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1.
Michel Guichardant Helmut Traitler Danièle Spielmann Howard Sprecher Paul-André Finot 《Lipids》1993,28(4):321-324
Leukotrienes have been shown to play an important role as mediators in various disease processes, including asthma and inflammation;
thus, their synthesis is tightly regulated. The major precursor of leukotrienes is arachidonic acid (20∶4n−6). Fatty acids
which are structurally similar to 20∶4n−6, such as eicosatrienoic acid (20∶3n−6; dihomogammalinolenic acid) and eicosapentaenoic
acid (20∶5n−3; timnodonic acid) have been found to inhibit leukotriene biosynthesis. Because of the structural similarity
of octadecatetraenoic acid (18∶4n−3; stearidonic acid) with 20∶4n−6, the present study was undertaken to determine whether
stearidonic acid also exerts an inhibitory effect on the 5-lipoxygenase pathway. Human leukocytes were incubated with 18∶4n−3
(20 μM or 10 μM), 20∶5n−3 (20 μM) or 20∶3n−6 (20 μM) and subsequently stimulated with 1 μM ionophore A23187 and 20∶4n−6 (20
μM or 10 μM). The 5-lipoxygenase products were then measured by high-performance liquid chromatography. Leukotriene synthesis
was reduced by 50% with 20 μM 18∶4n−3 and by 35% with 10 μM 18∶4n−3. Formation of 5S,12S-di-hydroxy-eicosatetraenoic acid and of 5-hydroxy-eicosatetraenoic acid was decreased by 25% with 20 μM 18∶4n−3 and by 3%
with 10 μM 18∶4n−3. The inhibition observed with 20 μM 18∶4n−3 appeared to be of the same order as that observed with 20 μM
20∶5n−3; the inhibition observed with 18∶4n−3 was shown to be dosedependent. The inhibition produced by 20 μM 20∶3n−6 was
greater than that observed with either 20 μM 18∶4n−3 or with 20 μM 20∶5n−3. The results suggest that stearidonic acid, which
is found, for example, in blackcurrant seed oil (which also contains the 20∶3n−6 precursor), may play a role in suppressing
inflammation. 相似文献
2.
Kenji Ishihara Masakazu Murata Masaki Kaneniwa Hiroaki Saito Kazuki Shinohara Mari Maeda-Yamamoto Ken-ichi Kawasaki Tooru Ooizumi 《Lipids》1998,33(11):1107-1114
6,9,12,15,18,21-Tetracosahexaenoic acid (24∶6n−3) was isolated from a brittle star, Ophiura sarsi Lütken, at>95% purity to evaluate its physiological functions. The effects of 24∶6n−3 on the production of leukotriene (LT)-related
compounds such as LTB4, LTC4 and 5-hydroxyeicosatetraenoic acid, and the accumulation and release of histamine in an MC/9 mouse mast cell line were studied.
We found that 24∶6n−3 could inhibit the antigen-stimulated production of LT-related compounds as well as other n−3 polyunsaturated
fatty acids (PUFA) such as eicosapentaenoic acid (20∶5n−3) and docosahexaenoic acid (22∶6n−3), which are major n−3 PUFA in
fish oils; 24∶6n−3 was also shown to reduce the histamine content in MC/9 cells at 25 μM (27% reduction from the control),
and the effect was diminished with increase of the fatty acid concentration (up to 100 μM). These two n−3 PUFA, 20∶5n−3 and
22∶6n−3, also reduced the histamine content (16 and 20% reduction at 25 μM, respectively), whereas arachidonic acid (20∶4n−6)
increased it (18% increase at 25 μM). Spontaneous- and antigen-induced release of histamine was not influenced with these
PUFA (at 25 μM). Ionophore-stimulated release of histamine was suppressed by the PUFA (13,9,15, and 11% reduction with 20∶4n−6,
20∶5n−3, 22∶6n−3, and 24∶6n−3, respectively). The patterns of the effects of 24∶6n−3 on the synthesis of eicosanoids and histamine
content were more similar to those of 22∶6n−3 than 20∶5n−3. From these results, 24∶6n−3 can be expected to have anti-inflammatory
activity and antiallergic activities similar to those of 22∶6n−3. 相似文献
3.
Leonard AE Kelder B Bobik EG Chuang LT Lewis CJ Kopchick JJ Mukerji P Huang YS 《Lipids》2002,37(8):733-740
In mammalian cells, Sprecher has proposed that the synthesis of long-chain PUFA from the 20-carbon substrates involves two
consecutive elongation steps, a Δ6-desaturation step followed by retroconversion (Sprecher, H., Biochim. Biophys. Acta 1486, 219–231, 2000). We searched the database using the translated sequence of human elongase ELOVL5, whose encoded enzyme elongates
monounsaturated and polyunsaturated FA, as a query to identify the enzyme(s) involved in elongation of very long chain PUFA.
The database search led to the isolation of two cDNA clones from human and mouse. These clones displayed deduced amino acid
sequences that had 56.4 and 58% identity, respectively, to that of ELOVL5. The open reading frame of the human clone (ELOVL2)
encodes a 296-amino acid peptide, whereas the mouse clone (Elovl2) encodes a 292-amino acid peptide. Expression of these open
reading frames in baker's yeast, Saccharomyces cerevisiae, demonstrated that the encoded proteins were involved in the elongation of both 20-and 22-carbon long-chain PUFA, as determined
by the conversion of 20∶4n−6 to 22∶4n−6, 22∶4n−6 to 24∶4n−6, 20∶5n−3 to 22∶5n−3, and 22∶5n−3 to 24∶5n−3. The elongation activity
of the mouse Elovl2 was further demonstrated in the transformed mouse L cells incubated with long-chain (C20-and C22-carbon) n−6 and n−3 PUFA substrates by the significant increase in the levels of 24∶4n−6 and 24∶5n−3, respectively. This
report demonstrates the isolation and identification of two mammalian genes that encode very long chain PUFA specific elongation
enzymes in the Sprecher pathway for DHA synthesis. 相似文献
4.
The effect of fish oil high in docosahexaenoic acid (22∶6n−3) and low in eicosapentaenoic acid (20∶5n−3) in formula on blood
lipids and growth of full-term infants was studied. Infants were fed formula with about 15% oleic acid (18∶1), 32% linoleic
acid (18∶2n−6), 4.9% linolenic acid (18∶3n−3) and 0, 0.10 or 0.22% 22∶6n−3, or 35% 18∶1, 20% 18∶2n−6, 2.1% 18∶3n−3 and 0,
0.11 or 0.24% 22∶6n−3 from 3 d to 16 wk of age (n=16, 18, 17, 21, 17, 16, respectively). The formulae had <0.1% 20∶5n−3 and no arachidonic acid (20∶4n−6). Breast-fed infants
(n=26) were also studied. Plasma phospholipid and red blood cell (RBC) phosphatidylcholine (PC) and phosphatidylethanolamine
(PE) fatty acids were determined at 3 d and 4, 8, and 16 wk of age. These longitudinal analyses showed differences in blood
lipid 22∶6n−3 between breast-fed and formula-fed infants depending on the feeding duration. At 16 wk, infants fed formula
with 0.10, 0.11% 22∶6n−3, or 0.22% 22∶6n−3 had similar 22∶6n−3 levels in the plasma phospholipid and RBC PC and PE compared
with breast-fed infants and higher 22∶6n−3 than infants fed formula without 22∶6n−3. Formula with 0.24% 22∶6n−3, however,
resulted in higher plasma phospholipid 22∶6n−3 than in breast-fed infants at 16, but not 4 or 8 wk of age. Plasma and RBC
phospholipid 20∶4n−6 was lower in formula-fed than breast-fed infants, but no differences in growth were found. Higher blood
lipid C20 and C22 n−6 and n−3 fatty acids in infants fed formula with 20% 18∶2n−6 and 2.4% 18∶3n−3 compared with 32% 18∶2n−6 and 4.9% 18∶3n−3
show the increase in blood lipid 22∶6n−3 in response to dietary 22∶6n−3 depending on other fatty acids in the formula. 相似文献
5.
This study examined the effects of n−3 and n−6 polyunsaturated fatty acid alimentation on murine peritoneal macrophage phospholipids.
Mice were fed complete diets supplemented with either corn oil predominantly containing 18∶2n−6, borage oil containing 18∶2n−6
and 18∶3n−6, fish/corn oil mixture containing 18∶2n−6, 20∶5n−3 and 22∶6n−3, or fish/borage oil mixture containing 18∶2n−6,
18∶3n−6, 20∶5n−3 and 22∶6n−3. After two weeks, the fatty acid levels of glycerophosphoserines (GPS), glycerophosphoinositols
(GPI), sphingomyelin (SPH), and of the glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) phospholipid subclasses
were determined. We found that mouse peritoneal macrophage GPC contain primarily 1-0-alkyl-2-acyl (range for the dietary groups, 24.6–30.5 mol %) and 1,2-diacyl (63.2–67.2 mol %), and that GPE contains 1-O-alk-1-enyl-2-acyl (40.9–47.4 mol. %) and 1,2-diacyl (44.2–51.2 mol %) subclasses. In general, fish oil feeding increased
macrophage 20∶5n−3, 22∶5n−3 and 22∶6n−3 levels while simultaneously reducing 20∶4n−6 in GPS, GPI, GPE and GPC subclasses except
for 1-O-alk-1′-enyl-2-acyl GPC. Administration of 18∶3n−6 rich diets (borage and fish/borage mixture) resulted in the accumulation
of 20∶3n−6 (2-carbon elongation product of 18∶3n−6) in most phospholipids. In general, the novel combination of dietary 18∶3n−6
and n−3 PUFA produced the highest 20∶3n−6/20∶4n−6 phospholipid fatty acid ratios. This study demonstrates that marked differences
in the responses of macrophage phospholipid classes and subclasses exist following dietary manipulation. The reduction of
20∶4n−6, while simultaneously increasing 30∶3n−6 and n−3 PUFA levels, may be important in relation to the putative beneficial
effects of 20∶3n−6 and fish oil on macrophage eicosanoid and platelet activating factor (PAF) biosynthesis. 相似文献
6.
Egg yolk was enriched with α-linolenic acid (18∶3n−3) by feeding laying hens diets containing flax, canola or soybean seeds.
Fertilized eggs were incubated and the fatty acid composition of whole body, liver, plasma, brain and the cholesterol content
of plasma and liver tissue of the hatched chicks were studied. Eggs enriched with 18∶2n−6 fatty acids by feeding hens diets
containing sunflower seeds were used as the controls. Feeding flax enriched (P<0.05) egg yolk and the developing progeny with 18∶3n−3, 20∶5n−3, 22∶5n−3 and 22∶6n−3. Feeding sunflower seeds resulted in
an increase (P<0.05) of 18∶2n−6, 20∶4n−6, 22∶4n−6 and 22∶5n−6. The predominant polyunsaturated fatty acid of the brain was docosahexaenoic
acid (22∶6n−3) which was higher (P<0.05) in the flax and canola fed group. The cholesterol content of the liver tissue was lower (P<0.05) in chicks hatched from hens fed flax seeds. This study indicates that 18∶3n−3 and 18∶2n−6 in the maternal diet are
potent modulators of long-chain polyunsaturated n−3 or n−6 fatty acid and of cholesterol content in the developing progeny. 相似文献
7.
The fatty acid compositions of lipids from two species of Crinoidea and two species of Ophiuroidea have been investigated
with open-tubular gas chromatography. About 5–10% of tetracosahexaenoic acid was found in total fatty acids from all the samples,
and the structure was determined as all-cis-6,9,12,15,18,21-tetracosahexaenoic acid [24∶6(n−3)] by13C-NMR of the methyl esters and mass spectrometric analyses of the methyl esters, the pyrrolidides and the ozonolysis products.
The 24∶6(n−3) was concentrated in the polar lipids rather than neutral lipids. The n−3 hexaenoic structure suggested chain
elongation of 22∶6(n−3) as the source.
The 5-olefinic acids (5−18∶1, 5−20∶1, 5,11- and 5,13−20∶2) were low in Crinoidea (0.2–1.3%) but were present in higher levels
(2.5–5.2%) in Ophiuroidea. Polyunsaturated acids found other than 24∶6(n−3) were 20∶4(n−6), 20∶5(n−3) and 22∶6(n−3) as major
components and 16∶3(n−3), 18∶2(n−6), 18∶3(n−6), 18∶3(n−3), 18∶4(n−3), 20∶2(n−9), 20∶2(n−6), 20∶3(n−6), 20∶3(n−3), 21∶5(n−3)
and 22∶5(n−3) as minor components in all the samples. 相似文献
8.
The fate of labeled linoleic, α-linolenic, and higher homologs of α-linolenic acid administered to the yellow clam,Mesodesma mactroides, was investigated. It was found that the clam incorporated the acids dissolved in sea water and converted 18∶2 (n−6) into
20∶2 (n−6) and 18∶3 (n−3) into 18∶4 (n−3) and 20∶3 (n−3). The addition of casein hydrolysate to the sea water increased the
desaturation capacity of the clam and allowed the conversion of 18∶2 (n−6) into 18∶3 (n−6) to be demonstrated. An enhanced
desaturation of 18∶3 (n−3) into 18∶4 (n−3) was also demonstrated. After 12 hr administration of the acid, no radioactivity
was found in arachidonic, 20∶5 (n−3), or 22∶6 (n−3). Feeding the clams a culture ofPhaeodactylum tricornutum previously incubated with 1-14C-α-linolenic acid demonstrated that all the homologs of the α-linolenic series were found in the clam without any important
changes. Six hour administration of labeled linolenic acid resulted in the incorporation of the acid into diglycerides and
phospholipids.
Member of the carrera del Investigador Cientifico of the Consejo Nacional de Investigaciones Cientificas y Tecnicas 相似文献
9.
Duplicate groups of Atlantic salmon (Salmo salar) post smolts were given diets in which the lipid component was either fish oil or a mixture of corn oil and lard. This difference
in the dietary lipid did not significantly affect growth over a period of sixteen weeks.
Proportions of docosahexaenoic acid [22∶6(n−3)] and total (n−3) fatty acids in the polar lipids of liver and white muscle
were unaffected by this difference in dietary lipid component over the time period used. Fish given the diet containing corn
oil and lard had significantly higher levels of 20∶2(n−6), 20∶3(n−6) and 20∶4(n−6) in the polar lipids of these tissues than
were present in the tissues of the fish given diets containing fish oil. There results suggest that linoleic acid [18∶2(n−6)]
undergoes elongation and desaturation to arachidonic acid [20∶4(n−6)] in post-smolt Atlantic salmon. 相似文献
10.
Diets containing either fish oil or sunflower oil, both of which supplied the minimum required level of n−3 fatty acids, were
given to Atlantic salmon (Salmo salar) postsmolts for a period of 16 weeks. In fish fed sunflower oil, the phospholipids of gills showed increased 18∶2n−6 (2–13-fold),
20∶2n−6 (4.5–12-fold) and 20∶−6 (2–8-fold). In addition, phosphatidylethanolamine had increased 20∶4n−6 (1.5-fold). Changes
of a similar magnitude were observed in the phospholipids of blood leucocytes except that, in addition, 20∶4n−6 was elevated
in phosphatidylserine (1.7-fold) and phosphatidylinositol (1.4-fold). Both tissues showed a general decrease in phospholipid
20∶5n−3 (up to 3-fold), which caused an increase in 20∶4n−6/20∶5n−3 ratio (1.3–6-fold). The elongation and desaturation products
of 20∶4n−6, 22∶4n−6 and 22∶5n−6 were not increased as a result of feeding sunflower oil. When isolated gill cells were stimulated
with the calcium ionophore A23187, 12-hydroxy-8,10,14,17-eicosapentaenoic acid (12-HEPE) was the major lipoxygenase product
from salmon given fish oil. 12-HEPE was significantly reduced in salmon given sunflower oil. When stimulated with A23187,
the lipoxygenase products derived from whole blood of fish given sunflower oil showed decreased levels of leukotriene B5, 12-HEPE and 12-hydroxy-5,8,10,14-eicosatetraenoic acid. 相似文献
11.
The influence of age and cholesterol on polyunsaturated fatty acids (PUFa) levels was studied in young and old male Sprague-Dawley
rats. Animals were fed a fat-free diet supplemented with 10% (by wt) safflower oil with or without 1% cholesterol for 8 wk.
As a result of cholesterol feeding, proportions of linoleic acid (18∶2n−6) and dihomo-γ-linolenic acid (30∶3n−6) were increased
and and that of arachidonic acid (20∶4n−6) was decreased in the liver and platelet phospholipids in 64-wk-old rats, suggesting
inhibitory effects of cholesterol on 20∶4n−6 synthesis from 18∶2n−6. The prominent age-dependent effect on the levels of PUFA
was a retention of C−22 n−3 PUFA, accompanied by decreased C−22 n−6 PUFA and increased 20∶3n−6 in the liver and platelet phospholipids.
Ratio of 20∶3n−6/20∶4n−6 increased in 64-wk-old rats regardless of dietary cholesterol, suggesting depressed Δ5-desaturase
with age. In aorta phospholipids, 20∶3n−6 content and 20∶3n−6/20∶4n−6 ratio increased with cholesterol supplementation, but
not with age. These results suggest that changes of PUFA composition of platelet phospholipids with age are closely linked
with changes in liver phospholipids. The 20∶4n−6 content in both platelet and aorta phospholipids is kept constant, despite
other n−6 and n−3 PUFA being affected by age. 相似文献
12.
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
13.
Liver nuclear incorporation of stearic (18∶0), linoleic (18∶2n−6), and arachidonic (20∶4n−6) acids was studied by incubation
in vitro of the [1-14C] fatty acids with nuclei, with or without the cytosol fraction at different times. The [1-14C] fatty acids were incorporated into the nuclei as free fatty acids in the following order: 18∶0>20∶4n−6≫18∶2n−6, and esterified
into nuclear lipids by an acyl-CoA pathway. All [1-14C] fatty acids were esterified mainly to phospholipids and triacylglycerols and in a minor proportion to diacylglycerols.
Only [1-14C] 18∶2n−6-CoA was incorporated into cholesterol esters. The incorporation was not modified by cytosol addition. The incorporation
of 20∶4n−6 into nuclear phosphatidylcholine (PC) pools was also studied by incubation of liver nuclei in vitro with [1-14C]20∶4n−6-CoA, and nuclear labeled PC molecular species were determined. From the 15 PC nuclear molecular species determined,
five were labeled with [1-14C]20∶4n−6-CoA: 18∶0–20∶4, 16∶0–20∶4, 18∶1–20∶4, 18∶2–20∶4, and 20∶4–20∶4. The highest specific radioactivity was found in
20∶4–20∶4 PC, which is a minor species. In conclusion, liver cell nuclei possess the necessary enzymes to incorporate exogenous
saturated and unsaturated fatty acids into lipids by an acyl-CoA pathway, showing specificity for each fatty acid. Liver cell
nuclei also utilize exogenous 20∶4n−6-CoA to synthesize the major molecular species of PC with 20∶4n−6 at the sn-2 position. However, the most actively synthesized is 20∶4–20∶4 PC, which is a quantitatively minor component. The labeling
pattern of 20∶4–20∶4 PC would indicate that this molecular species is synthesized mainly by the de novo pathway. 相似文献
14.
The present study was designed to investigate the metabolism of the n−3 olyunsaturated fatty acids (PUFA) in adipose tissue
and its dependence upon dietary factors. Changes in the positional distribution of the fatty acids in triacylglycerols from
retroperitoneal adipose tissue were studied as a function of time on rats fed for 4 wk a diet enriched with fish oil. The
stereospecific analysis of triacylglycerols was based on random formation ofrac-1,2-diacylglycerols by Grignard degradation. This was followed by synthesis ofrac-phosphatidic acids and treatment with phospholipase A2. In the triacylglycerols of the fish oil diet, 57% of the total n−3 fatty acids were in position 3,i.e., two-thirds of 22∶5n−3 and 22∶5n−3 were esterified insn-3 position, whereas 22∶6n−3 was equally distributed in positions 2 and 3. After 4 wk of feeding fish oil, the fatty acid
composition of adipose tissue triacylglycerols reached a steady state. Half of the n−3 fatty acids were found in position
3, namely 75% of 22∶5n−3, 50% of 20∶5n−3 and 18∶4n−3 and 45% of 22∶6n−3, the latter being equally distributed in positions
2 and 3. This pattern of distribution resembled that found in triacylglycerols of the fish oil diet, except for a higher proportion
of 20∶5n−3 in adipose tissue in position 1 at the expense of position 3. Throughout the 4-wk period of fish oil feeding, the
distribution pattern of minor n−3 fatty acids (18∶4n−3 and 22∶5n−3) in adipose tissue triacylglycerols remained unchanged.
On the other hand, at the onset of fish oil feeding, 20∶5n−3 and 22∶6n−3 became concentrated in position 3, but thereafter
20∶5n−3 was progressively incorporated into position 1 and 22∶6n−3 into position 2. We thus conclude that n−3 fatty acids
are differentially esterified in triacylglycerols of white adipose tissue. Despite the complex sequence of hydrolysis and
acylation steps involved, the positional distribution of n−3 fatty acids was found to be similar in both the fish oil diet
and the stored fat, in contrast to what was observed for nonessential fatty acids. 相似文献
15.
Because alterations in the dietary content of fatty acids are an important method for modulating macrophage eicosanoid production,
we have quantitated the levels of n−6 and n−3 polyunsaturated fatty acids in peritoneal macrophage individual phospholipids
from mice fed diets (3 wk) with either safflower oil (SAF), predominantly containing 18∶2n−6, borage (BOR) containing 18∶2n−6
and 18∶3n−6, fish (MFO) containing 20∶5n−3 and 22∶6n−3, and borage/fish mixture (MIX) containing 18∶2n−6, 18∶3n−6, 20∶5n−3
and 22∶6n−3. Dietary n−3 fattya cids were readily incorporated into macrophage phosphatidylcholine (PC), phosphatidylethanolamine
(PE), phosphatidylserine (PS) and phosphatidylinositol (PI). The increase in n−3 fatty acid levels was accompanied by a decrease
in the absolute levels of 18∶2n−6, 20∶4n−6 and 22∶4n−6 in PC, PE and PS. Interestingly, PI 20∶4n−6 levels were not significantly
lowered (P>0.05) in MIX and MFO macrophages relative to SAF and BOR. These data demonstrate the unique ability of this phospholipid
to selectively maintain its 20∶4n−6 levels. In BOR and MIX animals, 20∶3n−6 levels were significantly increased (P<0.05) in
all phospholipids relative to SAF and MFO. The combination of borage and fish oils (MIX diet) produced the highest 20∶3n−6/20∶4n−6
ratio in all phospholipids. These data show that the macrophage eicosanoid precursor levels of 20∶3n−6, 20∶4n−6 and n−3 acids
can be selectively manipulated through the use of specific dietary regimens. This is noteworthy because an increase in phospholipid
levels of 20∶3n−6 and 20∶5n−3, while concomitantly reducing 20∶4n−6, may have therapeutic potential in treating inflammatory
disorders. 相似文献
16.
Total lipid, phospholipid, and FA composition and distribution of FA between polar lipids (PL) and neutral lipids (NL) were
investigated in the boreal soft coral Gersemia rubiformis from the Bering Sea. The total lipids were mostly hydrocarbons and waxes (33.7%) and PL (33.1%). The content of monoalkyldiacylglycerols
(9.7%) exceeded the content of TAG (6.7%). PC and PE constituted 31.4% and 25.6% of total phospholipids, respectively. Principal
FA were 16∶0, 16∶1n−7, 18∶0, 18∶1n−9, 18∶1n−7, 20∶1n−7, 20∶4n−6, 20∶4n−3, 20∶5n−3 22∶5n−3, 22∶6n−3, 24∶5n−6, and 24∶6n−3.
Most n−6 PUFA (52% of total FA) were associated with the PL fraction; this was especially true for arachidonic and tetracosapentaenoic
acids. The NL were enriched with mono-, di-, trienoic, and n−3 PUFA. The variation in EPA levels in both NL and PL suggests
an origin of this acid from lipids of diatoms consumed by the corals. 相似文献
17.
The incorporation and metabolism of α-linolenic acid (18∶3n−3) and its Δ6 desaturase product, stearidonic acid (18∶4n−3),
were compared by NIH-3T3 cells. In the presence of fetal calf serum, cells accumulated exogenously added 18∶3n−3 and 18∶4n−3
apparently at the expense of oleic acid (18∶1n−9). Both 18∶3n−3 and 18∶4n−3 were elongated and desaturated to eicosatetraenoic
acid (20∶4n−3), eicosapentaenoic acid (20∶5n−3) and docosapentaenoic acid (22∶5n−3), but not to docosahexaenoic acid (22∶6n−3),
and were incorporated into phospholipids and triacylglycerols. Over a 4−d period, the growth of NIH-3T3 cells was slightly
stimulated in the presence of 18∶3n−3 (20 μg/mL) but was strongly inhibited in the presence of 18∶4n−3 at the same concentration.
This inhibition may be caused by enhanced lipid peroxidation as a result of the high levels of 18∶4n−3 present. 相似文献
18.
The addition of long-chain polyunsaturated fatty acids (LCP: C20, and C22) to infant formula may permit fatty acid accretion
rates similar to breast-fed infants, and may have long-term outcome benefits, such as improved visual acuity and cognitive
development. Although fish oil may provide a source of n-3 LCP, sources of n-6 LCP have been more difficult to identify. The
present study evaluates the effects of n-3 and n-6 LCP derived from single-cell oils on liver, plasma, and brain fatty acid
levels in a neonatal animal model. Newborn rat pups were suckled for 14 d by dams receiving diets containing n-3 LCP alone
or combinations of n-3 LCP and increasing doses of linoleic acid (18∶2n−6) or arachidonic acid (20∶4n−6). Dietary groups received
2% n−3 LCP and 1, 2, or 5% of either 18∶2n−6 or 20∶4n−6. The 20∶4n−6 source also contained modest levels of 18∶2n−6. At the
termination of the study, liver, plasma, and brain were obtained from the rat pups and the phospholipid fatty acid profiles
determined. The results indicate complex interactions of n−3 and n−6 fatty acids. Groups receiving dietary 20∶4n−6 incorporated
higher levels of n−6 LCP into tissues than did the groups receiving 18∶2n−6. The brain was relatively resistant to changes
in fatty acid composition compared with the liver and plasma. As expected, tissue n−3 LCP levels were reciprocally related
to n−6 levels. The present results document that single-cell LCP oils are bioavailable in a neonatal animal model. The use
of 20∶4n−6 is a more effective means of supporting n−6 status than the use of 18∶2n−6. These results may have implications
for the addition of LCP to infant formula. 相似文献
19.
J. T. Venkatraman R. K. Tiwari B. Cinader J. Flory T. Wierzbicki M. T. Clandinin 《Lipids》1991,26(3):198-202
Inbred congenic mice of strains MRL/Mp-lpr/lpr (lpr/lpr) and MRL/Mp-+/+ (+/+) were fed nutritionally adequate semipurified
diets containing 20% (w/w) fat and differing in linoleic acid content. Levels of linoleic acid (18∶2n−6) and arachidonic acid
(20∶4n−6) in phospholipids of splenocytes, liver mitochondria and liver nuclear envelopes were determined. Membranes of lpr/lpr
mice exhibited significantly lower levels of 18∶2n−6 and 20∶4n−6 in phospholipids compared with the +/+ strain. The high linoleic
acid diet increased incorporation of 18∶2n−6 and 20∶4n−6 in most phospholipid fractions of these membranes. These observations
indicate that genotype as well as dietary 18∶2n−6 content significantly influenced incorporation of 18∶2n−6 and 20∶4n−6 into
membrane phospholipids. The results also suggest that membrane compositional abnormalities found in the lpr/lpr mice, which
develop lymphoma and age faster than +/+ mice, are not restricted to the immune system but also extend to other organs. Differences
observed in phospholipid fatty acid composition in splenocytes and liver subcellular membranes for mice fed diets differing
in linoleic acid content suggest that the early expression of the lpr gene resulting in progression of autoimmunity may be
delayed through dietary manipulation. 相似文献
20.
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