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1.
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
2.
Groups of rats were fed from weaning with diets containing 5% by wt of hydrogenated coconut oil (HCO), safflower oil, or a
concentrate of ethyl elaidate and linolelaidate (TRANS) as the sole source of dietary fat. Fatty acid composition of the lipid
classes from serum, liver, heart, and kidney was determined, and the serum lecithin: cholesterol acyl transferase (LCAT) activities
were assayed for each animal. Serum LCAT activity was increased by both the HCO and TRANS diets in the early stages of the
development of an essential fatty acid (EFA) deficiency but was suppressed in the animals of the TRANS group as they became
older. The HCO and TRANS groups exhibited changes in tissue lipid fatty acid composition, as well as reduced growth, characteristic
of an EFA deficiency. Conversion of oleic acid to eicosatrienoic acid was impaired in the animals fed the TRANS diet, greatly
increasing the octadecenoic acid content of the tissue lipids at the expense of eicosatrienoic acid. The TRANS diet also suppressed
incorporation of eicosatrienoic acid into cholesteryl esters of tissue and serum, indicating that, when fed as the sole source
of unsaturated fat,trans fatty acids influenced the metabolism of unsaturated fatty acids and cholesterol. 相似文献
3.
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
4.
Metabolic responses to essential fatty acid-deficiency in rats include an increased rate of triglyceride secretion into the
plasma, a large reduction in the HDL1 plasma lipoprotein concentration, and increased concentrations of liver triacylglycerols and cholesteryl esters. Because
of differences in the types of EFA-deficient diets used, it is not clear whether these responses were solely due to the absence
of EFA from the diet or whether saturated fat, or differences in acyl group chain length in this fat, might be responsible.
Therefore, we fed rats diets differing only in amounts and kinds of fat, and measured triacylglycerol secretion rates and
liver concentrations of triacylglycerols and cholesteryl esters, for comparison with our earlier measurements of plasma high
density lipoprotein subpopulations in rats fed exactly the same diets. The purified diets contained either no fat, 5% by weight
hydrogenated coconut oil, 5% hydrogenated cottonseed oil, or each of these three diets supplemented with 1% safflower oil,
or 5% corn oil. We also fed some rats a nonpurified stock diet for comparison with literature reports. The present results
indicate that the metabolic responses to essential fatty acid deficiency described above are definitely due to essential fatty
acid-deficiency and not to the presence or chain length of acyl groups in saturated fat in the diet.
Presented in part at the May 1984 meeting of the American Oil Chemists' Society in Dallas, Texas. 相似文献
5.
Nutritional evaluation of a medium-chain triglyceride (MCT) preparation, containing about 75% octanoic acid and 25% decanoic
acid, was carried out in short- and long-term experiments in rats. A casein diet containing 19.6% MCT and 2.5% safflower oil,
the latter to supply essential fatty acids, was compared with similar diets containing conventional dietary fats. Data obtained
in a 47-week study showed that the MCT diet supported normal growth and development. At autopsy, carcass protein and ash levels,
vital organ weights and composition were similar to those in rats fed conventional fats. Histological study showed that intestinal
and liver sections were normal after 47 weeks on the MCT-containing diet. In general, rats fed MCT had slightly lower growth
rates and caloric efficiency values, less carcass fat and smaller epididymal fat pads than animals fed conventional dietary
fats. Little C8 and C10 were found in depot fat. The MCT diet also supported normal reproducton, as indicated by litter size and number. During lactation
the volume of milk secreted by the rats receiving the MCT diet was smaller and contained a lower level of fat than that secreted
by the rats receiving an oleo oil diet, resulting in slower gains in weight in the MCT group. After weaning, growth of the
rats fed MCT compared favorably with that attained by the animals on the diet containing oleo oil. 相似文献
6.
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
7.
Studies are reported on the relative effects of in vivo oxidation produced by diets devoid of vitamin E and the consumption
of oxidized fat. Rats of the Sprague-Dawley strain were raised from weaning on a sucrose-casein diet containing minerals and
vitamins in the required amounts, supplemented with 10% of safflower oil, menhaden oil, hydrogenated coconut oil or no fat.
Animals of ca. 185 g of the group fed the 10% safflower oil were then switched for 4 weeks to safflower or menhaden oil-supplemented
diets that were allowed to oxidize by exposing them to room temperature in the dark for 2–8 days. For comparison with effects
of in vivo oxidation, animals were raised from weaning on similar fresh diets devoid of vitamin E. Consumption of oxidized
fat was accompanied by loss of weight, effects on the size of the organs, changes in triglyceride levels and production of
TBA-reacting substances in the tissues. There was no effect on the induced swelling of liver mitochondria or the susceptibility
of erythrocytes to hemolysis in these animals. Growth was also suppressed in the animals fed the vitamin E-free diets, and
in vivo oxidation in these animals produced marked effects on the membrane properties of erythrocytes and liver mitochondria. 相似文献
8.
R. B. Alfin-Slater H. Hansen R. S. Morris D. Melnick 《Journal of the American Oil Chemists' Society》1969,46(10):563-568
In general, the native tocopherols in polyunsaturated vegetable oils such as cottonseed oil, corn oil and their lightly hydrogenated
products include sufficient vitamin E for growth, reproduction, lactation and normal lipid metabolism in the rat. The administration
of vitamin E to animals fed diets deficient in essential fatty acids (e.g., a hydrogenated coconut oil or a fat-free diet)
does not stimulate growth or reproductive performance per se, although testes development in the male rats is improved and
some improvement in lipid metabolism is also noted. Hemolysis of the erythrocytes in vitro by hydrogen peroxide is increased
in animals on diets rich (30%) in polyunsaturated vegetable oils or on diets providing no essential fatty acids at all. However,
the conditions of the in vitro hemolysis test are not related to those in vivo and the in vitro test is not a measure of erythrocyte
fragility. In addition, the in vitro hemolysis test does not necessarily reflect plasma tocopherol levels nor an abnormal
nutritional state as a result of subsistence on high linoleate, low tocopherol intake, but rather measures the susceptibility
to oxidation of a labile biological substrate and indicates the effective balance between potentially oxidizable lipids (polyunsaturates)
in the stroma of the red blood cell and the antioxidant present (tocopherol or vitamin E). The labile lipid substrate may
be either of exogenous origin (diet) or may be formed endogenously through tissue synthesis (as a result of an essential fatty
acid deficiency). It is concluded that the in vitro hemolysis test may not be a valid indicator of vitamin E nutriture unless
it is used in conjunction with other nutritional tests. 相似文献
9.
Studies are reported of the effect of an essential fatty acid (EFA) deficiency on synthesis of triglycerides (TG) and phospholipids
(PL) and secretion of these compounds by livers of male Sprague-Dawley rats. Animals were fed a semipurified diet containing
corn oil or hydrogenated coconut oil (HCO) as the sole source of fat or no fat from weaning to 20 weeks of age. Liver function
of the animals in each group was compared by an isolated liver perfusion technique with perfusates containing erythrocytes
and linoleate, and in vivo experiments via tail vein injection of palmitate-3H. Perfusion experiments showed that an EFA deficiency reduced the ability of the liver to secrete TG and PL. Accumulation
of TG in the liver and its diminished secretion into the blood of EFA deficient animals were demonstrated by in vivo experiments
with palmitate-3H. The rate of conversion of linoleate to arachidonate and synthesis of PL was greater in livers of EFA deficient rats than
in the control, corn oil fed animals. The results suggest a relationship of EFA metabolism to lipid transport.
One of five papers to be published from the Symposium “Lipid Transport” presented at the AOCS Meeting, New Orleans, April
1970. 相似文献
10.
Semipurified diets containing different lipids were fed to rat dams during lactation and subsequently to their pups for 33
weeks post-weaning. Some rats within each group were exposed to oxygen at hyperbaric pressure (OHP). Lipid peroxide levels
were lower in lungs of rats fed 7% hydrogenated coconut oil or 10% butter as compared with their controls, fed 7% corn oil
or 10% safflower oil, respectively. Exposure to OHP increased lung peroxide levels. This increase varied with the type of
fat in the diet. Studies of the fatty acid composition indicate that lipid peroxide levels generally increased with an increase
in the levels of 18∶2 in lung total lipids. The results suggest that the type of dietary lipid may alter the susceptibility
of the animal to pulmonary oxygen toxicity. 相似文献
11.
Effect of an essential fatty acid (EFA) deficiency in the rat on the incorporation of leucine-14C and glucosamine-14C into serum and liver protein are reported. Weanling male rats of the Sprague-Dawley strain were raised on a fat-free diet
for 10–12 weeks and then switched to diets supplemented with 10% corn oil or 10% hydrogenated coconut oil. Leucine-14C or glucosamine-14C was injected into the tail veins of the animals of each group. At selected intervals up to 120 min after the injections,
the animals were sacrificed and the radioactivity of the liver and serum proteins was measured. The levels of triglyceride
(TG) in the serum and the liver were also determined. Less radio-activity was incorporated into the serum β-lipoprotein (β-LP)
fraction of the hydrogenated coconut oil than the corn oil fed animals injected with leucine-14C, but no differences were observed in the incorporation of radioactivity into the liver protein and both albumin and globulin
fractions of the serum of these groups of animals. In the similar experiments with glucosamine-14C less radioactivity was incorporated into the β-LP fraction of the serum and into the smooth endoplasmic reticulum of the
liver in the hydrogenated coconut oil (EFA deficient) than the corn oil fed animals. Time course studies also indicated that
less radioactivity was incorporated into the β-LP fraction than into the albumin and globulin fractions of the serum of the
hydrogenated coconut oil group. These findings suggest that an EFA deficiency results in an impairment of the synthesis or
release of lipoprotein. 相似文献
12.
Studies are reported on the effects of dietarytrans fatty acids on the 6- and 9-acyl desaturase activities in the liver microsomes of rats fed essential fatty acid (EFA)-deficient
and non-FFA-deficient diets. In experiment I, weanling male rats were fed a semisynthetic diet with either 10% safflower oil
(SAF) or 10% hydrogenated coconut oil (HCO). At the age of one year, half of the dietary fat was replaced by a supplement
containing elaidate, linolelaidate andcis,trans-trans,cis-18∶2 (TRANS) for 12 weeks. In experiment II, male rats which were kept from weaning on a 10% SAF diet for one year received
one of the following fat supplements for a 12-week period: 10% HCO, 9% HCO+1% TRANS, or 5% HCO+5% TRANS. Feeding TRANS depressed
the 6-desaturase activity in the liver microsomes, especially in the EFA-deficient rats (HCO+TRANS group of experiment I).
Unlike the 6-deaturase activity, the 9-desaturase activity was not inhibited by the dietarytrans fatty acids and was significantly stimulated in the non-EFA-deficient rats (SAF+TRANS group of experiment I and HCO+TRANS
groups of experiment II). This was evidenced by incubation reactions and by comparisons of fatty acid consumptions and microsomal
fatty acid levels, showing extra biosynthesis of 16∶1 and 18∶1 when TRANS was fed. The biosynthesis of essential (n−6) fatty
acids was depressed by the TRANS supplement in EFA-deficient as well as in non-EFA-deficient animals. 相似文献
13.
Weanling male Wistar rats were fed for five weeks on standard rat chow (23 g fat/kg diet) or one of four synthetic diets with
butterfat, coconut oil, corn oil, or fish oil as the main lipid source (100 g fat/kg diet). In all diets, 10% of the fat was
provided as corn oil to prevent essential fatty acid deficiency. Significant differences were observed in the saturated, monounsaturated,
and polyunsaturated fatty acid composition, and in the ratio of cholesterol to phospholipid, in the hepatocyte membranes.
The fluidity of hepatocyte plasma membranes was assessed using the fluorescence recovery after photobleaching technique and
steady-state fluorescence anisotropy of diphenylhexatriene. No significant differences were found in the fluidity of plasma
membranes between animals on the different fat diets, despite diet-induced changes in their fatty acid composition. However,
the proportion of lipid free to diffuse in the plasma membrane varied with diet, being significantly greater (P<0.05) in animals fed chow (63.7%), coconut oil (61.5%), and butterfat (57.6%) diets than in those fed the corn oil (47.3%)
diet. Animals fed fish oil showed an intermediate (50.0%) proportion of lipid free to diffuse. The data support the hypothesis
that dietary lipids can change both the chemical composition and lateral organization (lipid domain structure) of rat hepatocyte
plasma membranes. 相似文献
14.
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
15.
Nanna Philipson Brandorff 《Lipids》1980,15(4):276-278
During pregnancy and lactation, female rats were fed diets containing either 28% partially hydrogenated marine oil (28MO),
2% arachis oil (2AO), or no fat (FF). Milk lipid composition was examined by gas chromatographic analysis of the gastric content
of 10-day-old suckling pups. An increase to 45% in the milk content of long chain monoenoic acids, 18∶1, 20∶1 and 22∶1, reflects
the fatty acid composition of the marine oil. Milk fatty acids of medium chain length comprised 6%, 31% and 24% of total fatty
acids in the (28MO), (2AO) and (FF) groups, respectively, suggesting that a high-fat diet (28MO) inhibits the lipid synthetic
activity of mammary glands. The amount of dienoic C18-acids (6%) in the group fed (28MO) containing no essential fatty acids (EFA) was similar to the amount of 18∶2 in the group
receiving a low-fat, EFA-rich diet (2AO). However, only half the dienoic acid from the milk of the (28MO)-fed animals was
linoleic acid, which was most likely mobilized from fat depots. 相似文献
16.
Omega-3 fatty acids influence the function of the intestinal brush border membrane. For example, the omega-3 fatty acid eicosapentaenoic
acid (20∶5ω3) has an antiabsorptive effect on jejunal uptake of glucose. This study was undertaken to determine whether the
effect of feeding α-linolenic acid (18∶3ω3) or EPA plus docosahexaenoic acid (22∶6ω3) on intestinal absorption of nutrients
was influenced by the major source of dietary lipid, hydrogenated beef tallow or safflower oil. Thein vitro intestinal uptake of glucose, fatty acids and cholesterol was examined in rats fed isocaloric diets for 2 weeks: beef tallow,
beef tallow + linolenic acid, beef tallow + eicosapentaenoic acid/docosahexaenoic acid, safflower oil, safflower oil + linolenic
acid, or safflower oil + eicosapentaenic acid/docosahexaenoic acid. Eicosapentaenoic acid/docosahexaenoic acid reduced jejunal
uptake of 10 and 20 mM glucose only when fed with beef tallow, and not when fed with safflower oil. Linolenic acid had no
effect on glucose uptake, regardless of whether it was fed with beef tallow or safflower oil. The jejunal uptake a long-chain
fatty acids (18∶0, 18∶2ω6, 18∶3ω3, 20∶4ω6, 20∶5ω3 and 22∶6ω3) and cholesterol was lower in salfflower oil than with beef tallow.
When eicosapentaenoic acid/docosahexaenoic acid was given with beef tallow (but not with safflower oil), there was lower uptake
of 18∶0, 20∶5ω3 and cholesterol. The demonstration of the inhibitory effect of linolenic acid or eicosapentaenoic acid/docosahexaenoic
acid on cholesterol uptake required the feeding of a saturated fatty acid diet (beef tallow). These changes in uptake were
not explained by differences in the animals’ food intake, body weight gain or intestinal weight. Feeding safflower oil was
associated with an approximately 25% increase in the jejunal and ileal mucosal surface area, but this increase was prevented
by combining linolenic acid or eicosapentaenoic acid/docosahexaenoic acid with safflower oil. Different inhibitory patterns
were observed when mixtures of fatty acids were present together in the incubation medium, rather than in the diet: for example,
when 18∶0 was in the incubation medium with 20∶4ω6, the uptake of 20∶4ω6 was reduced, whereas the uptake was unaffected by
18∶2ω6 or 20∶5ω3. Thus, (1) the inhibitory effect of eicosapentaenoic acid/docosahexaenoic acid on jejunal uptake of glucose,
fatty acids and cholesterol was influenced by the major dietary lipid, saturated (beef tallow) or polyunsaturated fatty acid
(safflower oil); and (2) different omega-3 fatty acids (linolenic acid versus eicosapentaenoic acid/docosahexaenoic acid)
have a variable influence on the intestinal absorption of nutrients. 相似文献
17.
Effects of dietarytrans acids on the interconversion of linoleic acid was studied using the liver microsomal fraction of rats fed a semipurified
diet containing fat supplements of safflower oil (SAFF), hydrogenated coconut oil (HCO) at 5 and 20% levels or a 5% level
of a supplement containing 50.3% linolelaidic and 24.3% elaidic acids devoid ofcis,cis-linoleic acid (TRANS). Growth rate was suppressed to a greater extent with the animals fed the 20% than the 5% level of the
HCO-supplemented diets and still further by the TRANS diet compared to the groups fed the SAFF diets. Food intake was greater
in the groups fed the HCO than the SAFF-supplemented diets, demonstrating the marked effect of an essential fatty acid (EFA)
deficiency on feed efficiency. In contrast to an EFA deficiency produced by the HCO supplement, which stimulated the in vitro
liver microsomal biosynthesis of arachidonic acid, diets containing the TRANS supplement exacerabated the EFA deficiency and
depressed 6-desaturase activity of the liver microsomal fraction. The liver microsomal fraction of the animals receiving this
supplement also was more sensitive to fatty acid inhibition of the desaturation of linoleic acid than those obtained from
animals fed either the SAFF or HCO diets. It is suggested that dietarytrans acids alter the physical properties of the 6-desaturase enzyme system, suppressing its activity, which increases the saturation
of the tissue lipids and, in turn, the requirement for EFA or polyunsaturated fatty acids. 相似文献
18.
The fate of an oral dose of [4-14C] cholesterol given to rats grown on diets with 20% safflower oil or 20% hydrogenated coconut oil was determined by analysis
of digestive tract, feces and tissues. The pattern of isotope distribution did not support the view that rats fed a saturated
fat absorb less cholesterol than those fed an unsaturated fat. Fasted animals growth on the diet with 5% of these two fats
and beef fallow showed no clear difference in the amount of digitonin-peecipitable sterol in their intestines. A shorter transit
time for intestinal contents was observed with the saturated fat groups. It is concluded that neither absorption of cholesterol
from the gut nor secretion of β-hydroxy sterol into the gut accounts for the hypocholesterolemic effect of polyunsaturated
fat.
Journal Paper No. 4951 AES, Purdue University. 相似文献
19.
In previous studies, zinc-deficient rats force-fed a diet with coconut oil as the major dietary fat developed a fatty liver,
whereas zinc-deficient rats force-fed a diet with linseed oil did not. The present study was conducted to elucidate the reason
for this phenomenon. In a bifactorial experiment, rats were fed zinc-adequate or zinc-deficient diets containing either a
mixture of coconut oil (70 g/kg) and safflower oil (10 g/kg) (“coconut oil diet”) or linseed oil (80 g/kg) (“linseed oil diet”)
as a source of dietary fat, and activities of lipogenic and glycolytic enzymes in liver were determined. In order to ensure
adequate food intake, all the rats were force-fed. Zinc-deficient rats on the coconut oil diet developed a fatty liver, characterized
by elevated levels of triglycerides with saturated and monounsaturated fatty acids. These rats also had markedly elevated
activities of the lipogenic enzymes acetyl-CoA carboxylase, fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH),
6-phosphogluconate dehydrogenase (6PGDH), and citrate cleavage enzyme, whereas activities of malic enzyme and glycolytic enzymes
were not different compared with zinc-adequate rats on the coconut oil diet. In contrast, rats receiving the linseed oil diet
had similar triglyceride concentrations regardless of zinc status, and activities of lipogenic enzymes and glycolytic enzymes
were not different between the two groups. Zinc-deficient rats fed either type of dietary fat exhibited statistically significant
correlations between activities of FAS, G6PDH, 6PGDH and concentrations of saturated and monounsaturated fatty acids in liver.
The concentrations of serum lipids were elevated in zinc-deficient rats fed either type of dietary fat. These results demonstrate
that fatty liver in zinc-deficient rats on the coconut oil diet is caused by elevated activities of lipogenic enzymes, and
not by disturbed lipid secretion from liver. Dietary linseed oil prevents both the elevation of lipogenic enzyme activity
and fatty liver in zinc-deficient rats. 相似文献
20.
The effect of various dietary fats on membrane lipid composition, fatty acid profiles and membrane-bound enzyme activities
of rat cardiac sarcolemma was assessed. Four groups of male weanling Charles Foster Young rats were fed diets containing 20%
of groundnut, coconut, safflower or mustard oil for 16 weeks. Cardiac sarcolemma was prepared from each group and the activities
of Na+,K+-ATPase, 5′-nucleotidase, Ca2+-ATPase and acetylcholinesterase were examined. ATPase activities were similar in all groups except the one fed coconut oil,
which had the highest activities. Acetylcholinesterase activity was also similar in all the groups, however, it was significantly
higher in the group fed mustard oil. No significant changes were observed among the groups in 5′-nucleotidase activity, in
the cholesterol-to-phospholipid molar ratio and in sialic acid content. The coconut, safflower and mustard oil diets significantly
increased cholesterol and phospholipid contents and the lipid-to-protein ratio of cardiac sarcolemma as compared to feeding
the groundnut oil diet. The fatty acid composition of membrane lipids was quite different among the various groups, reflecting
the type of dietary fat given. The total unsaturated-to-saturated fatty acid ratio was not different among the various groups;
however, the levels of some major fatty acids such as palmitic (16∶0), oleic (18∶1) and linoleic (18∶2) acids were significantly
different. Cardiac sarcolemma of the group fed safflower oil had the highest polyunsaturated fatty acid content. The results
suggest that dietary fats induce changes not only in the fatty acid composition of the component lipids but also in the activities
of sarcolemmal enzymes involved in the regulation of cardiac function. 相似文献