生命早期使用抗生素对生命后期喂饲高脂饲料大鼠炎症因子的影响

目的探索哺乳期使用抗生素对断乳后喂饲高脂饲料大鼠的影响。方法将24只出生7天的SD大鼠仔鼠,随机分为高脂抗生素组(ATHF组)和高脂对照组(HF组),分别灌胃剂量为150 mg/kg·d的阿莫西林溶液和生理盐水,持续10天。断乳后两组仔鼠均喂饲高脂饲料。观察两组仔鼠体重、脏器系数、空腹血糖、血脂、血清炎症因子水平等的变化。结果两组仔鼠间体重、脏器系数、空腹血糖及血脂均没有统计学差异。研究结束时,ATHF组与HF组相比仔鼠血清瘦素浓度升高,但差异没有统计学意义(2 033.09±822.7 vs 1 746.23±556.7,P>0.05);血清脂联素(5 791.35±932.3 vs 4 755.55±536.6,P<0.05)、IL-6(449.93±85.4 vs 353.94±72.2,P<0.05)、C反应蛋白水平(7 556.52±746.7 vs 6 678.84±869.2,P<0.05)均增加,差异有统计学意义。结论生命早期使用抗生素可以加重生命后期使用高脂饮食所引发的成年期大鼠全身慢性炎症反应。     

Lung lipids and pulmonary silicosis in rats

Summary In the development of pulmonary silicosis in rats studies on changes in the total, esterified, free cholesterol and phospholipids were made in lungs, liver and blood plasma over a period of 200 days. Total cholesterol, its fractions and phospholipid content increased with time in the lungs of silicotic animals. Histochemically sudanophilic materials were observed in the cytoplasm of pulmonary macrophages. Changes similar to those of lungs were not observed in liver and blood plasma, and it has been concluded that the increased lipid content of lungs during experimental pulmonary silicosis may be due to the localised degenerative action of silica on macrophages.     

Quantitative ultrastructural evidence of myelin malformation in optic nerves of rats submitted to a multideficient diet

Pups were subjected to malnutrition by feeding the lactating mothers a multi-deficient (8% protein content) diet, known as regional basic diet (RBD), from birth up to weaning. The weanings were fed the same diet until 60 days of age. Ultrastructure of the optic nerve was analyzed at postnatal (P) day P8, P13, P21, P30 and P60. Electron microscopy revealed that at P8 the process of myelination has not started yet in neither groups. At P 13 different stages of myelination were observed and, in the experimental group, the optic nerve showed non-organized axon bundles and empty spaces. Control optic nerve at P21 exhibited axons with fully developed myelin sheath; whereas malnourished group had many axons being enveloped by myelin with anomalous alteration. These alterations were present in malnourished group at P30 and P60. Quantitative analysis showed statistically significant difference between control and malnourished groups when compared to the percentage of myelinated axons, axons with myelin anomalous alterations (MAA) and non-myelinated axons. Also, the myelin area was significantly smaller in malnourished groups when compared to control group. Finally, a high percentage of large non-myelinated fibers were found in the malnourished group. In conclusion, our results show that early malnutrition by a multideficient diet (RBD) affects permanently the optic nerve organization and myelination, indicating an impairment of nerve transmission and a probable dysfunction in the visual ability.     

Functional and morphological abnormalities in the retina of albino rats fed with a low protein diet after weaning.

Previously, we have reported a morphological study of the retina in albino rats fed with a low protein diet. The aim of this study is to verify our previous data and to obtain further informations about morphological and functional damages of the retina following low protein diet in albino rats. For this purpose the retinas of a group of weanling albino rats fed with a hypoproteic diet were studied with Light Microscopy (LM), Electron Microscopy (EM) and Electroretinography (ERG). Our results pointed out a correlation between the anatomic and functional ocular damages and proteinic malnutrition. LM showed a vacuolar degeneration of the optic fiber layer; the EM confirmed these results showing an optic fiber cytoskeleton modification together with glial proliferation. The functional damage as well seems to be correlated to the nutritional imbalance: the scotopic ERG in the experimental group shows a significant decrease (p less than 0.001) of the b-wave amplitude.     

Less body fat accumulation in rats fed a safflower oil diet than in rats fed a beef tallow diet

The effects on body fat accumulation of long-term feeding of high fat diets of differing fatty acid composition were studied in rats. The rats were meal-fed isoenergetic diets based on safflower oil or beef tallow for 4 mo. Each diet was freshly prepared every day throughout the experimental period. Oxygen consumption and carbon dioxide production for 6 h after meals were measured between the 50th and 54th d of the experimental period. Oxygen consumption for 3 h after meals was significantly greater in the safflower oil diet group than in the beef tallow diet group, indicating greater diet-induced thermogenesis in the former group. From the assessment of respiratory quotient, the fat oxidation rate was also higher in the former. After the experimental period (4 mo), body fat accumulation was significantly less in the rats fed safflower oil. This difference was, at least in part, ascribed to increased diet-induced thermogenesis and fat oxidation. Serum triacylglycerol level was markedly lower in the rats fed safflower oil than in those fed beef tallow. The lipoprotein lipase activities in heart and soleus muscle after meals appeared to be higher in the former than in the latter. These results suggest that the consumption of the safflower oil diet increased lipoprotein lipase activity in heart and skeletal muscle, resulting in the elevation of fat oxidation rate and the depression of serum triacylglycerol level.     

Body fat accumulation is greater in rats fed a beef tallow diet than in rats fed a safflower or soybean oil diet

The effects of dietary fats , consisting of different fatty acids, on body fat accumulation and uncoupling protein (UCP) in interscapular brown adipose tissue were studied in rats. Metabolisable energy in experimental diets based on safflower oil, soybean oil or beef tallow was measured strictly (experiment 1). Male Wistar rats were then meal-fed an isoenergetic diet for 8 weeks (experiment 2). Each group of rats showed the same weight gain during the 8-week experimental period. Carcass fat content was greater in rats fed the beef tallow diet than in those fed the with the safflower or soybean oil diets, whereas the weight of abdominal adipose tissue was the same for all three dietary groups. Gene expression of UCP1 and the UCP content of the interscapular brown adipose tissue was lower in the beef tallow diet group than in the other dietary groups. A negative correlation was observed between carcass fat content and n-6 unsaturated fatty acid content in dietary fats. These results suggest that the greater body fat accumulation in rats fed the beef tallow diet results from lower expression of UCP1 mRNA and lower UCP content in brown adipose tissue. n-6 Polyunsaturated fatty acids may be the most effective fatty acids in limiting body fat.     

断乳后低钙膳食对高脂膳食大鼠肥胖影响

目的探讨断乳后低钙膳食对高脂膳食大鼠肥胖的影响。方法80只刚断乳雄性Wistar大鼠按体重随机分为2组,分别给予低钙或正常钙膳食3周,然后以正常饲料喂养3周。第6周末各组动物又随机分成2组,分别喂饲高脂饲料和基础饲料,观察肥胖发生情况。结果断乳后低钙膳食大鼠食用高脂饲料后体脂含量、血脂、瘦素水平显著升高,高密度脂蛋白（HDL）、游离三碘甲状腺原氨酸（FT3）水平显著降低。结论断乳后给予低钙膳食可能促进高脂膳食大鼠肥胖的发生。     

Immune dysfunction in rats fed a diet deficient in copper

Rat pups maintained on copper (Cu)-adequate (6ppm), Cu-deficient (2 ppm) or Cu-depleted (0 ppm) diets from parturition were killed at 8-wk. Liver Cu and serum-ceruloplasmin levels confirmed that on the 0- and 2-ppm diets, a Cu-deficient state was induced. Although body weight was unaffected by the deficiency, the liver, heart, and thymus weights (% body weight) were altered. Hepatomegaly occurred in females fed 0-ppm Cu and males fed 2-ppm Cu. Heart weights increased in both sexes fed 0-ppm Cu. Thymus weights decreased in male rats fed 0-ppm Cu. Antibody titers and natural killer-cell cytotoxicity were markedly suppressed in the animals fed 0-ppm Cu. Male rats given 2-ppm Cu showed reduced antibody titer. Delayed-type hypersensitivity and prostaglandin E2 levels were not significantly affected. These studies suggest that certain components of the immune system are Cu dependent.     

断乳后不同饲料构成对高脂膳食大鼠肥胖发生的影响

目的研究断乳后不同饲料构成对高脂膳食大鼠肥胖发生的影响。方法雄性Wistar大鼠出生后24天断乳,按体重随机分为A、B、C三组,分别给予高碳水化合物供能的基础饲料、高蛋白质供能饲料和高不饱和脂肪供能饲料。3周后均转为基础饲料。2周后再按体重将A组分为A1、A2两组,A1组继续基础饲料,A2、B、C组则转为以猪油为主的高脂膳食,6周后结束实验。分别在不同处理期末每组随机处死8只动物,称重、留取脂肪组织,计算脂体比,采血检测血糖、血脂和激素指标。结果断乳后喂饲高不饱和脂肪饲料可以显著降低高脂膳食大鼠的体重、体脂肪含量和脂体比(P<0.05),显著降低胰岛素水平、提高胰岛素敏感性(P<0.05),显著增加胰高血糖素、甲状腺激素等促脂解激素的水平(P<0.05),增加瘦素敏感性(P<0.05),改善高脂膳食大鼠的瘦素抵抗。早期喂饲高蛋白质饲料也有一定的降低体重、体脂肪含量和促脂解作用趋势,但是该组的血糖值高于A2组。结论断乳后给予高不饱和脂肪饲料可以显著抑制高脂膳食大鼠的肥胖发生。     

Modification of vitamin A metabolism in rats fed a copper-deficient diet

The liver is the main storage site of vitamin A and copper. Inverse relationships between copper and vitamin A liver concentrations have been suggested. We have investigated the consequences of a copper-deficient diet on liver and blood vitamin A storage in Wistar rats. Animals were fed either a copper-deficient diet for 45 days from weaning, or an identical diet containing adequate amounts of copper. Concentrations of vitamin A were determined by isocratic high performance liquid chromatography using UV detection. We have observed in the liver of the rats fed a copper-deficient diet a significantly higher mean level of retinyl esters (148 +/- 37 micrograms/g of liver) and retinol (3.3 +/- 1.4 micrograms/g of liver) compared to the mean concentration of the retinyl esters (53 +/- 8.5 micrograms/g of liver) (p less than 0.01) and retinol (1.4 +/- 0.5 micrograms/g of liver) (p less than 0.01) in controls. Opposite results were observed in the serum of the group fed a copper-deficient diet as these rats had a significantly lower level of retinol (22 +/- 4 micrograms/100 ml) compared to the mean concentration in the controls (64 +/- 20 micrograms/100 ml) (p less than 0.01). These findings suggest that a copper-deficient diet may cause defective transport of vitamin A from liver to blood. This experimental model may be useful to further investigate unusual liver vitamin A and copper concentrations observed in children during various hepatobiliary diseases.     

Alteration in skin composition of young rats fed liquid protein diet

The effects of liquid protein diet (LPD) on the collagen metabolism of developing skin tissue was examined in young rats fed a 20% liquid protein diet starting at day 23 after birth. Other rats were pair-fed, but with a 20% casein diet, and another group of rats were fed a 20% casein diet ad libitum. The LPD rats rapidly lost their hair, and they were smaller and weighed less than the pair-fed and ad libitum rats. None of the LPD-fed rats survived beyond day 53 of the study. Collagen contents of the skin continuously increased in all age groups, while hexosamine content decreased from day 23 to 35. From day 23 to 35, noncollagenous protein content in the ad libitum group decreased about 40% and in the LPD and pair-fed groups, about 50%; from day 35 to 48, the decrease was about 35% in the ad libitum group and only about 14% in both the LPD and pair-fed groups. The ratio of Type III to I collagen in the LPD group at days 35 and 48 was greater than that of the ad libitum group. Current observations suggest that LPD alters biochemical composition of the skin on young, growing rats.