Lard-fed Group Research Articles

Effect of dietary fat type on anxiety-like and depression-like behavior in mice

Dietary fat plays an important role in higher brain functions. We aimed to assess the short and long term intake of three different types of dietary fat (soybean oil, lard, and fish oil) on anxiety-like and depression-like behavior in mice. For the short term intake assessment, a behavioral test battery for anxiety and depression was carried out for a 3-day feeding period. For the long term intake assessment, a behavioral test battery began after the 4-week feeding period. During the short term intake, the time spent in the open arms of the elevated plus-maze was the longest in the fish oil fed group, followed by the soybean oil and lard-fed groups. The elevated plus-maze is a common animal model to assess anxiety, in which an increased time spent in the open arms indicates an anxiolytic effect. The difference between the fish oil-fed group and lard-fed group was statistically significant (p < 0.01), but there was no significant difference between the soybean oil-fed group and the other two groups. Similar results were observed after a 4-week feeding period. On the other hand, there was no significant difference among the three groups in behavior tests to evaluate depression. Thus, the dietary fat types appeared to influence anxiety but not depression in mice, both in short term (3 days) and long term (4 weeks) feeding.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-165) contains supplementary material, which is available to authorized users.

COMPARISON OF HYPOCHOLESTEROLEMIC ACTIVITY OF TEA SEED OIL WITH COMMONLY USED VEGETABLE OILS IN HAMSTERS

Interest in tea seed oil (named tea oil) as a cooking oil is increasing. However, its effect on blood cholesterol is not known. This study was therefore conducted to compare the hypocholesterolemic activity of tea oil with grape seed, canola and corn oils. Results showed that plasma total cholesterol (TC), non-high-density lipoprotein-cholesterol (non-HDL-C) and triacylglycerols (TG) in hamsters fed with a 0.1% cholesterol diet containing tea, grape, canola or corn oil were significantly reduced compared with those in lard-fed group. Tea oil decreased only non-HDL-C and had no or little effect on HDL-C concentration, while grape oil reduced both. Unlike grape oil, tea oil up-regulated sterol regulatory element binding protein (SREBP-2) and low-density lipoprotein receptor. Besides, tea oil-fed hamsters excreted less neutral but greater acidic sterols compared with other three oils. Differences between tea oil and the tested vegetable oils could be attributable partially to the greatest oleic acid (>80%) and least phytosterol content in tea oil. PRACTICAL APPLICATIONS Although tea leaves are used worldwide, tea oil is only used in some Asian countries. Extensive research has shown the health benefits of tea drinking. However, benefit associated with the consumption of tea seed oil remains unclear. We have shown that tea seed oils were able to lower plasma cholesterol equally as grape, canola and corn oil in hamsters fed a 0.1% cholesterol diet. The hypocholesterolemic activity of tea oil was characterized by decreasing only non-high-density lipoprotein-cholesterol (non-HDL-C) and having no effect on HDL-C concentration. Most importantly, tea oil could up-regulate sterol regulatory element binding protein 2 and low-density lipoprotein receptor. It was further demonstrated that hamsters fed the tea oil diet excreted lesser neutral but greater acidic sterols compared with other three vegetable oils. These results suggest that the tea seed oil could be an alternative healthy oil for human consumption.

Aging accelerates dietary lard-induced increase in blood pressure in rats

We investigated whether the dietary lard-induced increase in blood pressure (BP) is accelerated in aged rats compared to young ones. Three-month-old (young group), 10-month-old (middle-age group), and 18-month-old (older group) F344/N male rats were used. The rats were fed either chow alone or chow in which 50% of the energy content was from substituted lard. Systolic BP (SBP) and body weights (BW) were determined weekly during each 7-week feeding period. A Steady-state plasma glucose (SSPG) method was used to determine the insulin sensitivity. Bilateral testicular fat mass (epididymal fat; Epi-F) was removed in order to evaluate weight (Epi-FW). SBP began to increase at 2 weeks in the older lard-fed group, at 4 weeks in the middle-age lard-fed group, and at 5 weeks in the young lard-fed group after feeding was begun. There was no significant difference in the basal values of SBP among any ages-groups of the rats. After 4 weeks of lard feeding, increases in SBP, plasma insulin, leptin level, SSPG and Epi-FW/BW were observed in the older lard-fed group. In the younger rats, however, only hyperinsulinemia developed. At 7 weeks, increased BP in the younger rats was accompanied by increased plasma leptin level, SSPG and Epi-FW/BW. In summary, aging accelerates development of a dietary lard-induced increase in BP, which may be caused by the hyperleptinemia that may be the result of increased susceptibility to insulin resistance and/or visceral adiposity in older rats.

Uterine artery function in pregnant rats fed a diet supplemented with animal lard.

We hypothesised that maternal uterine artery vascular dysfunction could contribute to cardiovascular dysfunction in offspring of rats fed a diet rich in fat. Sprague-Dawley rats were fed for 10 days prior to pregnancy and throughout gestation either: (a) a control breeding diet, or (b) the same diet supplemented with 20 % w/w lard, vitamins, essential micronutrients and protein to control values. At 20 days gestation vascular function was assessed in uterine arteries and third-order mesenteric arteries. Vascular reactivity in response to application of potassium, noradrenaline, the thromboxane analogue U46619, acetylcholine and nitric oxide was assessed. Maternal plasma concentrations of factors likely to contribute to endothelial dysfunction were measured. Maximum acetylcholine-induced relaxation was impaired in the mesenteric arteries of the lard-fed dams (max % relaxation: lard-fed, 69.7 +/- 6.48; control, 85.37 +/- 2.69, P = 0.03). Uterine artery vascular function was similar in the two groups (max % acetylcholine-induced relaxation: lard-fed, 73.7 +/- 4.01; control, 77.5 +/- 4.72, P = 0.98). Concentrations of plasma lipids, 8-epi-PGF(2alpha) and leptin were normal, whereas insulin and corticosterone concentrations were raised in the lard-fed group (insulin (ng ml(-1)): lard-fed, 8.04 +/- 0.47; control, 1.35 +/- 0.37, P < 0.0001; corticosterone (ng ml(-1)): lard-fed, 1164.0 +/- 170.9; control, 541.9 +/- 96.3, P = 0.005). Fetal and placental weights were reduced in lard-fed dams (fetus (g): lard-fed, 4.27 +/- 0.38; control, 2.96 +/- 0.40, P = 0.025; placenta (g): lard-fed, 0.72 +/- 0.06; control, 0.57 +/- 0.04, P = 0.05). Cardiovascular dysfunction in offspring is not associated with reduced uterine artery endothelial function but is associated with activation of the hypothalamic-pituitary-adrenal axis, hyperinsulinaemia and fetoplacental growth retardation.

Pinus pinaster Oil Affects Lipoprotein Metabolism in Apolipoprotein E-Deficient Mice

The aim of the present study was to assess the antiatherogenic properties of Pinus pinaster (maritime pine) seed oil. To this end, the effects of P. pinaster oil supplementation on lipoprotein levels and atherosclerotic lesions were compared to those of lard or sunflower oil in apolipoprotein E-deficient mice. Plasma total cholesterol (P < 0.0001) and VLDL + intermediary density lipoprotein (IDL)-cholesterol (P < 0.0001) levels were lower in mice fed P. pinaster and sunflower oil than in those fed the lard diet. In contrast, triglycerides (P < 0.0001) and VLDL + IDL-triglycerides (P < 0.0001) levels were higher in mice fed P. pinaster oil than sunflower oil or lard. The VLDL + IDL lipid composition of apolipoprotein E-deficient mice fed P. pinaster oil was intermediate between that of lard-fed transgenic mice and that of wild-type mice fed nonpurified diet. Using the Triton WR1339 method, the fractional catabolic rate of plasma triglycerides was found to be lower in mice fed P. pinaster oil (P < 0.0001) than sunflower oil or lard diet, suggesting a defective clearance of triglycerides in the P. pinaster group. Finally, the susceptibility of triglyceride-rich lipoproteins to in vitro lipoprotein lipase-mediated lipolysis was lower in the P. pinaster oil-fed group than in the lard-fed group. Despite the differences in VLDL + IDL level and lipid composition, the surface areas of aortic atherosclerotic lesions were not significantly different among mice fed P. pinaster, sunflower or lard diets. In conclusion, the results of the present study indicated that feeding P. pinaster oil had no better preventive effect on aortic atherosclerotic lesion extension in apolipoprotein E-deficient mice than other saturated or polyunsaturated fats.

ラード投与ラットにおける血中Ｌ‐トリプトファンの消失に及ぼす血清遊離脂肪酸レベルの影響

In rats fed a 40% lard-containing diet for 2 h after fasting for 24 h, the concentration of free fatty acid, or nonesterified fatty acid (NEFA) in serum was about 1, 600μEq/l, which was about four times higher than that of rats fed a control diet. This lard-diet feeding increased the concentration of free L-tryptophan (Trp) in the serum, but did not affect the serum total Trp and albumin concentrations, or Trp concentration and tryptophan 2, 3-dioxygenase activity in the liver. When the relationship between NEFA and free Trp concentration in the serum was checked, there was a significant positive correlation between the two. The rate of increase of free serum Trp concentration was much higher at serum NEFA concentrations exceeding 1, 000μEq/l than at concentrations of less than 1, 000μEq/l. When control and lard-fed rats were injected i. v. with a Trp solution (100μmol/kg BW), the disappearance rate of total blood Trp in the lard-fed group was significantly higher than that in the control group at 0.5, 1, and 3 min after the injection, but there was no difference in the rate between the two groups thereafter. When the control and lard-fed rats were injected i. v. with a Trp solution (100μmol/kg BW) containing [3H] Trp, there was no difference in radioactivity in the liver, brain, kidney, spleen, and muscle between the two groups 10 min after the injection. These results suggest that under physiological conditions (ca. 100 prvi Trp and 4% albumin), an increase in free serum Trp concentration subsequent to an increase in the serum NEFA level does not have a large influence on the transport of Trp into the liver.

Dietary fish oil effects on biliary lipid secretion and cholesterol gallstone formation in the African green monkey

We studied two groups of adult male African green monkeys to assess the effects of dietary fish oil on biliary lipid secretion and cholesterol gallstone formation. One group was fed 0.8 mg cholesterol/kcal and 42% of calories as fat with half of the fat calories derived from lard; the other group was fed a similar diet except for the isocaloric substitution of menhaden oil for lard. After 21/2 to 3 yr, necropsies were performed and the presence of gallstones was determined. Gallbladder bile specimens were analyzed for cholesterol saturation index, as well as for bile acid species and biliary phospholipid fatty acid composition. Our results showed that 67% of animals fed the lard diet had cholesterol gallstones compared with only 22% of animals in the group fed the fish oil diet (p = 0.08). The cholesterol saturation index of gallbladder bile also tended to be higher in the lard-fed group (1.15 ± 0.11) compared with the fish oil-fed group (0.86 ± 0.09, p = 0.06). No differences between the two dietary groups were noted in the percentages of the various types of bile acids. However, a greater percentage of ω-3 fatty acids and a lesser percentage of 18:1, 18:2 and 20:4 fatty acids were found in the biliary phospholipids from the fish oil-fed group compared with the lard-fed group. Biliary lipid secretion rates were then measured during isolated recirculating liver perfusion performed with a constant sodium taurocholate infusion. A significantly greater biliary phospholipid secretion rate was noted in the fish oil-fed animals compared with the lard-fed animals, whereas bile acid and cholesterol secretion rates were similar between the diet groups. We conclude that the increased biliary phospholipid secretion observed in the fish oil-fed group produced a less lithogenic gallbladder bile, which in turn resulted in a less frequent occurrence of gallstones in that group. In addition the increased phospholipid secretion was probably favored by the enrichment of biliary phospholipids with relatively less hydrophobic ω-3 fatty acids. (Hepatology 1991;14:679-684.)

Dietary fish oil effects on biliary lipid secretion and cholesterol gallstone formation in the African green monkey*1

We studied two groups of adult male African green monkeys to assess the effects of dietary fish oil on biliary lipid secretion and cholesterol gallstone formation. One group was fed 0.8 mg cholesterol/kcal and 42% of calories as fat with half of the fat calories derived from lard; the other group was fed a similar diet except for the isocaloric substitution of menhaden oil for lard. After 2 1/2 to 3 yr, necropsies were performed and the presence of gallstones was determined. Gallbladder bile specimens were analyzed for cholesterol saturation index, as well as for bile acid species and biliary phospholipid fatty acid composition. Our results showed that 67% of animals fed the lard diet had cholesterol gallstones compared with only 22% of animals in the group fed the fish oil diet (p = 0.08). The cholesterol saturation index of gallbladder bile also tended to be higher in the lard-fed group (1.15 +/- 0.11) compared with the fish oil-fed group (0.86 +/- 0.09, p = 0.06). No differences between the two dietary groups were noted in the percentages of the various types of bile acids. However, a greater percentage of omega-3 fatty acids and a lesser percentage of 18:1, 18:2 and 20:4 fatty acids were found in the biliary phospholipids from the fish oil-fed group compared with the lard-fed group. Biliary lipid secretion rates were then measured during isolated recirculating liver perfusion performed with a constant sodium taurocholate infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary fat on biliary lipids composition of gallbladder bile in miniature swine ( Sus scrofa)

1. 1. Weaning animals (34 days old) were fed for 6 months with four diets that differed only in the quantity and quality of fat sources (control group 3.2% (w/w), lard-fed group 7.6% (w/w), olive-oil-fed group 10.4% (w/w), and sunflower-oil-fed group 10.5% (w/w). Samples were collected and assessed after animals were killed at 6 months of age. 2. 2. Our results show that the quality of fat did not alter biliary lipids composition of the gallbladder bile composition in miniature swine after 6 months adaptation to the diet, except for a significant increase of the phospholipid concentration in the lard-fed group with regard to the control group. 3. 3. The highest and lowest bile cholesterol saturation indices were observed in sunflower and lard-fed groups, respectively showing in all cases saturation indices far from the saturation point.

Learning and memory impairment in rats fed a high saturated fat diet

At the age of 1 month, three separate groups of Long-Evans rats were placed on 20% (w/w) fat (40% of calories) diets high in either saturated fatty acids (lard-based) or polyunsaturated fatty acids (soybean oil-based) or standard laboratory chow (Purina, 4.5% (w/w) fat). After 3 months, all rats were administered three tests of learning and memory--Olton's radial arm maze, a variable-interval delayed alternation task, and the Hebb-Williams maze series. The lard-fed group was impaired on all tests. The soybean oil-fed group was slightly impaired on some measures, relative to the chow-fed group, but consistently performed better than the lard-fed group. The results indicate that a diet high in saturated fatty acids can impair a wide range of learning and memory functions and are in line with biochemical and physiological evidence showing widespread effects of such diets on brain function.

Alteration of high density lipoprotein subfractions of nonhuman primates fed fish-oil diets. Selective lowering of HDL subfractions of intermediate size and density.

Two groups of adult male African green grivet monkeys (12 animals in each group) were fed atherogenic diets containing 40% of total calories as fat with half of the fat calories derived from lard or menhaden oil and 0.8 mg cholesterol/kcal for a period of 10 months to ascertain the effect of such diets on lipoprotein concentrations, composition, and distribution. After 8 months on this diet, the animals' lipoproteins were isolated from their plasma by ultracentrifugation and agarose column chromatography, and these were characterized chemically. Compared with the lard-fed group, the menhaden oil-fed animals had significantly lower total plasma cholesterol (decreases 33%), HDL cholesterol (decreases 33%) and apo A-I (decreases 30%) concentrations and LDL molecular weights (decreases 15%). Although the fish-oil diets resulted in an average similar reduction of LDL cholesterol concentrations (decreases 34%), the decrease was not statistically significant. The lipid and apoprotein compositions of plasma LDL and HDL were similar between the two groups of animals. The distribution of HDL subfractions was determined by gradient gel electrophoresis and density gradient ultracentrifugation. The fish-oil group had a significant reduction in protein (decreases 46%) of HDL subfractions of intermediate size (80 to 88 A) compared to the lard-fed group. By density gradient ultracentrifugation, there was a 35% to 40% lower concentration of protein in the d = 1.10-1.13 g/ml subfraction of fish-oil-fed monkeys. Thus, feeding fish oil to nonhuman primates results in a selective decrease in the concentration of HDL subfractions of intermediate size and density compared to lard-fed animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Garlic on Lipid Metabolism in Rats Fed Cholesterol or Lard

Effects of garlic on lipid metabolism were studied in three experiments using different aged male rats fed a diet containing 1% cholesterol or 15% lard. Lyophilized garlic was supplemented at 2% and 4% of the diet. Plasma glucose was not changed by dietary treatments. Rats fed cholesterol and lard diets increased plasma cholesterol and triglycerides compared to controls. Garlic decreased plasma cholesterol in cholesterol- and lard-fed rats, but decreased plasma triglycerides only in the lard-fed group. Garlic supplementation decreased very low density lipoprotein cholesterol and increased high density lipoprotein cholesterol. The liver weight, total liver lipid and cholesterol were increased in rats fed the cholesterol diet but a supplementation of garlic decreased those parameters by about 30%. Dietary cholesterol and lard decreased hepatic glucose-6-phosphate dehydrogenase and malic enzyme activities: the garlic supplementation further decreased these enzyme activities. Garlic feeding increased the excretion of the neutral steroids in both 16-week and 10-week-old rats and bile acids in only 16-week-old pair-fed rats. Garlic at the 2% level was similarly effective on lipid metabolism as at 4%. These results demonstrate that garlic increases the excretion of neutral and acidic steroids and exerts hypocholesterolemic effects in cholesterol-fed rats.garlic lipid metabolism cholesterol lipoprotein cholesterol bile acids lipogenic enzymes