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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.
The effect of 22∶6ω3 acid provided by dietary fish oil on the development of germinal tissue of rat testes, fatty acid composition
of lipids, and linoleic or α-linolenic acid Δ6 desaturation capacity was investigated. Results were compared to those obtained
in animals fed methyl palmitate and sunflower seed oil (linoleate). At 7 and 9 weeks of age, development of germinal tissue
of animals fed fish oil was normal. The fatty acid composition showed a decrease in 22∶5ω6 acid content and an increase in
22∶6ω3 acid in triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine. The fatty acid Δ6 desaturation capacity
of testicules microsomes was increased. It is suggested that 22∶6ω3 acid may functionally replace 22∶5ω6 acid in germinal
tissue. 相似文献
3.
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
4.
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
5.
A study was made of the influence of semisynthetic diets of low and high unsaturation on the fatty acid composition and desaturation-chain
elongation enzymatic activity of the liver microsomal fractions of male Sprague-Dawley rats of different ages. Groups of rats
were fed 5 or 20% coconut oil (CO), or a 5 or 20% mixture of corn and menhaden oils (3∶7) (CME) from weaning to 100 wk of
age. Growth rate and food consumption were measured during this period in which animals were sacrificed at 36, 57, 77 and
100 wk of age. Both the level and composition of the dietary fat supplements produced marked effects on the fatty acid composition
of the liver microsomal lipids. In general, the fatty acid composition of the microsomal fractions reflected that of the dietary
fat and was more unsaturated with the higher level of fat fed. The rate of conversion of linoleic to arachidonic acid in assays
performed in vitro with liver microsomal preparations from animals of the different groups also showed marked differences.
The 6-desaturase-chain elongation activity was higher in the 5% than 20% group and corresponded to the essential fatty acid
(EFA) status of the animals in these groups as represented by the triene-tetraene ratio of the microsomal lipid. The relationship
of the 6-desaturase activity to fatty acid composition of the microsomal lipid indicated that if varied directly with the
level of 20∶3ω9, 18∶1 and 16∶1 and was inhibited by arachidonic acid. The activity of the 6-desaturase enzyme system was lowest
in the liver microsomal fraction obtained from the animals fed the CME diets and appeared to be suppressed by the high levels
of 20∶5 and 22∶6 that accumulated in the microsomal lipid. Accordingly, the levels of arachidonic acid were lower in the microsomal
lipid of these groups than those of the corresponding CO groups in spite of a greater abundance of linoleic acid in the diet.
The data suggest that the activity of the 6-desaturase-chain elongation system is regulated by the fatty acid composition
of the microsomal lipid as influenced by the composition of the dietary fat. 相似文献
6.
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
7.
Groups of male Holtzman strain rats were fed from weanling one of the following diets: 20% hydrogenated soybean fat (20% HF),
and 20% HF plus 2%, 3% and 4% corn oil, respectively, for 20 weeks. The animals were killed, and the heart phospholipid fractions
isolated by chromatographic procedures. The levels and distribution of the docosapolyenoic acids, especially 22∶5ω3, were
compared among the animals fed the corn oil supplemented and nonsupplemented diets. Although dietary linolenate (18∶3ω3) level
was very low in the nonsupplemented diet, 22∶5ω3 accounted for 8.4% of the total fatty acids of heart total phospholipids
when this diet was fed-half the level of total eicosatetraenoic acids. The amounts of 22∶5ω3 were decreased by corn oil supplementation
of the diet and got down to the “normal” range of 2.0–2.5% at corn oil supplementation levels greater than 2%. The docosapolyenoic
acids were confined largely to the phosphatidylcholine and phosphatidylethanolamine classes of phospholipids. These findings
are discussed from the standpoint of the structural role of the phospholipids in the heart subcellular fractions. 相似文献
8.
Effects of diets high in saturated fat and cholesterol on the lipid composition of canine platelets 总被引:1,自引:0,他引:1
The phospholipid composition of platelets from dogs on various experimental diets was determined. Thyroidectomized foxhounds
were fed a control diet or the control diet supplemented with (1) beef tallow, (2) beef tallow and cholesterol, or (3) beef
tallow, cholesterol, and safflower oil for 23 weeks prior to isolation of platelets. Platelets from animals fed the control
diet contained 36.7% phosphatidylcholine (PC), 22.8% phosphatidylethanolamine (PE), 18.4% sphingomyelin (Sph), 11.8% phosphatidylserine
(PS), 6.3% phosphatidylinositol (PI), and 2.2% lysophosphatidylcholine. The PE was 77.6% in the plasmalogen form. No highly
significant changes in the phospholipid class composition resulted from the experimental diets. Cholesterol supplementation
of the diets, however, caused consistent alterations in the fatty acid compositions of the platelet phospholipids including
increases in the percentages of 18∶1ω9 (oleic acid), 18∶2ω6 (linoleic acid), and 20∶3ω6 (homo-gamma linolenic acid) and a
decrease in the percentage of 20∶4ω6 (arachidonic acid). Addition of safflower oil to the tallow-cholesterol diet partially
reversed these effects. These cholesterol-induced alterations in fatty acid composition could be due to exchange with plasma
lipids, de novo synthesis, or altered platelet metabolism. The mechanism remains to be determined.
Der. Nelson’s current affiliation is the Lipid Metabolism Branch, Division of Heart and Vascular Diseases, National Heart,
Lung, and Blood Institute. 相似文献
9.
Methyl linolenate 18∶3ω3 and docosahexaenoate 22∶6ω3 were incorporated in semipurified diets at several levels and fed to
trout previously maintained on a fat-free diet. After 14 weeks, the weight gain and feed conversion of the fish on each diet
were determined. The fatty acid composition of the lipid from each group of fish was analyzed by gas liquid chromatography.
Both 18∶3ω3 and 22∶6ω3 fed at the 1% level supported maximum growth of the fish. The control group, which were fed no ω3 fatty
acids, exhibited a shock syndrome, poor appetite and a very slow growth rate. Tissue fatty acid analysis revealed eicosatrienoic
acid 20∶3ω9 accumulated in the phospholipid fraction of this group. The 20∶3ω9 level was lowered when either 18∶3ω3 or 22∶6ω3
was included in the diet. Analysis showed that the dietary 18∶3ω3 was rapidly converted by the fish into 22∶6ω3 with a high
concentration in the phospholipid. However 22∶6ω3 fed to the fish remained unchanged and little or no retroconversion of this
fatty acid was observed.
Presented in part at the AOCS Meeting, Atlantic City, October 1971.
Technical paper no. 3247, Oregon Agricultural Experiment Station. 相似文献
10.
Existence of a dietary maximal level or threshold for incorporation of ω3 fatty acids into membrane phospholipids is of interest
as it may further define understanding of the dietary requirement for ω3 fatty acids. To test whether feeding increasing levels
of dietary ω3 fatty acids continues to increase membrane ω3 fatty acid content, weanling rats were fed a nutritionally adequate
semipurified diet which provided increasing amounts of C20 and C22 ω3 fatty acids, such as 20∶5ω3 and 22∶6ω3. Dietary 20∶5ω3 and 22∶6ω3 were provided by substituting a purified shark oil concentrate
of high 22∶6ω3 content for safflower oil high in 18∶2ω6. After four weeks of feeding, nuclear envelopes from four animals
in each diet group were prepared, lipid was extracted and phospholipids separated. Arachidonic acid content in membrane phosphatidylcholine,
phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine was significantly reduced by feeding increased dietary
levels of ω3 fatty acids. Decline of 20∶4ω6 level in phospholipid tended to stabilize when the dietary content of total ω3
fatty acids reached 4–5% of total fatty acids. Above this level, dietary ω3 fatty acids did not result in a further decrease
in membrane content of 20∶4nω6. Increase in membrane phospholipid content of 20∶5ω3 occurred as the dietary intake of ω3 fatty
acids increased from 1.1% to 5% of total fatty acids. A dietary ω3 fatty acid level of 2.2–3% was sufficient to result in
maximum incorporation of 22∶6ω3 into membrane phosphatidylcholine and phosphatidylethanolamine, but not into phosphatidylinositol
or phosphatidylserine. 相似文献
11.
This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing
from a typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of
saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6
women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each
group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The
VLF diet reduced both the low density lipoprotein (LDL)-and high density lipoprotein (HDL)-cholesterol levels; addition of
the monounsaturated fats and PUFA increased the HDL-cholesterol levels, whereas butter increased the cholesterol levels in
both the LDL- and HDL-fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18∶2ω6) and
eicosapentaenoic acid (20∶5ω3) and to increases in palmitoleic (16∶1), eicosatrienoic (20∶3ω6) and arachidonic acids (20∶4ω6)
in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception
of 16∶1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18∶1 and significant
decreases in all ω3 PUFA except 22∶6 compared with the usual diet. The addition of safflower oil resulted in significant increases
in 18∶2 and 20∶4ω6 and significant decreases in 18∶1, 20∶5ω3 and 22∶5ω3. These results indicate that the reduction of saturated
fat content of the diet (<6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated
fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects.
Although the VLF vegetarian diet reduced both LDL- and HDL-cholesterol levels, the long-term effects of VLF diets are unlikely
to be deteterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition
of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the
addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon
eicosanoid precursor fatty acids in the plasma. This suggests that advice on plasma lipid lowering should also take into account
the effect of the diet on the fatty acid profile of the plasma lipids. 相似文献
12.
The effect of dietary supplementation with fish oil as compared to corn oil on the lipid dynamics and calcium ATPase activity
of rat skeletal sarcoplasmic reticulum was examined. After four-week supplementation with fish oil, the levels of eicosapentaenoic
(20∶5ω3), docosapentaenoic (22∶5ω3) and docosahexaenoic (22∶6ω3) acids in the total lipids were 5.3, 5.5 and 28.1% of the
total fatty acids, respectively. In contrast, with corn oil only 22∶6 was found (8.9%). The level of these fatty acids in
phosphatidylethanolamine from the membranes of animals fed fish oil was 4.2 (20∶5), 5.4 (22∶5) and 49.1% (22∶6); and for phosphatidylcholine
it was 5.4 (20∶5), 4.6 (22∶5) and 17.4% (22∶6). Again, in corn oil fed animals, only 22∶6 was found in appreciable amounts,
namely 28.3% in phosphatidylethanolamine and 1.8% in phosphatidylcholine. The steady state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene
(DPH) was used to assess lipid order and was found to be only slightly less for membranes from animals supplemented with fish
oil (0.120) as compared to those supplemented with corn oil (0.124). The calcium ATPase was found to be unaffected by supplementation
consistent with the observed modest changes in lipid order as well as with suggestions that the enzyme is relatively insensitive
to the level of unsaturation. It could be argued that if large increases in fatty acyl polyunsaturation in mammalian cell
membranes would lead to marked alterations in bulk membrane lipid motional properties, this may not be in the interest of
preserving physiological function. The complex mixture of phospholipid molecular species present in natural membranes may
buffer against this by a type of passive adaptation, without the expenditure of metabolic energy, thus providing a homeoviscous
environment able to optimally support membrane protein function. 相似文献
13.
In order to determine to what extent maternal diet influenced the brain lipids of young rats, female rats were maintained
on diets differing in fatty acid composition. Fatty acid determinations on the total brain lipids of the young from these
dams indicated that the maternal dietary lipids influence the polyunsaturated fatty acid composition of these animals. A maternal
diet with a high linoleic-linolenic acid ratio (corn oil) resulted in lower levels of 22∶6ω3 and higher levels of 22∶5ω6 than
one with a low linoleic-linolenic acid ratio (grain). Transfer of young rats at birth to a foster mother, which was fed a
diet differing from that of the natural dam, resulted in brain polyunsaturated fatty acid patterns at weaning similar to those
of the natural young, and suckling, of the foster mother, thus indicating that the maternal diet in the immediate postnatal
period can modify the brain lipids of young rats prior to weaning. The brain lipids of young rats from dams which were fed
corn oil exhibited a marked tendency to incorporate 22∶6ω3 in the immediate postnatal period in spite of a relatively high
linoleic-linolenic acid ratio in the milk. 相似文献
14.
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
15.
Ana Maria P. Lottenberg Helena C. F. Oliveira Edna R. Nakandakare Eder C. R. Quintão 《Lipids》1992,27(5):326-330
The mechanism by which ω3 fatty acids lower plasma triacylglycerol levels was investigated. Rats were fed fish oil, olive
oil (10% fat by weight) or a nonpurified diet 4% fat by weight) for 15 days. Lipoprotein lipase was inhibited by intra-arterial
administration of Triton WR 1339 to estimate hepatic triacylglycerol output. Rats fed the olive oil diet showed a higher rate
of triacylglycerol formation than rats fed the ω3 fatty acid diet or the low-fat diet. All three groups showed identical rates
of removal from plasma of intraarterially administered artificial chylomicrons that had simultaneously been labeled with cholesteryl
[1-14C]oleate and [9,10(n)-3H]triolein. Liver radioactivity and total fat content were lowest in rats fed the fish oil diet, indicating that ω3 fatty
acids were preferentially metabolized in liver. Chylomicrons obtained from donor rats fed either fish oil containg [14C]cholesterol or olive oil containing [3H]cholesterol were removed at similar rates when infused together intraarterially into recipient animals. A slower formation
of plasma very low density lipoprotein triacylglycerols in rats fed fish oil is probably due to a faster rate of oxidation
of the fatty acid chains in the liver resulting in decreased plasma triacylglycerol concentrations. 相似文献
16.
Epidemiological and laboratory animal model studies have provided evidence that the effect of dietary fat on colon tumorigenesis
depends on the amount of fat and its composition. Because of the importance of the composition of dietary fat and of tissue
membrane fatty acid composition in tumor promotion, experiments were designed to investigate the relative effects of high
fat diets rich in ω3, ω6 and ω9 fatty acids and colon carcinogen on the phospholipid fatty acid composition of liver, colon,
small intestine, erythrocytes and blood plasma. At 6 wk of age, groups of animals were fed diets containing 5% corn oil (LFCO),
23.5% corn oil (HFCO), 23.5% olive oil (HFOO), and 20.5% fish oil plus 3% corn oil (HFFO). Two weeks later all the animals
except the vehicle-treated animals received azoxymethanes.c. once weekly for 2 wk at a dose rate of 15 mg/kg body weight. Animals were sacrificed 5 d later and liver, colon, small intestine
and erythrocytes and blood plasma were analyzed for phospholipid fatty acids. The results indicate that the phospholipid fatty
acid composition of liver, colon and small intestine of HFCO diet fed animals, were not significantly different from those
fed the LFCO diet. The levels of palmitoleic acid and linoleic acid were increased in erythrocytes and blood plasma of the
animals fed the HFCO diet compared to those fed the LFCO diet. Feeding the HFCO diet significantly increased the oleic acid
content and decreased the linoleic acid and arachidonic acid levels in various organs when compared to the HFCO diet. Animals
fed the HFFO diet showed a marked increase in eicosapentaenoic acid and docosahexaenoic acid and a decrease in linoleic acid
and arachidonic acid levels as compared to those fed the HFCO diet. The results also indicate that carcinogen treatment had
only a minimal effect on the phospholipid fatty acid composition. 相似文献
17.
We have studied the effect of various diets on the phospholipid fatty acid composition andin vitro Δ5 desaturase activity of hepatic microsomes derived either from the normal or streptozotocin-induced diabetic rat. The diets
studied were the standard rat chow diet and a basal fat-free diet supplemented either with 20 percent saturated fat, 20 percent
unsaturated fat, or 20 percent menhaden oil. Phospholipid fatty acid composition analysis revealed that the normal rat fed
the saturated fat or menhaden oil diet had significantly decreased arachidonate levels, consistent with decreased Δ5 desaturase
activities and decreased 18∶2n−6 intake. On the contrary, the unsaturated fat diet decreased dihomo-γ-linolenate and increased
arachidonate levels, without increased Δ5 desaturase activity. Streptozotocininduced diabetes resulted in decreased arachidonate
and Δ5 desaturase activity. The unsaturated fat diet fed to the diabetic rat also failed to correct this decreased Δ5 desaturase
activity. The unsaturated fatty acids in this diet also displaced a substantial amount of n−3 fatty acids in both normal and
diabetic microsomes, due to the competition between these two fatty acid families for incorporation into the membrane phospholipids.
Conversely, the menhaden oil diet fed to the normal and diabetic rats displaced n−6 fatty acids, reduced Δ5 desaturase activity,
and enhanced 22∶6n−3 incorporation into diabetic microsomes. 相似文献
18.
Partially hydrogenated marine oils containing 18∶1-, 20∶1- and 22∶1-isomers and partially hydrogenated peanut oil containing
18∶1-isomers were fed as 24–28 wt % of the diet with or without supplement of linoleic acid. Reference groups were fed peanut,
soybean, or rapeseed oils with low or high erucic acid content. Dietary monoene isomers reduced the conversion of linoleic
acid into arachidonic acid and the deposition of the latter in liver and heart phosphatidylcholine. This effect was more pronounced
for the partially hydrogenated marine oils than for the partially hydrogenated peanut oil. The content oftrans fatty acids in liver phospholipids was similar in groups fed partially hydrogenated fats. The distribution of various phospholipids
in heart and liver was unaffected by the dietary fat. The decrease in deposition of arachidonic acid in rats fed partially
hydrogenated marine oils was shown in vitro to be a consequence of lower Δ6-desaturase activity rather than an increase in
the peroxisomal β-oxidation of arachidonic acid. The lower amounts of arachidonic acid deposited may be a result of competition
in the Δ6-desaturation not only from the C22-and C20-monoenoic fatty acids originally present in the partially hydrogenated
marine oil, but also from C18- and C16-monoenes produced by peroxisomal β-oxidation of the long-chain fatty acids.
Part of this work was presented at the ISF-AOCS Congress, New York City, 1980. 相似文献
19.
The purpose of this study was to examine the influence of long-term feeding of dietary fat rich in either n−3 or n−6 fatty
acids on the availability of arachidonic acid (20∶4n−6) in major phospholipids of gastric mucosa in rats. Three groups of
male Wistar rats were fed either a standard diet, a cod liver oil-enriched diet (10% by weight), or a corn oil-enriched diet
(10% by weight) for 8 mon. Dietary cod liver oil significantly reduced the level of 20∶4n−6 in phosphatidylcholine (PC) and
in phosphatidylethanolamine (PE) of gastric mucosa. The loss of 20∶4n−6 was compensated for by eicosapentaenoic acid (20∶5n−3)
in PC, whereas the decrease in 20∶4n−6 in PE corresponded to the increase in three n−3 fatty acids: 20∶5n−3, docosapentaenoic
acid (22∶5n−3), and docosahexaenoic acid (22∶6n−3). The level of 20∶5n−3 was higher than the level of 22∶6n−3 both in PC and
PE of mucosa in rats fed cod liver oil. Diets supplemented with corn oil increased the level of 18∶2n−6 but decreased the
monoene fatty acids 16∶1 and 18∶1n−7 in PC but not in PE of gastric mucosa. The 20∶4n−6 levels of both PC and PE were markedly
reduced by dietary cod liver oil, to about one-third of control levels. Similar changes were also observed in the stomach
wall. Gastric erosions were observed in all rats exposed to restriction stress, but this form of stress induced twice the
number of erosions in rats fed fish oil compared to control rats or rats fed corn oil. We conclude that a diet rich in fish
oil altered the balance between n−6 and n−3 fatty acids in major gastric mucosal phospholipids, markedly reduced the availability
of 20∶4n−6, and increased the incidence of gastric erosions induced by restriction or emotional stress. 相似文献
20.
The metabolism of α-linolenic acid from canola oil was studied in eight normolipidemic men. The 42-day study was divided into
three periods: a 6-day pre-experimental and two 18-day experimental. Approximately 75% of the dietary fat (28% of total energy)
was provided by a mixture of fats during the pre-experimental period and either canola oil (CO) or sunflower oil (SO) during
the experimental periods. The CO and SO diets were fed in a cross-over design. The ratios of linoleic to linolenic acid were
2.6∶1 and 73.9∶1 in the CO and SO diets, respectively. Dietary fat source had an effect on plasma phospholipid fatty acids:
18∶1n−9, 18∶3n−3 and 20∶5n−3 were higher (p<0.05), and 18∶2n−6 was lower in the phosphatidylcholine fraction; 18∶1n−9 was
higher and 20∶4n−6 lower in the phosphatidyl-ethanolamine fraction; and 18∶1n−9 and 20∶5n−3 were higher and 20∶4n−6 and 22∶6n−3
were lower in the alkenylacyl-ethanolamine phospholipid fraction on the CO diet as compared to the SO diet. Consumption of
the canola oil diet resulted in higher n−3 fatty acid levels and lower n−6 fatty acid levels in plasma phospholipids than
consumption of the sunflower oil diet. 相似文献