Effects of dietary saturated,monounsaturated and polyunsaturated fats on plasma lipids and lipoproteins in diabetic rats*

The effects of altering the type of dietary fat on plasma lipid and lipoprotein levels were investigated in streptozotocin‐diabetic rats fed non‐purified diets containing corn oil, olive oil, cod‐liver oil, sheep tallow and lard. After 32 days of experimental feeding, plasma levels of glucose, triglycerides, total cholesterol, low density and high density lipoprotein cholesterol were determined. Body weights and food intake were also measured. In neither animal group did the type of fat in the diet affect significantly the plasma levels of lipids and lipoproteins and their calculated ratios, and plasma glucose, body weight change or accumulative food intakes. In all studied diabetic rats, significant correlations were observed between body weight change and the following plasma variables: total cholesterol level (r = —0.37, P < 0.03), low density lipoprotein cholesterol level (r = —0.38, P<0.03) and triglycéride concentration (r = —0.36, P < 0.04). A significant positive correlation (r = 0.60, P < 0.0003) was also found between plasma levels of glucose and triglycérides. No significant correlations were noticed between accumulative food intakes and any of the studied variables. It is concluded that, in uncontrolled hyperglycemia in diabetes, the type of fat in the diet exerts little or no influence on plasma lipid and lipoprotein concentrations.     

Interrelationship of plasma triglycerides and HDL size and composition in rats fed different dietary saturated fats

We investigated the relative effects of different dietary saturated fats on the size distribution, apolipoprotein (apo) and chemical composition of HDL in fasted rats. Male Sprague-Dawley rats (174 +/- 2 g) were fed diets containing 0.035% cholesterol and 16% fat (wt/wt) from corn oil (CO diet) or from 2% CO plus 14% butterfat (BF diet), beef tallow (BT diet), palm oil (PO diet) or coconut oil (CN diet) for 6 wk. Apparent lipid digestibility was significantly lower with the PO and BT diets vs. the CO, BF and CN diets. Plasma total cholesterol levels were significantly higher in rats fed the PO and BT diets than in rats fed the BF and CN diets but were not different among the PO-, BT- and CO-fed groups. Nondenaturing gradient gel electrophoresis immunoblot analysis indicated that HDL apo A-I and E resided on particles with significantly smaller modal diameters in rats fed all saturated fats compared with those fed the CO diet. Chemical analyses indicated that HDL generally contained proportionately less protein and more triglyceride, free cholesterol and apo E with saturated fat feeding than with CO diet feeding. Significantly higher plasma and VLDL triglyceride levels were noted with ingestion of the BT, PO or CN diet than with the CO diet. Butterfat feeding resulted in lower plasma triglycerides and HDL-esterified cholesterol than did feeding the other saturated fats. Very low density lipoprotein triglyceride concentrations were inversely correlated with HDL modal diameter of apo E containing lipoproteins (P less than 0.005). These data provide further evidence of the interrelationship of triglyceride and HDL metabolism and suggest that mechanisms independent of cholesterol ester transfer protein may mediate this response in rats.     

Effect of dietary protein or amino acids on the rapid change in plasma zinc concentration in rats fed zinc deficient diets

The effects of dietary protein or amino acids on the rapid fall in plasma zinc concentration was studied in rats fed zinc deficient diets. After a 24 hr. fast, young (100 g) rats were given access to a single zinc deficient meal containing various amounts and types of protein or amino acids. Sixteen hours later, plasma zinc levels were determined. EDTA-treated soy protein, egg white and an amino acid mixture, when fed as 20% of the test meal, caused a significant (P<0.05) depression of plasma zinc concentration compared to rats given the zinc deficient meal without protein or amino acids. Plasma zinc could also be significantly lowered (P<0.05) under these conditions by a variety of absorbable chelating agents fed at 2% of the test meal. The effect of dietary protein on plasma zinc concentration could not be attributed to increased urinary zinc excretion in these studies.     

Effect of dietary fiber on bioavailability of zinc and copper and histology in rats

Effects of prolonged use of dietary fiber on the absorption of zinc and copper were determined. In addition, differences in histopathology of small intestine, liver and kidney were evaluated. Four groups of rats were fed semipurified diets containing no fiber (C) 7.5% of either pectin (P,) guar meal (G.) or carrot (Ca). Radioisotopes with short half lives (^69mZn and ⁶⁴Cu) were used to measure absorption and endogenous losses of zinc and copper. Fiber did not adversely affect (P<.05) the absorption or endogenous excretion of either isotopes. At the end of the experimental period distribution of the absorbed zinc in gastrointestinal tract, liver and kidney was measured using ⁶⁵Zn as a tracer. The ⁶⁵Zn content of the intestinal tissues and liver was higher (P<.05) in the pectin group which also showed maximum incidence of blunting and fusion of the villi of distal ileum. The growth rate and weight of the rats on the pectin diet were significantly lower (P<.05) than on the control diet.     

Regulation of plasma and liver total cholesterol levels by dietary oleic acid in rats fed a high-cholesterol diet.

The effects of diets containing fats and oils or fatty acids on the lipid metabolism were investigated in male rats of the Wistar strain fed hypercholesterolemic diets, especially focusing our attention on the correlation between dietary oleic acid (OLE) contents and the levels of plasma and liver total cholesterol (T-CHOL) or the fatty acid profiles in plasma and liver CHOL-ester. In the rats fed the free (FR)-type fatty acids, the concentrations of plasma and liver T-CHOL were high and the amounts of neutral steroids excreted into the feces were low when compared with those of rats given the triacylglycerol (TG)-type fatty acids, showing that TG-type fatty acids suppress the intestinal CHOL absorption more than the FR-type fatty acids do. The concentrations of plasma T-CHOL were highest in rats fed the oleic acid (OLE)-rich diets, followed in order by rats supplied with the palmitic acid (PAL)-rich diets, the hydrogenated coconut oil (HCO) diet, and the linoleic acid (LIN)-rich diets; the lowest was in rats given tristearin (TSTE) and linseed oil (LIS) diets. A positive correlation was obtained between the dietary OLE contents and the levels of plasma and liver T-CHOL or OLE in the plasma and liver CHOL-ester, and an inverse correlation between dietary OLE contents and the amounts of excreted neutral steroids. These results suggest that the dietary OLE contents regulate the levels of plasma and liver T-CHOL in CHOL-loaded rats.     

The interrelated effects of n-6/n-3 and polyunsaturated/saturated ratios of dietary fats on the regulation of lipid metabolism in rats

The effects of various n-6/n-3 (0.45-9.31) and polyunsaturated/saturated (P/S; 0.25-6.08) ratios of dietary fatty acids on various lipid parameters were studied in rats using a combination of palm oil, safflower oil, soybean oil and perilla oil. When the n-6/n-3 ratio was changed while maintaining a constant P/S ratio (1.2), the concentration of serum cholesterol tended to increase linearly with the increasing n-6/n-3 ratio, whereas liver cholesterol tended to decrease. Serum triglyceride level increased linearly up to a n-6/n-3 ratio of approximately 5, whereas liver triglyceride was not influenced. When the n-6/n-3 ratio was kept relatively constant (5.6-6.4), serum and liver cholesterol levels decreased up to a P/S ratio of approximately 2, whereas serum triglyceride tended to be low below this value. The ratio of arachidonate to linoleate in tissue phosphatidylcholine (PC) was also influenced by the n-6/n-3 and P/S ratios; it increased up to a n-6/n-3 ratio of approximately 4, whereas it decreased up to a P/S ratio of approximately 2. The percentage of eicosapentaenoic and docosahexaenoic acid (n-3) in tissue phosphatidylcholine was positively related to dietary n-3 fatty acid levels. Prostacyclin (PGI2) production by thoracic aorta reached a plateau at a n-6/n-3 ratio approximately 5, whereas it tended to decrease with an increasing P/S ratio. Platelet production of thromboxane A2 exhibited a parabola-like pattern with a peak value at a n-6/n-3 ratio of approximately 2, whereas it was independent of the P/S ratio.(ABSTRACT TRUNCATED AT 250 WORDS)     

NaFeEDTA预防大鼠铅中毒的研究及其对锌、铜的影响

为探讨乙二胺四乙酸铁钠 (NaFeEDTA)在预防大鼠铅中毒及减低铅毒性中的作用 ,同时研究其对锌、铜二元素的影响 ,采用随机分组的动物实验设计方法 ,将 60只Wistar大鼠随机分为空白对照组、模型对照组、阳性药物组和高、中、低NaFeEDTA组 ,共 6组 ,除空白对照组外 ,对其余各组大鼠进行持续性染铅 ,而且除模型对照组外的 4个染铅组分别同时给予二巯基丁二酸 (DMSA)、高、中、低浓度的NaFeEDTA溶液。 5周后实验结束 ,对相关指标进行测定。结果显示 ,三个NaFeEDTA组的血红蛋白含量均显著高于其它各组 ,同时其血铅、脑铅、肝脏铅、肾脏铅及胫骨铅含量显著低于模型对照组 ,而且它们的肝脏铅、肾脏铅和胫骨铅含量与每日每只大鼠铁补充量之间存在显著负相关 ,相关系数分别为 - 0 4432、- 0 61 34和 - 0 3878;除中、高浓度NaFeEDTA组的脑锌水平低于模型对照组以及低浓度NaFeEDTA组的肾脏铜含量高于模型对照组外 ,其余各NaFeEDTA组的脏器锌、铜含量与模型对照组相比均无显著性差异。提示NaFeEDTA可有效提高大鼠的血红蛋白含量 ,能够预防大鼠铅中毒 ,减低铅对大鼠的毒性作用 ;同时对体内锌、铜含量无太大影响     

接触二硫化碳大鼠铜水平与血浆LCAT活性的变化及关系的研究

ＳＤ大鼠分别用５ｍｇ／ｍ３和５０ｍｇ／ｍ３ＣＳ２吸入染毒６个月。结果表明：５０ｍｇ／ｍ３ＣＳ２接触组肝铜含量显著减少（Ｐ＜０．０５），血浆ＬＣＡＴ活性显著抑制（Ｐ＜０．０１）。肝铜含量与血浆ＬＣＡＴ活性呈正线性相关（Ｐ＜０．０１）。实验结果提示：ＣＳ２能引起铜代谢紊乱，降低体内铜水平；血浆ＬＣＡＴ是一种铜酶；ＣＳ２可通过干扰铜代谢，从而抑制ＬＣＡＴ活性，引起脂质代谢紊乱。     

Total body content of copper and other essential metals in rats fed fructose or starch

The effects of dietary carbohydrate and copper on whole body levels of copper and other essential minerals were investigated. Weaned male rats were pair-fed diets containing 62% fructose or cornstarch with either adequate (6–7 mg/kg) or deficient (0.5–0.7 mg/kg) copper (Cu) for 32–33 days. Recommended levels of other minerals were present in all diets. Total copper in whole body was approximately 2-fold higher in rats fed copper-supplemented diets than copper-deficient diets and was independent of the type of dietary carbohydrate. Whole body levels of zinc, iron, manganese and magnesium were independent of dietary copper and carbohydrate. Selenium content of rats fed copper-deficient diet with fructose was 35% higher than in those fed copper-adequate diet with fructose. Rats fed the copper-deficient diet containing starch had a whole body calcium level 17–23% lower than that of the other dietary groups. These results demonstrate that the copper-carbohydrate interaction is not a result of carbohydrate-dependent effects on the retention of dietary copper and other essential minerals.     

Effects of dietary taurine supplementation on plasma and liver lipids in OVX rats fed calcium-deficient diet

Taurine supplementation has been shown to have an effect on lowering blood lipids in ovariectomized (OVX) rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on OVX rats fed calcium-deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received a sham operation (Sham). Each rat group was further divided into the control diet and the taurine supplemented (2.0 g/100 g diet) diet group. All rats were fed on calcium-deficient diet and deionized water ad libitum for 6 weeks. Plasma and liver lipids were determined by using commercial kits. LDL-cholesterol concentrations were estimated with the equation of Friedewald et al. (1972). There were no significant differences in body weight gain and food intake between the control and taurine group within Sham and OVX groups, but body weight gain, food intake, and food efficiency ratio was higher in the OVX group. Concentrations of plasma total cholesterol, triglyceride, LDL-cholesterol were significantly lower in the taurine fed group of OVX rats fed Ca deficient diet, while HDL-cholesterol concentration was increased in the taurine fed group. Therefore, in this study, we examined whether taurine also prevented hypercholesterolemia induced by ovarian hormone deficiency in ovariectomized rats when they were fed a calcium-deficient diet. These results indicate that taurine may have some beneficial effects on hypercholesterolemia and hypertriglyceridemia in OVX rats fed calcium-deficient diet.     

长春地区0~12个月健康婴儿血清铁、镁、锌、铜参考区间的建立

目的 建立长春地区0~12个月健康婴儿血清铁、镁、锌、铜参考区间,为临床诊疗提供依据。方法 根据卫生行业标准WS/T 402-2012,经临床标准和实验室标准筛选后,选取2014年1月-2017年12月在吉林大学第一医院儿童体检中心体检的8 905名0~12月健康婴儿,使用日立7600-210全自动生化分析仪检测血清铁、镁、锌、铜,进行年龄、性别分组。使用SPSS 21.0统计软件进行分析,获得不同年龄段和性别分组的参考区间。结果 血清铁浓度随着月龄增加呈逐渐下降趋势,而血清镁浓度随月龄增加而逐渐升高。血清锌水平随月龄增加而逐渐升高,男婴、女婴分别在7~8个月、5~6个月达到高峰,此后逐渐下降。血清铜含量随着月龄增加,在11~12个月达高峰。四种微量元素参考区间均有年龄差异(P<0.05),血清铜在4~12个月开始有性别差异(P<0.05)。结论 建立各地区婴儿年龄与性别相关的血清元素参考区间对正确评估婴儿发育具有重要意义。     

The effect of low doses of dietary cadmium oxide on the disposition of trace elements (zinc,copper, iron), hematological parameters,and liver function in rats

The Zn, Cu, and Fe concentrations in selected organs, tissues and in the excreta of male Wistar rats, exposed to dietary CdO (2.80 and 7.15 ppm) for 40 and 60 days, were investigated. Concomitantly hematological values and serum enzyme activities were recorded. Zn levels of spleen, kidney, testes, muscle and feces were not affected by the Cd treatment. After 40 days of Cd exposure, the Zn concentration in the hair decreased, while the Zn level of the lung slightly increased. During the feeding trial, Cd produced an increase of liver Zn by about 24%. Femur Zn decreased and Zn in urine increased after 60 days of exposure to 7.15 ppm Cd. Except in hair and urine, the Cu concentration in all organs and tissues investigated remained unchanged. Hair Cu levels decreased after 40 days of Cd exposure but increased after 60 days. At this time, elevated Cu concentration in urine was recorded. After exposure to 7.15 ppm Cd, the Fe content of the lung, liver, spleen, testes, muscle, femur and blood decreased significantly. After 60 days on the 7.15 ppm diet, highest reductions (30%–60%) of Fe content were recorded in the lung, liver, and spleen. Similar to Zn and Cu, the Fe concentration in urine increased at that time. No changes were found in the Fe content of hair, kidney, and feces. In spite of a disturbed Fe metabolism, an anaemic response of Cd-treated rats was not observed. Hematocrit and hemoglobin remained unchanged and the number of red blood cells slightly increased after 40 days of Cd exposure. While the activity of serum alkaline phosphatase was not affected by dietary Cd, the activities of serum-GOT and serum-GPT increased after exposure to 7.15 ppm Cd indicating disturbed hepatic functions.     

铁和锌对染铅大鼠股骨矿物质含量和骨密度的影响

目的　以大鼠为模型 ,观察饲料中添加不同铁 (1 0、5 0和 2 5 0mg kg)和锌 (1 0、4 0和 2 0 0mg kg)水平对低剂量铅 (0和 2 0 0mg kg)毒性的拮抗作用。方法　断乳一周Wistar雄性大鼠按体重随机被分成 1 1组 ,每组 1 0只。其中 1 0组饲以不同铁、锌和铅水平的饲料 ,另设 1组为未染铅正常对照 ,饲以基础正常饲料 ,1 2周后处死大鼠测定股骨生长发育有关指标。结果　研究发现 ,铅污染抑制大鼠骨骼的生长发育 ,能降低骨骼中矿物质含量和骨密度 ,补充铁锌后能改善大鼠股骨的重量和长度 ,增加股骨矿物质含量和骨密度 ,同时会增加骨铅含量。提示　需要进一步研究铅影响骨骼生长发育的机制     

微机极谱法同时测定人头发中锌 铁 锰3种微量元素

锌、铁、锰都是有重要生理功能的人体必需微量元素。极谱法测定这 3种元素已经有很多研究[1] 。若用常规分析方法 ,需在不同的底液中分别测定 ,工作强度较大。简便、快速、多元素分析是微量元素检测的发展方向。由于微机伏安 /极谱扫描范围较宽[2 ] ,头发中这 3种元素的含量又相对较高 ,因此有可能进行多种元素的同时测定。在硼砂底液中 ,研究了人头发中锌、铁、锰同时测定的条件。由于微机极谱法设备简单 ,价格低和测定元素多等特点 ,利于推广使用     

Serum levels of polyunsaturated fatty acids are low in Chinese men with metabolic syndrome,whereas serum levels of saturated fatty acids,zinc, and magnesium are high

The purpose of this study was to examine the hypothesis that serum levels of phospholipid (PL) fatty acids (FA) and minerals are associated with the components of metabolic syndrome (MetS) in the Chinese population and the profiles of changes may differ from patients with MetS from Western countries. The levels of serum PL, FA, and minerals were examined in 201 subjects (52 with MetS and 149 healthy controls without any MetS components) in China. The saturated FA proportion in serum was significantly higher, whereas the proportion of total polyunsaturated FA (PUFA), n-3 and n-6 PUFA (22:6n-3: −16%, P = .006; 20:4n-6: −36%, P < .001), and estimated δ-5 desaturase were significantly lower in the MetS group compared with those that are not MetS. Subjects with MetS had higher levels of serum Zn (P = .037) and Mg (P < .001) than subjects without MetS. The proportion of n-3 PUFA was significantly negatively correlated with body mass index and waist circumference. In conclusion, serum PL FA composition and serum minerals in Chinese men with MetS differed significantly from that of healthy individuals, reflecting a decrease in n-3 and n-6 PUFA, especially 22:6n-3 and 20:4n-6, and an increase in saturated FA, magnesium, and zinc. These changes may reflect improper dietary intake in subjects with MetS, and dietary modification could be useful to prevent MetS and as an adjunctive therapy.     

Differential effect of high dietary iron on α-tocopherol and retinol levels in the liver and serum of mice fed olive oil– and corn oil–enriched diets

The influence of dietary fats on cellular α-tocopherol and retinol uptake in iron overload is poorly understood. The aim of this study was to investigate the effect of a high-iron diet on the retinol and α-tocopherol levels in mice fed olive oil– and corn oil–enriched diets. Mice were fed for 3 weeks a standard mouse chow (the control group) and diets enriched with 5% by weight of corn oil or olive oil. Diets of the mice fed corn oil and olive oil were additionally supplemented with 1% by weight carbonyl iron. Both dietary oils and iron increased the liver iron uptake. High-iron feeding induced oxidative stress in mice liver, measured as a thiobarbituric acid-reactive substance level. Both fats and iron induced changes in the liver fatty acid composition. Liver retinol and α-tocopherol stores increased with iron supplementation in the olive oil–enriched diet, with a simultaneous decrease in serum. The results suggest that the influx of α-tocopherol and retinol from serum to the liver is induced by high dietary iron. This redistribution appears to be stronger for retinol than for α-tocopherol and is also higher in mice fed olive oil than in mice fed corn oil, suggesting that the composition of dietary lipids is important in the treatment of high-iron tissue conditions. In conclusion, the results of this study suggest that the increase of hepatic α-tocopherol and retinol levels in the olive oil–based diet is a dietary-dependent responsive mechanism that probably is not primarily related to an increased risk of oxidative damage induced by high-iron intake.     

烹调油烟致大鼠肝脂质过氧化和锌铜铁钙含量变化的研究

目的通过观察肝组织脂质过氧化和元素含量的变化,探讨烹调油烟致肝损伤的毒作用机理.方法利用SD大鼠动式吸入烹调油烟浓度(43±4)mg/m3为染毒组,吸入加热空气(24～28℃)为阴性对照组,分别于染毒第20、40、60天收集肝脏标本测定肝组织SOD活性和MDA及Zn、Cu、Fe、Ca含量.结果烹调油烟可使肝组织MDA含量增高,SOD活性下降;钙铁值随染毒时间延长增多,锌降低.结论烹调油烟致肝脂质过氧化和元素钙铁超载锌降低,可能存在对肝损伤的协同作用.     

Pantethine, a derivative of vitamin B5 used as a nutritional supplement, favorably alters low-density lipoprotein cholesterol metabolism in low- to moderate-cardiovascular risk North American subjects: a triple-blinded placebo and diet-controlled investigation

Safety and efficacy of a biologically active derivative of vitamin B₅ (pantethine) on total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) metabolism was studied in North American subjects at conventional low to moderate cardiovascular disease (CVD) risk. A total of 120 subjects initiated a therapeutic lifestyle change (TLC) diet 4 weeks before randomization (baseline) and maintained the diet throughout a 16-week study period; at baseline, subjects were randomized in a triple-blinded manner to either pantethine (600 mg/d, baseline to week 8, and 900 mg/d, weeks 9-16) or identically labeled, nonbiologically active placebo (n = 60 per group). We hypothesized that pantethine would lower TC and low-density lipoprotein in low-CVD-risk North American subjects in a similar manner as reported in high-CVD-risk subjects studied mainly in Italy and Japan. While sustaining a TLC diet and in comparison with placebo, pantethine demonstrated significant (P < .005) and sustained reductions (from baseline to week 16) in TC (6 mg/dL, 0.16 mmol/L, 3%), LDL-C (4 mg/dL, 0.10 mmol/L, 4%), and apolipoprotein B (4 mg/dL, 0.04 g/L, 5%). Our data suggest that pantethine supplementation for 16 weeks (600 mg/d for weeks 1-8 then 900 mg/d for weeks 9-16) is safe and significantly lowers TC and LDL-C over and above the effect of TLC diet alone. Although the absolute magnitude of these effects was small in these low- to moderate-risk North Americans (4-6 mg/dL), the results are noteworthy as prior studies have shown that, for each 1 mg/dL (0.026 mmol/L) reduction in LDL-C, there is a concomitant 1% reduction in overall future CVD risk.     

A high ratio of dietary n-3/n-6 polyunsaturated fatty acids improves obesity-linked inflammation and insulin resistance through suppressing activation of TLR4 in SD rats

Dietary ratios of n-3/n-6 polyunsaturated fatty acids (PUFAs) have been implicated in controlling markers of metabolic disorders, including obesity, insulin resistance (IR), inflammation, and lipid profiles, which are also presumed to be partly related to type 2 diabetes mellitus (T2DM). However, molecular mechanisms of the different PUFAs related to metabolic disorders have not been systematically addressed. The present study aimed to investigate the impact of dietary n-3/n-6 PUFA ratios on obesity and IR and, further, to determine the underlying mechanisms. For 16 weeks, 32 SD male rats, randomly divided into four groups (n = 8 per group), received one of the following diets: normal chow, high saturated fatty acid (SFA), high n-3/n-6 PUFA ratio (1∶1, PUFA^1:1), or low n-3/n-6 PUFA ratio (1∶4, PUFA^1:4). Following the experimental diet period, metabolic parameters related to obesity and IR were measured. Compared to SFA diet-fed rats, PUFA^1:1 diet-fed rats exhibited decreased body and visceral fat weight, lowered blood lipids, and improved glucose tolerance and insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of circulating pro-inflammatory cytokines, including tumor necrosis factor α, interleukin-6, and C-reactive protein. Moreover, the TLR4 protein and mRNA levels were markedly down-regulated by PUFA^1:1 compared with SFA; however, PUFA^1:4 diet-fed rats failed to exhibit these changes. Cumulatively, our data highlight a role for a PUFA^1:1 diet in the prevention of obesity and related metabolic disorders by suppressing the activation of TLR4, a critical modulator of pro-inflammatory cytokines.