconditioning (PC) on the alterations of the intestinal mucosal function and the inflammatory response upon mesenteric IR. Methods. Male Wistar rats were gavaged with green fluorescent protein-expressing E. coli suspensions. Animals were randomized into three groups (n = 15), sham-operated, IR-, and PC-groups, and underwent 60 minutes of superior mesenteric artery occlusion, followed by 6 hours of reperfusion. Postconditioning was performed at the onset of reperfusion. Blood and tissue samples were taken at the end of reperfusion, for histological, bacteriological, and plasma examinations. Results. The PC-group presented a more favorable claudin-2, claudin-3, claudin-4, and zonula occludens-1 membrane expression profile, and significantly lower rates of bacterial translocation to distant organs and plasma D-lactate levels compared to the IR-group. Histopathological lesions, plasma I-FABP, IL-6, and TNF-α levels were significantly lower in the PC-group compared to the IR-group. Conclusion. The use of postconditioning improved the integrity of the intestinal mucosal barrier upon mesenteric IR, and thus reduced the incidence of bacterial translocation and development of a systemic inflammatory response.

Baicalin attenuates intestinal ischemia/reperfusion injury and alters intestinal expression of Nrf2 and HO-1 in rats

AIM: To investigate the protective effects of baicalin against intestinal ischemia-reperfusion (IIR) injury in rats.

METHODS: Thirty-two male Wistar rats were randomly and equally divided into four groups: control (SO), baicalin (BA), IIR, and baicalin + IIR (BA + IIR). IIR was induced by clamping the superior mesenteric artery (SMA) for 60 min and restoring blood supply for two hours. The rats in the SO and BA groups underwent a laparotomy, and the SMA was separated without occlusion. The rats in the BA and BA + IIR groups were given baicalin (100 mg/kg, 1 mL) by introperitoneal injection 30 min before model creation. The rats in the SO and IIR groups were given normal saline (1 mL). Intestinal histopathologic changes were examined. Serum superoxide dismutase (SOD) and malondialdehyde (MDA) levels were determined by WST and thiobarbituric acid method, respectively, and plasma D-lactic acid level was assayed by ELISA. The expression of NF-E2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) in intestinal tissues was determined by immunohistochemistry (IHC) and Western blot (WB).

RESULTS: In the IIR group, the Chiu's score (3.99 ± 0.24 vs 0.30 ± 0.08, P < 0.01), serum MDA level (3.41 ± 0.23 vs 1.59 ± 0.25, P < 0.01) and plasma D-lactic acid level (174.27 ± 33.84 vs 52.40 ± 12.12, P < 0.01) were significantly higher than those in the SO group. Nrf2 and HO-1 expression in intestinal tissues in the IIR group was significantly higher than that in the SO group (IHC: 0.326 ± 0.024 vs 0.289 ± 0.041, 0.298 ± 0.025 vs 0.258 ± 0.027, P < 0.05; WB: 1.062 ± 0.056 vs 0.584 ± 0.048, 1.019 ± 0.041 vs 0.592 ± 0.037, P < 0.01). In the IIR group, serum SOD activity decreased significantly compared with the SO group (100.08 ± 3.20 vs 136.88 ± 5.93, P < 0.01). In the BA group, Nrf2 and HO-1 expression in intestinal tissues increased significantly in comparison with the SO group (IHC: 0.322 ± 0.028 vs 0.289 ± 0.041, 0.284 ± 0.009 vs 0.258 ± 0.027, P < 0.05; WB: 1.077 ± 0.038 vs 0.584 ± 0.048, 1.027 ± 0.042 vs 0.592 ± 0.037, P < 0.01). Compared with the IIR group, intestinal tissue injury was significantly reduced (2.95 ± 0.26 vs 3.99 ± 0.24, P < 0.01), serum MDA level (3.09 ± 0.15 vs 3.41 ± 0.23, P < 0.01) and plasma D-lactic acid decreased significantly (108.04 ± 20.19 vs 174.27 ± 33.84, P < 0.01), and serum SOD activity (116.11 ± 4.12 vs 100.08 ± 3.20, P < 0.01) and expression of Nrf2 and HO-1 in intestinal tissues increased significantly (IHC: 0.371 ± 0.024 vs 0.326 ± 0.024, 0.336 ± 0.031 vs 0.298 ± 0.025, P < 0.01; WB: 1.541 ± 0.100 vs 1.062 ± 0.056, 1.458 ± 0.071 vs 1.019 ± 0.041, P < 0.01) in the IIR + BA group.

CONCLUSION: Our data suggest that baicalin alleviates IIR injury possibly by activating the Nrf2-ARE pathway.

Carnitine deficiency in OCTN2-/- newborn mice leads to a severe gut and immune phenotype with widespread atrophy, apoptosis and a pro-inflammatory response

We have investigated the gross, microscopic and molecular effects of carnitine deficiency in the neonatal gut using a mouse model with a loss-of-function mutation in the OCTN2 (SLC22A5) carnitine transporter. The tissue carnitine content of neonatal homozygous (OCTN2^−/−) mouse small intestine was markedly reduced; the intestine displayed signs of stunted villous growth, early signs of inflammation, lymphocytic and macrophage infiltration and villous structure breakdown. Mitochondrial β-oxidation was active throughout the GI tract in wild type newborn mice as seen by expression of 6 key enzymes involved in β-oxidation of fatty acids and genes for these 6 enzymes were up-regulated in OCTN2^−/− mice. There was increased apoptosis in gut samples from OCTN2^−/− mice. OCTN2^−/− mice developed a severe immune phenotype, where the thymus, spleen and lymph nodes became atrophied secondary to increased apoptosis. Carnitine deficiency led to increased expression of CD45-B220⁺ lymphocytes with increased production of basal and anti-CD3-stimulated pro-inflammatory cytokines in immune cells. Real-time PCR array analysis in OCTN2^−/− mouse gut epithelium demonstrated down-regulation of TGF-β/BMP pathway genes. We conclude that carnitine plays a major role in neonatal OCTN2^−/− mouse gut development and differentiation, and that severe carnitine deficiency leads to increased apoptosis of enterocytes, villous atrophy, inflammation and gut injury.

Changes of PACAP immunoreactivities and cytokine levels after PACAP-38 containing intestinal preservation and autotransplantation

Small bowel is one of the most sensitive organs to ischemia-reperfusion injury, which is a significant problem during transplantation. Pituitary adenylate cyclase-activating polypeptide (PACAP) has cytoprotective effect in ischemic injuries of various tissues. The aim of our study was to measure changes of PACAP-38 and PACAP-27 immunoreactivities and cytokine levels in intestinal grafts stored in PACAP-38-containing preservation solution. Small bowel autotransplantation was performed on male Wistar rats. Grafts were stored in University of Wisconsin (UW) solution at 4 °C for 1 h (group (G)I), for 3 h (GII), and for 6 h (GIII) and in PACAP-38-containing UW solution for 1 h (GIV), for 3 h (GV), and for 6 h (GVI). After preservation, performing vessel anastomosis reperfusion began, which lasted 3 h in each group. Tissue biopsies were collected after laparotomy (control) and at the end of the reperfusion periods. Intestinal PACAP-38 and PACAP-27 immunoreactivities were measured by radioimmunoassay. To measure cytokines from tissue homogenates, we used rat cytokine array and Luminex Multiplex Immunoassay. Levels of PACAP-38 and PACAP-27 immunoreactivity decreased after 1 and 3 h preservation compared to control levels. This decrease was significant following 6 h cold storage (p < 0.05). Values remained significantly higher in grafts stored in PACAP-38-containing UW. Cytokine array revealed that expression of the soluble intercellular adhesion molecule-1 (CD54) and L-selectin (CD62L/LECAM-1) was increased in GIII. Both 6 h cold storage in PACAP-38-containing UW solution and 3 h reperfusion caused strong reduction in these cytokines activation in GVI. RANTES (CCL5) levels were increased in all groups. Strong activation of the tissue inhibitor of metalloproteinase-1 was in GIII. However, PACAP-38-containing cold storage could decrease its activation in GVI. Furthermore, strong activation of the tissue inhibitor of metalloproteinase-1 was detected in 6 h preserved grafts without PACAP-38 (GIII). PACAP-38-containing cold storage could decrease its activation in GVI. Our present study showed that PACAP-38 and PACAP-27 immunoreactivities decreased in a time-dependent manner during intestinal cold preservation, which could be ameliorated by administration of exogenous PACAP-38 to the preservation solution. Moreover, PACAP-38 could attenuate tissue cold ischemic injury-induced changes in cytokine expression.