Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phosphlipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.     

Growth, lipid metabolism and pathology of two strains of rats fed high fat diets.

Studies were carried out on Sprague-Dawley (SD) and Chester Beatty (CB) rats to determine whether the difference in incidence of myocardial lesions can be related to dietary factors and parameters known to be affected in SD rats fed rapeseed oils. The two strains of young, male rats were fed diets which contained 20% by weight of either corn, LEAR (low erucic acid) or HEAR (high erucic acid rapeseed) oils for a period of up to 16 weeks. A significantly lower incidence of focal myocardial necrosis was observed in CB rats than in SD rats. The incidence of this heart lesion in CB rats was similar between all diets; in SD rats a higher incidence was observed in the groups fed rapeseed oils. In both strains the growth rates of rats fed LEAR and corn oils were similar; growth rates with HEAR oil diets were much lower than the other oils. Severe myocardial lipidosis was only evident in rats fed HEAR oil, but no strain differences were observed. The pattern and extent of lipidosis, including cardiac and hepatic lipid levels and fatty acid compositions, were similar in both strains at the time periods studied. Cardiac triglycerides and free fatty acids increased in rats fed HEAR oil, but no strain differences were evident. Strain differences were found in the levels of a few cardiac phospholipids of rats fed HEAR oil, however, the relative fatty acid compositions of each phospholipid were remarkably similar. Microscopic examination of the livers showed no evidence that feeding rapeseed oil caused any specific effect which could be related to differences in heart lesion response. There was no evidence to indicate that differences in heart lesion response between the two rat strains could be related to cardiac triglycerides, free fatty acids or phospholipids.     

Lipoprotein lipid and protein responses to dietary fat and diabetes in rats

Dietary and insulin-deficiency types of hyperlipidemia were compared in adult normal and streptozotocin-induced diabetic male breeder rats. High beef tallow, high corn oil or low fat diets (BT, CO and LF, respectively) were fed ad libitum for 2 months. Glucose and insulin were measured in plasma and total cholesterol, free cholesterol, cholesteryl ester, triglycerides and apoproteins in very low density, low density and high density lipoproteins (VLDL, LDL and HDL, respectively). Diet did not affect plasma glucose or insulin levels. LDL-triglycerides were higher in BT and diabetic than in CO and LF rats. HDL-free cholesterol levels were higher in CO- and LF-than in BT-fed rats. Diabetes resulted in a decrease in HDL-cholesterol. Diabetic animals had higher HDL-apoA-I (apolipoprotein A-I) levels than did CO- and LF- but not BT-fed rats. VLDL-triglycerides were higher in diabetic than in normal rats, with no dietary differences in normal rats. In LDL, apoB levels were lower and apoE levels were higher in LF-fed rats than in animals fed high fat diets. Diabetes resulted in an increase in LDL-apoB but a decrease in LDL-apoE. HDL-apoE levels were higher, although HDL-apoA-I levels were lower in LF than in high fat-fed rats. The results related to lipoprotein composition supported the hypothesis that excess intake of a diet high in saturated fat may contribute to a metabolic pattern that resembles that of a diabetic state.     

Effects of capsaicin on lipid metabolism in rats fed a high fat diet

Effects of capsaicin, a pungent principle of hot red pepper, were studied in experiments using male rats fed a diet containing 30% lard. Capsaicin was supplemented at 0.014% of the diet. The level of serum triglyceride was lower when capsaicin was present in the diet than when it was not. Levels of serum cholesterol and pre-beta-lipoprotein were not affected by the supplementation of capsaicin. The perirenal adipose tissue weight was lower when capsaicin was present in the diet than when it was not. Hepatic enzyme activities of glucose-6-phosphate dehydrogenase and adipose lipoprotein lipase were lower in rats fed the 30% lard diet than in those fed a nonpurified diet. Activities of these two enzymes were higher when capsaicin was added to the diet than when it was not. Hepatic acetyl-CoA carboxylase, beta-hydroxyacyl-CoA dehydrogenase, and adipose hormone-sensitive lipase activities were not affected by capsaicin feeding. Lipid absorption was not affected by the supplementation of capsaicin. The perirenal adipose tissue weight and serum triglyceride were decreased as the level of capsaicin in the diet increased up to 0.021%. These results suggest that capsaicin stimulates lipid mobilization from adipose tissue and lowers the perirenal adipose tissue weight and serum triglyceride concentration in lard-fed rats.     

Effect of Chlorella vulgaris on lipid metabolism in Wistar rats fed high fat diet

This study was performed to investigate effects of Chlorella vulgaris on lipid metabolism in rats fed high fat diet. Sixty 6-week-old male Wistar rats were divided into two groups; normal diet group and high fat diet group, then the rats in each group were further divided into three subgroups and fed 0%, 5% and 10% (w/w) chlorella-containing diets, respectively, and raised for 9 weeks. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity and total protein and albumin concentration were not different among groups. Serum total lipids and liver TG concentration were significantly lower in 5% and 10% chlorella groups than 0% chlorella group in high fat diet groups (p<0.05). Serum TG, serum total cholesterol, liver total lipid and liver total cholesterol concentrations were significantly lower in 10% chlorella groups than 0% chlorella group in high fat diet groups (p<0.05). Fecal total lipid, TG and total cholesterol excretions were significantly higher in 5% and 10% chlorella groups than 0% chlorella groups in normal diet and high fat diet groups, respectively (p<0.05). These results suggest that Chlorella vulgaris is effective for prevention of dyslipidemia which may be due to the modulation of lipid metabolism and increased fecal excretion of lipid.     

食用竹炭粉对高脂模型大鼠脂肪代谢的影响

目的探讨食用竹炭粉(bamboo charcoal powder,BCP)对高脂模型大鼠的降脂作用及其机制。方法 4周龄SPF级雄性SD大鼠,随机分成5组:空白对照组,高脂模型对照组和BCP低、中、高剂量(2.81、5.62、11.24 g/kg)干预组。各组每日灌胃相应剂量的竹炭粉或蒸馏水,连续90 d。股动脉取血测定肝肾功能等生化指标;取肝、肾及双侧肾脏及附睾周围的脂肪称重;取左侧肝叶做组织病理学检查;制备肝匀浆,检测总胆固醇(TC)、甘油三酯(TG)、总抗氧化能力(T-AOC)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和丙二醛(MDA)含量。结果从第4周起高脂模型对照组体重显著高于同期空白对照组,同时高脂模型对照组脂/体比、血清谷丙转氨酶(ALT)、TG和极低密度脂蛋白(VLDL)均高于空白对照组;高脂模型对照组肝脏可观察到明显的脂肪变性,肝脏中MDA、TC和TG含量均高于空白对照组,表明造模成功。BCP各剂量组与高脂模型对照组比较,体重、肝重及脂/体比均明显降低,血清ALT、TG和VLDL浓度降低,肝脏脂肪变性程度减轻,同时肝脏中TC和MDA浓度也均降低,T-AOC、SOD和CAT活性升高。结论食用竹炭粉具有减少高脂模型大鼠体内脂肪蓄积、降血脂、减轻肝脏脂肪变性的作用,其机制可能与减轻体内脂质过氧化作用有关。     

谷物膳食纤维对脂代谢紊乱小鼠肝脏脂毒性影响

目的 观察不同类型谷物膳食纤维(DF)对脂代谢紊乱小鼠血脂和肝脏脂毒性影响。方法 48只雄性C57BL/6J小鼠(6周龄)按体重随机分为4组:对照组、模型组、燕麦DF组、小麦DF组, 连续干预24周,实验期间每周称体重并记录摄食量, 每8周内眦静脉采血, 进行血脂和血糖连续动态观察;干预结束后测定空腹血糖、血清总胆固醇(TC)、甘油三酯(TG)和游离脂肪酸(FFAs)及肝组织TG含量。结果 与对照组比较, 模型组小鼠体重[(37.69±2.66)g]、空腹血糖[(8.21±2.06)mmol/L]、血清TC、TG、FFAs水平 [分别为(2.69±0.45)、(1.77±0.64) mmol/L、(2.12±0.38) mEq/L]明显升高(P<0.05);与模型组比较, 燕麦DF与小麦DF组小鼠体重[分别为(34.41±2.93)、(34.43±1.72)g]、血清TC、TG水平[分别为(2.03±0.44)、(2.22±0.50)与(1.64±0.43)、(1.39±0.41) mmol/L]均明显下降(P<0.05);燕麦DF组小鼠血清FFAs水平[(1.75±0.49) mEq/L]明显降低(P<0.05)。结论 谷物DF可以改善脂代谢紊乱小鼠血脂和肝脏脂毒性, 燕麦DF改善血脂和肝脏脂毒性的作用优于小麦DF。     

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.     

菰米对高脂诱导脂代谢紊乱大鼠肝脏脂毒性的作用

目的观察由米面和菰米等不同构成饲料对高脂饲料大鼠血脂、游离脂肪酸(FFA)和瘦素(leptin)水平的作用,探讨菰米对高脂饲料诱导的脂代谢紊乱大鼠血脂及肝脏脂毒性的作用。方法 44只雄性SD大鼠随机分为阴性对照组、高脂模型组、米面组和菰米组;以相应饲料连续喂养8周,测定各组大鼠体重、血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、FFA和leptin等指标,同时肝脏组织行病理切片检查。结果与阴性对照组相比,高脂模型组和米面组大鼠的血清TC、TG、FFA和leptin水平显著上升(P<0.05),HDL-C水平显著降低(P<0.05),肝脏发生脂肪变性;与高脂模型组和米面组相比,菰米组大鼠的血清TC、TG、FFA水平显著下降(P<0.05),HDL-C水平显著升高(P<0.05),leptin水平稍低于高脂模型组和米面组,但无显著性差异,肝脏脂肪变性程度显著减轻。结论菰米具有降低高脂饲料诱导的脂代谢紊乱大鼠血脂水平和肝脏脂毒性的作用。     

魔芋精粉对高脂饲料喂养大鼠的脂质代谢及血液粘度的影响

用高脂饲料加入魔芋精粉喂饲健康雄性SD大鼠6周，观察魔芋精粉对大鼠血脂水平及血液粘度的影响，结果表明，魔芋精粉能有效地降低高脂组大鼠血清总胆固醇，甘油三酯及血清酯质过氧化物，同时可提高高密度脂蛋白胆固醇及高密度脂蛋白胆固醇／总胆固醇比值，降低大鼠血液粘度，但对大鼠摄食量及生长无不良影响。     

Influence of dietary fiber on lipid metabolism in meal-fed rats

The effects of the four major components of dietary fiber--cellulose, hemicellulose, pectin and lignin--on lipid metabolism were studied in meal-fed Wistar rats maintained on a cholesterol-free semipurified diet for 21 days. Transit time was decreased and fecal weight increased compared to rats fed a fiber-free diet. Rats fed cellulose or lignin gained significantly less weight than rats fed hemicellulose or pectin. The fibers had no effect on serum cholesterol levels, but serum triacylglycerol levels were significantly higher in rats fed cellulose. Liver cholesterol levels were higher in cellulose-fed rats but liver triacylglycerol levels were highest in rats fed hemicellulose or pectin. Hepatic cholesterol 7 alpha-hydroxylase and HMG-CoA reductase activities were highest in rats fed cellulose and pectin, respectively. Epididymal fat cell size was similar in all groups but fat cell number was highest in pectin-fed rats. Perirenal fat cell size was greatest in rats fed cellulose or lignin and fat cell number in rats fed cellulose or hemicellulose. Lipoprotein lipase activity (per 10(6) cells) was elevated in epididymal fat of rats fed pectin and in perirenal fat of rats fed hemicellulose. Carcass lipid accumulation was highest in rats fed cellulose or lignin. Rats fed cellulose accumulated significantly higher levels of carcass cholesterol and triacylglycerol. Of the fibers fed, cellulose led to an accumulation of serum, liver and carcass lipid. The four fibers fed represent purified and altered forms of cellular components and the observed effects cannot be extrapolated to diets containing foods rich in one or another of these components.     

The influence of dietary fat on fat metabolism and body fat deposition in meal-feeding and nibbling rats.

1. An experiment was done with rats (body-weight 160 g) to study the effects on fat metabolism and body composition of low (10 g/kg)- or high (140 g/kg)- fat diets fed as one meal for one 4 h period/d (meal-feeders) or as six spaced meals/d (nibblers). The daily energy intake/unit metabolic body-weight (body-weight 0.73) was the same for all four groups, and this level of intake was about 80% of that consumed by rats allowed unrestricted access to the low-fat diet. The experimental period was 76 d. 2. Rats given the high-fat diet deposited more body fat/d and, as a result, grew faster and were energetically more efficient than rats given the low-fat diet depressed de novo lipogenesis from glucose in epididymal and perirenal fat pads, whose fatty acid composition resembled that of the diet. 3. For both diets meal-feeders had greater stomach plus small intestine weights than nibblers and had higher plasma free fatty acid levels, when they were killed 15 h after their last meal. 4. Meal-feeders given the low-fat diet had the greatest rate of lipogenesis for fat pads. 5. Meal-feeders given the high-fat deposited less of the main dietary fatty acids in their fat pads. 6. There was no evidence that meal-feeders eating a high-fat diet adapt their metabolism completely that they become more efficient utlizers than those nibbling this diet. Meal-feeders eating the low-fat diet became no fatter than nibblers of this diet, possibly because they were eating less than their daily ad lib. intake.     

Comparisons of glucose and lipid metabolism in rats fed diacylglycerol and triacylglycerol oils

The effects of dietary 1,3-diacylglycerol-rich oil (DG oil) on biochemical findings related to glucose and lipid metabolisms were investigated in comparison with triacylglycerol oil (TG oil) in normal rats. Young (7 wk-old) and old (8 mo-old) rats were fed a synthetic diet containing 10% (by weight) DC or TG oil for 1, 4, 8, or 12 wk. The body weights, epididymal and perirenal adipose tissue weights, and feed efficiency were not significantly different in the dietary oil groups during any feeding period. The plasma and liver triacylglycerol concentrations were not different in the dietary groups, except that the plasma triacylglycerol concentrations were rather lower only in the portal vein of rats fed DG oil. The plasma glucose and free fatty acid concentrations were significantly higher in rats fed DG oil as compared to TG oil. In the old rats fed DG oil for 8 wk, the fasted plasma glucose and insulin concentrations were elevated and glucose intolerance was observed. The insulin receptor expression was not different due to dietary oil, but was markedly reduced with aging. Thus, the anti-obesity and lipid-lowering effects of dietary DG oil were not found. Moreover, it appeared that the glucose intolerance might be induced by dietary DG oil, particularly in the old rats.