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At least 37 records · Page 2Linked to original sources
PubMed1987

Regulation of hepatic very-low-density lipoprotein secretion in rats fed on a diet high in unsaturated fat.

Rats were fed ad libitum on either a standard, high-carbohydrate, chow diet or a similar diet supplemented with 15% unsaturated fat (corn oil). Hepatocytes were prepared either during the dark phase (D6-hepatocytes) or during the light phase (L2-hepatocytes) of the diurnal cycle. In hepatocytes from rats fed on the unsaturated-fat-containing diet, secretion of very-low-density lipoprotein (VLDL) triacylglycerol was inhibited to a greater extent in the D6- than in the L2-hepatocytes. Plasma non-esterified fatty acid concentrations were elevated to the same extent at both D6 and L2 in the unsaturated-fat-fed animals. The secretion of VLDL esterified and non-esterified cholesterol was relatively insensitive to changes in the unsaturated-fat content of the diet. This resulted in proportionate increases in the content of these lipid constituents compared with that of triacylglycerol in the nascent VLDL. There was also an increase in the ratio of esterified to non-esterified cholesterol in the nascent VLDL produced by hepatocytes of the unsaturated-fat-fed animals. In the D6-hepatocytes from the unsaturated-fat-fed animals, the decrease in the secretion of VLDL triacylglycerol could not be reversed by addition of exogenous oleate (0.7 mM) to the incubation medium. In contrast, addition of a mixture of lactate (10 mM) and pyruvate (1 mM) stimulated both fatty acid synthesis de novo and the rate of VLDL triacylglycerol secretion. Secretion of esterified and non-esterified cholesterol also increased under these conditions. Insulin suppressed the secretion of VLDL triacylglycerol and cholesteryl ester under a wide range of conditions in all types of hepatocyte preparations. Non-esterified cholesterol secretion was unaffected. In hepatocytes prepared from the fat-fed animals, these effects of insulin were more pronounced at D6 than at L2. Glucagon also inhibited VLDL lipid secretion in all types of hepatocyte preparations. The decrease in cholesterol secretion was due equally to decreases in the rates of secretion of both esterified and non-esterified cholesterol.

Animals↗
PubMed1968

Effect of ingestion of unsaturated fat on lipolytic activity of rat tissues.

Homogenates of some rat tissues, incubated in Tris-maleate buffer containing bovine serum albumin, olive oil emulsion, heparin, and serum, liberated free fatty acids. The total lipolytic activity in tissues of rats fed a low fat, 20% lard, or 20% corn oil diet for 6 wk was measured. Similar activities were found in all the livers, but there was a significant increase in the total lipolytic activity of the mucosa, epididymal fat, and mesenteric tissues after ingestion of an unsaturated fat diet as compared with that containing a more saturated fat. From measurements of the lipolytic activity in the presence of 1 M NaCl or 0.2 M NaF and in the absence and presence of heparin and serum, the conclusion is drawn that more lipoprotein lipase was present in adipose tissue of rats on unsaturated fat diets. An increase in available lipoprotein lipase after unsaturated fat diets may aid in clearing lipids from the blood of these rats and thus in producing the lower blood lipid levels obtained.

Adipose Tissue↗
PubMed1983

Caffeine and unsaturated fat diet significantly promotes DMBA-induced breast cancer in rats.

The following study was carried out to determine the possibility of caffeine being a promoter of breast cancer development in animals consuming vegetable fat. A controlled study, comparing the time of mammary tumor development and the number of tumors was carried out in Sprague-Dawley rats which had been given 20 mg of DMBA at seven weeks of age. This study evaluated the tumor promotional effects of caffeine alone, caffeine and unsaturated fat in combination, unsaturated fat alone, and a standard rat chow diet. The results show that the rats which consumed caffeine and unsaturated fat had the earliest development of tumor and the most multiple tumor occurrence. Average time to tumor development was 95 days. The fat or standard chow rats had an average time to tumor development of 134 and 140 days, respectively. The caffeine-alone rats had a mean time to tumor development of 188 days. The combination of an unsaturated fat diet and caffeine significantly shortened the time to tumor development when compared with the other three groups.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

Enhancement of DMBA-induced mammary cancer in Wistar rats by unsaturated fat and cholestyramine.

Promotion of 7,12-dimethylbenzantracene (DMBA)-induced mammary cancer in Wistar rats, by diets containing unsaturated fat (USF) and unsaturated fat plus 4% cholestyramine (USF+ CHST) was compared to that in rats fed saturated fat (SF). The diets were fed for 100 or 200 days. Histologic examination of grossly normal mammary tissue, as well as of any tumor mass, showed a significant increase in the incidence and size of mammary tumors in USF and USF + CHST groups when compared to SF group. Moreover, in the USF + CHST group one tumor developed in one rat as early as 100 days. The serum total lipids, triglycerides and cholesterol esters decreased significantly at 200 days in USF and USF + CHST groups. These results suggest that a diet high in unsaturated fat alone, or in combination with 4% cholestyramine, promotes DMBA-induced mammary cancer in Wistar rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

Effect of the inclusion time of dietary saturated and unsaturated fats before slaughter on the accumulation and composition of abdominal fat in female broiler chickens.

The aim of this experiment was to assess the effects of four different feeding programs designed to include tallow, a saturated fat at 0, 8, 12, and 28 d prior to slaughter on female broiler performance and the deposition, fatty acid profile, and melting point of abdominal fat. The following treatment groups were established according to dietary inclusion--from 21 to 49 d of age--of: sunflower oil (SUN), sunflower oil followed by tallow during the last 8 d (SUN + 8TALL), sunflower oil followed by tallow during the last 12 d (SUN + 12TALL), and tallow (TALL). The diets were designed to be isoenergetic and isonitrogenous. Abdominal fat deposition increased linearly with increasing number of days in which birds were fed the tallow-enriched diet. However, linear and quadratic response patterns were found between days before slaughter in which the birds were fed the tallow-enriched diet and abdominal fat melting points. This result suggested an exponential response in which 85% of the maximum level was already attained when the dietary fat type changed from an unsaturated to a saturated condition during the last 8 d of the feeding period. The use of an unsaturated fat source during the first stages of growth, and the substitution of a saturated fat for a few days before slaughter, may offer the advantage of lower abdominal fat deposition and an acceptable fat fluidity compared with the use of a saturated fat source during the whole growing and finishing period.

Abdomen↗
PubMed2005

Effects of conjugated linoleic acid supplementation on blood lipids and adiposity of rats fed diets rich in saturated versus unsaturated fat.

Conjugated linoleic acid (CLA) may decrease adiposity and improve blood lipid profiles under some conditions. The goal of this study was to determine the effects of CLA supplementation on blood lipid profiles and adiposity of rats fed a diet containing a primarily saturated fat versus a diet containing a primarily unsaturated fat. Twenty-eight male Sprague-Dawley rats were randomly assigned to one of four diets containing coconut oil, coconut oil with CLA, corn oil or corn oil with CLA. After 28 days, blood was collected and serum concentrations of total cholesterol (TC), HDL-cholesterol (HDL-C), and triacylglycerols (TG) were assessed. Food intake, body weights, and epididymal fat pads were measured. No significant differences (p>0.05) were noted among groups for amount of food consumed, weight gained, food efficiency ratio or serum TG concentrations. TC concentrations were lower (p<0.05) in the CLA-supplemented rats that were fed coconut oil but not those consuming corn oil. Serum HDL-C was lower (p<0.05) in rats consuming corn oil but was not significantly different (p>0.05) for CLA supplemented groups. Epididymal fat pads weighed significantly more (p<0.05) in the coconut oil fed group compared to the corn oil fed group, but there was no significant difference (p>0.05) between the corn oil and coconut oil + CLA group. Overall, this study suggests that CLA is more beneficial for control of blood lipids and adiposity when supplemented to a diet rich in saturated versus unsaturated fat.

Adipose Tissue↗
PubMed1996

Antitumor effect of pre-transplantation local hyperthermia and augmentation by dietary unsaturated fat.

Antitumor effects of pre-transplantation hyperthermia and its correlation to immunological changes in the host animals and enhancement by dietary unsaturated fat have been studied. Leg muscles of mice were locally heated (41 degrees-43 degrees C, 40 min) and fibrosarcoma cells were inoculated into the heated and unheated sites and tumor growth time was determined. Spleen cell activity and plasma levels of interleukins (IL1 and 2) [RIA kits] were assessed. Muscle and tumor fatty acid profiles were modified by feeding mice with unsaturated fat supplemented diet and analysed by GLC. Pre-transplantation hyperthermia suppressed the tumor growth on both heated and unheated contralateral legs of mice. These effects were associated with increased spleen cell activity and plasma levels of IL1 and 2. Diet rich in unsaturated fat altered the fatty acid profiles of the leg muscles and tumors and inhibited tumor growth. It also potentiated the antitumor effect of pre-transplantation hyperthermia. In conclusion, mild local hyperthermia induces both direct and abscopal antitumor effects which may be ascribed to stimulation of host's antitumor immune responses and these effects are augmented by unsaturated fat supplemented diet.

Animals↗
PubMed1999

Higher lipid accumulation in broilers fed on saturated fats than in those fed on unsaturated fats.

1. Two experiments were conducted to assess the effect of fat sources differing in degree of saturation on the performance of and fat deposition in broiler chickens fed on isocaloric and isonitrogenous diets. 2. There were no differences in initial body weight between sexes but female broilers had lower daily gains (P<0.0001), final weights (P<0.0001) and food intakes (P<0.0001) than males. Abdominal fat pad weight was lower in male broilers than in female (P<0.001). 3. There were no significant differences in intake, weight gain, final body weight or food-to-gain ratios between birds fed on diets differing solely in the degree of fat saturation. Broilers fed on diets containing an animal fat blend or tallow had higher abdominal fat pad weight (P<0.001) and intramuscular lipid content (P=0.0085) than those fed on diets containing sunflower oil. 4. It was concluded that dietary fat saturation affects fat accumulation in broiler chickens.

Adipose Tissue↗