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1.
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
2.
The growth rate of a human mammary carcinoma, MX-1, was significantly reduced in athymic “nude” mice fed fish oil. Tumors
from the fish oil-fed animals also showed a greater sensitivity to two anti-neoplastic agents, mitomycin C and doxorubicin.
Mitochondria were isolated from control livers, host livers and tumors from fish oil-and corn oil-fed animals, and increased
levels of 20∶5n−3 and 22∶6n−3 were found in mitochondrial lipids in all three tissues from the fish oil-fed animals. To investigate
the effect of dietary n−3 fatty acids on lipid metabolism, the activity of the acyl-CoA:carnitine acyltransferase and three
acyl-CoA desaturases were measured. Carnitine acyltransferase activity toward all four acyl-CoA substrates tested was markedly
increased in mitochondria from liver by feeding fish oil. In mitochondria from tumors, feeding fish oil resulted in an increased
activity toward only 18∶3n−3. These data suggest that fish oil may induce an increase in the oxidation of fatty acids. The
Δ9-desaturase activity was decreased in microsomes from liver and tumor from fish oil-fed animals. However, both the Δ6 and Δ5 desaturases were increased in tumor and in control liver as a result of feeding fish oil. The Δ5 desaturase was not altered in microsomes from the host animals. The effect of fish oil on the Δ5 and Δ6 desaturases may involve alterations to metabolism of specific polyunsaturated fatty acids especially in the tumor tissue. 相似文献
3.
The aim of the present study was to investigate the influence of partially hydrogenated vegetable and marine oils on membrane
composition and function of liver microsomes and platelets with particular reference to the metabolism of linoleic acid and
the production of arachidonic acid metabolites. Four groups of male weanling rats were fed linoleic acid supplemented diets
containing 20% (w/w) of partially hydrogenated low erucic acid rapeseed oil (HLRSO), partially hydrogenated herring oil (HHO),
olive oil (OO) and trierucin + triolein (TE) for 10 weeks. An additional two groups were fed partially hydrogenated low erucic
acid rapeseed oil and partially hydrogenated herring oil without linoleic acid supplementation (HLRSO- and HHO-, respectively).
Substantial amounts oftrans fatty acids were incorporated into liver microsomes (12.6% in group HLRSO) and platelets (7.0% in group HLRSO-). This incorporation
was not dependent on the dietary linoleic acid level. Hepatic microsomal Δ5-desaturase activity was significantly increased after HLRSO feeding compared to OO feeding. Δ6-Desaturase activity did not vary in the linoleic acid supplemented groups. Both Δ5- and Δ6-desaturase activities were significantly increased in groups without linoleic acid supplementation.
Docosenoic acid was incorporated into platelet phospholipids in contrast to liver microsomes. In the platelet, docosenoic
acid seemed to have a special preference for phosphatidylserine. Very small amounts were incorporated into platelet phosphatidylinositol.
Feeding diets HLRSO, HHO and OO did not influence rat platelet cyclooxygenase or 12-lipoxygenase activity. Platelets from
rats fed TE, however, produced significantly less 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) than platelets from
rats fed OO. Feeding of HLRSO- and HHO- resulted in a significantly diminished production of the arachidonic acid metabolites
12-HETE, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 6-keto-prostaglandin F1α in stimulated platelets and aorta. Thus, high dietary levels oftrans isomers of monoenoic acids do not interfere with platelet cyclooxygenase or lipoxygenase activity provided sufficient amounts
of linoleic acid are available. 相似文献
4.
Male Sprague Dawley rats were fed semipurified diets containing 20% fat for 15 weeks. The dietary fats were corn oil, soybean
oil, palm oil, palm olein and palm stearin. No differences in the body and organ weights of rats fed the various diets were
evident. Plasma cholesterol levels of rats fed soybean oil were significantly lower than those of rats fed corn oil, palm
oil, palm olein or palm stearin. Significant differences between the plasma cholesterol content of rats fed corn oil and rats
fed the three palm oils were not evident. HDL cholesterol was raised in rats fed the three palm oil diets compared to the
rats fed either corn oil or soybean oil. The cholesterol-phospholipid molar ratio of rat platelets was not influenced by the
dietary fat type. The formation of 6-keto-PGF1α was significantly enhanced in palm oil-fed rats compared to all other dietary treatments. Fatty acid compositional changes
in the plasma cholesterol esters and plasma triglycerides were diet regulated with significant differences between rats fed
the polyunsaturated corn and soybean oil compared to the three palm oils. 相似文献
5.
Male weanling rats were fed vitamin E-deficient and vitamin E-supplemented diets containing 5% corn oil or cod-liver oil for
16 weeks, after which their adipose tissue lipids were extracted and analyzed in a nitrogen atmosphere for carbonyl compounds
and fatty acids.
The vitamin E-deficient cod-liver oil-fed rats, exhibiting incisor depigmentation and darkened adipose tissue, yielded lipids
which had a lower iodine value, contained less polyunsaturated fatty acids, and contained more carbonyl compounds, particularly
alkanals and alk-2-enals, than the lipids from the animals fed the vitamin E-supplemented cod-liver oil diet. The tissues
of the vitamin E-deficient corn oil-fed rats contained less linoleate and more monocarbonyl compounds than those of the vitamin
E-supplemented corn oil-fed animals.
The results indicate that vitamin E protection is necessary for the incorporation of C20 and C22 fatty acids into the tissues from the diet and that in the deficiency of vitamin E, a low level of autoxidation occurs in
the tissues. 相似文献
6.
Lennart Svensson 《Lipids》1983,18(3):171-178
The influence of dietary partially hydrogenated marine oils on distribution of phospholipid fatty acids in rat liver microsomes
was studied with particular reference to the metabolism of linoleic acid. Five groups of weanling rats were fed diets containing
20% (w/w) peanut oil (PO), partially hydrogenated peanut oil (HPO), partially hydrogenated Norwegian capelin oil (HCO), partially
hydrogenated herring oil (HHO), and rapeseed oil (RSO) for 10 weeks. The partially hydrogenated oils were supplemented with
linoleic acid corresponding to 4.6 cal % in the diets. Accumulation of linoleic acid and reduced amount of total linoleic
acid metabolites were observed in liver microsomal phospholipids from rats fed partially hydrogenated oils as compared to
PO feeding. The most striking effects on the distribution of ω6-polyunsaturated fatty acids was obtained after feeding HHO,
a marine oil with a moderate content oftrans fatty acids in comparison with HPO but rich in isomers of eicosenoic and docosenoic acids. Liver microsomal Δ6-as well as Δ6-desaturase activities as measured in vitro were reduced in rats kept on HHO as compared to PO dietary treatment. The results
obtained suggest that the dietary influence of partially hydrogenated marine oils on the metabolism of linoleic acid might
be better related to the intake of isomeric eicosenoic and docosenoic acids than to the total intake oftrans fatty acids. 相似文献
7.
Male rats were fed on a fat-free diet for 8 weeks and then switched to diets containing 10% hydrogenated coconut oil (HCO),
safflower oil (SFO) or evening primrose oil (EPO). Half of each group was also given 1% of cholesterol in the diet. After
5 further weeks, plama, red cell and liver fatty acids were measured in the various lipid fractions. Plasma and liver cholesterol
also were estimated. In almost all fractions and on all three diets, feeding cholesterol led to accumulation of the substrates
of desaturation reactions and to deficits of the products of these reactions. The results were consistent with inhibition
of Δ-6, Δ-5 and Δ-4 desaturation of n−6 essential fatty acids. Since the diets were deficient in n−3 fatty acids, levels were
very low but were also consistent with inhibition of desaturation. In contrast, cholesterol had relatively less consistent
effects on 20∶3n−9, suggesting that desaturation of n−9 fatty acids was less inhibited. Plasma cholesterol levels rose sharply
in the HCO and SFO groups but not at all in the EPO group. EPO contains the product of Δ-6 desaturation, 18∶3n−6, suggesting
that conversion of linoleic acid to 18∶3n−6 and possibly to further metabolites may be important for the cholesterol-lowering
effect of polyunsaturates. 相似文献
8.
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
9.
In the present study, changes in phospholipid compositions of liver microsomes, erythrocyte membranes, platelets, aorta, cardiac
muscle and brain of rats fed olive oil were compared with those of rats fed sunflower oil. Four groups of rats starting at
weaning were fed for four weeks a basal diet containing 5 or 25% olive oil or sunflower oil. We found that oleic acid was
higher and linoleic acid was lower in membrane phospholipids of olive oil fed rats compared to sunflower oil fed rats. Polyunsaturated
fatty acids of the n−3 series were markedly elevated in all tissues of rats on the olive oil diets relative to those on the
sunflower oil diets. The results are consistent with a lower linoleic/linolenic acid ratio induced by the olive oil diets,
suggesting a positive correlation between olive oil ingestion and n−3 polyunsaturated fatty acid levels in cell and tissue
lipids. The study suggests that an adequate intake of olive oil may enhance the conversion of n−3 fatty acids. 相似文献
10.
Male Sprague-Dawley rats four weeks or eight months of age were fed purified diets containing 10% fat, either as a blend of
safflower oil and palm olein (polyunsaturated fatty acids, PUFA, 34%), a blend of linseed oil and palm olein (PUFA, 33%) or
sardine oil (PUFA, 33%) for four weeks. In other trials, sterol contents were made equivalent by supplementing cholesterol
to a blend of corn oil and palm olein (PUFA, 30%) or phytosterol to sardine oil (PUFA, 30%). Fish oil was hypolipidemic in
rats of different ages, but it tended to increase liver cholesterol in adult animals and this was not improved by the addition
of phytosterol. The age-dependent increase in liver cholesterol was not duplicated in rats fed a vegetable fat blend supplemented
with cholesterol. At both ages, liver 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was lower in the sardine oil
than in the other groups. There were no significant age- or diet-related differences in the activity of liver cholesterol
7α-hydroxylase. Fecal steroid excretion was comparable in age-matched rats fed diets supplemented either with cholesterol
or phystosterol. Sardine oil reduced the Δ6-desaturase activity markedly as compared with linseed oil, and age-dependent reduction
of the desaturase activity was observed in all dietary groups examined. Thus, the results showed a specific effect of fish
oil on lipid metabolism. 相似文献
11.
The fatty acid composition of phospholipids in peritoneal exudate cells and spleen cells was assessed in five rat strains
fed four test diets of differing fatty acid composition. Distinctive patterns of fatty acids were seen in the total phospholipid
preparations in both cell types in response to the diets which contained either olive, sunflower, linseed or fish oil. In
general, similar fatty acid profiles were seen in each of the rat strains fed the same diet with the only evidence of possible
genetic (strain) variation being a relative deficiency of Δ4 desaturase in Dark Agouti rats. 相似文献
12.
To investigate the effects of dietary fat quality on synthesis and esterification of cholesterol, Syrian hamsters were fed
diets containing corn, olive, coconut or menhaden oils (10% w/w) with added cholesterol (0.1% w/w). After 3 weeks, animals
were sacrificed 90 min following IP injection of3H2O. Synthesis of free cholesterol and movement of free cholesterol into ester pools were measured from3H-uptade rate in liver and duodenum. Plasma total cholesterol and triglycerides levels were highest in coconut oil-fed animals,
whereas hepatic total cholesterol and ester levels were elevated in olive oil-fed animals, as compared with all other groups.
No diet-related differences were seen in duodenal cholesterol or total fatty acid content. In duodenum, uptake of3H per g tissue into cholesterol was greater compared with liver; however, within each tissue,3H-uptake into cholesterol was similar across groups. Notably,3H-uptake into cholesterol ester in liver was highest in menhaden oil-fed animals. These data suggest that menhaden fish oil
consumption results in enhanced movement of newly synthesized cholesterol into ester as compared with other fat types. 相似文献
13.
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
14.
The effect of corn oil, coconut oil, and medium-chain triglyceride (MCT, a glyceride mixture consisting almost exclusively
of fatty acids of 8 and 10 carbons in length) ingestion on lipid metabolism was studied in chicks. In chicks fed cholesterol-free
diets, MCT ingestion elevated plasma total lipids and cholesterol and depressed liver total lipids and cholesterol when compared
to chicks receiving the corn oil diet. As a consequence of the opposite effects of MCT ingestion on plasma and liver cholesterol
and total lipids, the plasma-liver cholesterol pool was not altered. When cholesterol was included in the diets, dietary MCT
depressed liver and plasma total lipids and cholesterol as compared with corn oil, consequently also lowered the plasmaliver
cholesterol pool.
The in vitro cholesterol and fatty acid synthesis from acetate-1-14C was higher in liver slices from chicks fed MCT than in those from chicks fed corn oil. The percentage of radioactivity from
acetate-1-14C incorporated into the carboxyl carbon of fatty acids by liver slices was not altered by MCT feeding, indicating that the
increased acetate incorporation represented de novo fatty acid synthesis. The conversion of palmitate-1-14C to C18 acids was increased in liver of chicks fed MCT, implying that fatty acid chain elongating activity was also increased. Studies
on the conversion of stearate-2-14C to mono- and di-unsaturated C18 acids showed that hepatic fatty acid desaturation activity was enhanced by MCT feeding. Data are presented on the plasma
and liver fatty acid composition of chicks fed MCT-, corn oil-, or coconut oil-supplemented diets.
The principles of laboratory animal care, as promulgated by the National Society for Medical Research, were observed. 相似文献
15.
Bertram I. Cohen Erwin H. Mosbach Nariman Ayyad Shigeo Miki Charles K. McSherry 《Lipids》1992,27(7):526-532
We tested two hypotheses, i) whether the type and the amount of fat in the diet will affect the formation of cholesterol gallstones
in the hamsters, and ii) whether palmitic acid, a major fatty acid component of butterfat, can act as a potentiator of cholesterol
cholelithiasis in the hamster. Young, male golden Syrian hamsters (Sasco) were fed a semipurified diet containing casein,
corn starch, cellulose and cholesterol (0.3%) to which various types and amounts of fat (butterfat, olive oil, menhaden oil,
corn oil) were added. All diets contained 2% corn oil to supply essential fatty acids to the growing hamsters. No deaths or
illness occurred during the experiment. Animals fed the semipurified diet plus 4% butterfat (group 1) had a gallstone incidence
of 63%. Replacement of butterfat with either olive oil, corn oil or menhaden oil prevented the formation of cholesterol gallstones
entirely (groups 2–4). When total butterfat was increased from 4% to 8% (group 8), the incidence of cholesterol gallstones
increased to 80%. Substitution of 4% olive oil (group 5), corn oil (group 6), or menhaden oil (group 7) for the additional
4% butterfat significantly reduced gallstones to 35%, 45% and 30%, respectively. The replacement of 4% butterfat with 1.2%
palmitic acid gave the highest incidence of cholesterol gallstones (95%). These results suggest that butterfat (and one of
its components, palmitic acid) intensifies gallstone formation in this model whereas mono- and polyunsaturated fats act as
inhibitors of cholesterol cholelithiasis. A fatty acid, possibly palmitic acid, appears to act as lithogen in our model. 相似文献
16.
The effect of dietary n−3 fatty acids on prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) levels in rat salivary glands and gingiva was examined in two separate nutritional studies. In the first set of experiments,
two groups of male weanling Sprague-Dawley rats were fed semipurified diets containing 10% corn oil (control group) or 10%
menhaden oil (experimental group). Rats were killed after 8 wk on the diets; the fatty acid composition of total phospholipids
and the concentrations of PGE2 and its precursor, arachidonic acid, were measured in gingiva and submandibular salivary glands (SMSG). Dietary n−3 fatty
acids were incorporated into the tissue phospholipids. Arachidonic acid levels were reduced by 56% in gingiva and SMSG of
rats fed menhaden oil compared with the control rats fed the diet containing corn oil. The concentrations of PGE2 in SMSG and gingiva of rats fed the diet containing menhaden oil were reduced by 74% and 83%, respectively. In a subsequent
nutritional study, we tested whether the diet-induced reduction in tissue arachidonic acid levels would also result in a corresponding
decrease in LTC4 production. Three groups of rats were fed diets containing 5% corn oil (group 1), 4% ethyl ester concentrate of n−3 fatty
acids plus 1% corn oil (group 2), or 5% ethyl ester concentrate of n−3 fatty acids (group 3). After 6 wk of feeding, gingiva
and SMSG were analyzed for arachidonic acid content andin vitro production of LTC4. Arachidonic acid content of total phospholipids was about 60% lower in gingiva and 69% lower in SMSG of rats fed the ethyl
ester concentrate of n−3 fatty acids (groups 2 and 3) than those of the control group fed the corn oil diet (group 1). Upon
incubation with calcium ionophore, gingiva and SMSG from rats fed the n−3 fatty acids rich diet produced significantly less
TLC4 than those from rats of the control group. Because PGE2 and LTC4 are believed to be important biochemical mediators of periodontal disease, one may speculate that a diet-induced reduction
in their levels may have a beneficial effect upon the course of the disease. The function of salivary glands may also be altered
because of the role of these eicosanoids in salivary secretions.
Presented in part for the Hatton Award Competition at the American Association for Dental Research Meeting, San Francisco,
California, March 15–19, 1989, and at the International Association for Dental Research Meeting, Acapulco, Mexico, April 17–21,
1991. 相似文献
17.
This study investigates the effect of various dietary saturated fatty acid (SFA) profiles on plasma lipid parameters and tissue
fatty acid composition in rats. The experiment was designed to monitor polyunsaturated fatty acids (PUFA) levels, while examining
different amounts and types of SFA. Four isocaloric diets were prepared, containing 10–11 mol% of fatty acids (FA) as linoleic
acid (LNA) and 2.5 mol% as α-linolenic acid (ALA), leading to an identical and well-balanced LNA/ALA ratio. The initial rapeseed
oil/corn oil mixture providing ALA and LNA was enriched with olive oil to prepare the olive oil diet. The butterfat diet was
supplemented with butterfat, containing short-chain SFA (C4:0–C10:0, 17 mol% of FA), lauric acid (C12:0, 3.2 mol%), myristic
acid (C14:0, 10.5 mol%) and palmitic acid (C16:0, 14.5 mol%). The saturates diet was supplemented with trilaurin, trimyristin
and tripalmitin to obtain the same level of lauric, myristic and palmitic acids as the butterfat diet, without the short-chain
SFA. The trimyristin diet was enriched with trimyristin only. The results showed that the butterfat diet contributed to specific
effects, compared to the olive oil diet and the saturates and trimyristin diets: a decrease in plasma total, LDL- and HDL-cholesterol,
higher tissue storage of ALA and LNA, and a higher level of (n-3) highly unsaturated fatty acids in some tissues. This study
supports the hypothesis that in diets with identical well-balanced LNA/ALA ratios, short chain SFA may decrease circulating
cholesterol and increase tissue polyunsaturated fatty acid content in the rat. 相似文献
18.
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
19.
Male Sprague-Dawley rats were fed for 8 weeks a corn oil (CO) diet or a hydrogenated coconut oil (HCNO) diet. These diets
were fed in the absence or presence of eicosa-5,8,11,14-tetraynoic acid (TYA). The inclusion of TYA in the HCNO diet reduced
the levels of 12∶0 and 14∶0 in the total fatty acids of livers and plasma. With either diet, the presence of TYA caused an
alteration in the fatty acid composition of these tissues so as to reduce the values of the ratios: 16∶1/16∶0, 18∶1/18∶0,
and 20∶4/18∶2. These results suggest that dietary TYA can influence the hepatic metabolism of medium chain fatty acids and
that it may inhibit the desaturase enzyme involved in the synthesis of not only 20∶4 but also of monoenoic fatty acids. 相似文献
20.
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