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1.
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
2.
The metabolism of α-linolenic acid from canola oil was studied in eight normolipidemic men. The 42-day study was divided into
three periods: a 6-day pre-experimental and two 18-day experimental. Approximately 75% of the dietary fat (28% of total energy)
was provided by a mixture of fats during the pre-experimental period and either canola oil (CO) or sunflower oil (SO) during
the experimental periods. The CO and SO diets were fed in a cross-over design. The ratios of linoleic to linolenic acid were
2.6∶1 and 73.9∶1 in the CO and SO diets, respectively. Dietary fat source had an effect on plasma phospholipid fatty acids:
18∶1n−9, 18∶3n−3 and 20∶5n−3 were higher (p<0.05), and 18∶2n−6 was lower in the phosphatidylcholine fraction; 18∶1n−9 was
higher and 20∶4n−6 lower in the phosphatidyl-ethanolamine fraction; and 18∶1n−9 and 20∶5n−3 were higher and 20∶4n−6 and 22∶6n−3
were lower in the alkenylacyl-ethanolamine phospholipid fraction on the CO diet as compared to the SO diet. Consumption of
the canola oil diet resulted in higher n−3 fatty acid levels and lower n−6 fatty acid levels in plasma phospholipids than
consumption of the sunflower oil diet. 相似文献
3.
A previous study has shown that the long and very long chain FA (VLCFA) content of the rat retina responds to changes in dietary
n−6/n−3 ratio of the fat fed (1). The present study tested whether similar changes in these FA are associated with alterations
in rhodopsin content and rhodopsin phosphorylation after light treatment. Weanling rats were fed diets containing 20% (w/w,
40% energy) fat with either high (4.8%, w/w) or low (1.2%, w/w) n−3 FA. After 6 wk of feeding, half of the animals in each
group were exposed to light for 48 h at 350 lx or were kept in complete darkness. In the rod outer segment, the high n−3 diet
treatment increased the level of 20∶5n−3 and 22∶6n−3 and reduced the levels of 20∶4n−6 and 24∶4n−6 in PC, PE, and PS. After
the feeding of a high n−3 FA diet, total n−3 pentaenoic VLCFA from C24 to C34 increased in PC, whereas the n−6 tetra- and pentaenoic VLCFA decreased. No changes occurred in n−3 hexaenoic VLCFA regardless
of the level of 22∶6n−3 in the diet. After light exposure, animals fed a high n−3 FA diet showed reduction in 22∶6n−3 as well
as in n−6 and n−3 VLCFA in PC. FFA and TG fractions contained increased levels of both 20∶4n−6 and 22∶6n−3 after light exposure.
Dark-adapted rhodopsin content and rhodopsin phosphorylation in the rod outer segment of rats fed the low n−3 FA diet were
higher than in animals fed a high n−3 FA diet. After light exposure, animals fed the low n−3 FA diet lost more rhodopsin compared
to animals fed the high n−3 FA diet, resulting in less phosphorylation of rhodopsin. Results indicate that the FA composition,
rhodopsin content, and phosphorylation in visual cells is influenced by the dietary n−3 FA fed as well as by light exposure.
The results also imply that 22∶6n−3 may not be the precursor for synthesis of hexaenoic VLCFA. 相似文献
4.
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
5.
Cardiolipin (CL) is a unique mitochondrial phospholipid, containing up to 85 wt% 18∶2n−6 in mammals. The influence of maternal
dietary fatty acids on the acyl composition of offspring CL has not been examined previously. Adult female mice were thus
fed diets rich in 18∶1n−9 (olive oil), 18∶2n−6 (safflower oil), 18∶3n−3 (linseed oil) or 20∶5n−3 and 22∶6n−3 (fish oil/safflower,
9∶1, w/w), for a five month period, encompassing two breeding cycles. Offspring from the second breeding cycle were then fed
these diets. The acyl composition of CL, phosphatidylcholine and phosphatidylethanolamine from liver and heart was evaluated
from mice killed 3, 18 and 42 days after parturition. The primary nutrient sources at these three time points were transplacental
nutrients, breast milk and the diet, respectively. Maternal diet was found to influence the acyl composition of CLvia both placental transfer of fatty acids and breast milk. Fish oil feeding resulted in replacement of a substantial portion
of 18∶2n−6 with 22∶6n−3; after 42 days, the area% of 18∶2n−6 in heart CL was reduced from 62% in safflower oil fed mice to
12%. In comparison to fish oil feeding, linseed oil feeding resulted in a much lower accumulation of 22∶6n−3. Olive oil feeding
resulted in substantial replacement of 18∶2n−6 with 18∶1n−9 (18∶2n−6 was reduced from 62% to 31%). Physiologically, these
findings are relevant because changes in CL acyl composition may influence the activity of associated inner mitochondrial
membrane enzymes.
This work was presented in part as an Honored Student Award paper at the 82nd Annual AOCS Meeting, Chicago, IL, May 1991. 相似文献
6.
The effects of clofibrate on the content and composition of liver and plasma lipids were studied in mice fed for 4 wk on diets
enriched in n−6 or n−3 polyunsaturated fatty acids (PUFA) from sunflower oil (SO) or fish oil (FO), respectively; both oils
were fed at 9% of the diet (dry weight basis). Only FO was hypolipidemic. Both oil regimes led to slightly increased concentrations
of phospholipids (PL) and triacylglycerols (TG) in liver as compared with a standard chow diet containing 2% fat. Clofibrate
promoted hypolipidemia only in animals fed SO. Its main effect was to enlarge the liver, such growth increasing the amounts
of major glycerophospholipids while depleting the TG. SO and FO consumption changed the proportion of n−6 or n−3 PUFA in liver
and plasma lipids in opposite ways. After clofibrate action, the PUFA of liver PL were preserved better than in the absence
of oil supplementation. However, most of the drug-induced changes (e.g., increased 18∶1n−9 and 20∶3n−6, decreased 22∶6/20∶5
ratios) occurred inrrespective of lipids being rich in n−6 or n−3 PUFA. The concentration of sphingomyelin (SM), a minor liver
lipid that virtually lacks PUFA, increased with the dietary oils, decreased with clofibrate, and changed its fatty acid composition
in both situations. Thus. oil-increased SM had more 22∶0 and 24∶0 than clofibrate-decreased SM, which was significantly richer
in 22∶1 and 24∶1. 相似文献
7.
Joanna K. Chan Bruce E. McDonald Jon M. Gerrard Vivian M. Bruce Bonnie J. Weaver Bruce J. Holub 《Lipids》1993,28(9):811-817
The effect of dietary α-linolenic acid (18∶3n−3) and its ratio to linoleic acid (18∶2n−6) on platelet and plasma phospholipid
(PL) fatty acid patterns and prostanoid production were studied in normolipidemic men. The study consisted of two 42-d phases.
Each was divided into a 6-d pre-experimental period, during which a mixed fat diet was fed, and two 18-d experimental periods,
during which a mixture of sunflower and olive oil [low 18∶3n−3 content, high 18∶2/18∶3 ratio (LO-HI diet)], soybean oil (intermediate
18∶3n−3 content, intermediate 18∶2/18∶3 ratio), canola oil (intermediate 18∶3n−3 content, low 18∶2/18∶3 ratio) and a mixture
of sunflower, olive and flax oil [high 18∶3n−3 content, low 18∶2/18∶3 ratio (HI-LO diet)] provided 77% of the fat (26% of
the energy) in the diet. The 18∶3n−3 content and the 18∶2/18∶3 ratio of the experimental diets were: 0.8%, 27.4; 6.5%, 6.9;
6.6%, 3.0; and 13.4%, 2.7, respectively. There were appreciable differences in the fatty acid composition of platelet and
plasma PLs. Nevertheless, 18∶1n−9, 18∶2n−6 and 18∶3n−3 levels in PL reflected the fatty acid composition of the diets, although
very little 18∶3n−3 was incorporated into PL. Both the level of 18∶3n−3 in the diet and the 18∶2/18∶3 ratio were important
in influencing the levels of longer chain n−3 fatty acid, especially 20∶5n−3, in platelet and plasma PL. Production of 6-keto-PGF1α was significantly (P<0.05) higher following the HI-LO diet than the LO-HI diet although dietary fat source had no effect on bleeding time or thromboxane
B2 production. The present study showed that both the level of 18∶3n−3 in the diet and its ratio to 18∶2n−6 were important in
influencing long-chain n−3 fatty acid levels in platelet and plasma PL and that prostanoid production coincided with the diet-induced
differences in PL fatty acid patterns. 相似文献
8.
The objective of this study was to test the hypothesis that increasing maternal dietary 18∶3n−3 by decreasing the 18∶2n−6/18∶3n−3
ratio will increase the 18∶3n−3 and 22∶6n−3 content of the whole body, liver, skin (epidermis, dermis, and subcutaneous tissue),
epididymal fat pads, and muscles (arms and legs) of 2-wk-old rat pups. Sprague-Dawley dams at parturition were fed semipurified
diets containing either a low (18∶2n−6 to 18∶3n−3 ratio of 24.7∶1) or a high (18∶2n−6 to 18∶3n−3 ratio of 1.0∶1) 18∶3n−3 fatty
acid content. During the first 2 wk of life, rat pups received only their dams' milk. Fatty acid composition of the pups'
stomach contents (dams' milk), whole body, brain, liver, skin, epididymal fat pads, and muscles was determined. The stomach
fatty acid composition of 18∶3n−3 reflected the dams' diet. The content of 18∶3n−3 in whole body, brain, liver, skin, epididymal
fat pads, and muscles was significantly (P<0.05) greater in rat pups fed the high compared with the low 18∶3n−3 fatty acid diet. The 22∶6n−3 content of the whole body,
brain, skin, epididymal fat pads, and muscles was not quantitatively different in rat pups fed either the low or high 18∶3n−3
fatty acid diet. The 20∶5n−3 and 22∶5n−3 content of the whole body, skin, and epididymal fat pads was significantly increased
in rat pups fed the high compared with the low 18∶3n−3 fatty acid diet. High content of 18∶3n−3 was found in the skin of rat
pups fed either a low or high 18∶3n−3 fatty acid diet. These findings demonstrate that high maternal dietary 18∶3n−3 significantly
increases the 18∶3n−3 but not the 22∶6n−3 content of the whole body, brain, skin, epididymal fat pads, and muscles with approximately
39 and 41% of the whole body 18∶3n−3 content being deposited in the skin of suckling rat pups fed either the low or high 18∶3n−3
diet, respectively. 相似文献
9.
P. Hoffmann H. -U. Block J. Beitz Ch. Taube W. Forster P. Wortha P. Singer E. Naumann H. Heine 《Lipids》1986,21(12):733-737
Following the suckling period, four groups of male four-week-old spontaneously hypertensive rats (SHR) were fed semisynthetic
diets with 14% (by weight) of either sunflower seed oil [46% 18∶2(n−6); linoleic acid (LA)-rich], linseed oil [62.5% 18∶3(n−3)+12.9%
18∶2(n−6); α-linolenic acid (LNA)-rich], evening primrose oil [9.2% 18∶3(n−6)+71% 18∶2(n−6); γ-linolenic acid (LNA)-rich]
or hydrogenated palm kernel fat [1.5% 18∶2(n−6); polyunsaturated fatty acid (PUFA)-deficient], respectively, up to an age
of 18 wk. All diets enriched with PUFA provoked an attenuation of hypertension development. The effect was lowest in the LA-rich
group and highest in the γ-LNA-rich group. Differences in fatty acid composition of renal phospholipids between groups reflect
the fatty acids present in the respective dietary fats. Renomedullary production of PGF2α was significantly reduced in α-LNA-rich and slightly diminished in γ-LNA-rich fed rats. Aortic formation of 6-keto-PGF1α and TXB2 was increased in animals fed the γ-LNA-rich diet. Thus, the attenuation of hypertension development cannot be explained only
by changes in prostanoid formation. Other mechanisms possibly involved should be pursued. 相似文献
10.
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
11.
Effect of dietary n−3 and n−6 polyunsaturated fatty acids on lipid-metabolizing enzymes in obese rat liver 总被引:2,自引:0,他引:2
Isabelle Niot Joseph Gresti Jacqueline Boichot Georges Semporé Georges Durand Jean Bézard Pierre Clouet 《Lipids》1994,29(7):481-489
This study was designed to examine whether n−3 and n−6 polyunsaturated fatty acids at a very low dietary level (about 0.2%)
would alter liver activities in respect to fatty acid oxidation. Obese Zucker rats were used because of their low level of
fatty acid oxidation, which would make increases easier to detect. Zucker rats were fed diets containing different oil mixtures
(5%, w/w) with the same ratio of n−6/n−3 fatty acids supplied either as fish oil or arachidonic acid concentrate. Decreased
hepatic triacylglycerol levels were observed only with the diet containing fish oil. In mitochondrial outer membranes, which
support carnitine palmitoyltransferase I activity, cholesterol content was similar for all diets, while the percentage of
22∶6n−3 and 20∶4n−6 in phospholipids was enhanced about by 6 and 3% with the diets containing fish oil and arachidonic acid,
respectively. With the fish oil diet, the only difference found in activities related to fatty acid oxidation was the lower
sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition. With the diet containing arachidonic acid, peroxisomal
fatty acid oxidation and carnitine palmitoyltransferase I activity were markedly depressed. Compared with the control diet,
the diets enriched in fish oil and in arachidonic acid gave rise to a higher specific activity of aryl-ester hydrolase in
microsomal fractions. We suggest that slight changes in composition of n−3 or n−6 polyunsaturated fatty acids in mitochondrial
outer membranes may alter carnitine palmitoyltransferase I activity. 相似文献
12.
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
13.
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
14.
High levels of n−6 docosapentaenoic acid (22∶5n−6) have been reported in the retina of guinea pigs fed commercially-prepared
grain-based rations (commercial diet). In rats and monkeys, high levels of 22∶5n−6 are an indicator of n−3 polyunsaturated
fatty acid (PUFA) deficiency. We have examined the fatty acid composition of the retina and brain in guinea pigs fed a commercial
diet or one of three semi-purified diets containing three different levels of n−3 PUFA. The diets comprised a diet deficient
in n−3 PUFA (semi-purified diet containing safflower oil), two diets containing α-linolenic acid (standard commercial laboratory
diet and semi-purified diet containing canola oil), and a diet containing α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic
acid (DHA) (semi-purified diet containing canola oil, safflower oil, and fish oil). Two groups of guinea pigs were given the
diets from day 1 to 4 wk or day 1 to 8 wk, when they were sacrificed and the retinal tissues were extracted and analyzed for
PUFA content by gas-liquid chromatography. Fatty acid analyses of the retinal phospholipids of the four-week-old animals revealed
that the group fed DHA (from the fish oil) had the highest level of DHA (32%), compared with values of 19 and 13% for the
groups fed canola oil diet and commercial diet, respectively, and 2% for the group fed the diet deficient in n−3 PUFA. The
levels of 22∶5n−6 in the retinal lipids were inversely related to the DHA values, being 0.6, 6.6, 11.4, and 20.6 for the fish
oil, canola oil, commercial diet, and safflower oil diet groups, respectively. The long-chain PUFA profiles in the brain phospholipids
of the four-week-old group were similar to those from the retina. The retinal PUFA values for the eight-week-old animals were
similar to the four-week-old group. The safflower oil diet induced a greater deficit of DHA in retinal lipids than has been
reported in rats and monkeys fed similar diets. The guinea pigs fed the commercial diet had retinal and brain PUFA patterns
similar to that produced by n−3 PUFA-deficient diets in rats and monkeys. Guinea pigs fed the canola oil diet had significantly
greater retinal DHA levels than those fed the commercial diet, but lower than those fed fish oil. The data suggest that the
guinea pig has a reduced capacity for DHA synthesis from α-linolenic acid as compared with other mammals. Supplementation
of guinea pig diets with fish oil produced high retinal and brain DHA levels and prevented the accumulation of 22∶5n−6. 相似文献
15.
The sciatic nerve of rats fed sunflower oil (6 mg 18∶3n−3/100 g of diet) presented dramatic alterations in the long chain
polyunsaturated fatty acids in comparison with those fed soy oil (130 mg 18∶3n−3/100 g of diet). In both 15-day-old and 60-day-old
animals fed sunflower oil, 22∶6n−3 (cervonic acid) was fourfold less, 22∶5n−6 was 10-fold greater; adrenic acid (22∶4n−6)
was slightly greater and arachidonic acid (20∶4n−6) was close to that in rats fed soy oil. The percentage distribution of
total polyunsaturated fatty acids as well as the individual saturated and monounsaturated fatty acids were the same in both
groups.
When the sunflower oil-fed animals were switched to a soy oil-containing diet for either 15 or 60 days, the percentage distribution
of 22∶6n−3 increased slowly to reach the control value 2.5 months later. Conversely 22∶5n−6 decreased slowly. The decay of
22∶5n−6 was more rapid than the increase of 22∶6n−3. 相似文献
16.
The effects of different dietary oils on the fatty acid compositions of liver phospholipids and the desaturation and elongation
of [1-14C]18∶3n−3 and [1-14C]18∶2n−6 were investigated in isolated hepatocytes from Atlantic salmon. Atlantic salmon smolts were fed diets containing
either a standard fish oil (FO) as a control diet, a 1∶1 blend of Southern Hemisphere marine oil and tuna orbital oil (MO/TO),
sunflower oil (SO), borage oil (BO), or oliver oil (OO) for 12 wk. The SO and BO diets significantly increased the percentages
of 18:2n−6, 18:3n−6, 20:2n−6, 20:3n−6, and total n-6 polyunsaturated fatty acids (PUFA) in salmon liver lipids in comparison
with the FO diet. The BO diet also increased the percentage of 20:4n−6. Both the SO and BO diets significantly reduced the
percentages of all n−3 PUFA in comparison with the FO diet. The OO diet significantly increased the percentages of 18:1n−9,
18:2n−6, total monoenes, and total n−6 PUFA in liver lipids compared to the FO diet, and the percentages of all n−3 PUFA were
significantly reduced. With [1-14C]18:3n−3, the recovery of radioactivity in the products of Δ6 desaturation was significantly greater in the hepatocytes from
salmon fed SO, BO, and OO in comparison with the FO diet. The BO diet also increased the recovery of radioactivity in the
products of Δ5 desaturation. Only the BO diet significantly affected the desaturation of [1-14C]18:2n−6, increasing recovery of radioactivity in both Δ6- and Δ5-desaturation products. In conclusion, dietary BO, enriched
in γ-linolenic acid (18:3n−6), significantly increased the proportions of both 20:3n−6 and 20:4n−6 in salmon liver phospholipids
and also significantly increased the desaturation of both 18:2n−6 and 18:3n−3 in salmon hepatocytes. The possible relationships
between dietary fatty acid composition, tissue phospholipid fatty acid composition, and desaturation/elongation activities
are discussed. 相似文献
17.
The health benefits of long-chain n−3 PUFA (20∶5n−3 and 22∶6n−3) depend on the extent of incorporation of these FA into plasma
and tissue lipids. This study aimed to investigate the effect of the background dietary fat (saturated, monounsaturated, or
n−6 polyunsaturated) on the quantitative incorporation of dietary 18∶3n−3 and its elongated and desaturated products into
the plasma and the liver lipids of rats. Female weanling Wistar rats (n=54) were randomly assigned to six diet groups (n=9). The fat added to the semipurified diets was tallow (SFA), tallow plus linseed oil (SFA-LNA), sunola oil (MUFA), sunola
oil plus linseed oil (MUFA-LNA), sunflower oil (PUFA), or sunflower oil plus linseed oil (PUFA-LNA). At the completion of
the 4-wk feeding period, quantitative FA analysis of the liver and plasma was undertaken by GC. The inclusion of linseed oil
in the rat diets increased the level of 18∶3n−3, 20∶5n−3, and, to a smaller degree, 22∶6n−3 in plasma and liver lipids regardless
of the background dietary fat. The extent of incorporation of 18∶3n−3, 20∶5n−3, and 22∶5n−3 followed the order SFA-LNA>MUFA-LNA>PUFA-LNA.
Levels of 22∶6n−3 were increased to a similar extent regardless of the type of major fat in the rat diets. This indicates
that the background diet affects the incorporation in liver and plasma FA pools of the n−3 PUFA with the exception of 22∶6n−3
and therefore the background diet has the potential to influence the already established health benefits of long-chain n−3
fatty acids. 相似文献
18.
L. Ulmann J. P. Blond C. Maniongui J. P. Poisson G. Durand J. Bézard G. Pascal 《Lipids》1991,26(2):127-133
The combined effects of age and dietary n−6 and n−3 fatty acids were studied in 3-, 6- and 9-month-old rats. At each age,
two groups were fed diets containing 5% (w/w) of vegetable oils rich in either 18∶3n−6 (borage group) or 18∶3n−6 plus 18∶4n−3
(black currant group), for a period increasing with age. A control group was fed the essential fatty acids 18∶2n−6 and 18∶3n−3
only. For each group, Δ6, Δ5 and δ9 desaturase activities were measured in liver microsomes, and fatty acid composition was
determined in microsomal phospholipids. Desaturase activity varied as a function of age and dietary lipids. Δ6 Desaturation
of 18∶3n−3 was more sensitive to these factors while Δ6 desaturation of 18∶2n−6 and Δ9 desaturation were more dependent on
season than the other two. Desaturase activity was influenced more by the black currant than by the borage diet, especially
at 6 and 9 months of age. A large proportion of arachidonic acid was maintained in the microsomes independent of the diet.
Changes in the fatty acid composition did not strictly reflect the differences in desaturase activities. The effects of the
two factors (age and diet) on the activities of the desaturases are complex, suggesting that the enzymes are susceptible to
other factors as well. 相似文献
19.
Eurasian perch, Perca fluviatilis, were fed a semipurified fat-free diet for 4 wk, followed by a 16% feeding supplementation of either olive oil (OO), safflower
oil (SO), linseed oil (LO), or cod liver oil (CLO) as the only lipid source in each diet for 10 wk. Significant reductions
in total lipid of tissues were observed (31.4% in viscera, 66.7% in muscle, and 74.1% in liver) after feeding the fat-free
diet. The SO-, LO-, and CLO-fed fish significantly increased lipid deposition in liver and viscera compared to fish fed the
OO diet; however, muscle lipid levels were not significantly affected. Large amounts of dietary 18∶1n−9 were incorporated
directly into tissue lipids when fish were fed the OO diet. The LO diet significantly elevated 18∶4n−3, 20∶5n−3, 22∶5n−3,
and 22∶6n−3 in the liver compared to fish fed OO or SO diets, and the n−3/n−6 ratio was 16 times that of the SO group, with
significantly high desaturation and elongation products of 18∶3n−3. These results suggest that Δ6 and Δ5 desaturases are highly
active in Eurasian perch, and that the enzymes at this dietary n−3/n−6 ratio favor 18∶3n−3 over 18∶2n−6 as substrate. The
SO diet significantly increased 18∶3n−6, 20∶3n−6, and 22∶5n−6 in the liver and significantly decreased EPA and DHA. This indicates
that desaturation enzymes were not specifically favoring n−3 over n−6 acids in perch lipid metabolism, and that these elongation
and desaturation enzymes were influenced by n−3 and n−6 FA content in the diet. The present study indicates that high tissue
content of DHA in the muscle of Eurasian perch was attributable to the greater ability for n−3 acid bioconversion. 相似文献
20.
Roberto J. de Antueno Richard C. Cantrill Yung-Sheng Huang Michele Elliot David F. Horrobin 《Lipids》1993,28(4):285-290
This study was undertaken to investigate the total plasma fatty acid composition and the relationship between plasma triacylglycerol
(TG) levels and liver Δ9 desaturase activity in mice fed n−3 and/or n−6 fatty acid or hydrogenated coconut oil (HCO) (maximum
25 mg/g) supplemented diets. Generally, plasma TG levels and Δ9 desaturase activity were inversely correlated with the ratio
of the sum of long chain n−3 fatty acids to 18∶2n−6 and to the ratio of the sum of long chain n−3 fatty acids to 18∶n−3, but
they were positively correlated with the ratio of products and substrates (18∶1/18∶0) of the enzyme in plasma total lipids.
The n−3 fatty acid (mainly 20∶5n−3) enriched diet, when compared to the HCO diet at 21 d, caused a significant reduction in
plasma TG levels but not in Δ9 desaturase activity. However, a marked reduction in plasma TG content (50–60%) and Δ9 desaturase
activity (55–70%) was observed when both 20∶5n−3 and 18∶3n−6 were supplemented in the diet. The plasma TG levels and Δ9 desaturase
activity rose again when the animals were fed the HCO diet or chow. The results suggest that low dose supplementation of a
mixture of n−3 (mainly 20∶5n−3) and n−6 (18∶3n−6) fatty acids modified both plasma TG content and liver Δ9 desaturase activity,
in parallel. 相似文献