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1.
Male and female weanling rats were fed diets containing 2 or 42% of calories as corn oil or 40% as beef tallow plus 2% as
corn oil until they were 12 or 18 weeks of age. Incorporation of C14-acetate into lipids of serum and liver and concentration of lipids in serum, liver, and carcass at the end of these periods
were determined.
Net synthesis of noncholesterol lipid was repressed by changing the diet from 2% to 42% of calories from either dietary fat
in both sexes and at both ages. Cholesterol net synthesis was enhanced 29-fold in males and 22-fold in females fed 42% corn
oil compared to 2% corn oil to the age of 12 weeks. It was enhanced only 2.6-fold for males and 3.4-fold for females by 40%
beef tallow plus 2% corn oil. At 18 weeks of age cholesterol synthesis in males fed 42% corn oil was 7.3 and in females 9.1
times the value for those fed 2% corn oil. At this age the values for rats fed 40% beef tallow plus 2% corn oil were 1.2 and
3.7 times those for 2% corn oil fed rats of the respective sexes. 相似文献
2.
A line of mice was developed which exhibited spontaneous obesity when fed commercial laboratory ration low in fat content.
Obese mice were compared to a nonobese related line to determine whether energy source in the diet would affect onset of obesity.
Experimental diets-beef tallow (38% of calories as beef fat and 2% as corn oil), corn oil (40% corn oil) or low-fat (2% corn
oil)-were instituted ad libitum at the time of weaning. When the mice reached 6 months of age, lipogenesis was investigated
by injecting intravenously3H2O and glucose-U-14C.3H2O and glucose-U-14C incorporation into fatty acids of fed mice was greater for obese than for lean mice. Fatty acid synthesis was inhibited
by high-fat diets compared to low-fat diet in both lines. Of the 2 high-fat diets, the corn oil diet inhibited fatty acid
synthesis about twice as much as beef tallow diet. There was no line effect on tritium incorporation into cholesterol. Cholesterol
synthesis from glucose-U-14C was greater in obese than lean mice. Diets had no effect on tritium and glucose-U-14C incorporation into cholesterol. Fasting reduced fatty acid synthesis in all mice, but total body fatty acid synthesis was
not affected by lines or dietary treatment under fasted conditions. These data suggest that degree of lipogenesis, in part,
explains obesity. A failure of inhibition of lipogenesis or an enhanced efficiency in fat deposition by feeding beef tallow
compared to corn oil diet may explain the fact that lean mice fed the beef tallow diet tended to be more obese that lean mice
fed corn oil or low-fat diets. 相似文献
3.
Ethyl-14C-acetoacetate was used to trace oxidation and metabolism of acetoacetate when rats were fed a high fat diet (80% of total
calories from beef tallow or corn oil, carbohydrate free), a high carbohydrate diet (2% corn oil) or a high carbohydrate diet
with restriction of calories to one half of ad lib. consumption for two weeks. The rate of expiration of14CO2 in all groups of animals did not differ significantly and was not related to plasma concentration of acetoacetate. The high
fat diets slightly enhanced the oxidation of acetoacetate to14CO2 over a 3 hr period compared to other diets. Incorporation of acetoacetate into fatty acids did not differ significantly among
groups. Rats fed the high carbohydrate diet ad lib. incorporated into liver cholesterol more acetoacetate than did any other
group, but dietary unsaturated fat resulted in greater incorporation of acetoacetate into cholesterol than saturated fat.
High calorie and high beef tallow groups were ketonemic but the low concentration of plasma acetoacetate in rats fed a high
corn oil diet indicates that unsaturated fatty acids are not ketogenic. The data show that utilization of acetoacetate is
not significantly reduced in a ketonemic condition and support the premise that overproduction of ketone bodies is the cause
of ketonemia. Rats appeared to be normal during the two-week period when no carbohydrate was included in the diet.
Presented at the AOCS Meeting, Chicago, October, 1967. 相似文献
4.
Groups of male and female rats were fed diets containing (calorie basis) 2% corn oil (low-fat, LF), 42% corn oil (CO) or 2%
corn oil plus 40% beef tallow (BT) for 2 weeks. Then rats of each sex and diet group were given an intraperitoneal injection
of14C-acetate,- stearate- oleate or linoleate. Acetate incorporation into cholesterol and rate of oxidation of each fatty acid
were determined. Specific activity of cholesterol was higher in females than males, higher with 40% lipid in the diet than
with 2% corn oil and higher for CO than BT. Linoleate was oxidized more rapidly than oleate which exceeded stearate. An index
of dietary lipid oxidation was computed based on fatty acid oxidation rate, per cent of each fatty acid in the diet and per
cent of lipid calories in the diet. Serum cholesterol-14C was found to be proportional to dietary lipid oxidation index. 相似文献
5.
Jacqueline Dupont 《Journal of the American Oil Chemists' Society》1965,42(11):903-907
Young adult female rats were fed diets containing 2% of calories from corn oil plus 20, 40, 60 or 80% of calories as beef
tallow or diets containing 2% corn oil and the calorie allowance restricted to 80, 60, 40 or 20% of ad libitum consumption.
Incorporation of C14-acetate into cholesterol and total fat was determined as an indication of rate of synthesis.
As dietary fat was increased there was a linear increase in cholesterol radioactivity, as measured in serum, liver and carcass.
As calories were decreased there were small but significant increases in cholesterol radioactivity. There was a highly significant
decrease in incorporation of acetate into total fat as dietary fat increased, and a decrease in total fat radioactivity when
calorie intake was restricted. The differences in rate of cholesterol biosynthesis were not accompanied by differences in
total quantity of cholesterol. The conclusion reached was that utilization of fat for energy results in accelerated cholesterol
biosynthesis.
Presented in part at the annual meeting of the Federation of American Societies for Experimental Biology, Chicago, 1964. 相似文献
6.
Male Wistar rats were fed for 4 wk on diets containing 2% oxidized corn oil. Liver tissue was then studied to determine the
effect of feeding peroxidized oil on lipogenic enzymes. Although substances which reacted with thiobarbituric acid increased
in liver microsomes and mitochondria with increasing peroxide values of the dietary corn oil fed, the activities of glucose-6-phosphate
dehydrogenase, malic enzyme and acetyl-CoA carboxylase in liver were unchanged. However, when rats were fed for 2 wk on diets
containing 10% fat, of which 0.5, 5 or 10% was unoxidized corn oil and the remainder was hydrogenated beef tallow filler,
the lipogenic enzyme activities and also the liver triglyceride levels were observed to decrease with increasing amounts of
dietary corn oil. Therefore, although a synthetic diet containing corn oil was easy to oxidize spontaneously, the reductions
of lipogenic enzymes in rats fed the diet would not have been caused by lipid peroxides but by unsaturated fatty acids themselves. 相似文献
7.
This study was designed to examine the effects of dietary n−3 and n−6 polyunsaturated fatty acids (PUFA) on postprandial lipid
levels and fatty acid composition of hepatic membranes. Male Sprague-Dawley rats were trained for a 3−h feeding protocol and
fed one of five semipurified diets: one fat-free diet or one of four diets supplemented with 10% (by weight) each of corn
oil, beef tallow, perilla oil, and fish oil. Two separate experiments were performed, 4-wk long-term and 4-d short-term feeding
models, to compare the effects of feeding periods. Postprandial plasma lipid was affected by dietary fats. Triacylglycerol
(TG) and total cholesterol levels were decreased in rats fed perilla oil and fish oil diets compared with corn oil and beef
tallow diets. Hepatic TG and total cholesterol levels were also reduced by fish oil and perilla oil diets. Fatty acid composition
of hepatic microsomal fraction reflected dietary fatty acids and their metabolic conversion. The major fatty acids of rats
fed the beef tallow diet were palmitic, stearic, and oleic. Similarly, linoleic acid (LA) and arachidonic acid in the corn
oil group, α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) in the perilla oil group, and palmitic acid and docosahexaenoic
acid (DHA) in the fish oil group were detected in high proportions. Both long- and short-term feeding experiments showed similar
results. In addition, microsomal DHA content was negatively correlated with plasma lipid levels. Hepatic lipid levels were
also negatively correlated with EPA and DHA contents. These results suggest that n−3 ALA has more of a hypolipidemic effect
than n−6 LA and that the hypolipidemic effect of n−3 PUFA may be partly related to the increase of EPA and DHA in hepatic
membrane. 相似文献
8.
Male weanling rats were fed semi-synthetic diets high in saturated fat (beef tallow) vs high in linoleic acid (safflower oil)
with or without high levels of α-linolenic acid (linseed oil) for a period of 28 days. The effect of feeding these diets on
cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding linseed oil with beef tallow
or safflower oil had no significant effect on serum levels of cholesterol. Serum cholesterol concentration was higher in animals
fed the safflower oil diet than in animals fed the beef tallow diet without linseed oil. Feeding linseed oil lowered the cholesterol
content in liver tissue for all dietary treatments tested. Consumption of linseed oil reduced the arachidonic acid content
with concomitant increase in linoleic acid in serum and liver lipid fractions only when fed in combination with beef tallow,
but not when fed with safflower oil. Similarly, ω3 fatty acids (18∶3ω3, 20∶5ω3, 22∶5ω3, 22∶6ω3) replaced ω6 fatty acids (20∶4ω6,
22∶4ω6) in serum and liver lipid fractions to a greater extent when linseed oil was fed with beef tallow than with safflower
oil. The results suggest that the dietary ratio of linoleic acid to saturated fatty acids or of 18∶3ω3 to 18∶2ω6 may be important
to determine the cholesterol and arachidonic acid lowering effect of dietary α-linolenic acid. 相似文献
9.
Our objective was to determine the relative rates ofin vivo triglyceride (TG) secretion and the composition of very low density lipoproteins (VLDL) in rats fed different dietary saturated
fats. Male Sprague-Dawley rats (150–200 g) were fed diets containing 16% corn oil, or 14% butterfat, 14% beef tallow, 14%
olive oil, or 14% coconut oil plus 2% corn oil for 5 wk. Changes in plasma TG specific radioactivity were determined in individual,
unanesthetized fasted rats after injection of 100 μCi [2-3H]glycerol. Nonlinear regression analysis using a 2-compartment model was used to determine the fractional rate constant for
TG turnover in plasma. The plasma TG pool was 33–40% larger with beef tallow than with corn, olive or coconut oil feeding
(p<0.05), and 20% larger with beef tallow than with butterfat feeding. The rate of TG secretion into plasma (mg/min/100 g
body weight) was 60% higher in animals fed beef tallow than corn or coconut oil (p<0.05) and 26–33% higher in animals fed
beef tallow than olive oil or butterfat. Differences in VLDL composition (% wt) were also noted. Our data suggest that greater
TG secretion is the primary factor contributing to the larger TG pool with ingestion of beef tallow relative to butterfat,
corn or coconut oil. These results suggest that different dietary saturated fats have unique effects on TG metabolism in rats.
Presented in part at the 1990 meeting of the Federation of American Societies for Experimental Biology in Washington, D.C.
(see ref. 1). 相似文献
10.
Comparative effects of feeding dietary linoleic (safflower oil) and α-linolenic (linseed oil) acids on the cholesterol content
and fatty acid composition of plasma, liver, heart and epididymal fat pads of rats were examined. Animals fed hydrogenated
beef tallow were used as isocaloric controls. Plasma cholesterol concentration was lower and the cholesterol level in liver
increased in animals fed the safflower oil diet. Feeding the linseed oil diet was more effective in lowering plasma cholesterol
content and did not result in cholesterol accumulation in the liver. The cholesterol concentration in heart and the epididymal
fat pad was not affected by the type of dietary fatty acid fed. Arachidonic acid content of plasma lipids was significantly
elevated in animals fed the safflower oil diet and remained unchanged by feeding the linseed oil diet, when compared with
the isocaloric control animals fed hydrogenated beef tallow. Arachidonic acid content of liver and heart lipids was lower
in animals fed diets containing safflower oil or linseed oil. Replacement of 50% of the safflower oil in the diet with linseed
oil increased α-linolenic, docosapentaenoic and docosahexaenoic acids in plasma, liver, heart and epididymal fat pad lipids.
These results suggest that dietary 18∶2ω6 shifts cholesterol from plasma to liver pools followed by redistribution of 20∶4ω6
from tissue to plasma pools. This redistribution pattern was not apparent when 18∶3ω3 was included in the diet. 相似文献
11.
Jacqueline Dupont 《Lipids》1970,5(11):908-914
Female rats (200 g) were fed a nutritionally adequate diet containing 1% by weight of corn oil (low-fat, LF), 21% of corn
oil (CO) or 20% of beef tallow plus 1% of corn oil (BT) for two weeks. Food was removed for 8–12 hr, then each rat was refed
for 1 hr. Each rat was injected ip with Na-3H-acetate and U-14C-Na-palmitate, (P),-oleate (O) or-linoleate (L). Expired CO2 was collected for 2 hr. Liver, heart and serum were obtained for analysis of total lipid14C and3H and cholesterol14C and3H. Oxidation of L was twice as great as O or P when the LF diet was fed. CO and BT diets doubled oxidation of O to equal L,
and increased oxidation of P, 50%. In liver and serum P was retained to a greater extent than O or L on BT and CO diets. Incorporation
of acetate into total lipid was highest on LF diet and reduced by feeding either CO or BT. Incorporation of acetate into cholesterol
was greater when BT or CO was fed than for LF.14C was incorporated into cholesterol in such small amounts that it was barely detectable and could not be counted accurately.
Conclusions are that (a) dietary fat affects rate of oxidation of uniformly labeled palmitate and oleate, but not linoleate,
(b) acetate is a more ready precursor to cholesterol than is fatty acid carbon, and (c) the acetate incorporated into cholesterol
when polyunsaturated fat is fed is not derived directly from fatty acid carbon. The failure of incorporation of fatty acid
carbon into cholesterol within 2 hr of administration opens the question of compartmentation of acetate as to its metabolic
source.
Colorado Agricultural Experiment Station Scientific Series Paper No. 1510. 相似文献
12.
Gisela Runge H. Steinhart E. J. Schwarz M. Kirchgeßner 《European Journal of Lipid Science and Technology》1987,89(10):389-393
A two-factorial study in which different types of fat (beef tallow, fish oil, corn oil, linseed oil) at an equal proportion of 12% but with varied α-tocopheryl acetate additions (A: 80 mg/B: 500 mg/kg diet) were fed, was carried out with 200 carp (Cyprinus carpio L.). The carp in the control groups received a 12% greater hydratable cornstarch proportion instead of the fat addition. A total of 26 fatty acids were determined, of which the decanoic, docosanoic and cis-11-octadecenoic acid were demonstrated for the first time in carp. The different fat or carbohydrate additions influenced the fatty acid composition of the edible portion (muscle and skin) significantly. Analogous to the fat in the feed the greatest quantity of long-chain, polyunsaturated fatty acids was found in the fish oil groups; feed groups with corn oil contained approximately 35% linoleic acid and feed groups with linseed oil approximately 32% linolenic acid (ω3). In contrast the groups with hydratable cornstarch and beef tallow were characterized by the high portion of oleic acid. The influence of the varied α-tocopheryl acetate additions was small overall. By means of the two-factorial variation of analysis, effects of the treatment was only shown for a few fatty acids (14: 0,18: 1ω7,20: 1ω9). On the basis of the resulting interactions between fat type and α-tocopheryl acetate addition, ist was indicated that predominantly for the more highly unsaturated fatty acids of the ω3 and ω6 series, the fatty acid pattern was not totally independent of the α-tocopheryl acetate content of the feed. 相似文献
13.
Dietary fat and colon cancer: Animal model studies 总被引:9,自引:0,他引:9
Bandaru S. Reddy 《Lipids》1992,27(10):807-813
Since it was first suggested that high dietary fat is a risk factor in colon cancer, there have been several studies to test
this hypothesis. Epidemiologic studies suggested a positive association between dietary fat and colon cancer. Laboratory animal
model studies demonstrated that not only the amount of rat, but also types of fat differing in fatty acid composition are
important determining factors in colon tumor development. Chemically-induced colon tumor incidence was increased in rats fed
the semipurified diets containing 23% corn oil, safflower oil, lard or beef tallow (high-fat) as compared to those fed 5%
corn oil, safflower oil, lard or beef tallow diets (low-fat). Diets containing 23% conconut oil, olive oil or fish oil, or
high-fat diets containing varying levels oftrans fat, had no colon tumor-enhancing effect compared to their respective low fat diets. The stage at which the effect of dietary
fat is exerted appears to be mostly during the post-initiation phase of colon carcinogenesis. Lack of a colon tumor enhancing
effect of dietary fish oil is observed both during the initiation and postinitiation phases. The mechanisms by which various
dietary fats increase colon carcinogenesis are not fully understood. In most instances, however, the high-fat diet appears
to enhance tumorigenesis through elevation of agents, such as secondary bile acids, that act as promoters of tumor development.
Lack of colon tumor promotion by dietary fish oil andtrans fat appears to be mediated through their effect on mucosal ornithine decarboxylase activity, colonic secondary bile acids
and/or prostaglandin synthesis.
Based on a paper presented at the Symposium on Lipids in Cancer held at the AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
14.
Injections of [24-14C] chenodeoxycholate and3H-cholate were made by heart puncture into 300 g male rats that bore T-cannulas in their bile ducts. The animals had been
raised on diet A, containing glucose, cholesterol and cholate, or diet B, containing sucrose and cholesterol; each of the
diets contained 5% safflower oil or 5% beef tallow as variables. From analysis of bile samples collected from the T at intervals
over a 5 day period, it was observed that the safflower oil group fed diet B had a 17% shorter cholate half-life, a 29% larger
cholate pool size and 52% higher rate of cholate synthesis than those fed beef tallow in the same diet. The safflower group
fed diet A also had a larger cholate pool size, but synthesis and half-life were obscured by cholate feeding. Chenodeoxycholate
turnover data were not obtainable because the decay curves were bimodal for all treatments and hence did not conform to a
simple pool model. It is concluded that dietary safflower oil causes more rapid formation of cholate than does dietary beef
tallow in the cholesterol-fed rat.
Journal Paper No. 4952 AES, Purdue University. 相似文献
15.
The in vivo fatty acid synthesis rate, selected enzyme activities and fatty acid composition of rat white adipose tissue from
animals fed semisynthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then
refed a fat-free (FF) diet for 48 hr. They were then divided into three groups. One group was continued on the FF diet for
48 hr. Another group was fed a diet containing 44% of calories from corn oil (CO). The final group was fed a diet containing
44% of calories from completely hydrogenated soybean oil (HSO). The animals on the FF diet had a marked increase in adipose
tissue fatty acid synthesis during the 96-hr feeding peroid (as measured by3H incorporation into adipose fatty acids). Addition of either CO or HSO to the diets did not significantly inhibit fatty acid
synthesis in dorsal or epididymal adipose tissue. The activities of the enzymes' fatty acid synthetase, ATP-citrate lyase
and glucose-6-phosphate dehydrogenase increased on the FF diet and generally were not inhibited significantly by the addition
of either fat to the diets. Linoleic acid was the major polyunsaturated fatty acid (ca. 22%) in adipose tissue. Monounsaturated
fatty acids (palmitoleic, oleic,cis-vaccenic) made up ca 38% of the total adipose fatty acids, while saturated fatty acids accounted for about 32% (myristic,
palmitic and stearic). White adipose tissue in mature male rats was a major depot for n−3 fatty acids. There were differences
in the fatty acid composition of epididymal and dorsal adipose tissue, particularly in their content of long chain, polyunsaturated
fatty acids with epididymal tissue containing more of these compounds than dorsal fat. The fatty acid composition of the white
adipose tissue did not change significantly during fasting or 96 hr of refeeding the FF diets. The addition of HSO to the
diet for 48 hr had little influence on the adipose tissue fatty acid composition, but the addition of CO to the diet caused
a 7% increase in the dorsal adipose tissue linoleate content (as percentage of total dorsal adipose tissue fatty acids) within
48 hr compared to animals fed the stock diet and those starved for 48 hr. The fatty acid synthesis data indicated that adipose
tissue in the rat can continue to be a source of de novo fatty acid synthesis in animals consuming high-fat diets. 相似文献
16.
The liver and plasma lipids and fatty acid composition of rats fed synthetic diets of differing fat type and content were
studied. All animals were starved for 48 hr and then refed a high carbohydrate, fat-free diet for 48 hr. They were then divided
into three groups and fed for an additional 48 hrs the following: group 1, the fat-free diet; group 2, a diet containing 44%
of calories from corn oil; and group 3, a diet containing 44% calories from completely hydrogenated soybean oil. The total
lipid concentration of the liver in the animals on the fat-free diet was elevated at 72 and 96 hr. The addition of either
saturated or unsaturated fat in the diet at 48 hr prevented this accumulation. The total phospholipid and cholesterol concentrations
of the liver were relatively uninfluenced by any diet in this study. Plasma total fatty acid concentration was elevated at
72 hr in the animals on a fat-free diet compared to those fed the stock diet, starved for 48 hr or fed the fat-containing
diets. By 96 hr, however plasma fatty acid concentrations in all groups were similar to those in animals fed only the stock
diet. The release of de novo synthesized fatty acids into plasma from the liver was strongly inhibited by dietary fat, either
saturated or polyunsaturated. With the fat-free diet there was a significant increase in the saturated and monounsaturated
fatty acids in both liver and plasma. The addition of corn oil to the diet facilitated a reversion of the fatty acid composition
in liver and plasma to that found in the animals fed the stock diet ad libitum, but saturated fat did not. No effect of diet
on the fatty acid composition of the red cells was observed during the course of this study. Exogenous saturated fatty acids,
although similar chemically to the fatty acids synthesized by the liver, may have physiological actions that differ from endogenously
synthesized fat. 相似文献
17.
The effect of diets high (15%) in saturated (beef tallow) or polyunsaturated (corn or cottonseed oil) fatty acids on the fatty
acid composition of sphingomyelin from canine erythrocytes and platelets and sphingomyelin and neutral glycosphingolipids
of swine erythrocytes was determined. Sphingolipids of platelets and erythrocytes from animals fed high levels of corn or
cottonseed oil exhibited a dramatic alteration in their fatty acid composition, most notable of which was a 50% reduction
in nervonic acid (24∶1ω9) as compared to levels observed in control or tallow fed animals. This decrease was compensated for
by a quantitatively similar increase in a C24 dienoic acid. The long chain dienoic acid was isolated by silver nitrate thin layer chromatography and determined by analysis
of its oxidation products to be Δ15, 18-tetracosadienoic acid (24∶2ω6). When the animals were fed the diets high in polyunsaturates,
the 24∶2ω6 represented 13, 20, and 9% of the sphingomyelin fatty acids from canine erythrocytes, platelets, and swine erythrocytes,
respectively, and 5% of the neutral glycosphingolipid fatty acids of swine erythrocytes. In contrast, the 24∶2ω6 represented
less than 4% of the total cellular sphingolipid fatty acids in animals fed the control or high beef tallow diets. The 24∶1ω9
in the sphingolipids of the animals fed the polyunsaturated diet was roughly equal to that of 24∶2ω6, whereas in the sphingolipids
of animals fed the control or saturated fat (beef tallow) diet, the 24∶1ω9 was twice these values. Since sphingomyelin is
a membrane component, the increase in unsaturation (24∶2ω6) in its fatty acid moiety induced by dietary polyunsaturates may
affect membrane fluidity and may alter membrane properties.
Dr. Nelson’s current affiliation is with the Lipid Metabolism Branch, Division of Heart and Vascular Diseases, National Heart,
Lung, and Blood Institute. 相似文献
18.
Lipid metabolism was studied in rats fed diets containing corn oil, coconut oil, or medium-chain triglyceride (MCT), a glyceride
mixture containing fatty acids of 8 and 10 carbons in length. The ingestion of MCT-supplemented, cholesterolfree diets depressed
plasma and liver total lipids and cholesterol as compared with corn oil-supplemented diets. In rats fed cholesterol-containing
diets, plasma cholesterol levels were not influenced by dietary MCT, but liver cholesterol levels were significantly lower
than in animals fed corn oil. In vitro cholesterol synthesis from acetate-1-14C was lower in liver slices of rats that consumed MCT than in similar preparations from corn oil-fed rats. Studies of fatty
acid carboxyl labeling from acetate-1-14C and the conversion of palmitate-1-14C to C18 acids by liver slices showed that chain-lengthening activity is greater in the liver tissue of rats fed MCT than in the liver
of animals fed corn oil. The hepatic fatty acid desaturation mechanisms, evaluated by measuring the conversion of stearate-2-14C to oleate, was also enhanced by feeding MCT.
Adipose tissue of rats fed MCT converts acetate-1-14C to fatty acids at a much faster rate than does tissue from animals fed corn oil. Evidence is presented to show that the
enhanced incorporation of acetate into fatty acids by the adipose tissue of rats fed MCT represents de novo synthesis of fatty
acids and not chain-lengthening activity. Data are also presented on the fatty acid composition of plasma, liver, and adipose
tissue lipids of rats fed the different fats under study. 相似文献
19.
Rats were fed diets high in either saturated fat (beef tallow) or α-linolenic acid (linseed oil) or eicosapentaenoic and docosahexaenoic
acids (fish oil) with or without 2% cholesterol supplementation. Consumption of linseed oil and fish oil diets for 28 days
lowered arachidonic acid content of plasma, liver and heart phospholipids. Addition of 2% cholesterol to diets containing
beef tallow or linseed oil lowered 20∶4ω6 levels but failed to reduce 20∶4ω6 levels when fed in combination with fish oil.
Feeding ω3 fatty acids lowered plasma cholesterol levels. Addition of 2% cholesterol to the beef tallow or linseed oil diet
increased plasma cholesterol concentrations but not when fish oil was fed. Feeding the fish oil diet reduced the cholesterol
content of liver, whereas feeding the linseed oil diet did not. Dietary cholesterol supplementation elevated the cholesterol
concentration in liver in the order: linseed oil > beef tallow > fish oil (8.6-, 5.5-, 2.6-fold, respectively). Feeding fish
oil and cholesterol apparently reduced 20∶4ω6 levels in plasma and tissue lipids. Fish oil accentuates the 20∶4ω6 lowering
effect of dietary cholesterol and appears to prevent accumulation of cholesterol in plasma and tissue lipids under a high
dietary load of cholesterol. 相似文献
20.
The impact of a moderate Zn deficiency on growth and plasma and liver lipids was investigated in two 4-week experiments with
male weanling rats fed fat-enriched diets. Semisynthetic, approximately isocaloric diets containing 3% soybean oil were supplemented
with either 7 or 100 mg Zn/kg diet and with 22% beef tallow (BT) or sunflower oil (SF). In Experiment 1, which compared the
dietary fat level and the fat source in a factorial design of treatments, all diets were fed ad libitum to 6 × 8 animals,
whereas intake of the high-Zn BT and SF diets was restricted in Experiment 2 (5 × 6 rats) to the level of intake of the respective
low-Zn diets. The low-Zn SF diet consistently depressed food intake and final live weights of the animals to a greater extent
than the other low-Zn diets, while intake and growth were comparable among the animals fed the high-Zn diets. The marginal
Zn deficit per se did not alter plasma triglyceride and cholesterol concentrations nor hepatic concentrations of triglyceride,
cholesterol and phospholipids. The fatty acid pattern of liver phospholipids did not indicate that chain elongation and desaturation
of fatty acids was impaired by a lack of zinc. It was concluded that dietary energy and fat intake, and fat source have a
greater effect on plasma and liver lipids than a moderate Zn deficiency. Marginally Zn-deficient diets enriched with sunflower
oil as a major energy source cause a greater growth retardation than diets rich in carbohydrates or beef tallow. 相似文献