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1.
14C1-Linolenic acid was incorporated into lipids of hearts, livers, and carcasses of male rats. We studied the influence of diet
composition on extent and distribution of radioactivity. A CHOW diet, a purified, essential fatty acid (EFA)-deficient diet,
a purified control diet, and EFA-deficient diets with four fatty acid supplements were used. Supplements of 18∶2n−6, 20∶4n−6,
18∶3n−3, and 22∶6n−3 were given as single doses. Radioactivities in liver phosphatidyl ethanolamines (PE), phosphatidyl cholines,
and neutral lipids were measured. The distribution of radioactivity among the fatty acids in liver phospholipids was determined.
Rats on CHOW diet incorporated far less radioactivity than any other group into lipids of hearts and livers. Most of the activity
in livers was recovered as 20∶5n−3 and 22∶6n−3 in all rats. In EFA-deficient rats, the radioactivity in 22∶6n−3 of liver PE
was still increasing 36 hr after14C1-linolenic acid had been administered. The n−6 supplements (18∶2n−6 and 20∶4n−6) seemed to reduce the conversion of 20∶4n−3
to 20∶5n−3 (desaturation), whereas the n−3 supplements (18∶3n−3 and 22∶6n−3) reduced the conversion of 20∶5n−3 to 22∶5n−3
(elongation). Formation of 22∶6n−3 may be controlled by 22∶6n−3 itself at the elongation of 20∶5n−3 to 22∶5n−3. 相似文献
2.
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
3.
(n−3) and (n−6) polyunsaturated fatty acids in the phosphoglycerides of salt-secreting epithelia from two marine fish species 总被引:3,自引:0,他引:3
Fatty acid analyses were carried out on phosphoglycerides isolated from microsomal fractions of the rectal gland of the dogfish,Scyliorthinus canicula, and gills of the cod,Gadus morhua. Ratios of (n−3)/(n−6) polyunsaturated fatty acids were ca. 10 for phosphatidylcholine, (PC), phosphatidylethanolamine (PE)
and phosphatidylserine (PS) from cod gills, reflecting high concentrations of 20∶5 (n−3) and 22∶6(n−3). The ratio for phosphatidylinositol
(PI) from cod gills was 1.3, reflecting high concentrations of 20∶4(n−6) as well as (n−3) polyunsaturates. PC, PE and PS from
rectal glands all had much lower (n−3)/(n−6) ratios than in cod gills, reflecting higher concentrations of 20∶4(n−6), but
the lowest ratio was again present in PI. The latter phospholipid had high concentrations of 18∶0 in both tissues. The relative
constancy of the fatty acid composition of PI in the two salt-secreting tissues and its similarity to mammalian phospholipids
is considered to reflect its specialized role in biomembranes. 相似文献
4.
Rats were fed for two generations a purified, linolenic acid-deficient diet in which the only source of lipid was purified
methyl linoleate. This diet contained about 38 mg linolenic acid/kg diet. Control rats were given the same diet supplemented
with methyl linolenate (2,500 mg/kg diet). Male and female rats ranged in age from weanling pups to adults. Lipids were extracted
from liver, brain, kidney, spleen, heart, muscle, gastrointestinal tract, lung, ovary, testis, adrenal, plasma, erythrocytes,
retina, and adipose tissue. Fatty acids of major phospholipid classes (choline phosphoglycerides, ethanolamine phosphoglycerides,
and mixed serine phosphoglycerides plus inositol phosphoglycerides) or of total lipid extracts were measured by gas liquid
chromatography. Growth rates and organ weights were similar in control and linolenic acid-deficient rats. The major effect
of the deficiency was to lower the proportions of n−3 fatty acids, especially 22∶6 n−3, in all the organs analyzed. Docosahexaenoic
acid (22∶6 n−3) was mainly replaced by 22∶5 n−6 in deficient rats. The greatest changes in composition were found in brain,
heart, muscle, retina, and liver. 相似文献
5.
Jeannie Leonardi Elise Termine Florence Morand Raymond Lafont Henri Portugal Huguette Lafont Gilles Nalbone 《Lipids》1987,22(7):517-522
Rats were fed lard-enriched (17%) or corn oil-enriched (17%) diets and were compared with rats fed a low fat (4.5%) diet.
Cardiac protein, DNA, phospholipid (PL) and fatty acid (FA) compositions were analyzed. Neutral phospholipase A, lysophospholipase
and creatine kinase activities in the membrane and cytosolic compartments were also investigated.
No significant modification of cardiac protein, DNA nor PL was observed among the three groups. Some alterations appeared
in the FA composition. A lard-enriched diet induced a significant increase of 22∶5n−3 and 22∶6n−3 in heart phosphatidylcholine
(PC) and phosphatidylethanolamine (PE), whereas a linoleic acid-rich diet induced a specific increase of 22∶4n−6 and 22∶5n−6
in these two major PL.
Compared to rats fed the low fat diet, membrane-associated phospholipase A activity, measured by endogenous hydrolysis of
membrane PC and PE, showed a significant increase (+45%) for both PL in rats fed corn oil. However, the activity of membrane-associated
phospholipases, measured with exogenous [1-14C]dioleoyl PC, was not different among the three groups of rats. Cytoplasmic activity was decreased in rats fed corn oil,
and lysophospholipase and creatine phosphate kinase activities were not significantly affected by diet.
FA modification of the long chain n−6 FA induced by corn oil may be responsible for the observed increase in phospholipase
activity. Physiological implications are suggested in terms of membrane degradation and prostaglandin production.
Presented in part at the International Symposium on Lipid Metabolism in the Normoxic and Ischemic Heart, Rotterdam, The Netherlands,
September 1986. 相似文献
6.
Although fatty acid-binding proteins (FABP) differentially affect fatty acid uptake, nothing is known regarding their role(s)
in determining cellular phospholipid levels and phospholipid fatty acid composition. The effects of liver (L)- and intestinal
(I)-FABP expression on these parameters were determined using stably transfected L-cells. Expression of L- and I-FABP increased
cellular total phospholipid mass (nmol/mg protein) 1.7- and 1.3-fold relative to controls, respectively. L-FABP expression
increased the masses of choline glycerophospholipids (ChoGpl) 1.5-fold, phosphatidylserine (PtdSer) 5.6-fold, ethanolamine
glycerophospholipids 1.4-fold, sphingomyelin 1.7-fold, and phosphatidylinositol 2.6-fold. In contrast, I-FABP expression only
increased the masses of ChoGpl and PtdSer, 1.2- and 3.1-fold, respectively. Surprisingly, both L- and I-FABP expression increased
ethanolamine plasmalogen mass 1.6- and 1.1-fold, respectively, while choline plasmalogen mass was increased 2.3- and 1.7-fold,
respectively. The increase in phospholipid levels resulted in dramatic 48 and 33% decreases in the cholesterol-to-phospholipid
ratio in L- and I-FABP expressing cells, respectively. L-FABP expression generally increased polyunsaturated fatty acids,
primarily by increasing 20∶4n−6 and 22∶6n−3, while decreasing 18∶1n−9 and 16∶1n−7. I-FABP expression generally increased only
20∶4n−6 proportions. Hence, expression of both I- and L-FABP differentially affected phospholipid mass, class composition,
and acyl chain composition. Although both proteins enhanced phospholipid synthesis, the effect of L-FABP was much greater,
consistent with previous work suggesting that these two FABP differentially affect lipid metabolism. 相似文献
7.
The fatty acid (FA) composition and distribution in a variety of phospholipids (PL) and neutral lipids (NL) at two discrete
stages during the embryonic rat brain development were investigated. Over 96% of the FA were acylated into fetal brain PL
at embryonic day 17 after the peak of neuronal proliferation and at embryonic day 20, one day prior to delivery. Phosphatidylcholine
constituted approximately 60% of the total PL pool, phosphatidylethanolamine (PE) 30%, phosphatidylserine (PS) 6%, and phosphatidylinositol
(PI) 4%. The diacylglycerols and triacylglycerols constituted 1–2% of the fetal brain lipids. α-Linolenic acid (18∶3n−3) and
linoleic acid (18∶2n−6) were found in very low amounts in all fetal brain PL and NL. The percentage of the n−6 polyunsaturated
FA, consisting of arachidonic acid (AA), 22∶4n−6 and 22∶5n−6, remained unchanged in all the fractions, except in Pl, in which
the proportion of AA increased. The concentration of docosahexaenoic acid (DHA) increased with age in all the fractions, with
the bulk of accumulation accounted for by its increase in PE and, to a lesser extent, in PS. This finding suggests a “DHA
accretion spurt” during the last three days of pregnancy. 相似文献
8.
Docosahexaenoic acid (DHA, 22∶6n−3) is one of the major polyunsaturated fatty acids esterified predominantly in aminophospholipids
such as ethanolamine glycerophospholipid (EtnGpl) and serine glycerophospholipid (SerGpl) in the brain. Synaptosomes prepared
from rats fed an n−3 fatty acid-deficient safflower oil (Saf) diet had significantly decreased 22∶6n−3 content with a compensatory
increased 22∶5n−6 content when compared with rats fed an n−3 fatty acid-sufficient perilla oil (Per) diet. When the Saf group
was shifted to a diet supplemented with safflower oil plus 22∶6n−3 (Saf+DHA) after weaning, 22∶6n−3 content was found to be
restored to the level of the Per group. The uptake of [3H]ethanolamine and its conversion to [3H]EtnGpl did not differ significantly among the three dietary groups, whereas the formation of [3H]lysoEtnGpl from [3H]ethanolamine was significantly lower in the Saf group than in the other groups. The uptake of [3H]serine, its incorporation into [3H]SerGpl, and the conversion into [3H]EtnGpl by decarboxylation of [3H]SerGpl did not differ among the three dietary groups. The observed decrease in lysoEtnGpl formation associated with a reduction
of 22∶6n−3 content in rat brain synaptosomes by n−3 fatty acid deprivation may provide a clue to reveal biochemical bases
for the dietary fatty acids-behavior link. 相似文献
9.
ROC-1 cells are a hybrid of C−6 rat glioma and rat oligodendroglia cells. Biochemically these cells resemble the oligodendroglia
parent, but their lipid composition is unknown. The phospholipid composition in mole % was: cardiolipin, 1.0; phosphatidylglycerol,
1.2; ethanolamine glycerophospholipids, 27.6; phosphatidylinositol, 5.8; lysophosphatidylethanolamine, 0.8; phosphatidylserine,
5.6; choline glycerophospholipids, 43.7; sphingomyelin, 13.7; phosphatidylinositol-4-monophosphate, 0.8; and lysophosphatidylcholine,
0.6. The choline and ethanolamine plasmalogens made up 7.2 and 18.4% of the total phospholipids, respectively. The phospholipid
composition reflects that of both parental cells. The cells had moderate to high levels of 20∶3n−9 indicating n−6 series fatty
acid deficiency. The phosphatidylinositol had very high 20∶3n−9 levels with a 20∶3n−9/20∶4n−6 ratio of 2.1 compared to 0.44
and 0.58 for ethanolamine glycerophospholipids (EtnGpl) and choline glycerophospholipids (ChoGpl) respectively. The saturated/polyenoic
fatty acid ratios were 0.40 for EtnGpl, 3.38 for ChoGpl and 1.48 for phosphatidylinositol. 相似文献
10.
Male Fischer rats were fed the AIN76A diet containing varying n−6/n−3 FA ratios using sunflower oil (SFO), soybean oil (SOY),
and SFO supplemented with EPA-50 and GLA-80 (GLA) as fat sources. Hepatocyte nodules, induced using diethylnitrosamine followed
by 2-acetylaminofluorene/partial hepatoctomy promotion, were harvested, with surrounding and respective dietary control tissues,
3 mon after partial hepatectomy. The altered growth pattern of hepatocyte nodules in rats fed SFO is associated with a distinct
lipid pattern entailing an increased concentration of PE, resulting in increased levels of 20∶4n−6. In addition, there is
an accumulation of 18∶1n−9 and 18∶2n−6 and a decrease in the end products of the n−3 metabolic pathway in PC, suggesting a
dysfunctional Δ-6-desaturase enzyme. The hepatocyte nodules of the SFO-fed rats exhibited a significantly reduced lipid peroxidation
level that was associated with an increaser in the glutathione (GSH) concentration. The low n−6/n−3 FA ratio diets significantly
decreased 20∶4n−6 in PC and PE phospholipid fractions with a concomitant increase in 20∶5n−3, 22∶5n−3, and 22∶6n−3. The resultant
changes in the 20∶4/20∶5 FA ratio and the 20∶3n−6 FA level in the case of the GLA diet suggest a reduction of prostaglandin
synthesis of the 2-series. The GLA diet also counteracted the increased level of 20∶4n−6 in PE by equalizing the nodule/surrounding
ratio. The low n−6/n−3 ratio diets significantly increased lipid peroxidation levels in hepatocyte nodules, mimicking the
level in the surrounding and control tissue while GSH was decreased. An increase in n−3 FA levels and oxidative status resulted
in a reduction in the number of glutathione-S-transferase positive foci in the liver of the GLA-fed rats. Modulation of cancer
development with low n−6/n−3 ratio diets containing specific dietary FA could be a promising tool in cancer intervention in
the liver. 相似文献
11.
Alterations in lipid composition occur in the retinal pigment epithelium and photoreceptor cells of the Royal College of Surgeons
(RCS) dystrophic rat, a model for inherited retinal degeneration. With respect to lipid composition of nonretinal tissues,
the developmental timing of lipid alterations and the incidence of dystrophy are unknown. We determined the fatty acid composition
in choline phosphoglycerides (ChoGpl) and ethanolamine phosphoglycerides (EtnGpl) in the brain, liver, and retina from dystrophic
RCS rats and from their nondystrophic congenics (controls) at the ages of 3 and 6 wk. At 3 wk, the fatty acid compositions
were specific to individual phospholipid classes without any difference between dystrophic and nondystrophic tissues. In plasma
phospholipids, there was an age-related increase in the relative contents of monounsaturated and n-3 polyunsaturated fatty
acids, with only minor differences between dystrophic and nondystrophic rats. At 6 wk, the fatty acid compositions in ChoGpl
and EtnGpl from dystrophic brain and retina were significantly different from those of nondystrophics. The effect of strain
on developmental changes in brain fatty acid composition was significant for 18∶0 and 22∶6n−3 in EtnGpl and for 16∶0, 18∶0,
18∶1n−9, and 20∶4n−6 in ChoGpl. The brain ChoGpl fatty acid composition in nondystrophic rats was similar at 6 wk to that
of normal rats, and there were almost no postweaning changes in the dystrophics. In retinal phospholipids, the effect of dystrophy
was to increase the 20∶4n−6 content in EtnGpl and to decrease 22∶6n−3 in ChoGpl. The 18∶2n−6 and 22∶6n−3 contents in dystrophic
liver ChoGpl were also significantly affected, while no difference was observed in the EtnGpl fraction. The dystrophy affected
the phospholipid fatty acid developmental changes in a tissue- and class-specific manner. Fatty acid metabolism could be selectively
altered in neural and nonneural tissues of developing dystrophic RCS rats. 相似文献
12.
On day seven of gestation, Wistar rats were assigned to a high essential fatty acid (EFA), low EFA, or a fat free diet. The
same diets were continued during lactation. On weaning, the offspring were fed the same diets as their mother. Rats were killed
at 222 days, brain capillary endothelia isolated, and total lipids extracted from the purified capillaries. The composition
of the constituent fatty acids of ethanolamine glycerophospholipid (EGP), choline glycerophospholipid (CGP), and the alk-1-eny
EGP composition from each diet is reported. A decrease in dietary EFA led to reduced proportions of total saturated acyl groups
in EGP with no change observed in the total saturated acyl groups from CGP, and an increase in monoenoic fatty acids, particularly
18∶1n−9 for each phospholipid class. The proportions of 20∶4n−6 in alk-1-enyl EGP were reduced in fat-free fed animals. In
addition, the relationship between 20∶3n−9 and 20∶4n−6 fatty acids in brain capillary endothelia were markedly increased with
a reduction in dietary fat. Low EFA and fat deficient animals showed a tendency to sequester 22∶6n−3. 相似文献
13.
Atlantic salmon post-smolts were fed diets rich in linoleic acid (sunflower oil, SO), α-linolenic acid (linseed oil, LO) or
long-chain polyunsaturated fatty acids (fish oil, FO) for a period of 12 wk. In the liver phospholipids of fish fed SO, the
levels of 18∶2n−6, 20∶2n−6, 20∶3n−6 and 20∶4n−6 were significantly elevated compared to both other treatment. In choline phospholipids
(CPL), ethanolamine phospholipids (EPL) and phosphatidylserine (PS) the levels of 22∶4n−6 and 22∶5n−6 were significantly elevated
in fish fed SO. In liver phospholipids from fish fed LO, 18∶2n−6, 20∶2n−6 and 20∶3n−6 were significantly elevated but 20∶4n−6,
22∶4n−6 and 22∶5n−6 were similar or significantly decreased compared to fish fed FO. Liver phospholipids from fish fed LO
had increased 18∶3n−3 and 20∶4n−3 compared to both other treatments while EPL and phosphatidylinositol (PI) also had increased
20∶5n−3. In fish fed LO, 22∶6n−3 was significantly reduced in CPL, PS and PI compared to fish fed FO. Broadly similar changes
occurred in gill phospholipids. Production of 12-lipoxygenase metabolites in isolated gill cells stimulated with the Ca2+-ionophore A23187 were significantly reduced in fish fed either SO or LO compared to those fed FO. However, the ratio 12-hydroxy-5,8,10,14-eicosatetraenoic
acid (12-HETE)/12-hydroxy-5,8,10,14,17-eicosapentaenoic acid (12-HEPE) was significantly elevated in stimulated gill cells
from SO-fed fish. Although mean values of thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) were increased in fish fed SO, they were not significantly different from those of the other two treatments. 相似文献
14.
The incorporation of 18∶2n−6, 18∶3n−3, 20∶4n−6 and 20∶5n−3 was greater at 10°C than at 22°C in Atlantic salmon (AS), rainbow
trout (RTG-2) and turbot (TF) cells. However, there were generally no significant differences between the amount of incorporation
of all four polyunsaturated fatty acids (PUFA) into total lipid within a cell type at either 22°C or 10°C. The distributions
of the PUFA between individual phospholipid classes at 22°C was essentially the same in AS and TF cells—with the C18 PUFA the order of incorporation in these cells was phosphatidylcholine (PC) > phosphatidylethanolamine (PE) > phosphatidic
acid/cardiolipin (PA/CL); with 20∶4n−6 the order was PE and phosphatidylinositol (PI)>PC; with 20∶5n−3, PE>PC. In RTG-2 cells
at 22°C the distributions of the C18 PUFA were similar to the other cell lines, but with 20∶4n−6 the order was PC>PI>PE, and with 20∶5n−3 it was PC>PE. At 10°C
the incorporation of C18 PUFA into PC increased and into PE and PA/CL decreased, in general, in all cell lines. Incorporation of 20∶5n−3 into PC and
PE was increased and decreased at 10°C, respectively, in AS and TF cells, whereas in RTG-2 cells the changes at 10°C were
opposite i.e., increased in PE and decreased in PC. With 20∶4n−6, incorporation into PC at 10°C was increased in all cell
lines with decreased incorporation into PI in AS and RTG-2 cells and into PE in AS and TF cells, whereas incorporation of
20∶4n−6 into PE increased in RTG-2 cells. The metabolismvia desaturation and elongation of the n−3 PUFA was greater than that of the equivalent n−6 PUFA in all cell lines, irrespective
of temperature. There was less conversion of the C18 PUFA at 10°C than at 22°C in RTG-2 and TF cells, but the conversion of 18∶3n−3 by AS cells was increased at 10°C. Temperature
had no effect on the conversion of the C20 PUFA. 相似文献
15.
Essential fatty acid (EFA)-deficient rats were fed highly purified methyl esters of docosahexaenoate (22∶6n−3), arachidonate
(20∶4n−6), alpha-linolenate (18∶3n−3) or oleate (18∶1n−9) (100 mg/day, tube fed for 3–10 days), and their plasma triacylglycerol
(TG) secretion rates were measured. Secretion rates of TG into plasma were reduced by tube-feeding 22∶6n−3, 20∶4n−6, 18∶3n−3,
but not 18∶1n−9, to EFA-deficient rats. A significant reduction occurred after feeding 22∶6n−3 for only three days. Feeding
22∶6n−3 or 18∶3n−3 to EFA-deficient rats for three days also reduced the activities of liver lipogenic enzymes and sharply
increased the proportions of 22∶6n−3 and 20∶5n−3 in liver phospholipid fractions. Mechanisms by which these EFA may reduce
lipogenesis are discussed. 相似文献
16.
The effect of supplementation with borage oil containing γ-linolenic acid (GLA, 18∶3n−6) on the levels and fattya cid compositions
of individual human platelet phospholipids was evaluated. For this purpose, male volunteers were given an average daily intake
of 5.23 g of GLA (as borage oil) for 42 days, after which the supplement was withdrawn for an additional 42-day period. No
significant differences were found in the relative amounts of the choline phospholipids (PC), ethanolamine phospholipids (PE),
phosphatidylserine (PS), phosphatidylinositol (PI), and sphingomyelin (SPH) at days 0, 22, 43, 64, and 85. However, marked
differences were observed in the fatty acid compositions of all the phospholipids including a marked, and reversible, rise
in the level of dihomo-γ-linolenic acid (DGLA, 20∶3n−6), without a significant elevation in arachidonic acid (AA, 20∶4n−6)
and decreases in n−3 polyunsaturated fatty acids. In the case of PC, a net rise in DGLA of 1.8 mol% was observed by day 22
(from 2.1 to 3.9 mol%). The DGLA/AA ratios at day 43 exhibited considerable variability across phospholipids with PC>PS>PE=PI;
the PC, PE, PS, and PI accounted for 67.6, 16.7, 12.9, and 2.6%, respectively, of the total DGLA in platelet phospholipids.
Interestingly, despite the lack of DGLA in SPH, this phospholipid exhibited a marked enrichment in nervonic acid (NA, 24∶1n−9)
from 16.2 to 24.7 mol% upon borage oil consumption. The observed alterations may represent biochemical strategies for adaptation
to dietary fatty acid modifications and the regulation of platelet membrane functioning. 相似文献
17.
Dietary deficiency of essential fatty acids of the n−3 and n−6 series is known to promote a compensatory increase in polyenoic
fatty acids of the n−9 series in the lipids of mammalian tissues. In the present study long-chain n−9 polyenes were found
to be normal components of the epididymis and especially of sperm isolated from that tissue, in healthy, well-fed, fertile
rats maintained on essential fatty acid-sufficient diets. The n−9 polyenes occurred in large concentrations in the choline
glycerophospholipids (CGP), the major phospholipid class of spermatozoa in epididymalcauda, and were highly concentrated in plasmenylcholine, the major subclass of CGP. The uncommon polyene 22∶4n−9 was found in the
highest proportion, followed in order of relative abundance by 22∶3n−9, 20∶3n−9 and 24∶4n−9. These polyenes were probably
derived from oleate (18∶1n−9) in much the same way as long-chain polyenes of the n−6 and n−3 series are derived from linoleate
(18∶2n−6) and linolenate (18∶3n−3), respectively. 相似文献
18.
Klaus Eder 《Lipids》1999,34(7):717-725
This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly
the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either
fresh oil or thermally treated oil (150°C, 6d). The dietary fats used were markedly different for lipid peroxidation products
(peroxide value: 94.5 vs. 3.1 meq O2/kg; thiobarbituric acid-reactive substances: 230 vs. 7 μmol/kg) but were equalized for their fatty acid composition by using
different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with dl-α-tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study
the effect of the oxidized oil on the desaturation of α-linolenic acid. During the whole period, all the rats were fed identical
quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil.
Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats
fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced
food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total
lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were
calculated. Rats fed the oxidized oil had reduced ratios of 20∶4n−6/18∶2n−6, 20∶5n−3/18∶3n−3, 20∶4n−6/20∶3n−6, and 22∶6n−3/22∶5n−3
in liver phospholipids and reduced ratios of 20∶4n−6/18∶2n−6, 22∶5n−3/18∶3n−3, and 22∶6n−3/18∶3n−3 in heart phospholipids.
Those results suggest a reduced rate of desaturation of linoleic acid and α-linolenic acid by microsomal Δ4-, Δ5-, and Δ6-desaturases.
Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty
acids and total saturated fatty acids, suggesting a reduced Δ9-desaturation. Besides those effects, the study observed a slightly
increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma,
and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized
oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance. 相似文献
19.
Adequate accumulation of polyunsaturated essential fatty acids, in particular docosahexaenoic acid (22∶6n−3), into membrane
phospholipids is critical for optimal fetal brain development. This process is maximal during the period of rapid neurite
outgrowth, neuritogenesis, which precedes the major growth phase, myelination. There is no information about differential
changes during gestation to individual brain phospholipid molecular species which contain 22∶6n−3. Such details of brain development
would be concealed by total fatty acid analysis of isolated phospholipid classes. We have detailed phosphatidylcholine (PC)
and phosphatidylethanolamine (PE) molecular species compositions in developing fetal guinea pig brain. Total brain PC concentration
increased substantially between 40 and 68 (term) d of gestation, corresponding to myelination, while PE increased in a biphasic
manner between 25–35 d, which was coincident with onset of neuritogenesis, and 40–68 d. Fetal brain development was accompanied
by complex changes in the concentration of individual phospholipid molecular species. During early gestation (25–40 d) 22∶6n−3
was enriched in both PC and PEsn−1 16∶0 molecular species. However, between 40 d and term there was no further increase in brain PC 22∶6n−3 content, while
brain PE was significantly enriched in both PE 18∶1/22∶6 and PE18∶0/22∶6. We hypothesize that accumulation of 22∶6n−3 intosn−1 18∶1 and 18∶0 species represents establishment of a 22∶6n−3-containing membrane PE pool which may be turned over more slowly
thansn−1 16∶0 species. Identification of specific changes in membrane phospholipids which are associated with defined events in
brain development may provide a basis for assigning functional roles to individual molecular species. 相似文献
20.
The distribution of D5-22∶6n−3 following ingestion of a pulse of D5-18∶3n−3 was measured quantitatively by GC-negative chemical ionization MS in lipid classes from liver, cecal mucosa, and
brain from rainbow trout to further our understanding of the processes determining accretion and turnover of 22∶6n−3 in fish.
The accretion of D5-22∶6n−3 was expressed in two ways, as percent enrichment and as ng D5-22∶6n−3/μg 22∶6n−3/mg D5-18∶3n−3 eaten. In cecal mucosa at 2 d post-dose, PC was the most enriched lipid class followed by PE and then TAG. Enrichment
fell in all lipid classes in cecal mucosa from 2 to 7 d post-dose of D5-18∶3n−3. In liver, PC was also the most enriched lipid class at 2 d, but in this tissue all lipid classes were more enriched
in D5-22∶6n−3 by 7 d. When expressed in terms of the 22∶6n−3 content of the different lipid classes, TAG became relatively less
important in cecal mucosa and more important in liver. Over a time course of 3 to 35 d, the percent enrichment of D5-22∶6n−3 in liver peaked at 7 d in PC, PE, PS, and PI and fell rapidly in TAG from 3 d. PC from liver was the most enriched
lipid class at 3 and 7 d, and thereafter PE was the most enriched lipid class. However, TAG had the highest specific activity
at all times except 7 d. In brain, the enrichment of D5-22∶6n−3 was very low in all lipid classes at 3 d and increased progressively to 35 d with PC and PE similarly enriched. TAG
from brain had the highest specific activity at all times. This study is the first to present quantitative information on
rates of accretion and depletion of newly synthesized 22∶6n−3 into the main lipid classes of fish tissues. 相似文献