Serum lipid levels correlate with solid tumor weight in hepatoma-bearing rats fed dietary fish oil

The effects of dietary fish oil (FO) on serum lipid levels and tumor proliferation were studied in Donryu rats subcutaneously implanted with the ascites hepatoma cell line AH109A. Solid tumor weight was significantly less and serum total cholesterol (T-Ch) level significantly lower in the groups fed the FO diet both before and after AH109A implantation than in the groups fed the corn oil diet. There were no significant effects in the serum lipid levels and tumor proliferation in the groups fed the FO diet only before or after the hepatoma implantation. The serum triacylglyceride, phospholipid, nonesterified fatty acid, T-Ch, and very-low-density lipoprotein+low-density lipoprotein-Ch levels showed significant positive correlations with the solid tumor weight. These results suggest that dietary FO ingestion after hepatoma implantation suppresses tumor proliferation and reduces serum lipid levels along with suppressing tumor proliferation.     

Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in rats

This study investigated whether hemostatic function can be modified by both the consumption of fish oil and the level of dietary selenium. Male Sprague-Dawley rats were fed for 8 wk semipurified diets containing 7% corn oil (by wt) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or without selenium supplementation. Consumption of the four diets caused no difference in weight gain, food intake or plasma malondialdehyde content. The selenium-supplemented rats had significantly higher levels of selenium and glutathione peroxidase activity in plasma. Fish oil feeding decreased ADP-induced platelet aggregation and increased bleeding time. The level of dietary selenium and type of oil interacted to influence the production of 6-keto-prostaglandin F1 alpha: more was produced when corn oil was fed in the selenium-deficient diets. These data suggest that the effect of dietary selenium on hemostatic function and the production of eicosanoids is minor.     

Effects of dietary fish oil on survival rate, plasma amino acid pattern, and inflammatory-related mediators in diabetic rats with sepsis

This study was designed to investigate the effects of dietary fish oil on survival rates, plasma amino acid profiles, and inflammatory-related mediators in diabetic rats with sepsis. Diabetes mellitus (DM) was induced in rats by streptozotocin. The DM rats were maintained for 4 weeks on medium fat (10%, w/w) diets containing either fish oil or safflower oil. After that, sepsis was induced by cecal ligation and puncture (CLP). There were 2 groups in this study: fish oil sepsis group (FOS) and safflower oil sepsis group (SOS). The survival rate was observed after CLP. Also, changes of the amino acid pattern as well as interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, prostaglandin (PG) E(2)at 6, 12, and 24 h after CLP were investigated. The results demonstrated that survival rates were not significantly different between the 2 groups. Plasma arginine levels were significantly lower in sepsis groups than that in the DM-chow group, regardless of whether the diabetic rats were fed fish oil or safflower oil. No significant differences were observed in plasma valine, leucine, isoleucine, glutamine, or arginine concentrations between the FOS and SOS groups at different time points. Concentrations of IL-1 beta in peritoneal lavage fluid (PLF) at 6 h and TNF-alpha at 6 h as well as at 12 h after CLP in the FOS group were significantly higher than those in the SOS group. PGE(2)levels in PLF, by contrast, were lower in the FOS group at 6 and 12 h after CLP than in the SOS group. These results suggest that differences in IL-1 beta, TNF-alpha, and PGE(2)levels in PLF in the early period of sepsis did not influence the survival rates and plasma amino acid profiles of the FOS and SOS groups. Compared with safflower oil, feeding diabetic rats with fish oil had no beneficial effects on survival rates and muscle protein breakdown. The immunologic impact of dietary n-3 polyunsaturated fatty acids on diabetic rats with sepsis requires further investigation.     

Effects of dietary fish oil or pectin on blood pressure and lipid metabolism in the DOCA-salt hypertensive rat

This study investigated the effects of diets containing fish oil or pectin on blood pressure and lipid metabolism in the deoxycorticosterone acetate (DOCA)-salt hypertensive rat. Three groups (8 rats/group) of unilaterally nephrectomized rats were fed for 21 d one of three purified diets: a) 8% fish oil + 2% safflower oil + 5% alpha cellulose (fish oil diet), b) 10% safflower oil + 5% pectin (pectin diet), or c) 10% safflower oil + 5% alpha cellulose (control diet). Each of the diets contained 6% NaCl and all rats received DOCA (30 mg/kg body wt, subcutaneously) twice weekly. Systolic blood pressure of rats fed fish oil was significantly lower (P less than 0.05) than that of rats fed the control diet; there was no significant difference between the pectin and control groups. Plasma renin activity and net sodium and potassium balances were similar among the three groups. Plasma total cholesterol, LDL cholesterol and HDL cholesterol were significantly lower (P less than 0.05) in the group fed the fish oil diet than in the group fed the control diet. Total, LDL and HDL cholesterol did not differ between rats fed the pectin and rats fed the control diet. Plasma triglyceride concentration did not differ among the three groups. Thus, dietary fish oil attenuated the development of DOCA-salt hypertension, unrelated to alterations of net sodium balance. Fish oil feeding also lowered total, LDL and HDL cholesterol, but did not alter the HDL/LDL ratio. In contrast, dietary pectin exerted no effect on blood pressure or lipid metabolism.     

Hepatic sulfur amino acid metabolism in rats with chronic renal failure

We recently demonstrated elevated plasma amino acid concentrations and abnormal responses to amino acid supplementation (e.g., elevated methionine and phenylalanine) in children with chronic renal failure (CRF). We also recently developed an improved model of CRF in which animals manifest abnormal tissue amino acid levels, marked anorexia and growth failure. The objective of the current study was to determine the etiology of elevations of sulfur amino acids in animals with chronic renal failure. Chronic renal failure, defined as creatinine clearance less than 30% of control values, was induced in male rats in a two-stage surgical procedure. Four groups were studied over 2, 4 and 6 wk: control (non-operated) control (sham-operated), pair-fed (sham-operated and pair-fed with uremics) and CRF. Animals with CRF were anorexic and growth-retarded. Although plasma sulfur amino acid levels tended to be lower in the uremic animals than in controls, hepatic tissue concentrations were higher. Methionine adenosyltransferase was higher, but cystathione synthase and cystathionase activities were not significantly different in rats with CRF compared to pair-fed controls. We conclude that uremia, not malnutrition, affected sulfur amino acid metabolism and that with CRF, a normal adaptive response to elevated methionine levels was occurring, sufficient to normalize sulfur amino acid pool size. Alternative causes of elevated sulfur amino acids must be sought.     

Hypocaloric lipid emulsions and amino acid metabolism in injured rats

The present study was designed to determine the degree and mechanism by which administration of medium-chain triglyceride emulsions spare body protein after injury. Forty male rats underwent venous catheterization and received nonsterile bilateral femur fractures. All rats received 2.5 g/day amino acids and either no additional calories (group I) or 20 kcal/day of either glucose (group II), a long-chain triglyceride emulsion (group III), a medium-chain triglyceride emulsion (group IV), or a structured lipid emulsion composed of 40% sunflower oil and 60% medium-chain triglycerides (group V). The diets were administered for 3 days, and rates of plasma leucine flux, oxidation, and incorporation into protein as well as tissue protein synthetic rates in liver and muscle were measured using the constant infusion of L-[1-14C]leucine. Results demonstrated that the administration of glucose or various lipid emulsions improved cumulative nitrogen balance significantly when compared to a diet containing amino acids alone. In addition, the administration of glucose or lipid emulsions significantly stimulated protein synthesis in liver and muscle. Moreover, a structured lipid emulsion of medium- and long-chain fatty acids produced significant increases in liver protein synthesis greater than that observed with either glucose or long-chain triglyceride emulsions. We conclude that added energy as fat or glucose reduces net protein catabolism and improves tissue protein synthesis in these injures rats and that lipid emulsions are as effective as dextrose. A structured triglyceride emulsion synthesized from medium- and long-chain fatty acids appears to better support hepatic protein synthesis.     

Effect of deep frying oil given with and without dietary cholesterol on lipid metabolism in rats

The purpose of the present study was to investigate the effect of dietary deep frying oil (DO) on levels of plasma and liver lipids, and fecal steroid excretion in rats. The DO was prepared by frying fresh soybean oil (FO) at 200°C, 6 h each, for four consecutive days. Male weanling Sprague-Dawley rats ingested diets containing 15% FO or DO with or without 1% cholesterol for 6 weeks. Rats on the DO diet with cholesterol had a lower food intake and body weight gain compared to the FO diet with cholesterol. The concentration of plasma esterified cholesterol was higher in rats on DO diet than in rats on FO diet, although the plasma triacylglycerols (TG) were similar between the groups. The DO diet resulted in a lower content of liver TG and cholesterol, and less excretion of acidic and neutral steroids than did the FO diet. These results showed that ingestion of frying oil with cholesterol aggravated hypercholesterolemia, even though absorption of dietary cholesterol may be lower in rats on DO diet.     

Effects of dietary ethanol on ascorbic acid and lipid metabolism, and liver drug-metabolizing enzymes in rats

Effects of dietary ethanol on ascorbic acid and lipid metabolism, and liver drug-metabolizing enzymes in rats fed a semi-purified diet containing a powdered ethanol preparation (30 cal% in the diet) were studied. Administration of ethanol increased urinary ascorbic acid excretion (p less than 0.001) and ascorbic acid level in the liver (p less than 0.001) and the spleen (p less than 0.01). The activity of hepatic aniline hydroxylase was increased (p less than 0.05) by ethanol feeding but that of aminopyrine N-demethylase was not. Increases of serum total and high-density-lipoprotein (HDL) cholesterol level, commonly observed by the administration of xenobiotics, were not observed. These results showed ethanol possessed rather similar properties to xenobiotics such as polychlorinated biphenyls (PCB) or 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane (DDT) in some metabolic changes. In this study, no accumulation of lipid in the liver was observed.     

橄榄油和鱼油对大鼠血脂和脂质过氧化的影响

为观察橄榄油和鱼油对大鼠血脂水平及脂质过氧化的影响 ,将 44只Wistar大鼠随机分成 4组 ,分别接受正常饲料、高脂饲料、高脂饲料加橄榄油灌胃 (4ml·kg- 1 ·d- 1 )和高脂饲料加鱼油灌胃 (4ml·kg- 1 ·d- 1 )处理。实验期 6周。结果显示 ,橄榄油和鱼油均能降低大鼠血清总胆固醇和甘油三酯水平 ,并且鱼油的效果较橄榄油好 ,鱼油能够显著提高高密度脂蛋白胆固醇 ;橄榄油和鱼油均可降低高脂饲料引起的肝 体比值增大 ,而且鱼油可以明显减少肾脏和睾丸周围脂肪。橄榄油组和鱼油组大鼠的血清丙二醛水平均明显下降 ;而且红细胞超氧化物歧化酶活性有所提高 ,表明橄榄油和鱼油对进食高脂饲料引起的体内过氧化物水平升高具有拮抗作用。结果提示橄榄油和鱼油对高血胆固醇、甘油三酯有降低作用 ,并能改善高脂所致体内过氧化状态异常 ,减轻对机体的过氧化损伤 ,鱼油的效果优于橄榄油     

Supranormal dietary folic acid supplementation: effects on methionine metabolism in weanling rats

There are nationwide folic acid (FA) fortification programmes of staple foods established or under consideration in order to prevent neural tube defects. Universal FA fortification still remains controversial because of the concern that additional FA in the diets of population groups (e.g. children and elderly) not initially targeted for fortification may suffer adverse effects. However, dietary surveys regarding folate generally deal with adults and little is known about the consumption and long-term effects of fortified food and supplements in growing individuals. Recent reports from our laboratory show several effects of high-dose folate supplementation in rats. In the present work, we studied the effect of FA on the methionine cycle in weanling (3-week-old) male rats after 4 weeks of supplementation with 40 mg FA/kg diet v. control (1 mg FA/kg diet). FA supplementation resulted in a reduction of homocysteine and creatinine concentrations v. control group. FA supplementation did not alter S-adenosylmethionine/S-adenosylhomocysteine ratio, DNA methylation, enzymatic activities or concentrations of vitamins involved in the nutritional regulation of the methionine cycle, except for folate. FA supplementation of 40 mg/kg did not lead to hepatic or renal damage. In conclusion, there were no apparent adverse effects on one-carbon metabolism after FA supplementation in the studied conditions.     

发育期补充鱼油对大鼠脑内脂肪酸组成及神经递质的影响

为观察发育期补充二十二碳六烯酸对大鼠脑内脂肪酸代谢和部分神经递质的变化,将孕鼠分为４组：正常对照组组（Ｏ）、添加ＤＨＡ的低（Ｌ）、中（Ｍ）、高（Ｈ）剂量组,于基础饲料中分别添加鱼油０、１７．５、３５和７０ｍｌ／ｋｇ,实验组饲料中的ＤＨＡ含量分别为７．５、１５和３０ｇ／ｋｇ。     

山楂叶总黄酮对高脂血症大鼠脂代谢的影响

目的 研究不同剂量的山楂叶总黄酮(hawthorn leaf flavonids,HLF)对实验性高脂血症大鼠脂代谢的影响.方法 建立大鼠高脂血症模型,观察不同剂量HLF对高脂血症大鼠血清及肝脏脂质、脂肪积累、不同组织脂蛋白脂肪酶(lipoprotein lipase,LPL)的影响.结果 与模型对照组相比,一定剂量的HLF能降低高脂血症大鼠血清以及肝脏甘油三酯(Triglyceride,TG)、胆固醇(Tricholesterol,TC)含量(P<0.05),并能有效地改善脂肪的积累(P<0.001);增加肌肉组织中LPL的含量(P<0.05),减少脂肪组织中LPL的含量(P<0.01).结论 HLF具有降血脂的作用,对高脂饮食引起的高脂血症和脂肪肝具有防治作用.     

Effect of sulfur amino acid supplementation of raw soy flour on the growth and pancreatic weights of rats

Rat feeding studies showed that L-cystine, L-cysteine, N-acetyl-L-cysteine and L-methionine enhance the nutritional quality of raw (unheated) soy flour as measured in rats by the protein efficiency ratio (PER). Pancreas weights of rats fed diets supplemented with sulfur amino acids were higher than those of rats fed unsupplemented diets. In some instances this increase resulting from nutritional improvement of the diet was relatively greater than that in total body weight. Explanations are offered for these effects in terms of the proposed biofeedback mechanism involving the gastrointestinal endocrine system and the hormone cholecystokinin. The observed stimulation of pancreatic growth by added sulfur amino acids may be closely associated with this pancreatic regulatory mechanism when activated in response to dietary trypsin inhibitors present in unheated soy protein. The extent to which pancreatic hypertrophy develops as a result of a given exposure to trypsin inhibitors may be limited when the total amount or quality of the protein in the diet is less than optimal.     

Regulation of sulfur amino acid metabolism in men in response to changes in sulfur amino acid intakes

We showed previously that 64% of the total dietary sulfur amino acid (SAA) requirement could be supported by dietary cysteine (Cys). However, the observation of such a sparing effect may be affected by the dietary intakes of SAA provided. The aim of this study was to compare methionine (Met) metabolism and transsulfuration (TS) in five healthy men fed three different diets (in random order) for 3 d each, with varying combinations of Met and Cys: 24 mg Met/(kg. d) and no Cys (diet A); 13 mg Met/(kg. d) and 11 mg Cys/(kg. d) (diet B); and 5 mg Met/(kg. d) and 19 mg Cys/(kg. d) (diet C). On d 3, Met kinetics and TS were assessed using orally administered L-[1-(13)C, methyl-(2)H(3)]methionine. Met demethylation (transmethylation, TM) significantly decreased as the dietary Met to Cys ratio decreased. Met TS was significantly lower during diets B [2.8 +/- 0.4 micro mol/(kg. h)] and C [1.5 +/- 0.5 micro mol/(kg. h)] than during diet A [7.8 +/- 2.9 micro mol/(kg. h)] (P < 0.05). The results of the present study indicate that when the ratio of Met to Cys fed is typical of that found in major food proteins and total SAA are sufficient to meet requirements, TS is significantly reduced compared with the case in which SAA needs are supplied by Met alone. We conclude that Cys sparing occurs through an increase in the fraction of the homocysteine pool destined for RM relative to TS (RM:TS).     

Effects of dietary protein on renal function and lipid metabolism in five-sixths nephrectomized rats

The objective of the present experiment was to examine the effect of substituting different quantities of soyabean protein for casein on renal function and lipid metabolism in rats with chronic renal failure induced by a five-sixths nephrectomy. Experimental animals were subjected to a nephrectomy and fed either casein or soyabean protein (200 or 100 g/kg diet). The diets were isoenergetic with identical fat, Na, K and P contents. Rats ingesting 200 g casein/kg diet showed a significantly (P<0.05) accelerated course of chronic renal failure, while the soyabean-protein groups showed retarded progression of the experimentally induced renal disease and hypercholesterolaemic effects. Rats in the low-soyabean-protein diet (100 g/kg) also demonstrated increased serum albumin and decreased serum triacylglycerol, total cholesterol concentrations and blood urea-N; however, the low-casein diet significantly (P<0.05) increased serum triacylglycerol. Results of the present study show that the replacement of casein by soyabean protein was related to the rate of progression of renal failure and improvement in lipid profiles in serum of five-sixths nephrectomized rats.     

Effect of dietary protamine on lipid metabolism in rats

Protamine has been widely used as a pharmaceutical product and natural food preservative. However, few studies have been conducted to assess the beneficial function of dietary protamine. This study examined the effects of dietary salmon protamine on serum and liver lipid levels and the expression levels of genes encoding proteins involved in lipid homeostasis in the liver of rats. Groups of male Wistar rats were fed AIN93G diet containing 2% or 5% protamine. After 4 weeks of feeding these diets, markedly decreased serum and liver cholesterol (CHOL) and triacylglycerol levels were noted. Increased activity of liver carnitine palmitoyltransferase-2 and acyl-CoA oxidase, which are key enzymes of fatty acid β-oxidation in the mitochondria and peroxisomes, was found in rats fed on protamine. Furthermore, rats fed protamine showed enhanced fecal excretion of CHOL and bile acid and increased liver mRNA expression levels of ATP-binding cassette (ABC) G5 and ABCG8, which form heterodimers and play a major role in the secretion of CHOL into bile. The decrease in triacylglycerol levels in protamine-fed rats was due to the enhancement of liver β-oxidation. Furthermore, rats fed protamine exhibited decreased CHOL levels through the suppression of CHOL and bile acid absorption and the enhancement of CHOL secretion into bile. These results suggest that dietary protamine has beneficial effects that may aid in the prevention of lifestyle-related diseases such as hyperlipidemia and atherosclerosis.     

Effects of dietary methionine, cystine, and glycine on endogenous hypercholesterolemia in hepatoma-bearing rats

The effects on hypercholesterolemia of dietary additions of cystine (Cys), methionine (Met), glycine (Gly), and a combination of Met and Gly to a 20% casein diet were studied in male Donryu rats subcutaneously implanted with an ascites hepatoma line of AH109A cells. The hepatoma-bearing rats fed the 20% casein diet lapsed into both endogenous hypertriglyceridemia and hypercholesterolemia when compared to hepatoma-free (normal) rats fed the same diet. The hypercholesterolemia was due to an elevation (3.2 fold) in the very low-density lipoprotein plus low-density lipoprotein (VLDL + LDL)-cholesterol (Ch) level. The high-density lipoprotein (HDL)-Ch level was slightly but significantly decreased. These lipoprotein changes in hepatoma-bearing rats resulted in a marked (4.5 fold) increase in the atherogenic index (AI, (VLDL + LDL)-Ch/HDL-Ch) in comparison with that of tumor-free rats. The dietary additions of 1.2% Met, 1.2% Cys, and a combination of 1.2% Met and 2.5% Gly significantly suppressed the hepatoma-induced increase in (VLDL + LDL)-Ch with no influence on the hepatoma-induced decrease in HDL-Ch, leading to a noticeable fall in AI. These results indicate that hepatoma-bearing rats are useful as an endogenously hyperlipidemic model and that some dietary amino acids are capable of improving hepatoma-induced hypercholesterolemia and abnormal serum lipoprotein profiles.