Overproduction of nitric oxide inhibits vascular reactivity in portal hypertensive rats

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Plasma D (-)-lactate as a new marker for diagnosis of acute intestinal injury following ischemia-reperfusion

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Effects of tetrandrine on gastric mucosa and liver in portal hypertensive rats

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Loss of neutral endopeptidase activity contributes to neutrophil activation and cardiac dysfunction during chronic hypomagnesemia: Protection by substance P receptor blockade

BACKGROUND/OBJECTIVE:

Hypomagnesemia (Hypo-Mg) in rodents leads to neurogenic inflammation associated with substance P (SP) elevations; neutral endopeptidase (NEP) is a principle cell surface proteolytic enzyme, which degrades SP. The effects of chronic Hypo-Mg on neutrophil NEP activity, cell activation and the associated cardiac dysfunction were examined.

METHODS/RESULTS:

Male Sprague-Dawley rats (180 g) were fed Mg-sufficient or Mg-deficient (Hypo-Mg) diets for five weeks. Enriched blood neutrophils were isolated at the end of one, three and five weeks by step gradient centrifugation. NEP enzymatic activity decreased by 20% (P value was nonsignificant), 50% (P<0.025) and 57% (P<0.01), respectively, for week 1, 3 and 5 Hypo-Mg rats. In association, neutrophil basal superoxide (•O₂⁻)-generating activities were elevated: 30% at week 1 (P value was nonsignificant), and fourfold to sevenfold for weeks 3 to 5 (P<0.01). Maximal phorbol myristate acetate-stimulated •O₂⁻ production by Hypo-Mg neutrophils increased twofold at week 5. Also, plasma 8-isoprostane levels were elevated twofold to threefold, and red blood cell glutathione decreased by 50% (P<0.01) after three to five weeks of chronic Hypo-Mg. When Hypo-Mg rats were treated with the SP receptor blocker (L-703,606), neutrophil NEP activities were retained at 75% (week 3) and 77% (week 5) (P<0.05); activation of neutrophil •O₂⁻ and other oxidative indexes were also significantly (P<0.05) attenuated. After five weeks, histochemical (hematoxylin and eosin) staining of Hypo-Mg-treated rat ventricles revealed significant white blood cell infiltration, which was substantially reduced by L-703,606. Echocardiography after three weeks of Hypo-Mg only showed modest diastolic impairment, but five weeks resulted in significant (P<0.05) depression in both left ventricular systolic and diastolic functions; changes in these functional parameters were attenuated by L-703,606.

CONCLUSION:

NEP activity regulates neutrophil •O₂⁻ formation by controlling SP bioavailability. When oxidative inactivation of NEP is prevented by SP receptor blockade, partial protection is afforded against cardiac contractile dysfunction.     

Low contrast medium and radiation dose for hepatic computed tomography perfusion of rabbit VX2 tumor

AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P 0.001;r = 0.879,P 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P 0.001;r = 0.930,P 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.     

Intravenous infusion of mesenteric lymph from severe intraperitoneal infection rats causes lung injury in healthy rats

AIM:To investigate whether mesenteric lymph from rats with severe intraperitoneal infection(SII)induces lung injury in healthy rats.METHODS:Twenty adult male specific pathogen-free Wistar rats were divided into two groups.Animals in the SII group received intraperitoneal injection of Escherichia coli(E.coli)at a dose of 0.3 mL/100 g.Control rats underwent the same procedure,but were injected with normal saline rather than E.coli.We ligated and drained the mesenteric lymphatic vessels and collected the mesenteric lymph.Mesenteric lymph collected from SII or control rats was infused intravenously into male healthy rats at a rate of 1 mL/h for 4 h.At the end of the infusion,all rats were sacrificed.Lungs were removed and examined histologically,and wet-to-dry weight(W/D)ratio and myeloperoxidase(MPO)activity were determined.Enzyme-linked immunosorbent assay(ELISA)was performed to determine the levels of the proinflammatory cytokines tumor necrosis factor(TNF)-αand interleukin(IL)-6.We performed Western blot to investigate the activation of Toll-like receptor(TLR)-4,and nuclear factor(NF)-κB p65.RESULTS:Compared with the control infusion group,there were obvious pathological changes in the SII group.The W/D ratio was significantly increased in the SII compared to control infusion group(5.86±0.06vs 5.37±0.06,P<0.01).MPO activity significantly increased in the SII infusion rats with a mean level of0.86±0.02 U/g compared to 0.18±0.05 U/g in the control group(P<0.01).The concentrations of TNF-αand IL-6 were significantly increased in the SII infusion group.The concentration of TNF-αwas significantly increased in the SII infusion rats compared to control infusion rats(2104.46±245.91 vs 1475.13±137.82pg/mL,P<0.01).The concentration of IL-6 was significantly increased in the SII infusion rats with a mean level of 50.56±2.85 pg/mL compared to 43.29±2.02 pg/mL(P<0.01).The expression levels of TLR-4(7496.68±376.43 vs 4589.02±233.16,P<0.01)and NF-κB(8722.19±323.96 vs 6498.91±338.76,P<0.01)were significantly increased in the SII infusion group compared to the control infusion group.The infusion of SII lymph,but not control lymph,caused lung injury.CONCLUSION:The results indicate that SII lymph is sufficient to induce acute lung injury.     

Effect of terlipressin on blood volume distribution in patients with cirrhosis

Background: Patients with cirrhosis and portal hypertension have an altered blood volume distribution and a hyperdynamic systemic circulation. Terlipressin is known to reduce portal pressure by decreasing splanchnic inflow, but its effect on the blood volume distribution is unknown. The aim of the study was to investigate changes in regional blood volume distribution and systemic haemodynamics after administration of terlipressin to patients with cirrhosis. Methods: Blood volume distribution was determined in 13 patients with cirrhosis and portal hypertension by a dual‐head gamma‐camera technique and systemic haemodynamics was measured before and after intravenous administration of terlipressin (2?mg). Results: Terlipressin increased the blood volume in the thorax region (+6.0%, P?P?P?r?=?0.88, P?Conclusions: Terlipressin ameliorates the hyperdynamic circulation, increases thorax and liver blood volumes, but produces no effect on the splanchnic blood volume. Besides decreasing the splanchnic inflow, terlipressin may affect portal pressure by causing vasodilatation of intrahepatic vessels.     

Increased angiogenesis and permeability in the mesenteric microvasculature of rats with cirrhosis and portal hypertension: an in vivo study.

BACKGROUND: In vivo evidence for angiogenesis in the splanchnic vasodilation in portal hypertension (PHT) and cirrhosis is lacking. Vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) are mediators of angiogenesis. The present study visualises in vivo structural changes (angiogenesis and vascular hyperpermeability) and examines the presence of VEGF and eNOS in the mesenteric microvasculature of animal models of PHT with and without cirrhosis. METHODS: Portal hypertension was induced by partial portal vein ligation (PPVL) and cirrhosis was induced by common bile duct ligation (CBDL) in rats. The mesenteric microcirculation was examined by intravital microscopy. Expression of VEGF, eNOS and CD31 in mesenteric tissue were studied by immunohistochemistry. RESULTS: An increased mesenteric angiogenesis was observed in PPVL and CBDL rats compared with Sham-operated and control rats, as shown by intravital microscopy and CD 31 staining. VEGF and eNOS expression was higher in CBDL and PPVL rats compared with control groups and correlated positively with vascular density. Macromolecular leakage was increased in cirrhotic rats compared with control and PPVL rats. CONCLUSION: Our study provides in vivo evidence of an increased angiogenesis in the mesenteric microvasculature of animal models of PHT and cirrhosis. Increased VEGF and eNOS expression in the mesentery of PPVL and CBDL rats may suggest their contribution. Microvascular permeability in the mesenteric vessels was only increased in cirrhotic rats.     

Antioxidant effect of N-acetylcysteine on prehepatic portal hypertensive gastropathy in rats

Background. Portal hypertension is a clinical syndrome associated with the development of a hyperdynamic circulation and gastroesophageal varices.Aim. To evaluate the antioxidant effect of N-acetylcysteine on portal hypertensive rats.Material and methods. Portal hypertension was induced by partial portal vein ligation (PPVL). Oxidative damage in the stomach was measured by lipoperoxidation trough thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activity; we also evaluated nitrates and nitrites level and histology stained by hematoxylin-eosin. We performed evaluation of portal pressure and measurement of vessels diameter. Liver damage was evaluated by measuring hepatic enzymes. The animals were divided in four experimental groups (n = 6): Sham-operated (SO), SO + NAC, Partial portal vein ligation (PPVL) and PPVL + NAC. N-acetylcysteine (10 mg/kg ip) was administered daily for 7 days and started 8 days after surgery.Results. The portal hypertensive group showed an increase in portal pressure, vessels diameter, levels of TBARS and nitrates and nitrites when compared to SO group. These values were accompanied by a decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activity. Histology showed dilated vessels in the gastric mucosa in the PPVL group. NAC was able to decrease portal pressure values, vessels diameter, TBARS and also nitrates and nitrites levels when compared to PPVL group. Furthermore, PPVL+NAC group presented an increase in SOD and GPx activity. N-acetylcysteine attenuated damage in gastric mucosa.Conclusion. Oxidative stress is associated with portal hypertension and that antioxidant NAC is able to minimize damages of PPVL in rats.     

Hemodynamic characterization in experimental liver cirrhosis induced by thioacetamide administration

Systemic and splanchnic hemodynamics in experimental liver cirrhosis in rats induced by thioacetamide were evaluated by the radioactive microsphere method. Cardiac output and regional blood flow were measured in conscious and anesthetized control and cirrhotic rats. The conscious thioacetamide-treatment rats had hyperdynamic circulation with an increased cardiac index (300±10 vs 258±3 ml/min/kg body weight,P<0.001) and increased portal venous inflow compared with the controls (64.60±2.4 vs 48.39±0.88 ml/min/kg body weight,P<0.001). Under pentobarbital anesthesia, the hyperdynamic circulation of the cirrhotic rats was maintained, with an increased cardiac index (276±7 vs 229±5 ml/min/kg body weight,P<0.001) and increased portal venous inflow compared with the controls (72.47±3.0 vs 54.08±1.2 ml/min/kg body weight,P<0.001). Portal pressure, portal venous resistance, and portal systemic shunting increased significantly while splanchnic arterial resistance decreased significantly in cirrhotic rats. Thioacetamide-induced cirrhosis is a useful model for the hemodynamic study of portal hypertension and remains useful in hemodynamic studies in the basal state under pentobarbital anesthesia.     

Rapamycin prevents mesenteric neo‐angiogenesis and reduces splanchnic blood flow in portal hypertensive mice

Aim: Increased angiogenesis in the mesenteric microvasculature of portal hypertensive animals may contribute to the development of splanchnic vasodilation associated with portal hypertension (PHT). Experimental data suggest that rapamycin may reduce angiogenesis and tumour growth by inhibiting the vascular endothelial growth factor (VEGF) pathway. This study determines whether rapamycin can prevent the neoangiogenesis in the mesentery of portal hypertensive mice and may influence the splanchnic vasodilation. Methods: PHT was induced by partial portal vein ligation (PPVL). PPVL and Sham mice were treated daily with rapamycin or placebo for 2 weeks. Protein expressions of VEGF, CD 31, Akt and p70S6 kinase (mTOR signalling pathway) were evaluated. Mesenteric blood flow (MBF) was measured by a perivascular flow probe. Results: Increased mesenteric angiogenesis and VEGF protein levels were observed in PPVL_placebo mice compared to Sham_placebo mice. Rapamycin treatment caused significant reduction in CD 31 positive endothelial cells and VEGF protein in the PPVL_rapamycine group compared to the PPVL_placebo group, to levels comparable with Sham_placebo and Sham_rapamycine groups. MBF was significantly higher in PPVL_placebo mice compared to the Sham_placebo mice. Rapamycin decreased significantly the MBF in PPVL_rapamycine mice compared to PPVL_placebo mice. Phospo‐Akt and p70S6 kinase protein levels were increased in the mesenteric tissue of PPVL_placebo mice compared to Sham_placebo mice, which were also prevented by treatment with rapamycin. Conclusions: An increased VEGF dependent neo‐angiogenesis is present in the mesentery of portal hypertensive mice. Rapamycin prevents angiogenesis in the mesenteric tissue and decreases the mesenteric blood flow in portal hypertensive mice, at least in part through an anti‐VEGF activity and influence on the mTOR signalling pathway.     

Stimulation of oval cell and hepatocyte proliferation by exogenous bombesin and neurotensin in partially hepatectomized rats

AIM: To investigate the effect of the neuropeptides bombesin (BBS) and neurotensin (NT) on oval cell proliferation in partially hepatectomized rats not pretreated with a known hepatocyte inhibitor.METHODS: Seventy male Wistar rats were randomly divided into five groups: I = controls, II = sham operated, III = partial hepatectomy 70% (PHx), IV = PHx + BBS (30 μg/kg per day), V = PHx + NT (300 μg/kg per day). Forty eight hours after liver resection, portal endotoxin levels and hepatic glutathione redox state were determined. α-fetoprotein (AFP) mRNA (in situ hybridisation), cytokeratin-19 and Ki67 antigen expression (immunohistochemistry) and apoptosis (TUNEL) were evaluated on liver tissue samples. Cells with morphological features of oval cells that were cytokeratin-19 (+) and AFP mRNA (+) were scored in morphometric analysis and their proliferation was recorded. In addition, the proliferation and apoptotic rates of hepatocytes were determined.RESULTS: In the control and sham operated groups, oval cells were significantly less compared to groups III, IV and V (P < 0.001). The neuropeptides BBS and NT significantly increased the proliferation of oval cells compared to group III (P < 0.001). In addition, BBS and NT induced a significant increase of hepatocyte proliferation (P < 0.001), whereas it decreased their apoptotic activity (P < 0.001) compared to group III. BBS and NT significantly decreased portal endotoxemia (P < 0.001) and increased the hepatic GSH: GSSG ratio (P < 0.05 and P < 0.001, respectively) compared to group III.CONCLUSION: BBS and NT stimulated oval cell proliferation in a model of liver regeneration, without use of concomitant suppression of hepatocyte proliferation as oval cell activation stimuli, and improved the hepatocyte regenerative response. This peptides-induced combined stimulation of oval cell and hepatocyte proliferation might serve as a possible treatment modality for several liver diseases.     

Protective effect of heme oxygenase-1 on Wistar rats with heart failure through the inhibition of inflammation and amelioration of intestinal microcirculation

Background Myocardial infarction (MI) has likely contributed to the increased prevalence of heart failure (HF). As a result of reduced cardiac function, splanchnic blood flow decreases, causing ischemia in villi and damage to the intestinal barrier. The induction of heme oxygenase-1 (HO-1) could prevent, or lessen the effects of stress and inflammation. Thus, the effect and mechanism thereof of HO-1 on the intestines of rats with HF was investigated. Methods Male Wistar rats with heart failure through ligation of the left coronary artery were identified with an left ventricular ejection fraction (LvEF) of < 45% through echocardiography and then divided into various experimental groups based on the type of peritoneal injection they received [MI: saline; MI + Cobalt protoporphyrin (CoPP): CoPP solution; and MI + Tin mesoporphyrin IX dichloride (SnMP): SnMP solution]. The control group was comprised of rats without coronary ligation. Echocardiography was performed before ligation for a baseline and eight weeks after ligation in order to evaluate the cardiac function of the rats. The bacterial translocation (BT) incidence, mesenteric microcirculation, amount of endotoxins (ET) in the vein serum, ileum levels of HO-1, carbon oxide (CO), nitric oxide (NO), interleukin (IL)-10, tumour necrosis factor-α (TNF-α), and the ileum morphology were determined eight weeks after the operation. Results The rats receiving MI + CoPP injections exhibited a recovery in cardiac function, an amelioration of mesenteric microcirculation and change in morphology, a lower BT incidence, a reduction in serum and ileac NO and TNF-α levels, and an elevation in ileac HO-1, CO, and interleukin-10 (IL-10) levels compared to the MI (P < 0.05) group. The rats that received the MI + SnMP injections exhibited results inverse to the MI (P < 0.05) group. Conclusions HO-1 exerted a protective effect on the intestines of rats with HF by inhibiting the inflammation and amelioration of microcirculation through the CO pathway. This protective effect could be independent from the recovery of cardiac function.     

Impact of intestinal ischemia/reperfusion and lymph drainage on distant organs in rats

AIM:To investigate the impact of intestinal ischemia/reperfusion(I/R) injury and lymph drainage on distant organs in rats.METHODS:Thirty-two Sprague-Dawley male rats,weighing 280-320 g,were randomly divided into blank,sham,I/R,and ischemia/reperfusion and drainage(I/R + D) groups(n = 8).All rats were subjected to 60 min ischemia by clamping the superior mesenteric artery,followed by 120 min reperfusion.The rats in the I/R + D group received intestinal lymph drainage for 180 min.In the sham group,the abdominal cavity was opened for 180 min,but the rats received no treatment.The blank group served as a normal and untreated control.A chromogenic limulus assay kit was used for quantita-tive detection of serum endotoxin.The serum concentrations of tumor necrosis factor-α(TNF-α),interleukin(IL)-6,IL-1β,soluble cell adhesion molecules(sICAM-1),and high mobility group protein box 1(HMGB1) were determined with an enzyme-linked immunosorbent assay kit.Histological evaluations of the intestine,liver,kidney,and lung were performed by hematoxylin and eosin staining and immunohistochemistry.HMGB1 protein expression was assayed by western blot analysis.RESULTS:The serum levels of endotoxin and HMGB1 in the I/R and I/R + D groups were significantly higher than those in the sham group(endotoxin,I/R and I/R + D vs sham:0.033 ± 0.004 EU/mL,0.024 ± 0.003 EU/mL vs 0.017 ± 0.009 EU/mL,respectively,P 0.05;HMGB1,I/R and I/R + D vs sham:5.473 ± 0.963 EU/mL,4.906 ± 0.552 EU/mL vs 0.476 ± 0.406 EU/mL,respectively,P 0.05).In addition,endotoxin and HMGB1 were significantly lower in the I/R + D group compared to the I/R group(P 0.05).The serum inflammatory factors IL-6,IL-1β,and sICAM-1 in the I/R and I/R + D groups were significantly higher than those in the sham group(IL-6,I/R and I/R + D vs sham:41.773 ± 9.753 pg/mL,19.204 ± 4.136 pg/mL vs 11.566 ± 2.973 pg/mL,respectively,P 0.05;IL-1β,I/R and I/R + D vs sham:144.646 ± 29.378 pg/mL,65.829 ± 10.888 pg/mL vs 38.178 ± 7.157 pg/mL,respectively,P 0.05;sICAM-1,I/R and I/R + D vs sham:97.360 ± 12.714 ng/mL,48.401 ± 6.547 ng/mL vs 33.073 ± 5.957 ng/mL,respectively;P 0.05).The serum TNF-α in the I/R group were significantly higher than in the sham group(45.863 ± 11.553 pg/mL vs 18.863 ± 6.679 pg/mL,respectively,P 0.05).These factors were significantly lower in the I/R + D group compared to the I/R group(P 0.05).The HMGB1 immunohistochemical staining results showed no staining or apparent injury in the blank group,and slight staining at the top of the microvillus was detected in the sham group.In the I/R group,both the top of villi and the basement membrane were stained for HMGB1 in most areas,and injury in the I/R + D group was less than that in the I/R group.HMGB1 expression in the liver,kidney,and lung of rats in the I/R + D group was significantly lower than the rats in the I/R group(P 0.05).CONCLUSION:Lymph drainage could block the "gutlymph" pathway,improve intestinal barrier function,and attenuate distant organ injury incurred by intestinal I/R.     

Effects of Dangshen on isolated gastric muscle strips in rats

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Protective effect of naringenin on acetic acid-induced ulcerative colitis in rats

AIM:To evaluate the ameliorative effect of naringenin(NG)during ulcerative colitis(UC)in rats.METHODS:Rats were treated with three different doses(25,50 and 100 mg/kg per day)of NG and a single dose of mesalazine(MES,300 mg/kg per day)for seven days prior to ulcerative colitis induction by4%acetic acid(AA).Twenty four hours after AA rectal administration,animals were scarified and the colonic tissues were dissected.Colonic mucus content was estimated using Alcian blue dye binding technique.In colon tissues,levels of total glutathione sulphadryls(T-GSH),non-protein sulphadryls(NP-SH)and thiobarbituric acid reactive substances(TBARS)were evaluated.The activities of the antioxidant enzymes,catalase(CAT)and superoxide dismutase(SOD)were measured.Concentrations of nucleic acids(DNA and RNA)and total protein were also estimated in colon tissues.Colonic levels of tumor necrosis factor-(TNF-),interleukin-1(IL-1),interleukin-6(IL-6),prostaglandin E2(PGE2)and nitric oxide(NO)were estimated.In cross section of colitis tissue the histopathological changes were observed.RESULTS:Colonic mucus content was decreased in AA compared to controls(587.09±65.59 mg/kg vs941.78±68.41 mg/kg,P<0.001).AA administration markedly reduced T-GSH(5.25±0.37 nmol/L vs 3.04±0.24 nmol/L,P<0.01),NP-SH(3.16±0.04 nmol/L vs 2.16±0.30 nmol/L,P<0.01),CAT(6.77±0.40 U/mg vs 3.04±0.2 U/mg,P<0.01)and SOD(3.10±0.11U/mg vs 1.77±0.18 U/mg,P<0.01)while TBARS,TNF-,IL-1,IL-6,PGE2 and NO levels(15.09±3.84nmol/L vs 59.90±16.34 nmol/L,P<0.01;113.56±1.91 pg/mg vs 134.24±4.77 pg/mg,P<0.01;209.20±36.38 pg/mg vs 422.19±31.47 pg/mg,P<0.01;250.83±25.09 pg/mg vs 638.58±115.9 pg/mg,P<0.01;248.19±36.98 pg/mg vs 541.74±58.34 pg/mg,P<0.01 and 81.26±2.98 mmol/g vs 101.90±10.73 mmol/g,P<0.001)were increased in colon of rats with UC compared controls respectively.Naringenin supplementation,significantly and dose dependently increased the colonic mucus content.The elevated TBARS levels were significantly decreased(39.35±5.86n     

Lack of effect of norfloxacin on hyperdynamic circulation in bile duct‐ligated rats despite reduction of endothelial nitric oxide synthase function: result of unchanged vascular Rho‐kinase?

Background/Aims: In cirrhosis, portal hypertension is maintained by splanchnic vasodilation owing to overproduction of the vasodilator nitric oxide (NO) and defective contractile signalling by Rho‐kinase. NO overproduction is partially caused by bacterial translocation from the gut to mesenteric lymph nodes. However, the effects of intestinal bacterial decontamination on hyperdynamic circulation or vascular contractility are unknown. We investigated the haemodynamic and vascular effects of norfloxacin in rats with secondary biliary cirrhosis. Methods: Cirrhosis was induced by bile duct ligation (BDL). One group was treated with norfloxacin (20 mg/kg/day, 5 days, orally). Bacterial growth in the lymph nodes was determined on blood agar plates. Invasive haemodynamic measurements were combined with coloured microspheres. Aortic contractility was assessed myographically. Protein expression/phosphorylation was examined by Western blot analysis. Results: Norfloxacin treatment of BDL rats abolished bacterial translocation to mesenteric lymph nodes. BDL rats had hyperdynamic circulation, including portal hypertension and splanchnic vasodilation. None of these parameters was changed by norfloxacin, although norfloxacin reduced endothelial NO synthase expression and phosphorylation. The latter was associated with a diminished activity of protein kinase G (PKG), which mediates NO‐induced vasodilation. However, norfloxacin had no effect on aortic contractility to methoxamine or Ca²⁺, or the aortic expression of RhoA, Rho‐kinase and β‐arrestin 2, or the phosphorylation of the Rho‐kinase substrate moesin. Conclusions: Short‐term treatment of BDL rats with norfloxacin does not change hyperdynamic circulation or vascular contractility, despite reduction of PKG activity.     

Exaggerated Liver Injury Induced by Renal Ischemia Reperfusion in Diabetes: Effect of Exenatide

Background/Aim:

This study was designed to investigate the possible effect of exenatide (Glucagon like Peptide-1 receptor agonist) on liver injury (distant organ) induced by renal ischemia reperfusion (IR) in diabetic rats.

Materials and Methods:

In vivo renal IR was performed in both type 2 diabetic and normal rats. Each protocol comprised ischemia for 30 minutes followed by reperfusion for 24 hours and a treatment period of 14 days before induction of ischemia.

Results:

Lipid peroxidation, xanthine oxidase activity, myeloperoxidase activity and nitric oxide level in liver tissue were significantly increased (P < 0.01, P < 0.001, P < 0.001, P < 0.05, respectively), after IR in diabetic rats compared to normal rats. Antioxidant enzymes like glutathione, superoxide dismutase, catalase and glutathione peroxidase were significantly reduced (P < 0.05, P < 0.05, P < 0.01, P < 0.05, respectively), after IR in diabetic rats compared to normal rats. Exenatide treatment significantly normalized (P < 0.01), these biochemical parameters in treated rats compared to diabetic IR rats. Serum creatinine phosphokinase activity and liver function enzymes were also significantly normalized (P < 0.001, P < 0.001, respectively), after administration of exenatide.

Conclusion:

Exenatide exerted protective effect on exaggerated remote organ (liver) injury induced by renal IR in diabetes.     

Activity of brush border membrane enzymes in proximal jejunum of portal hypertensive rats

Purpose. Malabsorption accompanies portal hypertension, especially when associated with chronic liver disease. The development of portal hypertension is accompanied by significant alterations in the splanchnic microcirculation. In this study, the effect of extrahepatic and intrahepatic portal hypertension on brush border membrane enzymes was estimated. Methods. Portal hypertension was induced in rats by partial portal vein ligation (PPVL) (n = 6) and common bile duct ligation (CBDL) (n = 6), and the activity of sucrase, lactase, alkaline phosphatase, and leucine aminopeptidase (LAP) in the intestinal homogenate was measured. Results. Intrasplenic pulp pressure (ISPP) (in cm of saline) was found to be elevated in PPVL (21.3 ± 1.47) and CBDL animals (21.5 ± 1.79) as compared with findings in their respective sham-operated controls (12.74 ± 0.86, 11.83 ± 1.04). Only sucrase and LAP activity was significantly elevated (P < 0.05) in the PPVL group. No changes were observed in the CBDL group. Conclusion. Only sucrase and LAP activities were increased in PPVL rats. Received: August 16, 2000 / Accepted: January 19, 2001