The role of alpha-tocopherol and allopurinol in lipid peroxidation and mitochondrial respiration in the ischemic rat liver

In the present study, the effects of alpha-tocopherol and allopurinol in liver ischemia and reperfusion injury on lipid peroxidation and mitochondrial respiratory function were investigated in rats. Ischemia was induced in the left and median liver lobes clamping the vessels for 90 minutes. After declamping reperfusion was continued for 60 minutes. Liver tissue was taken before and 90 minutes after ischemia and 60 minutes after reperfusion to measure lipid peroxides and mitochondrial respiratory function. In one group of rats alpha-tocopherol (10mg/kg) was given intraperitoneally for three consecutive days preoperatively and in the other group allopurinol (50mg/kg) was given intravenously 10 minutes before ischemia. alpha-Tocopherol caused inhibition of increase in lipid peroxides at reperfusion and improvement in lowering of mitochondrial respiratory function. This improvement was less than previously reported, probably due to not only reperfusion injury but also ischemic injury. Allopurinol, on the other hand, caused neither such inhibition nor such improvement, suggesting the other source of oxygen-derived free radicals than xanthine oxidase system.     

Changes in the levels of lipid peroxides in regenerating rat liver and the effect of pretreatment with CoQ10

The present study was undertaken to determine whether CoQ10 pretreatment could modify cellular free radical metabolism in regenerating rat liver and enhance hepatic DNA synthesis. Male Wistar rats (250-300 g) were used. Partial 70% hepatectomy was performed according to Higgins and Anderson. CoQ10 (6 mg/kg body weight) and its solvent as a placebo were injected intravenously 1 hour before operation. Twenty-four hours or 48 hours after 70% hepatectomy resulted in 55% or 50% decreases of hepatic ATP, and marked decreases of endogenous CoQ homologs (CoQ9 and CoQ10), alpha-tocopherol and reduced glutathione (GSH) in remnant liver and was accompanied by 2.5-fold increases in lipid peroxides. However, in CoQ10-treated animals synthesis of ATP was accelerated after 48 hours after partial hepatectomy. There were no changes in the levels of CoQ9, alpha-tocopherol, or GSH or in the level of the enhanced CoQ10 in regenerating liver. The pretreatment also completely suppressed the elevation of lipid peroxide. Moreover, CoQ10 administration markedly increased hepatic DNA synthesis at 48 hours after partial hepatectomy. These results indicate that cellular damage during hepatic regeneration is in part due to lipid peroxidation, and suggest that CoQ10 is effective in the pretreatment of liver resection.     

Characterization of heparan sulfate on hepatocytes in regenerating rat liver

Background/Purpose  Liver regeneration occurs through interactions between the receptors on hepatocytes, including proteoglycans (PGs) and glycosaminoglycans (GAGs), and various growth factors. We investigated serial changes in GAGs, particularly heparan sulfate (HS), in proliferating hepatocytes. Methods  We performed 70% hepatectomy in male Wistar rats, and we then isolated hepatocytes by a collagenase perfusion method after each surgery. DNA synthesis was evaluated by measuring proliferating cell nuclear antigen (PCNA). After we had treated the hepatocytes by delipidation and digestion with actinase E, endo-β-xylosidase, and α-amylase, we quantified GAGs by a carbazole-sulfuric acid method. GAGs were analyzed by ion-exchange chromatography, and changes in molecular weight of the HS component were investigated by size-fractionation HPLC. Results  Hepatocyte mitosis peaked at 24 h after the amount of GAGs was increased at 24 and 72 h after surgery. The amount of HS was slightly increased at 3 to 12 h after surgery, and then peaked at 24 h. The molecular weight of the HS declined by 12 h, but had recovered to the preoperative level by 24 h. Conclusions  These results suggested that this HS molecule, which contained about ten disaccharide units during proliferation, may be an initiator of hepatocyte proliferation.     

Hepatic protein synthesis in the regenerating rat liver after hepatopancreatectomy

To evaluate the effects of hepatopancreatectomy on the regenerative process of the liver, the serum protein changes, hepatic protein synthesis (HPS), and bromodeoxyuridine (BrdU) labeling index were measured in rats. Sprague-Dawley rats were divided into four groups according to the type of resection: A simple laparotomy was performed in the sham group; 68% of the liver was excised in the Hx group; 45% of the pancreas was excised in the Px group; and 45% of the pancreas and 68% of the liver were excised simultaneously in the HPx group. Serum total protein and albumin levels were significantly lower in the HPx group compared to the other three groups on postoperative day (POD) 3 (P<0.05). HPS was markedly increased in the Hx and HPx groups. In the Hx group, it was significantly higher, peaking on POD 2, compared to the HPx group (P<0.05), while in the HPx group, it was significantly higher compared to the Hx group (P<0.05), peaking on POD 3. The BrdU labeling index, as a marker of DNA synthesis, was significantly suppressed in the HPx group on POD 1 compared to the Hx group (P<0.05). Thus, compared to hepatectomy alone, hepatopancreatectomy suppresses DNA synthesis, causing a delay in the increase of protein synthesis in the regenerating liver, resulting in a more marked decrease in the serum protein level.     

Nitric oxide as an independent regulatory factor in regenerating rat liver

Nitric oxide production and lipid peroxidation modulate the proliferating activity of liver cells, but the relationship between enhanced nitric oxide production, lipid peroxidation, and liver regeneration remains unclear. We examined the role of nitric oxide and lipid peroxidation on experimental liver regeneration. Thirty-five male Wistar albino rats underwent a sham operation (I), partial hepatectomy alone (II, IV), partial hepatectomy and daily N-nitro-L-arginine methyl ester (L-NAME) treatment for 24-hrs (III) or 48-hrs (V). Liver tissue concentrations of catalase, nitrite and nitrate, glutathione, and serum levels of alaninaminotransferase and bilirubin were measured. CD34, Ki-67 and proliferating cell nuclear antigen were evaluated in liver samples. Compared with other groups, both of the L-NAME groups had decreased tissue nitric oxide concentrations. Nitrate and nitrite (nitric oxide) concentrations were higher in partial hepatectomy-alone groups, as were CD34 counts and proliferation indexes. Partial hepatectomy elevated catalase, and glutathione levels in all groups compared to the sham-operated controls. In conclusion, nitric oxide inhibition impaired hepatic regeneration following partial hepatectomy. An obvious effect of nitric oxide on lipid peroxidation in the context of hepatocyte and endothelial cell proliferation could not be demonstrated. Thus, while lipid peroxidation could influence some steps in liver regeneration, nitric oxide poses as an independent regulatory factor in regenerating rat liver.     

Neutrophil function and lipid peroxidation in a rat model of multiple organ failure

Multiple organ failure (MOF) was induced by sterile intraperitoneal inoculation of zymosan in the rat. This results in a typical triphasic illness with maximal clinical signs at Days 2 and 14. In this study, granulocyte superoxide production (unstimulated and phorbol myristic acid stimulated) was studied as well as lipid peroxidation (TBAR) in plasma, liver, and lung tissue. Mainly TBAR levels in liver and lung tissue closely correlated with the triphasic clinical illness, while bacteriological data did not. It is concluded that the severe inflammatory response in this experimental model probably is the result of excessive toxic oxygen radical production. The first phase of illness may mainly be due to oxygen radical formation by activated PMN, the third phase of illness to the production of lysosomal enzymes (proteinases) from PMN, and activated macrophages as indicated by elevated N-acetylglucosaminidase levels.     

Influence of preservation solutions on lipid peroxidation and mitochondrial respiration in rat kidneys

The role of hypothermic storage of rat kidneys on lipid peroxidation compared to its effect on mitochondrial respiratory parameters has been investigated. Rat kidneys were flushed with cold solutions of isotonic sodium chloride; Euro-Collins'; preservation solution containing histidine buffer, tryptophane, and alpha-ketoglutarate (HTK); or hypertonic citrate and then stored for 20 hr at 4 degrees C. After storage, the endogenous contents of malondialdehyde as well as the chemically (by Fe2+/ascorbic acid) and enzymatically (by Fe3+/ADP/NADPH) induced generation of malondialdehyde were measured in cortical homogenates and partly in mitochondria and microsomes by the thiobarbituric-acid reaction. Compared to the values measured in fresh, unstored kidneys, the levels of malondialdehyde were significantly higher in kidneys preserved in solutions of isotonic sodium chloride or HTK. This stimulating effect of the HTK solution on the generation of lipid peroxidation products could also be established when homogenate was incubated with this solution. Euro-Collins' and hypertonic citrate solution did not change the endogenous contents of malondialdehyde in kidneys during hypothermic storage. Both the chemically and enzymatically induced lipid peroxidation increased after hypothermic storage of kidneys in all solutions investigated. No direct relationship between the contents of malondialdehyde and respiratory mitochondrial parameters was detectable. The results demonstrate that the extent of lipid peroxidation does not correlate with preservation effectiveness.     

脂质过氧化抑制剂对大鼠肾脏低温保存的保护作用

目的　探讨脂质过氧化抑制剂预处理对大鼠肾脏低温保存的作用及其机制。方法　对低温保存的大鼠肾脏进行脂质过氧化抑制剂U74 0 0 6F的预处理 ,观察肾组织中脂质过氧化代谢产物丙二醛含量及诱导型一氧化氮合酶表达水平的变化。结果　U74 0 0 6F预处理可降低肾组织氧化反应水平 ,减少诱导性一氧化氮合酶的表达。结论　U74 0 0 6F预处理通过抑制细胞脂质过氧化减轻氧化反应和细胞因子带来的损伤 ,对低温保存的肾脏起到保护作用     

Effect of pentoxifylline on veno-occlusive priapism-induced corporeal tissule lipid peroxidation in a rat model

Objective: To investigate whether pentoxifylline could play a role in attenuation of the hazardous effects of ischemia/reperfusion on corporeal tissue in a rat model of veno-occlusive priapism (VOP). Materials and methods: Placebo and pentoxifylline were given to eight groups of rats prior to priapism being induced by a vacuum constrictive device for durations of 6 and 12 h, respectively. Half of the groups of rats that underwent the same duration of priapism (ischemic) were subjected to 1 h of detumescence after band removal (reperfusion). One group underwent no manipulation and no drug administration and served as a baseline determination (control). Corporeal homogenates were examined for lipid peroxidation (LP) derived malondialdehyde (MDA) accumulation via thiobarbituric acid assay. Results: MDA concentration differed significantly between VOP rats and controls (P < 0.001) but did not differ significantly between ischemic-only groups and reperfused groups (P > 0.05). In the pentoxifyllinepretreated groups, although MDA accumulation tended to be slightly lower than in the placebo groups, the difference was not statistically significant (P > 0.05) either in the 6- or 12-h duration priapic groups. Conclusions: LP, an indicator of radical oxygen metabolite (ROM) induced injury, occurs in rat corporeal tissue during and after abolishment of VOP. Single-dose pentoxifylline pretreatment failed to exert a protective effect on corporeal tissue in a rat model of VOP in terms of attenuation of LP.     

Effects of melatonin on lipid peroxidation and antioxidant enzymes in streptozotocin-induced diabetic rat testis

Aim:To examine the effects of melatonin treatment on lipid peroxidation(LPO)and the activities of antioxidantenzymes in the testicular tissue of streptozotocin(STZ)-induced diabetic rats.Methods:Twenty-six male rats wererandomly divided into three groups as follows:group Ⅰ,control,non-diabetic rats(n=9);group Ⅱ,STZ-induced,untreated diabetic rats(n = 8);group Ⅲ,STZ-induced,melatonin-treated(dose of 10 mg/kg-day)diabetic rats(n=9).Following 8-week melatonin treatment,all rats were anaesthetized and then were killed to remove testes from thescrotum.Results:As compared to group Ⅰ,in rat testicular tissues of group Ⅱ,increased levels of malondialdehyde(MDA)(P<0.01)and superoxide dismutase(SOD)(P<0.01)as well as decreased levels of catalase(CAT)(P<0.01)and glutathione peroxidase(GSH-Px)(P>0.05)were found.In centrast,as compared to group Ⅱ,in rat testiculartissues of group Ⅲ,levels of MDA decreased(but this decrease was not significant,P>0.05)and SOD(P<0.01)aswell as CAT(P<0.05)increased.GSH-Px was not influenced by any of the treatment.Melatonin did not signifi-cantly affect the elevated glucose concentration of diabetic group.At the end of the study,there was no significantdifference between the melatonin-treated group and the untreated group by means of body and testicular weight.Conclusion:Diabetes mellitus increases oxidative stress and melatonin inhibits lipid peroxidation and might regulatethe activities of antioxidant enzymes of diabetic rat testes.(Asian J Androl 2006 Sep;8:595-600)     

大鼠肝移植后肝切除-肝再生功能的探讨

目的 探讨肝移植后肝细胞的再生功能。方法 从肝左静脉根部到肝脏面的肝右叶和肝中叶交叉点进行肝切除。肝切除后定时屠杀,标本行苏木素-伊红(HE)、增殖细胞核抗原(PC-NA)染色检查。血液行动脉血酮体比(AKBR)测定、血清白蛋白测定。结果 术后第3天对照组的再生肝对残肝重量比为(2.19±0.18)倍,3、6、12个月实验组分别为(1.66±1.11、1.66±0.17、1.17±0.31)倍,与对照组相比差异有显著性(P<0.05)。对照组术后 1 d的 PCNA染色阳性细胞总数达最高值(459.2±21.5)个,7 d为(35.7±7.2)个。3、6、12个月实验组术后7 d分别为(356.2±40.8)个、(341.2±17.6)个、(359.7±23.0)个,与对照组相比差异有显著性(P<0.001)。实验组第3、7天的血清白蛋白值比对照组降低。对照组术后 1、3 d的 AKBR值分别是 0.56±0.26和0.79±0.12,全部实验组的 NBR值术后显低值,3、6、12个月实验组术后 1 d的 AKBR值分别为0.33±0.12、0.31±0.12、0.30±0.05,3 d分别为 0.29±0.09、0.28±0.09、0.26±0.15,与对照组相比差异均有非常显著性(P<0.01)。结论 移植肝脏肝切除后的再生功能,比正常肝组织缓慢。肝移植后肝脏的预备能减弱,再生延缓。     

酒精对大鼠前列腺抗氧化酶活性和脂质过氧化的影响

目的 探讨酒精对大鼠前列腺组织抗氧化酶活性和脂质过氧化水平的影响。方法 40只成年健康SD雄性大鼠随机均分为对照组、低剂量组、中剂量组和高剂量组，分别用50．0％、25．0％、12．5％的乙醇溶液和蒸馏水按10．0ml／kg每晚灌胃1次持续60d后，观察酒精毒染模型大鼠前列腺组织的形态结构的变化；用化学比色法测定前列腺组织中超氧化物岐化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH-Px）、丙二醛（MDA）和前列腺酸性磷酸酶（PAP）的水平。结果 随着酒精剂量的增加，SOD、CAT、GSH-Px活力和PAP含量呈先升高后下降的趋势，MDA含量和前列腺相对重量分别呈现上升和下降趋势，前列腺组织馆牛棼缩。结论 长期过量饮洒可导致大鼠前列腺绸织结构和功能异常，氧化应激在其中发挥了重要作用。