Development of hepatic lesions in male Fischer-344 rats fed AIN-76A purified diet

The suitability of the AIN-76A diet for Fischer-344 rats was investigated. This diet, proposed by the American Institute of Nutrition for use when a purified diet composed of refined ingredients and added vitamins and minerals is required, was tested in Sprague-Dawley rats. Male weanling Fischer-344 rats were fed three different lots of the AIN-76A diet from two suppliers. Increase in body weights and food consumption were compared to animals fed a cereal-based control diet. Animals were sacrificed at various intervals and tissues were taken for histopathological observation. By 8 weeks moderate to marked periportal lipidosis developed in livers of all rats fed the AIN-76A diet. Liver-body weight ratios over the 8-week period were significantly higher in rats fed AIN-76A diets compared to rats fed the control diet. However, growth rates of rats fed the AIN-76A diet were similar to growth rates of controls. Some rats fed the AIN-76A diet developed severe hemorrhagic lesions. The AIN-76A diet in its present form is not suitable for use with male Fischer-344 rats.     

Nutritional and pathological changes in male and female rats fed modifications of the AIN-76A diet

Male and female weanling Sprague-Dawley rats were fed either an AIN-76A diet or a modification of the AIN-76A diet containing no added DL-methionine but with higher levels of vitamins, fluoride and magnesium than in the AIN-76A diet. Both diets were fed, to groups of ten rats of each sex, at 18% protein or a reduced protein level of 13% for 12 wk. Within each sex, all diets produced comparable weight gains in rats at the end of 12 wk, except that the reduced-protein modified AIN-76A diet was associated with a reduction in weight gain in male rats. Both diet and protein level had statistically significant effects on the relative weights of some organs, particularly the kidney. The AIN-76A and the reduced-protein AIN-76A diets significantly increased the relative kidney weights (% body weights) of female rats, when compared with the effects of both modified AIN-76A diets (18 and 13% protein). Male rats fed both of the diets containing 18% protein had higher relative kidney weights than did those consuming both 13% protein diets. Females fed the modified diet containing 13% protein had significantly lower liver weights than the other groups. In both sexes, the two diets containing 18% protein caused significantly higher plasma urea nitrogen concentrations than did the lower protein diets. Kidney calcium concentrations varied with the diet, with dietary protein level, and with the sex of the animal. All diets caused small mineral (calcific) concretions of minimal to mild severity in the lumina of scattered renal tubules in the cortex and/or medulla of male rats. All female rats fed the AIN-76A and the reduced-protein AIN-76A diet had large, moderate or severe mineral concretions in the tubules at the corticomedullary junction and this was associated with increased renal calcium levels. The higher concentration of renal calcium at the lower dietary protein level (13%) was associated with severe corticomedullary junction mineralization. The higher protein diets were associated with an increased incidence of hyaline droplets in the cytoplasm of kidney cortical tubules in male rats.     

The urinary excretion of bacterial amino-acid metabolites by rats fed saccharin in the diet

Administration of a diet containing 7.5% saccharin to adult male rats for 40 days caused a three- to four-fold increase in the daily excretion of indican and rho-cresol. Indican is formed from indole which is a microbial metabolite of tryptophan, whilst rho-cresol is formed by the gut flora from tyrosine. The excretion of phenol, which is also a microbial metabolite of tyrosine, was abolished by saccharin administration for 40 days. Analysis of urines collected at 13, 18 and 24 months during a two-generation cancer bioassay showed that these changes occur throughout the life of saccharin-treated rats. These data indicate that saccharin changes the metabolism of amino acids by the gut flora, leading to an increased formation of products known to have promoting or co-carcinogenic properties.     

Foetal development in rats FED AIN-76A diets supplemented with excess calcium

This study was designed to evaluate the developmental effects of moderate dietary calcium increases in rats fed nutritionally adequate diets. Female Charles River CD/VAF Plus rats were given 0.50 (control), 0.75, 1.00 or 1.25% dietary calcium as calcium carbonate in AIN-76A diets for 6 wk before mating, during mating and for 20 days of gestation. On gestation day 20, the animals were killed and caesarean sections were performed. Both the non-pregnant and pregnant rats in the 0.75, 1.00 and 1.25% groups ate slightly more than did the control group during most of the intervals measured, but not all the increases were statistically significant. There was no consistent pattern of increase or decrease in weight gain. No dose-related changes were found in maternal clinical findings, the average number of implantations, resorptions and viable foetuses, or foetal length or weight. Under the conditions of the study, there were no statistically significant increases as compared with the control group in the litter incidence regarding specific external, visceral or skeletal variations of the foetuses. Dietary calcium was neither foetotoxic nor teratogenic at the concentrations used.     

膳食钙对高脂饮食大鼠肥胖形成的影响

目的 研究膳食钙摄入对高脂饮食大鼠肥胖形成的影响.方法 30只SD大鼠标准饲料饲养10d后,随机分为标准饲料(A)组(1.30%钙),高脂饲料(B)组(1.57%钙)和高脂加钙饲料(C)组(2.57%钙),饲养6周后处死,称量各组大鼠体重、体脂,用ELISA法测血清钙调激素甲状旁腺素(PTH)和1,25-(OH)2D3水平,用RT-PCR检测白色脂肪组织(WAT)中Vitmin D受体(VDR)、脂肪酸合成酶(FAS)、解偶联蛋白2(UCP2)基因mRNA表达水平.结果 (1)B组体重、Lee's指数、脂肪湿重显著高于A组和C组(P＜0.05);(2)C组的血清钙调激素水平均显著低于B组(P＜0.05);(3)C组VDR和FAS基因mRNA表达水平均显著低于B组(P＜0.05),C组UCP2基因mRNA表达水平均显著高于B组(P＜0.05).结论 高钙膳食可能通过降低血清钙调节激素水平,影响脂肪代谢和钙代谢,从而减少高脂饮食大鼠体重和脂肪重量的增加.     

Comparison of AIN-76A and AIN-93G diets: a 13-week study in rats.

Either purified or cereal-based diets may be used for toxicity testing in rats. Purified diets have advantages in terms of flexibility of formulation to meet specific study objectives and also assurance of relatively low levels of contaminants (e.g. heavy metals and pesticides). The American Institute of Nutrition recommended that the widely used purified diet AIN-76A be replaced by two newer diets, AIN-93G (for use during rapid growth, pregnancy and lactation) and AIN-93M (maintenance diet). The present study compared AIN-76A and AIN-93G by feeding these diets for 13 weeks to male and female rats. A cereal-based diet was also included for reference purposes. The groups fed purified diets had higher serum cholesterol and triglyceride levels than the chow-fed group. An increased incidence and severity of renal tubular mineralization in the purified diet groups was not observed in this study (in contrast to other published studies where rats were fed AIN-76A). Several histopathologic observations, including eosinophilic gastritis and mucification of gastric glands of the glandular stomach, occurred at higher rates in the AIN-76A group than the other dietary treatments. Hepatocellular fatty changes occurred in the purified diet groups at a significantly higher rate than in the chow diet group. In conclusion, AIN-93G is an appropriate diet for use in rat safety evaluation studies.     

The effect of ortho toluenesulfonamide and sodium saccharin on the urinary tract of neonatal rats.

The transplacental and postnatal effects of ortho-toluenesulfonamide (o-TS, 99.9% pure) and o-TS-free sodium saccharin on the urinary tract of neonatal rats, were examined in two experiments. In the first, o-TS in corn oil was administered by gavage throughout gestation and lactation at dosages of 0, 40, 100, or 250 mg o-TS/kg. After weaning, the pups were fed diets containing sufficient o-TS to provide the same dosages their respective dams received. Pups were killed at 8, 15, 21, and 105 days postpartum. The kidneys, urinary bladders, and urine filtrates were examined by light microscopy for calculi and the two organs were also examined histologically. A significant dose-response (p < 0.05) was found for the incidence of bladder calculi in 21-day-old pups and in 105-day old male and female rats. In a second experiment, male and female rats received one of the following dietary treatments for 100 days prior to mating: 0 (control), 2.5, 25, or 250 mg o-TS/kg, 250 mg o-TS/kg with 1% NH₄Cl in the drinking water, or 5% sodium saccharin. The dams were fed their respective diets during mating, gestation, and lactation. After weaning, the pups received their respective parents' diet. Pups were killed at 8, 21, and 105 days postpartum; kidneys, urinary bladders, and urine filtrates were examined as above. A significant dose-response (p < 0.05) was only found for the incidence of renal calculi and bladder lesions in 8-day-old pups from dams given diets that contained o-TS. However, there was no increased incidences of any urinary tract lesion in rats fed diets containing 250 mg o-TS and given 1% NH₄Cl in the drinking water, or in those fed a diet containing 5% sodium saccharin, or in older animals exposed only to o-TS. The administration of o-TS during gestation, lactation, and in the diet after weaning predisposes neonatal animals to urolithiasis and/or bladder lesions. These effects were not observed when a 1% solution of NH₄Cl was provided. Sodium saccharin, free of o-TS, did not have a similar effect.     

急性或慢性应激对高热量饲料喂养大鼠HPA轴的影响

目的 比较正常饲料或高热量饲料喂养大鼠,在有或无慢性应激长期刺激后,再给以一次急性应激前后下丘脑-垂体．肾上腺轴（HPA轴）功能的改变。方法雄性wistar大鼠分为正常饲料组（对照组）、高热量饲料（HCD）组、正常饲料慢性应激（CS）组及高热量饲料慢性应激（HCD＋CS）组。5周后,首先检测血脂并进行胰岛素敏感性试验;然后再给以一次急性应激,检测急性应激前后血液促’肾上腺皮质激素（ACTH）、皮质酮及血糖浓度的改变。结果与对照组比较,HCD及HCD＋CS组出现明显的血脂异常,但CS组无明显改变;三组均出现明显的胰岛素抵抗（IR）及HPA轴激活,但HCD＋CS组变化更明显。急性应激后,与对照组一样,三组HPA轴可进一步激活,但HCD组激活程度明显高于其它组。血糖变化与HPA轴激活相对应。结论长期高热量饲料喂养可明显提高因长期慢性应激或急性应激引起的HPA轴激活,尤其可使急性应激后的HPA轴激活程度大大提高。这种HPA轴的激活,与血糖升高、IR、血脂异常相对应。     

The effects of high dietary levels of sodium saccharin on mineral and water balance and related parameters in rats

The effects of sodium saccharin (NaS) treatment on mineral and water balance and a number of related parameters were studied over a 10-day period in 7-month-old Charles River CD rats. Eight groups of 10 male and 10 female rats were studied. In four of the groups the rats were the F1 offspring of rats that had been exposed to NaS at 1, 3, 5 or 7.5% in the diet and the offspring were treated with the same dietary levels of NaS as their parents. Prior treatment in two other groups was modified in order to evaluate the role of in utero exposure to NaS on the study parameters: rats in one group were only exposed in utero via dams fed diets containing 5% NaS while treatment in the other group did not include in utero exposure, but was started at birth via dams fed diets containing NaS and continued at a dietary concentration of 5% NaS. Second-generation rats in another group were fed diets containing 5% sodium hippurate (NaH), a compound with a number of physical and chemical properties similar to those of NaS; this group was included in order to evaluate the specificity of NaS and/or the effect of sodium on the study parameters. A group of untreated rats served as controls. Treatment-related effects were observed in most study parameters. In addition, a number of differences between male and female rats in baseline values and/or in response to NaS administration were observed. With increasing dietary levels of NaS body weights decreased, but there were increases in water consumption, faecal water content, and caecal weights. NaS treatment resulted in increased urine volume and decreased urine osmolality, changes in urine mineral concentrations (increased sodium, decreased potassium and zinc) and increases in fresh and dry bladder weights, bladder-tissue hydration, and mineral concentrations (sodium, potassium, magnesium and zinc) in bladder tissue. The parameters in which clear sex-related differences in baseline values were observed were body weight, food and water consumption, urine volume, urine osmolality, fresh bladder mass, bladder-tissue hydration and the concentrations of sodium, potassium, magnesium and zinc in the bladder tissue. With the exception of urine osmolality, the values were higher in females. Differences between males and females in response to treatment were observed for NaS consumption (increased in females), caecal weight (increased in females), NaS concentration in the urine (increased in males), and the concentration of sodium, potassium, magnesium and zinc in the bladder tissue (increased in males).(ABSTRACT TRUNCATED AT 400 WORDS)     

线粒体辅酶Q改善高脂饮食大鼠肾血流动力学的研究

目的探讨线粒体辅酶Q(MitoQ,Mitoquinone)对高脂饮食大鼠肾血流灌注的影响。方法 8周龄雄性SD大鼠30只,随机分成模型组(H组,n=10)、治疗组(HM组,n=10)和对照组(N组,n=10)。N组喂食基础饲料,H组、HM组喂食高脂饲料。9周后,HM组自饮水中加入MitoQ。三组大鼠继续喂养10周后进行肾脏声学造影检查,并检测大鼠血生化及肾组织丙二醛(MDA)含量,比较各指标的组间差异。结果与N组及HM组比较,H组大鼠肾皮质达峰时间(TTOP)延长,增强强度(A)及充盈速度(C)下降(P<0.01),总胆固醇(TC)、三酰甘油(TG)及低密度脂蛋白胆固醇(LDL-c)均明显增高(P<0.01),HM组与H组比较,以上各指标明显改善。H组血清及肾组织丙二醛(MDA)含量明显高于HM组及N组(P<0.01)。结论 MitoQ可降低机体内过氧化物含量,改善高脂饮食大鼠肾血流动力学状态。     

Dietary sodium intake: influence on calcium channels and urinary calcium excretion in spontaneously hypertensive rats.

Binding of the 1,4-dihydropyridine [3H]PN200 110 was employed as an index of cardiac Ca2+ channels in normotensive (WKY) and spontaneously hypertensive (SHR) rats during 4 weeks of normal (0.73% NaCl) and high (8% NaCl) sodium diets when the rats were between 20 and 24 weeks of age. Binding site density was not different at the beginning of the study but was increased significantly (P less than 0.01) after 1 week in the SHR on a high sodium diet; this difference was not apparent at 2, 3 or 4 weeks of the diet. During this same period, the urinary Ca2+ excretion in SHR was enhanced significantly (P less than 0.01) and the urinary calcium/sodium ratio was elevated during the high sodium intake period.     

The effect of simvastatin treatment on behavioral parameters, cognitive performance, and hippocampal morphology in rats fed a standard or a high-fat diet

The aim of this study was to examine the effect of simvastatin (SMV), a 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitor, in rats fed with a standard or a high-fat diet (HFD) throughout the prenatal and the postnatal periods. The emotional status of the animals was evaluated by elevated plus-maze and modified forced swimming tests, whereas cognitive performance was assessed by a Morris water maze task. Morphological changes in the hippocampus were examined by design-based stereology. HFD exposure significantly increased blood serum triglycerides without altering cholesterol levels relative to the controls. After four weeks of oral SMV (5 mg/kg) administration, serum triglycerides reverted to the control level. SMV caused significant anxiolytic, antidepressant-like, and nootropic effects in animals fed the standard diet. In the HFD group, enhanced anxiety and depression, and reduced cognitive performances of animals were reversed by SMV treatment. Although a total volume estimation of the hippocampal subfields indicated no significant change among the groups, the total number of pyramidal neurons decreased significantly in animals fed the HFD; following SMV treatment, this detrimental effect was reversed. In conclusion, chronic SMV administration has significant therapeutic potential for the treatment of affective and cognitive disorders with or without altering the serum lipid profiles.     

Effect of lignin-derived lignophenols on hepatic lipid metabolism in rats fed a high-fat diet

The effect of lignin-derived lignophenols on lipid metabolism in the livers of rats fed a high-fat diet was investigated. Rats fed a diet providing 45% of energy from fat were divided into 2 groups, namely 0% and 0.5% lignophenols-containing diets. The controls were fed a diet providing 10% of energy from fat. Plasma blood parameters, protein expression of acetyl-CoA carboxylase (ACC) and sterol regulatory element-binding protein (SREBP)-1, and SREBP-1c mRNA expression in the livers were examined. The plasma triglyceride levels in the rats fed lignophenols-containing diets were decreased. SREBP-1c mRNA expression in the rats fed lignophenols-containing diets was significantly reduced compared with the rats fed high-fat diets, and phosphorylated ACC protein in the rats fed lignophenols-containing diets was significantly increased. Our results suggested that lignophenols suppress the expression of SREBP-1c mRNA and the phosphorylation of ACC in the liver, and may lead to a decrease in plasma triglyceride levels.     

Effect of dietary carbohydrate type and content on the response of male rats to dietary sodium saccharin

The role of dietary carbohydrate composition and concentration in the response of male rats to sodium saccharin (NaS) was ascertained by comparing the response to 5% dietary NaS in rats given diets containing 65% starch, 50% sucrose together with 15% starch, 65% glucose, or 3% sucrose. NaS induced similar levels of caecal enlargement and increases in urine volume and bladder mass when given with any of the three forms of carbohydrate at 65% in the diet. However with the 3% sucrose diet, NaS caused a lesser caecal enlargement and no increase in urine volume or bladder mass. These findings suggest that NaS not only inhibits saccharide hydrolysis but also inhibits glucose transport. The significance of these findings in relation to NaS-associated bladder tumours is discussed.     

Effect of short-term administration of sodium saccharin on rhesus monkeys

Sodium saccharin (NaS) was incorporated into biscuits or the drinking-water and fed to rhesus monkeys at progressively increasing doses in order to determine the maximum dose that the monkeys would voluntarily consume and/or tolerate. Very little rejection of NaS-treated biscuits or drinking-water was observed. However, severe diarrhoea which precluded further treatment occurred when the dose of NaS reached 8.0% (approximately 1600 mg/kg body weight/day) in the biscuits and 0.48% (approximately 900–2400 mg/kg/day) in the drinking-water. An increase in fluid intake occurred in monkeys in both treatment groups. An increase in urine volume and a decrease in urine osmolality occurred in monkeys fed NaS in the drinking-water. No effects on body weight, food consumption or urine pH were observed in monkeys in either treatment groups. All animals rapidly recovered when they were given untreated biscuits or water. Therefore, although monkeys will voluntarily consume rather high doses of NaS incorporated into biscuits or drinking-water, adverse effects on their general well-being preclude such administration for more than a few days.     

Effect of inherent urine output on the response of male rats to 7.5% dietary sodium saccharin

Young male rats were preselected as high urine (57 g/kg body weight) or low urine (35 g/kg) voiders and were fed a diet containing 7.5% sodium saccharin (NaS) for 10 wk. Urine output was found to be a stable characteristic and high urine output was associated with increased water and feed consumption and increased weight gain. Rats responded in a very similar fashion to 7.5% dietary NaS regardless of their inherent urine output. NaS ingestion was associated with increases in water consumption, caecal mass and urine volume. Among rats that had ingested 7.5% dietary NaS for 10 wk there was a high incidence (12/20) of bladder epithelial hyperplasia. The results are discussed with regard to the concept that increased urine output is an important factor in NaS-induced bladder tumours.     

Effect of ascofuranone on serum lipids of rats fed a cholesterol rich diet.

Ascofuranone, a fungal metabolite, significantly reduced serum lipid levels, when orally administered to male Wistar rats fed a cholesterol rich diet. The treatment also resulted in a marked reduction of hepatic and cardiac cholesterol contents without affecting the body weight gain. The serum albumin/globulin ratio increased significantly in the treated rats. This increase is presumably due to the decrease of beta-lipoprotein. The mode of action differentiates from clofibrate in so far as the former effectively prevents hepatic and cardiac cholesterol deposits in the cholesterol feeding rats.     

An hypothesis of the mechanism of urinary bladder tumorigenesis in rat ingesting sodium saccharin

An hypothesis is presented of a mechanism for the sodium saccharin (NaS)-associated tumorigenesis of the urinary bladder that occurs in male rats. The ingestion of high doses of NaS is associated with increased urine volume and bladder mass. In rats with an inherently high urine output, the diuresis associated with NaS ingestion combined with the increasing diuresis that occurs with age in male rats results in a chronic demand for a bladder-volume increase that is met by excessive cell division of the bladder epithelium. This enhanced mitosis in the bladder epithelium can result in a significant incidence of bladder tumours. Male rats exposed to NaS during early life show an exacerbation of tumour incidence, and it is proposed that this is because the exacerbation of the effects of NaS on the gastro-intestinal and urinary tracts results in increased urine output and bladder hyperplasia in these rats.