Lack of effect of dietary alpha-tocopherol on chemically induced hepatocarcinogenesis in rats

We investigated the effects of alpha-tocopherol on diethylnitrosamine (DEN) initiation-phenobarbital (PB) promotion of hepatic foci in female Sprague-Dawley rats. Groups of eight rats were initiated with DEN (15 mg/kg) at 24 hours of age. After weaning, they received diets containing 500 ppm PB and various concentrations of alpha-tocopherol, deficient (0 ppm), adequate (100 ppm), and supplemented (5,000 ppm), for 24 weeks. Rats fed alpha-tocopherol-supplemented diets had significantly greater hepatic alpha-tocopherol levels than those fed alpha-tocopherol-deficient or -adequate diets (p < 0.05). Liver lipid peroxidation (measured as thiobarbituric acid-reactive substances) was significantly greater in rats fed alpha-tocopherol-deficient diets than in those fed alpha-tocopherol-adequate or -supplemented diets (p < 0.05). The dietary alpha-tocopherol level had no significant effect on the ratios of reduced glutathione (GSH) to oxidized GSH or reduced GSH to total GSH in the liver or on the plasma prostaglandin E2 concentration or on the activities of hepatic cytosolic and particulate protein kinase C. Rats fed alpha-tocopherol-adequate or -supplemented diets had significantly greater hepatic glutathione S-transferase, GSH reductase, and GSH peroxidase activities than those fed alpha-tocopherol-deficient diets (p < 0.05). The dietary alpha-tocopherol level did not significantly affect the formation of hepatic gamma-glutamyl transpeptidase- and placental glutathione S-transferase-positive foci. These results suggest that alpha-tocopherol does not influence hepatic foci formation and that reactive oxygen species may not be the underlying mechanism of hepatic foci formation in this DEN initiation-PB promotion model of hepatocarcinogenesis.     

Dietary tocotrienol reduces UVB-induced skin damage and sesamin enhances tocotrienol effects in hairless mice

We have previously reported that substantial amounts of tocotrienols were present in the skin of animals fed a diet containing a tocopherols and tocotrienols rich fraction (T-mix) extracted from palm oil, and further, that sesame lignans enhanced tocotrienol levels in the skin. The present studies were undertaken to determine whether dietary tocotrienols and those with sesamin could protect the skin from damage induced by UVB irradiation in hairless mice fed four diets: a vitamin E-free diet, a 50 mg/kg alpha-tocopherol diet, a 229 mg/kg T-mix (with 50 mg alpha-tocopherol) diet and a 229 mg/kg T-mix with 2 g/kg sesamin diet. In Experiment 1, mice were fed the diets for 6 wk, and half of the mice were exposed to 180 mJ/cm(2 )of UVB light once daily for 7 d. After the intensity of sunburn was scored, vitamin E and thiobarbituric acid reactive substances (TBARS) concentrations in the skin and liver were determined. In Experiment 2, hairless mice were initiated with a single application of 7, 12-dimethylbenz[a]anthracene (DMBA), then 1 wk later mice were fed the experimental diets and subjected to 180 mJ/cm(2) UVB irradiation twice weekly for 20 wk. Tumor incidences were counted once a week. Tocotrienols were detected in the skin of mice fed T-mix, but their concentrations were significantly lower than for alpha-tocopherol. Sesamin elevated tocotrienol contents in the skin. In spite of the high alpha-tocopherol contents, the effects of alpha-tocopherol on sunburn and incidence of tumor were slight. T-mix fed groups reduced the extent of sunburn and incidence of tumor, and further reduction of sunburn and incidence of tumor were observed in the T-mix with sesamin group. These results suggest that dietary tocotrienols protect the skin more strongly than alpha-tocopherol against damage induced by UVB and sesamin enhances tocotrienol effects.     

Ethanol ingestion combined with lowered carbohydrate intake enhances the initiation of diethylnitrosamine liver carcinogenesis in rats.

The effect of ethanol on the initiation of diethylnitrosamine- (DEN) induced liver carcinogenesis was investigated in rats. In the first experiment, eight-week-old male Wistar rats were maintained on four liquid diets: a basal diet (Group 1), a low-carbohydrate (low-CHO) diet (Group 2), a basal diet+ethanol (Group 3), or a low-CHO diet+ethanol (Group 4). After three weeks on these diets, 50 mg/kg of DEN was injected intraperitoneally. The plasma glutamic-oxaloacetic transaminase activity in Group 4 was higher 24 hours after DEN administration than in Groups 1 and 3. The plasma glutamic-pyruvic transaminase activity in Groups 3 and 4 was higher than in Groups 1 and 2. The number of gamma-glutamyltranspeptidase-positive foci per unit liver area 41 weeks after DEN administration was higher in Group 4 than in Group 1. The area of gamma-glutamyltranspeptidase-positive foci was greater in Groups 2 and 4 than in Group 1. In the second experiment, Groups 1 and 4 were given DEN orally (25 or 75 mg/kg). Plasma glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase activities 24 hours after DEN administration were significantly higher in Group 4 than in Group 1, but only when the dose of DEN was 75 mg/kg. In contrast, the number and area of placental glutathione S-transferase-positive foci per unit liver area were greater in Group 4 than in Group 1 only after 25 mg/kg of DEN. Thus the severity of hepatotoxicity and the incidence of precancerous liver lesions were not necessarily correlated. These findings together indicate that a combination of ethanol and a low-CHO diet enhances DEN-induced liver carcinogenesis in rats by increasing the bioactivation of DEN in the liver.     

Further evidence for chemopreventive potential of beta-carotene against experimental carcinogenesis: diethylnitrosamine-initiated and phenobarbital-promoted hepatocarcinogenesis is prevented more effectively by beta-carotene than by retinoic acid

The comparative effectiveness of beta-carotene (BC) and retinoic acid (RA) was investigated against two-stage rat liver carcinogenesis initiated by a single injection of diethylnitrosamine (DEN, 200 mg/kg i.p.) followed by promotion with phenobarbital (PB, 0.05%) in a basal diet. BC (500 mg/kg) or RA (200 mg/kg) was administered per os daily throughout the entire experiment, before the initiation, or during the promotional stage. Treatment with BC throughout the experiment or before initiation significantly reduced the incidence (p < 0.01), multiplicity (p < 0.05), and size of visible subcapsular hepatocyte nodules (HNs) and reduced (p < 0.001 or 0.05) nodular volume as a percentage of liver volume. The results with RA were of lesser extent than those observed with BC. There was a considerable depletion of hepatic BC and total vitamin A (retinol + ester) in HNs and nonnodular surrounding parenchyma (NNSP) of rats subjected to the DEN-PB regimen than their control counterparts. Treatment with BC significantly elevated hepatic BC and total vitamin A contents in HNs and NNSP compared with DEN-PB control, and the elevation was proportional to the duration of BC treatment. Long-term BC or RA treatment elicited a substantial decrement in reduced glutathione content and gamma-glutamyltranspeptidase activity and an increment in cytochrome P-450 content and glutathione peroxidase and glutathione S-transferase activities in the HNs and NNSP, which were otherwise reversed in rats that received DEN-PB treatment alone. Our results suggest that BC or RA has the potential to inhibit DEN-induced hepatocarcinogenesis through selective modulation of the antioxidant defense system and xenobiotic detoxification in the liver. It is also apparent that the beneficial effect of BC or RA is primarily exerted on the initiation phase and secondarily during the promotional stage of DEN-initiated rat liver carcinogenesis and that BC affords a better chemopreventive response than RA.     

Folate supplementation differently affects uracil content in DNA in the mouse colon and liver

High folate intake may increase the risk of cancer, especially in the elderly. The present study examined the effects of ageing and dietary folate on uracil misincorporation into DNA, which has a mutagenic effect, in the mouse colon and liver. Old (18 months; n 42) and young (4 months; n 42) male C57BL/6 mice were pair-fed with four different amino acid-defined diets for 20 weeks: folate deplete (0?mg/kg diet); folate replete (2?mg/kg diet); folate supplemented (8?mg/kg diet); folate deplete (0?mg/kg diet) with thymidine supplementation (1·8?g/kg diet). Thymidylate synthesis from uracil requires folate, but synthesis from thymidine is folate independent. Liver folate concentrations were determined by the Lactobacillus casei assay. Uracil misincorporation into DNA was measured by a GC/MS method. Liver folate concentrations demonstrated a stepwise increase across the spectrum of dietary folate levels in both old (P?=?0·003) and young (P?相似文献   

Effects of a dietary oxidized fat on cholesterol in plasma and lipoproteins and the susceptibility of low-density lipoproteins to lipid peroxidation in guinea pigs fed diets with different concentrations of vitamins E and C

To investigate the effect of a dietary oxidized fat on the concentrations of cholesterol in liver, plasma, and lipoproteins and the susceptibility of low-density lipoproteins (LDL) to lipid peroxidation, and to explore the effects of vitamins E and C, male guinea pigs were divided into five groups. Four groups were fed diets with an oxidized fat supplemented with 35 or 175 mg alpha-tocopherol equivalents/kg and 300 or 1000 mg of vitamin C/kg for 29 days. One group, used as a control, was fed the same basal diet with fresh fat with 35 mg alpha-tocopherol equivalents/kg and 300 mg of vitamin C/kg. Guinea pigs fed the oxidized-fat diets, irrespective of dietary vitamin E and C concentrations, had significantly lower concentrations of total cholesterol in the liver and a lower concentration of cholesterol in LDL than the control animals fed the fresh fat. According to the lag time before onset of lipid peroxidation, LDL of guinea pigs fed the oxidized-fat diet with 35 mg alpha-tocopherol equivalents and 300 mg vitamin C/kg were significantly more susceptible to copper-induced lipid peroxidation than those of guinea pigs fed the fresh fat diet. Within the groups fed the oxidized fat diets, increasing the dietary vitamin E concentration from 35 to 175 mg/kg significantly (p < 0.05) and increasing the dietary vitamin C concentration from 300 to 1000 mg/kg in tendency (p < 0.10) reduced the susceptibility of LDL to oxidation. LDL of guinea pigs fed the oxidized fat diets with 175 mg alpha-tocopherol equivalents/kg were even more resistant to oxidation than LDL of guinea pigs fed the fresh diet. In conclusion, the study shows that dietary oxidized fat influences the cholesterol metabolism and the susceptibility of LDL to lipid peroxidation; the latter can be modified by dietary vitamins E and C.     

抗氧化剂对黄曲霉毒素染毒的转基因小鼠肝肿瘤的防护

目的研究抗氧化剂２,３叔丁基４羟基茴香醚（ＢＨＡ）对黄曲霉毒素（ＡＦＢ１）染毒的乙型肝炎病毒（ＨＢＶ）转基因小鼠肝肿瘤发生的防护作用。方法对ＡＦＢ１染毒和未染毒的４９只转基因小鼠与４８只非转基因小鼠,测定肝醌还原酶（ＱＲ）和谷胱甘肽Ｓ转移酶（ＧＳＴ）活性、肝丙二醛（ＭＤＡ）含量、肝氧自由基浓度（ＯＦＲ）。结果染毒的转基因小鼠ＢＨＡ组肝腺瘤发生率１７％,癌变率０,显著低于普通饲料组的肝腺瘤发生率（６７％）和癌变率（２２％）。与普通饲料组比较,ＢＨＡ使肝ＯＦＲ和ＭＤＡ含量显著降低;ＢＨＡ组肝ＱＲ和ＧＳＴ活性平均升高３～７倍。结论ＢＨＡ能显著诱导肝脏生物转化Ⅱ相酶活性,清除氧自由基,抑制变异肝细胞生长,可能与抑制或延缓小鼠肝癌的发生、发展进程有关     

Dietary sesame lignans decrease lipid peroxidation in rats fed docosahexaenoic acid

We have previously reported that dietary sesamin and sesaminol, major lignans of sesame seed, elevate the alpha-tocopherol concentration and decrease the thiobarbituric acid reactive substance (TBARS) concentration in the plasma and liver of rats. In this study, the effects of dietary sesamin and sesaminol on the lipid peroxidation in the plasma and tissues of rats fed docosahexaenoic acid (DHA, 22:6 n-3) were examined. Male Wistar rats (4-wk-old) were divided into the following six experimental groups: control group, fed a basal diet: sesamin group, fed a diet with sesamin (2 g/kg); sesaminol group, fed a diet with sesaminol (2 g/kg); DHA group, fed a diet containing DHA (5 g/kg); DHA + sesamin group, fed a diet containing DHA with sesamin; and DHA + sesaminol group, fed a diet containing DHA with sesaminol. Each diet contained either 0.01 or 0.05 g D-alpha-tocopherol/kg, and the rats were fed the respective experimental diet for 5 wk. The dietary DHA elevated the TBARS concentration and also increased the red blood-cell hemolysis induced by the dialuric acid. The dietary sesamin and sesaminol lowered the TBARS concentrations and decreased the red blood hemolysis. The dietary sesamin and sesaminol elevated the alpha-tocopherol concentrations in the plasma, liver, and brain of the rats fed a diet with or without DHA. These results suggest that dietary sesame lignans decrease lipid peroxidation as a result of elevating the alpha-tocopherol concentration in rats fed DHA.     

A semipurified diet that suppresses phenobarbital promotion of hepatocarcinogenesis in the rat

Six groups of F344/N female rats were fed either a modified AIN‐76 diet (20% casein, 5 % corn oil, 65% cornstarch, 5% cellulose) (AIN) or a diet formulated by Dr. M. Pariza (PD) (30% casein, 10% partially hydrogenated corn oil, 40% sucrose, 15% cornstarch) beginning four days before 70% partial hepatectomy. One day after the surgery, one group fed each diet was intubated with 10 mg/kg diethylnitrosamine (DEN). One week later, these groups plus one control group fed each diet were given 0.05% phenobarbital in the diet for 6 or 14 months. After the rats were killed, blocks of liver tissue were frozen on dry ice and stored at — 70°C. Three frozen serial sections were stained for γ‐glutamyltransferase, ATPase, and glucose‐6‐phosphatase.

Numbers and volume of altered hepatic foci (AHF) were analyzed by stereological techniques. After 14 months of feeding these regimens, rats initiated with DEN and fed the AIN + PB had significantly greater numbers and a higher percent volume of the liver of most phenotypes of AHF than all other groups, including those fed PD + PB following initiation with DEN. The numbers of AHF exhibiting more complex phenotypes (i.e., scored by more than one marker) remained unaltered between 6 and 14 months. These findings indicate that the effectiveness of PB as a promoting agent in multistage hepatocarcinogenesis is significantly altered when fed with two different diets of known composition. Therefore, dietary composition can be a significant factor in studies of the stage of promotion in hepatocarcinogenesis.     

桦褐孔菌多糖对二乙基亚硝胺致肝脏损伤的保护作用

[目的]研究桦褐孔菌多糖（inonotus obliquus polysaccharide）对二乙基亚硝胺（DEN）致肝脏损伤的保护作用。[方法]将50只小鼠随机分为5组：阴性对照组（蒸馏水）,DEN组（20 mg/kg）,桦褐孔菌多糖高（600 mg/kg）、中（300 mg/kg）、低（150 mg/kg）剂量组。阴性对照组及桦褐孔菌3个剂量组每日灌胃,同时DEN组和桦褐孔菌3个剂量组隔日腹腔注射DEN,持续5周。采用HE染色法观察动物肝细胞核分裂相及枯否细胞数;采用酶动力学法测定肝组织匀浆上清液中谷胱甘肽-S-转移酶（GSTs）和微量丙二醛（MDA）含量;采用酶联免疫吸附法（ELISA）检测肝组织匀浆上清液中肿瘤坏死因子α（TNF-α）含量。[结果]DEN组肝组织中核分裂相和枯否细胞数明显多于阴性对照组（P〈0.01）,桦褐孔菌多糖高剂量组肝组织中核分裂相和枯否细胞数显著低于DEN组（P〈0.05）。DEN组肝组织中GSTs活性明显低于阴性对照组（P〈0.05）,MDA和TNF-α含量明显高于阴性对照组（P〈0.01或P〈0.05）。桦褐孔菌多糖高剂量组和中剂量组肝组织中GSTs活性明显高于DEN组（P〈0.01）,3个剂量组肝组织中MDA含量均显著低于DEN组（P〈0.01或P〈0.05）,只有高剂量组肝组织中TNF-α含量明显低于DEN组（P〈0.05）。[结论]桦褐孔菌多糖对DEN致肝脏损伤有一定的保护作用。     

白藜芦醇对小鼠非酒精性脂肪性肝炎干预作用

目的 探讨自噬通路在白藜芦醇(RSV)减轻蛋氨酸-胆碱缺乏(MCD)饮食诱导的非酒精性脂肪性肝炎(NASH)中的作用及机制。方法 雄性C57BL/6J小鼠40只,随机分为对照组、模型组、白藜芦醇低、高剂量组(100、250 mg/kg)(n=10);对照组和模型组小鼠分别喂饲基础饲料和MCD饲料,白藜芦醇组在喂饲MCD饲料同时给予RSV灌胃,4周后测定小鼠体重、肝重、血清中谷丙转氨酶(ALT)含量,分离小鼠肝脏,测定甘油三酯(TG)和丙二醛含量,苏木素-伊红染色观察肝组织形态学变化,油红O染色观察脂肪变性情况,Western blot检测自噬标志蛋白LC3及各通路蛋白的表达量。结果 与对照组比较,模型组小鼠血清ALT和肝组织TG含量[分别为(144.17±0.32)U/L和(112.77±0.88)mg/g]明显升高(P<0.01),肝脏LC3Ⅱ和腺苷酸活化蛋白激酶(AMPK)表达水平[分别为(1.27±0.01)、(1.81±0.09)]升高(P<0.05);与模型组比较,高剂量白藜芦醇组小鼠血清ALT含量、肝组织TG含量[分别为(83.16±0.40)U/L、(40.75±0.19)mg/g]明显降低(P<0.01),LC3Ⅱ、AMPK蛋白表达水平[分别为(2.25±0.14)、(3.01±0.16)]明显升高(P<0.01);蛋白激酶B(Akt)和哺乳动物雷帕霉素靶蛋白(mTOR)表达水平无明显变化。结论 白藜芦醇可以改善MCD饮食诱导的NASH,其机制可能与激活自噬AMPK途径有关。     

微囊藻毒素联合DEN诱发转基因小鼠体内遗传毒性实验研究

目的:应用λ/lacZ转基因小鼠检测MCLR是否具有增强DEN致突变能力。方法:实验分为DEN (2 5mg/kg) ,DEN加MCLR (1mg/kg)及生理盐水组,每周给药1次,连续4周。染毒4 8h后检测外周血微核细胞率。末次染毒7d后处死动物,提取组织DNA ,通过体外包装反应获得并测定肝脏、肺脏lacZ基因突变频率。结果:两个实验组诱发微核率与对照组相比差异无显著性,MCLR联合DEN实验组动物肝脏组织lacZ基因突变(MF)为2 0 9 6×10 -6,是对照组的4 7倍,肺脏MF也明显高于对照,是其3 4倍,但与DEN处理组相比差异无统计学意义。结论:MCLR联合DEN染毒并不能增加由DEN诱发的靶基因突变频率。     

A semipurified diet that suppresses phenobarbital promotion of hepatocarcinogenesis in the rat

Six groups of F344/N female rats were fed either a modified AIN-76 diet (20% casein, 5% corn oil, 65% cornstarch, 5% cellulose) (AIN) or a diet formulated by Dr. M. Pariza (PD) (30% casein, 10% partially hydrogenated corn oil, 40% sucrose, 15% cornstarch) beginning four days before 70% partial hepatectomy. One day after the surgery, one group fed each diet was intubated with 10 mg/kg diethylnitrosamine (DEN). One week later, these groups plus one control group fed each diet were given 0.05% phenobarbital in the diet for 6 or 14 months. After the rats were killed, blocks of liver tissue were frozen on dry ice and stored at -70 degrees C. Three frozen serial sections were stained for gamma-glutamyltransferase, ATPase, and glucose-6-phosphatase. Numbers and volume of altered hepatic foci (AHF) were analyzed by stereological techniques. After 14 months of feeding these regimens, rats initiated with DEN and fed the AIN + PB had significantly greater numbers and a higher percent volume of the liver of most phenotypes of AHF than all other groups, including those fed PD + PB following initiation with DEN. The numbers of AHF exhibiting more complex phenotypes (i.e., scored by more than one marker) remained unaltered between 6 and 14 months. These findings indicate that the effectiveness of PB as a promoting agent in multistage hepatocarcinogenesis is significantly altered when fed with two different diets of known composition. Therefore, dietary composition can be a significant factor in studies of the stage of promotion in hepatocarcinogenesis.     

草苁蓉提取物对HepG2细胞氧化应激损伤的保护作用

  目的  探讨草苁蓉环烯醚萜苷（IGBR）对二乙基亚硝胺（DEN）诱发大鼠肝癌细胞凋亡的影响及其可能作用机制。  方法  Wistar雄性大鼠随机分为对照组和模型组、5–氟尿嘧啶（5-FU）组、IGBR组,除对照组外,其余大鼠第1天给予腹腔注射DEN 200 mg/kg 1次,自由饮用0.05 %的DEN水溶液;5-FU组大鼠腹腔注射25 mg/kg 5-FU,每周3 次;IGBR组大鼠灌胃500 mg/kg IGBR每日1次。实验第12、20、28周末分批处死动物,TUNEL法检测肝细胞凋亡,Western blot法检测肝组织中Bax、Bcl-2和丝裂原活化蛋白激酶（MAPK）、磷脂酰肌醇3激酶/蛋白激酶B（PI3K/Akt）通路相关蛋白表达。  结果  与对照组比较,模型组大鼠肝细胞凋亡指数[（12.3 ± 0.4）%]明显升高;与模型组比较,5-FU组与IGBR组大鼠肝细胞凋亡指数[分别为（22.3 ± 0.2） %、（22.2 ± 0.1） %]明显升高（P < 0.05）,5-FU组与IGBR组之间差异无统计学意义（P > 0.05）。与对照组比较,模型组大鼠肝组织中p-ERK、p-Akt表达水平下降、p-JNK、p-p38表达水平升高,ERK、p38、JNK、Akt表达无显明变化;与模型组比较,5-FU组与IGBR组大鼠肝组织中Bcl-2和p-ERK、p-Akt表达水平下降,Bax和p-JNK、p-p38表达水平升高。  结论  IGBR可通过MAPK、PI3K/Akt信号通路,调节Bax和Bcl-2表达,诱发DEN大鼠肝癌细胞凋亡。     

不同剂量锌缺乏对小鼠及其胚胎发育的影响

目的 :　用昆明种雌性小鼠建立成不同程度缺锌动物模型 ,研究不同程度锌缺乏和孕早期补锌对小鼠及其胚胎发育的影响 ,并探求其发育毒性作用的阈剂量。方法 :　实验分两阶段进行。实验一用 36只初断乳 1 4～ 1 8g小鼠 ,分为低锌 (ZD)、中锌 (ZM)、常锌 (ZN)三组 ,喂饲含锌分别为 3.0± 0 .5、1 5、30 mg/kg的饲料 ,经 50 d喂养平均体重达 30 g后交配。实验二选用 80只 ,2 5～ 30 g成熟小鼠 ,随机分为低锌组 [ZD,饲料含锌 (3.0± 0 .5) mg/kg];低锌补锌组 (ZS,于孕第 7d将低锌饲料换为含锌 30 mg/kg的常锌饲料 ) ;边缘缺锌组 (MD,饲料含锌 9mg/kg) ;常锌组(ZN,饲料含锌 30 mg/kg)。 2 5d锌耗竭性喂养后交配。所有孕鼠于妊第 1 8d活杀。结果 :　实验一 :低锌组小鼠锌水平显著低于常锌组 (P<0 .0 5) ,有典型缺锌症状 ,几乎全部出现生长抑制 ,58.33%的小鼠衰竭死亡 ,存活小鼠亦不能正常交配妊娠。 1 5mg/kg剂量组小鼠则生长发育良好 ,各项指标与常锌组间无异 (P>0 .0 5)。实验二 :ZD组小鼠血清碱性磷酸酶 (AKP)活性 ,股骨锌含量显著低于 ZN组 (P<0 .0 1 ) ;该组小鼠胚胎有明显发育不良 ,畸胎及死胎出现率显著高于 ZN组 (P<0 .0 1 )。ZS组小鼠在孕第 7d补锌后活胎仔大小已趋正常 (P>0 .0 5) ,畸胎出现率与 ZD?     

Opposite effects of low and high dose supplementation of vitamin E on survival of MRL/lpr mice

OBJECTIVE: The purpose of this study is to investigate the effects of vitamin E supplementation on the autoimmune disease course in MRL/lymphoproliferative mice. METHODS: Three-month-old MRL/lymphoproliferative lpr female mice were fed an AIN-76 diet containing 50 mg/kg (control), 250 mg/kg (E5), 375 mg/kg (E7.5), or 500 mg/kg (E10) all-rac-alpha-tocopheryl acetate. Eight mice per group were killed for analysis after two months of experimental diets, and the rest of the mice were followed up to observe their proteinuria levels and life span. RESULTS: The data suggest that the life span of the E5 group was longer than the E10 group. Though alpha-tocopherol content in the plasma, liver, and kidneys increased in the mice fed the diet supplemented with vitamin E, the thiobarbituric acid reactive substance values in the liver and kidneys among these groups were not significantly different. IgM anti-ds-DNA and anticardiolipin antibodies were significantly higher in the E10 group than in those of the other groups. Phytohemagglutinin-stimulated interleukin (IL)-2 secretion was significantly lower, but concanavalinA-stimulated IL-4 and IL-10 production was significantly higher in the E10 group compared with the control group. The in vitro study also showed decreased IL-2 secretion and messenger RNA expression in phytohemagglutinin-stimulated splenocytes cultured in medium supplemented with high doses of vitamin E, but increased IL-2 with low doses of vitamin E. CONCLUSIONS: Our data suggest that low and high dose supplementation of vitamin E has the opposite effect on the survival of MRL/lpr mice. The inhibitory effect of Th1 from high vitamin E content may not be beneficial for those suffering from Th2 prone autoimmune diseases, such as systemic lupus erythematosus.     

Selective uptake of dietary tocotrienols into rat skin

Using a vitamin E mixture extracted from palm oil, the tissue distribution of dietary tocotrienols and tocopherols was examined in rats and mice. Wistar rats (4-wk-old) were fed a diet containing 48.8 mg/kg alpha-tocopherol, 45.8 mg/kg alpha-tocotrienol and 71.4 mg/kg gamma-tocotrienol for 8 wk. Nude mice (BALB/c Slc-nu, 8-wk-old) and hairless mice (SKH1, 8-wk-old) were fed the same diet for 4 wk. alpha-Tocopherol was abundantly retained in the skin, liver, kidney and plasma of rats and mice. alpha-Tocotrienol and gamma-tocotrienol were detected slightly in the liver, kidney and plasma, while substantial amounts of these tocotrienols were detected in the skin of both rats and mice. The present study suggests that the skin is a unique tissue in respect to its ability to discriminate between various vitamin E analogs.     

Zinc-induced metallothionein and copper metabolism in intestinal mucosa, liver, and kidney of rats

Large doses of parenteral zinc (Zn) and/or the feeding of high Zn diets to animals or humans for long periods affects copper (Cu) metabolism. Previous work suggests that Zn-induced metallothionein (MT) in intestinal epithelial cells binds Cu and inhibits its absorption. This study was designed to determine the effects of treating rats with high dietary or parenteral Zn on Cu metabolism and its relationship to MT in the intestinal epithelium, liver and kidney. Six-week-old male rats were fed for one week a control diet containing 42 mg Zn and 6 mg Cu/kg. They were then divided into three groups. One group continued to receive the control diet while another received a similar diet containing 560 mg Zn/kg. A third group, fed the control diet, received a subcutaneous dose of 90 mg Zn/kg body weight every 2–3 days for the duration of the experiment. Rats from each group were killed on days 7 and 14. Low Cu status in Zn-treated rats was indicated by lower than normal serum Cu concentration, serum ceruloplasmin activity, low liver and kidney Cu concentrations and low cytochrome C oxidase activity. None of these changes, however, were related to an increase in Cu as a result of Zn-induced MT in the intestinal epithelial cell. Instead, as the MT concentrations rose, Cu concentration decreased. This study suggests that the effects of high Zn treatment on Cu status are not the result of the long-held theory that Zn-induced intestinal MT sequesters Cu and prevents its passage to the circulation. Instead, it may be caused by a direct effect of high lumenal Zn concentrations on Cu transport into the epithelial cell.     

High dietary iron concentrations enhance the formation of cholesterol oxidation products in the liver of adult rats fed salmon oil with minimal effects on antioxidant status

The aim of this study was to investigate the effect of high dietary iron concentrations on the antioxidant status of rats fed two different types of fat. Four groups of male adult Sprague-Dawley rats were fed diets with adequate (50 mg iron supplemented per kg diet) or high (500 mg iron supplemented per kg diet) iron concentrations with either lard or salmon oil as dietary fat at 100 g/kg for 12 wk. The antioxidant status of the rats was profoundly influenced by the type of fat. Rats fed salmon oil diets had higher concentrations of thiobarbituric acid-reactive substances (TBARS) (P < 0.001), various cholesterol oxidation products (COP) (P < 0.001), total and oxidized glutathione (P < 0.05) and a lower concentration of alpha-tocopherol (P < 0.05) in liver and plasma than rats fed lard diets. The iron concentration of the diet did not influence the concentrations of TBARS, the activities of superoxide dismutase and glutathione peroxidase or the concentration of alpha-tocopherol in plasma or liver. The activity of catalase (P < 0.01) and the concentrations of total, oxidized and reduced glutathione (P < 0.05) in liver were slightly but significantly higher in rats fed high iron diets than in rats fed adequate iron diets, irrespective of the dietary fat. Rats fed the high iron diets with salmon oil, moreover, had higher concentrations of various COP in the liver (P < 0.001) than rats fed adequate iron diets with salmon oil. These results suggest that feeding a high iron diet does not generally affect the antioxidant status of rats but enhances the formation of COP, particularly if the diet is rich in polyunsaturated fatty acids.     

钒对动物消化腺发育的影响

选择1日龄AA肉鸡144羽,随机分为两组,试验组添加钒30 mg/kg,试验期42 d。于每周末每组取鸡6羽,解剖取小肠、肝、胰腺称重并取材制作切片。结果:试验组肝、胰腺的平均和相对质量均高于对照组,部分差异显著或极显著;肝枯否氏细胞较大;胰腺的亮胰岛数量多、体积大;小肠腺显著或极显著长于对照组。结论:日粮中添加30 mg/kg钒,可促进肉鸡消化腺的发育。