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1.
Recently, significant differences between rats fed a casein diet and rats fed a soybean protein diet have been observed in hepatic phospholipid fatty acid patterns (Sjöblom, L., and Eklund, A.,Biochim. Biophys. Acta 1004, 187–192, 1990). The influence of these two diets on the Δ6 desaturase activity was investigated in the present study because the hepatic desaturase system is a source of unsaturated fatty acids. The rats fed a casein diet showed higher desaturase activity than those fed soybean protein when using either linoleic acid (P<0.005) or oleic acid (P<0.05) as substrates. The phosphatidylcholine fraction of hepatic microsomes showed increases in oleic acid (P<0.005) and 20∶3ω9 (P<0.001) levels as well as decreases in stearic acid (P<0.001), linoleic acid (P<0.005) and arachidonic acid (P<0.005) levels in rats which were fed casein rather than soybean protein. Similar differences between the two groups were also observed in the phosphatidylethanolamine and phosphatidylinositol fractions. These data indicate that the qualitative properties of the dietary protein source may influence the fatty acid pattern of rat hepatic microsomes by interfering with Δ6 desaturase activity. 相似文献
2.
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
3.
The effect of different fatty acids supplemented to a fat-free diet on the activity of Δ5 desaturase was studied. Fat-free
diet produces a reduction in the conversion of eicosa-8,11,14-trienoic acid to arachidonic acid. The addition of thecis-ω6 acids, linoleic, γ-linolenic or arachidonic to the diet produces an increase of eicosatrienoic acid desaturation, shifting
Δ5 desaturase activity towards the controls on a balanced diet. This reactivation is apparently produced by induction of enzyme
biosynthesis since linoleate effect was suppressed by simultaneous cycloheximide injection. On the contrary, no changes in
Δ5 desaturation activity were found when the diet was supplemented with palmitic or 9-trans,12-trans-linoleic acid. The changes on the activity of Δ5 desaturase were compared with the fatty acid composition of plasma and liver
microsomes. 相似文献
4.
The effect of very low levels of dietary long-chain n−3 fatty acids on Δ6 desaturation of linoleic acid (18∶2n−6) and α-linolenic
acid (18∶3n−3), and on Δ5 desaturation of dihomo-γ-linolenic acid (20∶3n−6), in liver microsomes and its influence on tissue
fatty acids were examined in obese and lean Zucker rats and in Wistar rats. Animals fed for 12 wk a balanced diet containing
ca. 200 mg of long-chain polyunsaturated n−3 fatty acids per 100 g of diet were compared to those fed the same amount of α-linoleic
acid. Low amounts of long-chain n−3 fatty acids greatly inhibited Δ6 desaturation of 18∶2n−6 and Δ5 desaturation of 20∶3n−6,
while Δ6 desaturation of 18∶3n−3 was not inhibited in Zucker rats and was even stimulated in Wistar rats. Inhibition of the
biosynthesis of long-chain n−6 fatty acids was reflected in a decrease in arachidonic acid (20∶4n−6) content of serum lipids
when fasting, and also in the phospholipid fatty acids of liver microsomes. On the contrary, heart and kidney phospholipids
did not develop any decrease in 20∶4n−6 during fish oil ingestion. Docosahexaenoic acid (22∶6n−3), present in the dietary
fish oil, was increased in serum lipids and in liver microsome, heart, and kidney phospholipids. 相似文献
5.
6.
Experimental Mg2+ deficiency was induced in a group of rats by feeding them a Mg2+-deficient diet for 23 days. They were pair-fed to compare with a control group of rats fed a Mg2+-sufficient diet. In the Mg2+-deficient group the plasma total cholesterol and triglyceride levels were increased while HDL-cholesterol was decreased.
In the Mg2+-deficient group the plasma level of thiobarbituric acid reacting substances (TBARS) used as a measure for lipid peroxidation
was increased. The increase was attributed to the increased cytosolic Ca2+ in Mg2+-deficiency which can cause: 1) increase of hydro and endoperoxide levels as a consequence of the increase of arachidonic
acid release and eicosanoid synthesis in Mg2+-deficiency, and 2) inhibition of the mitochondrial respiratory activity and activation of Ca2+-dependent proteases which may activate the conversion of xanthine dehydrogenase to xanthine oxidase which generates active
O2 species. In the Mg2+-deficient group, the fatty acid composition of the liver microsomes indicated a slower rate of conversion of linoleic acid
to arachidonic acid which was consistent with the decrease of Δ6 desaturase activity in liver microsomes of Mg2+-deficient rats as measuredin vitro. The decrease of Δ6 desaturase activity was attributed to the lower concentration of actual enzyme molecules as a result
of the decreased rate of protein synthesis in Mg2+-deficiency. The possible effects of the increased catecholamine release in Mg2+-deficiency are discussed. 相似文献
7.
D. L. Thompson M. D. Jellum C. T. Young 《Journal of the American Oil Chemists' Society》1973,50(12):540-542
Total oil content and fatty acid composition of germ and endosperm oil were determined on grain from three inbred lines and
one variety of corn (Zea mays L.) grown in four phytotron environments and one standard greenhouse environment during seed maturation. Pronounced differences
occurred with reversals for relative percentages of oleic and linoleic acids of germ oil for one inbred line and for the variety.
Comparative trends were generally less pronounced for two of the inbred lines. Differences among environments were less evident
for palmitic, stearic, and linolenic acids of germ oil and for the fatty acids of the endosperm oil. Total oil was lowest
for two inbred lines and the variety grown in the high temperature environment (30 C day/26 C night). The magnitude of temperature
effects on oil content and oil composition varied among the four corn genotypes.
Journal article 3961 of the North Carolina State University Agricultural Experiment Station.
ARS, USDA. 相似文献
8.
Rapidly growing neonatal mammals accrete relatively large quantities of long chain (≥C20) polyunsaturated fatty acids (LCP) in membrane phospholipids. We have examined accumulation of ω6 LCP in suckling neonatal
rat pups during the first 14 d of life when their dams received essential fatty acids in the form of triglycerides containing
linoleic acid or arachidonic acid. Dietary levels of these fatty acids were either 1 or 5% of total dietary fatty acids. The
fatty acid profile of pup stomach contents (composed solely of the dams' milk) and plasma lipids, as well as liver and brain
phospholipids, were determined. Stomach linoleic and arachidonic acid levels reflected the diet of the dams. Pup plasma and
liver arachidonic acid levels increased progressively from the group receiving 1% linoleic acid to 5% linoleic acid and from
1% arachidonic acid to 5% arachidonic acid. Interestingly, brain phosphatidylethanolamine and phosphatidylcholine arachidonic
acid levels were more stable than plasma or liver levels. These results suggest that the brain may be capable of either selective
transport of ω6 LCP or chain elongation/desaturation of linoleic acid. These data indicate that care must be exercised when
adding LCP to infant formula since widely divergent accretion rates of arachidonic acid may occur in various tissues. 相似文献
9.
Robin A. Henderson Robert G. Jensen Carol J. Lammi-Keefe Ann M. Ferris Kenneth R. Dardick 《Lipids》1992,27(11):863-869
To examine the effect of fish oil supplementation on the fatty acid (FA) composition of human milk and maternal and infant
erythrocytes, five lactating women were supplemented with 6 g of fish oil daily for 21d. Usual maternal diets contained 1,147
mg of total n−3 FA, with 120 mg from very long-chain (>C18) n−3 FA. Supplementation increased dietary levels to 3,092 mg of total n−3 FA and 2,006 mg of very long-chain n−3 FA. Milk
samples were collected daily, prior to fish oil ingestion, and at 4-h intervals on days 1, 7, 14 and 21. Milk n−3 FA content
increased within 8 h and reached steady state levels within one week. The n−6 fatty acid content decreased. Erythrocyte eicosapentaenoic
acid content increased from 0.24% to 1.4% (P<0.01) in mothers and from 0.11% to 0.70% (P<0.05) in infants. Docosapentaenoic acid increased from 1.4% to 2.2% (P<0.05) in mothers and from 0.30% to 0.78% (P<0.01) in infants. There was no significant change in docosahexaenoic acid or n−6 fatty acid content. Maternal platelet aggregation
responses were variable. No differences in milk or plasma tocopherol levels were noted.
Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
10.
María T. Mitjavila María C. Rodríguez María P. Sáiz Sergio Lloret Juan J. Moreno 《Lipids》1996,31(6):661-666
Cells from rats fed with a tripalmitin diet showed a depletion of phospholipid arachidonate and n-3 fatty acids such as eicosapentaenoic
and docosahexaenoic acids (EPA and DHA). In rats fed fish oil diet, a significant reduction in archidonic acid (AA) content
was observed whereas EPA and DHA were incorporated into membranes lipids. These changes in lipid composition of membranes
did not affect cellular adherence, phagocytic capability, or [3H]AA incorporation. However, both tripalmitin and fish oil diets induced a decrease in [3H]AA mobilization stimulated by 4β-phorbol-12-myristate 13-acetate, A23187, or opsonized-zymosan in rat peritoneal macrophages.
These results demonstrate that the antiinflammatory effects of essential fatty acids deficiency or n-3 enrichment diets may
be associated with a decreased AA mobilization in resident rat peritoneal macrophages treated with proinflammatory agents. 相似文献
11.
12.
Raymond Reiser Bernadette Stevenson Mitsu Kayama R. B. R. Choudhury D. W. Hood 《Journal of the American Oil Chemists' Society》1963,40(10):507-513
Marine and fresh water fish were depleted of tissue unsaturated fatty acids to various degrees and subsequently presented with linoleic and linolenic acids at different dietary levels, at different temperatures, with and without other dietary fat. Examination of the tissue fatty acids demonstrated that marine and fresh water fish do not differ between themselves or from other classes of animals in the following basic mechanisms of deposition and interconversions of dietary fatty acids:
- 1)The fish are readily depleted of tissue polyunsaturated fatty acids. 相似文献
13.
Effects of dietary vegetable oil on atlantic salmon hepatocyte fatty acid desaturation and liver fatty acid compositions 总被引:5,自引:0,他引:5
Fatty acyl desaturase activities, involved in the conversion of the C18 EFA 18∶2n−6 and 18∶3n−3 to the highly unsaturated fatty acids (HUFA) 20∶4n−6, 20∶5n−3, and 22∶6n−3, are known to be under
nutritional regulation. Specifically, the activity of the desaturation/elongation pathway is depressed when animals, including
fish, are fed fish oils rich in n−3 HUFA compared to animals fed, vegetable oils rich in C18 FFA. The primary aims of the present study were (i) to establish the relative importance of product inhibition (n−3 HUFA)
vs. increased substrate concentration (C18 EFA) and (ii) to determine whether 18∶2n−6 and 18∶3n−3 differ in their effects on the hepatic fatty acyl desaturation/elongation
pathway in Atlantic salmon (Salmo salar). Smolts were fed 10 experimental diets containing blends of two vegetable oils, linseed (IO), and rapeseed oil (RO), and
fish oil (FO) in a triangular mixture design for 50 wk. Fish were sampled after 32 and 50 wk, lipid and FA composition of
liver determined, fatty acyl desaturation/elongation activity estimated in hepatocytes using [1-14C]18∶3n−3 as substrate, and the data subjected to regression analyses. Dietary 18∶2n−6 was positively correlated, and n−3
HUFA negatively correlated, with lipid content of liver. Dietary 20∶5n−3 and 22∶6n−3 were positively correlated with liver
FA with a slope greater than unity suggesting relative retention and deposition of these HUFA. In contrast, dietary 18∶2n−6
and 18∶3n−3 were positively correlated with liver FA with a slope of less than unity suggesting metabolism via β-oxidation and/or desaturation/elongation. Consistent with this, fatty acyl desaturation/elongation in hepatocytes was significantly
increased by feeding diets containing vegetable oils. Dietary 20∶5n−3 and 22∶6n−3 levels were negatively correlated with hepatocyte
fatty acyl desaturation. At 32 wk, 18∶2n−6 but not 18∶3n−3 was positively correlated with hepatocyte fatty acyl desaturation,
wheres the reverse was true at 50 wk. The data indicate that both feedback inhibition through increased n−3 HUFA and decreased
C18 fatty acyl substrate concentration are probably important in determining the level of hepatocyte fatty acyl desaturation
and that 18∶2n−6 and 18∶3n−3 may differ in their effects on this pathway. 相似文献
14.
Nine healthy male volunteers were given 15 Max EPA fish oil capsules providing 2.67 g of eicosapentaenoic acid (EPA, 20∶5ω3)
and 1.72 g of docosahexaenoic acid (DHA, 22∶6ω3) daily for 3 wk. Measurements were taken at baseline, at the end of the fish-oil
period, and at 2 and 6 wk postsupplementation. The effect of fish oil on plasma lipids and the fatty acid composition of individual
platelet phospholipids was studied. In general, the proportions of 20∶5ω3 and 22∶6ω3 in platelet phosphoglycerides were substantially
increased mainly at the expense of arachidonic acid (AA, 20∶4ω6). A large and significant increase in the relative EPA content
of phosphatidylcholine (PC) (P<0.001) and phosphatidylethanolamine (PE) (P<0.001) was noted at the end of the 3 wk supplementation.
We have also shown for the first time a small but significant (P<0.001) incorporation of EPA in phosphatidylserine (PS). Incorporation
of DHA was also detected in PC, PE and PS, whereas the relative AA content of these phospholipids was significantly reduced.
Fish oil supplementation led to a significant increase of 22∶5ω3 in PS and decreases of 20∶3ω6 in PC and 22∶4ω6 in PE. Postsupplementation
measurements showed a gradual return of all fatty acids to baseline levels. The fatty acid composition of the phosphatidylinositol
(PI) fraction remained unchanged throughout the trial period. We conclude that in humans ω3 fatty acids are incorporated into
platelet membrane phospholipid subclasses with a high degree of specificity. 相似文献
15.
Deodorization of vegetable oils: Prediction of trans polyunsaturated fatty acid content 总被引:1,自引:0,他引:1
Z. Kemény K. Recseg G. Hénon K. Kővári F. Zwobada 《Journal of the American Oil Chemists' Society》2001,78(9):973-979
Kinetics of the formation of trans linoleic acid and trans linolenic acid were compared. Pilot plant-scale tests on canola oils were carried out to validate the laboratory-scale kinetic
model of geometrical isomerization of polyunsaturated fatty acids described in our earlier publication. The reliability of
the model was confirmed by statistical calculations. Formation of the individual trans linoleic and linolenic acids was studied, as well as the effect of the degree of isomerization on the distribution of the
trans fatty acid isomers. Oil samples were deodorized at temperatures from 204 to 230°C from 2 to 86 h. Results showed an increase
in the relative percentage of isomerized linolenic and linoleic acid with an increase in either the deodorization time or
the temperature. The percentage of trans linoleic acid (compared to the total) after deodorization ranged from <1 to nearly 6%, whereas the percentage of trans linolenic acid ranged from <1 to >65%. Applying this model, the researchers determined the conditions required to produce
a specially isomerized oil for a nutritional study. The practical applications of these trials are as follows: (i) the trans fatty acid level of refined oils can be predicted for given deodorization conditions, (ii) the conditions to meet increasingly
strict consumer demands concerning the trans isomer content can be calculated, and (iii) the deodorizer design can be characterized by the deviation from the theoretical
trans fatty acid content of the deodorized oil. 相似文献
16.
Tsuneo Yamane Tomomasa Suzuki Tamotsu Hoshino 《Journal of the American Oil Chemists' Society》1993,70(12):1285-1287
An attempt was made to further increase the content of n-3 polyunsaturated fatty acid (n-3 PUFA) of fish oil by lipase-catalyzed
acidolysis (reaction between fish oil and n-3 PUFA-enriched free fatty acid) without solvent. A bioreactor system was constructed
composed of a water-jacketed packed-bed column and a substrate reservoir with a circulation pipeline between the packed-bed
column and the reservoir. By keeping the temperature of the reservoir at −10°C (for the first 20 h), followed by −20°C (for
the subsequent 40 h) during the batch acidolysis, crystals of free fatty acid appeared, which were removed intermittently
by a cotton plug packed in the tip of the outlet pipe in the reservoir. The n-3 PUFA content of the triacylglycerol fraction
increased a further 10% by the reduced temperature of the reservoir.
Bioreactors for Enzymatic Reaction of Fats and Fatty Acid derivatives, Part XV. 相似文献
17.
The effect of feeding 24 to 52-days-old male rats of the Wistar strain, with beans diet deficient in sulfur-containing amino acids or supplemented with 0.3% DL-methionine and two corn oil concentrations, 2% and 20% (g/kg/diet), on the glutathione content (GSH) in liver, and on the renal gamma glutamyl transpeptidase (GGTP) (E.C.2.3.2.2) activity was studied. Results indicated that rats fed the bean diet with 2% corn oil decreased significantly the liver GSH content and GGTP renal activity. Supplementation with 0.3% methionine and/or the 20% increment of the diet corn oil, significantly stimulated the liver GSH content and the transpeptidase activity in the kidney. It is postulated that the increase of polyunsaturated fatty acids, stimulated the GGTP activity as a way of increasing substrate bioavailability for synthesis de novo of liver GSH, necessary for the protection of the hydroperoxides formation, attributed to the increment of polyunsaturated acids at cellular level. 相似文献
18.
Although the reduction of serum triacylglycerol concentrations by dietary fish oil is a well-known effect, the exact mechanism
of this effect has not been previously studied in human subjects. Therefore, the aim of this study was (i) to examine the
effect of short-term fish oil supplementation on blood concentrations of ketone bodies, free fatty acids and triacylglycerol
in healthy humans and (ii) to verify whether the observed relationships between these variables would be consistent with reduced
lipolysis and/or enhanced hepatic fatty acid oxidation after fish oil supplementation. Twenty subjects (21–23 years, normal
liver function tests) were randomly divided into two groups to supplement their usual diet with either 30 g/d of fish oil
(n=11) or olive oil (n=9). Venous blood samples were drawn after an overnight fast, before and after 1, 3 and 7 d of fish
oil/olive oil supplementation. Blood concentrations of triacylglycerol and free fatty acids decreased consistently after fish
oil supplementation; the reduction was already significant after one day of fish oil (P<0.001 for triacylglycerol andP=0.01 for free fatty acids). In contrast, neither of these blood values changed after olive oil supplementation (P>0.10). No significant changes in glucose, insulin or ketone body levels were observed in either group after supplementation.
After fish oil, but not after olive oil supplementation, the ratio of blood ketone body levels to free fatty acid levels increased
significantly (P<0.05). Furthermore, after fish oil supplementation only, free fatty acid levels were significantly correlated with levels
of ketone bodies (day 7 of supplementation: r=0.90,P<0.001) and triacylglycerol (maximum value on day 3: r=0.77,P<0.01). These findings suggest that reduced lipolysis and increased hepatic β-oxidation/ketogenesis may contribute to reduced
triacylglycerol levels after ω3 fatty acid supplementation in humans. Turnover studies are needed in order to further quantitate
these processes. 相似文献
19.
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
20.
This study was conducted to investigate the effects of dietary cyclic fatty acid monomers (CFAM), contained in heated fat from a commercial deep-fat frying operation, on rat liver enzyme activity. A partially hydrogenated soybean oil (PHSBO) used 7 d (7-DH) for frying foodstuffs, or 0.15% methylated CFAM diets was fed to male weanling rats in comparison to a control group fed a nonheated PHSBO (NH) diet in a 10-wk experiment. All diets were isocaloric with 15% fat. Animals fed either CFAM or 7-DH diets showed increased hepatic content of cytochrome (cyt.) b5 and P450 and increased activity of (E.C. 1.6.2.4) NADPH-cyt. P450 reductase in comparison to the control rats. In addition, the activities of (E.C. 2.3.1.21) carnitine palmitoyltransferase-l and (E.C. 1.1.1.42) isocitrate dehydrogenase were significantly decreased when compared to that of rats fed the NH diet. A significantly depressed activity of (E.C. 1.1.1.49) glucose 6-phosphate dehydrogenase was also observed for these animals compared to the control rats fed NH diet. Moreover, liver and microsomal proteins were significantly increased when CFAM or 7-DH diets were fed to animals in comparison to controls while liver glycogen was decreased significantly in experimental groups of rats. The results obtained in this study indicate that the CFAM in the diet from either synthetic sources or used fats increase the activity of liver enzyme systems that detoxify them. 相似文献