共查询到20条相似文献,搜索用时 31 毫秒
1.
J. T. Venkatraman D. Pehowich B. Singh R. V. Rajotte A. B. R. Thomson M. T. Clandinin 《Lipids》1991,26(6):441-444
Experimental diabetes may manifest itself in a defect in liver microsomal fatty acid desaturation and increased activity of
glucose-6-phosphatase (G-6-Pase). The present study was designed to determine whether these changes could be normalized by
a change in the dietary fat consumed. Control and streptozotocin-induced diabetic rats were fed nutritionally adequate diets
which varied in fatty acid composition. Fatty acid analysis of liver microsomal phospholipids revealed that non-diabetic control
animals fed saturated fat (beef tallow) or a diet high in ω3 fatty acids (fish oil) exhibited a significantly higher level
of 18∶2ω6 and a lower level of 20∶4ω6 in the phosphatidylcholine and phosphatidylethanolamine fractions compared with diabetic
animals. Control and diabetic animals fed the high linoleic acid diet had similar levels of 18∶2ω6 in the microsomal phosphatidylcholine
and phosphatidylserine fractions. Microsomal G-6-Pase activity was higher in diabetic than in control animals. Activity of
G-6-Pase was lower in microsomes of control animals fed the soybean oil or the fish oil diet, but was not significantly reduced
in diabetic animals fed high polyunsaturated fats. Blood glucose levels were similar in control groups fed the different diets,
but the plasma hemoglobin A1c level was lower in diabetic animals fed the soybean oil diet. Cholesterol and triglyceride levels
were lower in diabetic animals fed the fish oil-based diet. The results suggest that dietary fat manipulation has the potential
to change at least some of the abnormalities in the microsomal membrane in experimental diabetes. 相似文献
2.
Studies are reported on the effects of dietarytrans fatty acids on the 6- and 9-acyl desaturase activities in the liver microsomes of rats fed essential fatty acid (EFA)-deficient
and non-FFA-deficient diets. In experiment I, weanling male rats were fed a semisynthetic diet with either 10% safflower oil
(SAF) or 10% hydrogenated coconut oil (HCO). At the age of one year, half of the dietary fat was replaced by a supplement
containing elaidate, linolelaidate andcis,trans-trans,cis-18∶2 (TRANS) for 12 weeks. In experiment II, male rats which were kept from weaning on a 10% SAF diet for one year received
one of the following fat supplements for a 12-week period: 10% HCO, 9% HCO+1% TRANS, or 5% HCO+5% TRANS. Feeding TRANS depressed
the 6-desaturase activity in the liver microsomes, especially in the EFA-deficient rats (HCO+TRANS group of experiment I).
Unlike the 6-deaturase activity, the 9-desaturase activity was not inhibited by the dietarytrans fatty acids and was significantly stimulated in the non-EFA-deficient rats (SAF+TRANS group of experiment I and HCO+TRANS
groups of experiment II). This was evidenced by incubation reactions and by comparisons of fatty acid consumptions and microsomal
fatty acid levels, showing extra biosynthesis of 16∶1 and 18∶1 when TRANS was fed. The biosynthesis of essential (n−6) fatty
acids was depressed by the TRANS supplement in EFA-deficient as well as in non-EFA-deficient animals. 相似文献
3.
Partially hydrogenated marine oils containing 18∶1-, 20∶1- and 22∶1-isomers and partially hydrogenated peanut oil containing
18∶1-isomers were fed as 24–28 wt % of the diet with or without supplement of linoleic acid. Reference groups were fed peanut,
soybean, or rapeseed oils with low or high erucic acid content. Dietary monoene isomers reduced the conversion of linoleic
acid into arachidonic acid and the deposition of the latter in liver and heart phosphatidylcholine. This effect was more pronounced
for the partially hydrogenated marine oils than for the partially hydrogenated peanut oil. The content oftrans fatty acids in liver phospholipids was similar in groups fed partially hydrogenated fats. The distribution of various phospholipids
in heart and liver was unaffected by the dietary fat. The decrease in deposition of arachidonic acid in rats fed partially
hydrogenated marine oils was shown in vitro to be a consequence of lower Δ6-desaturase activity rather than an increase in
the peroxisomal β-oxidation of arachidonic acid. The lower amounts of arachidonic acid deposited may be a result of competition
in the Δ6-desaturation not only from the C22-and C20-monoenoic fatty acids originally present in the partially hydrogenated
marine oil, but also from C18- and C16-monoenes produced by peroxisomal β-oxidation of the long-chain fatty acids.
Part of this work was presented at the ISF-AOCS Congress, New York City, 1980. 相似文献
4.
The lipid concentration and fatty acid composition of the whole liver and of cultured hepatocytes isolated from the livers
of rats fed ad libitum (fed), fasted for 24 hr (fasted), or fasted for 48 hr and then refed a fat-free, high carbohydrate
diet for 48 hr (refed) was studied. Hepatocytes were maintained as monolayer cultures in serum-free, lipid-free media and
their fatty acid composition was analyzed at 3, 24, 48, 72 and 96 hr. The livers of fed animals, as well as their hepatocytes,
contained less total lipid than those from animals on either of the other dietary regimes. Livers of fasted animals had three
times the amount of lipid found in the livers of fed animals, and the livers of refed animals contained five times the amount
of lipid as the livers of fed animals (all based on mg lipid/g wet weight of liver). The fatty acid composition of hepatocytes
after 3 hr of culturing was very similar to that of fresh liver when compared in each of the dietary regimes. However, while
the fatty acid compositions of livers and hepatocytes from fed and fasted animals were similar, the pattern in liver of refed
animals was quite distinct from that of the fed animals. In the fed and fasted animals palmitic acid (16∶0), stearic acid
(18∶0), oleic acid (18∶1[n-9]), linoleic acid (18∶2[n-6]) and arachidonic acid (20∶4[n-6]) were the major fatty acids of the
liver; in refed animals 16∶0, palmitoleic acid (16∶1[n-7]), 18∶0, 18∶1(n-9) andcis-vaccenic acid (the n-7 isomer of oleic acid) were the major fatty acids. During maintenance in culture the 18∶1(n-9) content
of the hepatocytes increased in cells from livers of animals on all three dietary regimes. The polyunsaturated fatty acid
content was similar in fresh livers and isolated hepatocytes in all samples when compared on the basis of μg fatty acid/mg
of hepatocyte or liver protein. It was also found that the polyunsaturated fatty acid content of hepatocytes was remarkedly
stable with time of culture when the cells were incubated in serum-free, lipid-free medium. Thus, isolated hepatocytes maintained
in serum-free medium appear to be a possible system for the evaluation of the effects of prior nutritional status on fatty
acid metabolism in the whole animal, not subject to hormonal and other somatic influences which often complicate the interpretation
of such nutritional studies. 相似文献
5.
Effects of growth hormone on phospholipid composition and fatty acyl distribution were studied in liver mitochondria of hypophysectomized
rats. After hypophysectomy, only cardiolipin showed a 25% decrease. Its fatty acyl distribution, which consisted mainly of
linoleic acid (55–60%) and oleic acid (20%), was unchanged. In phosphatidylcholine and phosphatidylethanolamine fractions
the contents of docosahexaenoic and arachidonic acids were decreased with a concomitant increase in linoleic acid content.
These changes could be accounted for by small but significant decreases in the activities of Δ9-desaturase (sucrose-induced), Δ5-desaturase and mitochondrial elongation enzymes. The activities of Δ6-desaturase NADH cytochrome b5 ferri-reductase, cytochrome b5, NADH cytochrome c reductase and microsomal elongation enzymes remained virtually unchanged. Injection of bovine growth hormone
daily for seven days restored cardiolipin and fatty acyl distribution and the enzyme activities. From these and other results,
we conclude that growth hormone-dependent increase of respiratory activity of liver mitochondria may be partly mediated by
the hormonal effects on membrane lipid distribution. 相似文献
6.
Dexamethasone depresses Δ6 and Δ5 and increases Δ9 desaturase and synthase activities. Therefore, we investigated the effect
on the fatty acid composition of microsomal liver lipids and phosphatidylcholine (PtdCho) molecular species. After 15 d of
treatment we found a notable decrease in arachidonic acid, a small decrease in stearic acid, and increases of linoleic, oleic,
palmitoleic, and palmitic acids in liver microsomal total lipids and PtdCho. The study of the distribution of the PtdCho molecular
species indicated that 18∶0/20∶4n−6, 16∶0/20∶4n−6, and 16∶0/18∶2n−6 predominated in the control animals. Dexamethasone, as
expected because of its depressing effect on arachidonic acid synthesis and activation of oleic and palmitic acid synthesis,
evoked a very significant decrease in 18∶0/20∶4n−6 PtdCho (P<0.001) and an important increase in 16∶0/18∶2n−6. The invariability of 16∶0/20∶4n−6 PtdCho could be related to the antagonistic
effect of arachidonic and palmitic acid synthesis. PtdCho species containing oleic acid were not significant. The bulk fluidity
and dynamic properties of the microsomal lipid bilayer measured by fluorometry using the probes 1,6-diphenyl-1,3,5-hexatriene
and 4-trimethylammonium-phenyl-6-phenyl-1,3,5-hexatriene showed no significant modification, probably owing to a compensatory
effect of the different molecular species, but changes of particular domains not detected by this technique are possible.
However, the extremely sensitive Laurdan detected increased lipid packing in the less-fluid domains of the polar-nonpolar
interphase of the bilayer, possibly evoked by the change of molecular species and cholesterol/phospholipid ratio. The most
important effect found is the decrease of arachidonic acid pools in liver phospholipids as one of the corresponding causes
of dexamethasone-dependent pharmacological effects. 相似文献
7.
Male weanling rats were fed semi-synthetic diets high in saturated fat (beef tallow) vs high in linoleic acid (safflower oil)
with or without high levels of α-linolenic acid (linseed oil) for a period of 28 days. The effect of feeding these diets on
cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding linseed oil with beef tallow
or safflower oil had no significant effect on serum levels of cholesterol. Serum cholesterol concentration was higher in animals
fed the safflower oil diet than in animals fed the beef tallow diet without linseed oil. Feeding linseed oil lowered the cholesterol
content in liver tissue for all dietary treatments tested. Consumption of linseed oil reduced the arachidonic acid content
with concomitant increase in linoleic acid in serum and liver lipid fractions only when fed in combination with beef tallow,
but not when fed with safflower oil. Similarly, ω3 fatty acids (18∶3ω3, 20∶5ω3, 22∶5ω3, 22∶6ω3) replaced ω6 fatty acids (20∶4ω6,
22∶4ω6) in serum and liver lipid fractions to a greater extent when linseed oil was fed with beef tallow than with safflower
oil. The results suggest that the dietary ratio of linoleic acid to saturated fatty acids or of 18∶3ω3 to 18∶2ω6 may be important
to determine the cholesterol and arachidonic acid lowering effect of dietary α-linolenic acid. 相似文献
8.
Docosahexaenoic acid (DHA, 22∶6n−3) is an n−3 polyunsaturated fatty acid which attenuates the development of hypertension
in spontaneously hypertensive rats (SHR). The effects of DHA on delta-9-desaturase activity in hepatic microsomes and fatty
acid composition were examined in young SHR. Two groups of SHR were fed either a DHA-enriched diet or a control diet for 6
wk. Desaturase activity and fatty acid composition were determined in hepatic microsomes following the dietary treatments.
Delta-9-desaturase activity was decreased by 53% in DHA-fed SHR and was accompanied by an increase in 16∶0 and a reduction
in 16∶1n−7 content in hepatic microsomes. The DHA diet also increased the levels of eicosapentaenoic acid (20∶5n−3) and DHA.
The n−6 fatty acid content was also affected in DHA-fed SHR as reflected by a decrease in gamma-linolenic acid (18∶3n−6),
arachidonic acid (20∶5n−6), adrenic acid (22∶4n−6), and docosapentaenoic acid (22∶5n−6). A higher proportion of dihomo-gamma-linolenic
acid (20∶3n−6) and a lower proportion of 20∶4n−6 is indicative of impaired delta-5-desaturase activity. The alterations in
fatty acid composition and metabolism may contribute to the antihypertensive effect of DHA previously reported. 相似文献
9.
Effects of zinc deficiency and castration on fatty acid composition and desaturation in rats 总被引:3,自引:0,他引:3
Sanda Clejan Mariano Castro-Magana Platon J. Collipp Ernesto Jonas Vaddanahally T. Maddaiah 《Lipids》1982,17(3):129-135
The effects of zinc deficiency and testosterone on fatty acid composition of plasma lipids and microsomes of liver, intestine
and testes were studied. The activities of fatty acid desaturase (Δ6 and Δ5) in rat liver and testes were also measured. A
significant decrease in the level of arachidonic acid was observed in plasma of normal rats fed the zinc-deficient diet. Castration
significantly decreased arachidonic acid but increased 20∶3 fatty acid, which is negligible in normal rats. Testosterone and
zinc administration restored arachidonic acid to normal values. Zinc deficiency does not significantly change the fatty acid
profile in liver, but castration decreased both arachidonic and 22∶6 fatty acid. Intestinal mucosal microsomes showed that
the predominant fatty acid in this tissue, palmitic acid, is independent of zinc status, whereas polyunsaturated fatty acids
18∶2 and 20∶4 were decreased by zinc-deficient diet or castration. Zinc deficiency sharply decreased 22∶5 fatty acid and to
some extent, other polyunsaturated fatty acids in testis microsomes. These changes in fatty acids are in agreement with increased
Δ9 desaturation and decreased Δ5 desaturase activity. In testes, both Δ6 and Δ5 desaturase activities are decreased in zinc
deficiency. It appears that zinc influences the conversion of linoleic to arachidonic acid, whereas testosterone influences
Δ6 desaturase activity. The data suggest that zinc deficiency may be one of the important factors in the causation of polyunsaturated
fatty acid deficiency, which in turn, may induce serum hypertriglyceridemia. 相似文献
10.
The activity of Δ6-desaturase of linoleic acid, a rate-limiting step in the formation of arachidonic acid, is decreased in
animal models of severe, uncontrolled diabetes. The aim of the study was to measure the activity of liver microsomal Δ6-desaturase
of spontaneously diabetic BioBreeding/Edinburgh rats receiving subcutaneous insulin daily and of genetically related nondiabetic
animals. The activity of Δ6-desaturase was then compared with indices of activity (plasma lipid fatty acid product/precursor
ratios) frequently used in human studies. Diabetic rats treated with insulin had 75±8% of the activity of microsomal Δ6-desaturase
of nondiabetic controls (P<0.05). Insulin withdrawal tended to reduce the activity further (61% of control), although the activity did not differ from
insulin-treated diabetic rats. The ratio of plasma phospholipid or cholesteryl ester γ-linolenic over linoleic acid was not
decreased in insulin-treated diabetic rats. By contrast, the ratio of γ-linolenic over linoleic acid of microsomes was almost
three-fold higher in insulin-treated diabetic rats (P<0.05). The γ-linolenic over linoleic acid ratio as an index of activity gave inconsistent results in insulin-deprived rats.
The ratio of γ-linolenic over linoleic acid of cholesteryl esters did not differ between control and diabetic rats, nor did
it correlate with microsomal Δ6-desaturase activity. Furthermore, the index of Δ6-desaturase activity, derived from the fatty
acid composition of microsomal phospholipids, did not correlate with microsomal Δ6-desaturase activity. Diabetes, even when
controlled by regular insulin injections, reduces the metabolism of linoleic acid, but the effect is less than previously
published. The fatty acid compositions of plasma and liver microsomal lipids are not reliable indices of Δ6-desaturase activity
in diabetes. 相似文献
11.
Comparative effects of feeding dietary linoleic (safflower oil) and α-linolenic (linseed oil) acids on the cholesterol content
and fatty acid composition of plasma, liver, heart and epididymal fat pads of rats were examined. Animals fed hydrogenated
beef tallow were used as isocaloric controls. Plasma cholesterol concentration was lower and the cholesterol level in liver
increased in animals fed the safflower oil diet. Feeding the linseed oil diet was more effective in lowering plasma cholesterol
content and did not result in cholesterol accumulation in the liver. The cholesterol concentration in heart and the epididymal
fat pad was not affected by the type of dietary fatty acid fed. Arachidonic acid content of plasma lipids was significantly
elevated in animals fed the safflower oil diet and remained unchanged by feeding the linseed oil diet, when compared with
the isocaloric control animals fed hydrogenated beef tallow. Arachidonic acid content of liver and heart lipids was lower
in animals fed diets containing safflower oil or linseed oil. Replacement of 50% of the safflower oil in the diet with linseed
oil increased α-linolenic, docosapentaenoic and docosahexaenoic acids in plasma, liver, heart and epididymal fat pad lipids.
These results suggest that dietary 18∶2ω6 shifts cholesterol from plasma to liver pools followed by redistribution of 20∶4ω6
from tissue to plasma pools. This redistribution pattern was not apparent when 18∶3ω3 was included in the diet. 相似文献
12.
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
13.
The lipid fatty acid pattern of normal liver, host liver, and Novikoff hepatoma was determined by gas liquid chromatography,
and Δ6-desaturase activity for linoleic acid was measured in the microsomal fractions. The results showed that, in Novikoff
hepatoma, there is a correlation between the low content of arachidonic acid and the low activity of Δ6-desaturase, a key
enzyme in the biosynthetic pathway of this acid. 相似文献
14.
Trans, trans-linoleate at 50 and 100% of dietary fat decreased kidney size and altered its composition.Trans, trans-linoleate as the sole source of dietary fat imparied growth and caused more severe symptoms of essential fatty acid deficiency
than was observed with hydrogenated coconut oil (HCO). The concentration of renal cholesterol, phospholipids (PL), triglycerides
(TG) and cholesteryl esters (CE) were also decreased. Linoleic (18∶2), homo-γ-linolenic acid (20∶3n6) and arachidonic acid
(20∶4n6) were significantly depressed in lipid classes, especially in PL and CE, by dietarytrans, trans-linoleate. The increase in eicosatrienoate (20∶3n9), especially in PL and CE of kidneys of rats fed HCO (essential fatty
acid deficient), was slight in rats fed 100%trans, trans-linoleate, indicating that thetrans, trans acid probably inhibited acyl elongation and desaturation. 相似文献
15.
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
16.
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
17.
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
18.
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
19.
The fatty acid profile of cardiolipin (CL) from brain and cardiac mitochondria was measured to determine whether CL isolated
from these two tissue sources responded similarly to alterations in dietary fat composition. Male Wistar rats were fed 20%
(w/w) diets containing 2 to 12% (w/w) 18∶2n-6 for four weeks. Despite higher baseline levels of CL 18∶2n-6 in cardiac (54±1%
of total fatty acids) compared to brain (13±1%) mitochondria, CL 18∶2n-6 levels increased in proportion to dietary 18∶2 levels.
The degree of change in 18∶2n-6 was comparable with both tissues showing an approximate 1.5- to 2-fold increase. The time
course of changes in CL fatty acid profile was examined in a subsequent experiment in which animals were fed 20% (w/w) fat
diets containing either 3 or 15% α-linoleate. Changes in cardiac CL 18∶1, 18∶2n-6, and 22∶6n-3 levels were observed within
one week of feeding. While statistically significant differences were not observed in brain CL until the second week of feeding,
the time course did not differ substantively from that observed in heart. The results from this study suggest that while baseline
fatty acid profile of cardiac and neural CL differ, mitochondria from both tissues show comparable sensitivity to changes
in dietary fat composition. Furthermore, it would appear that the turnover rate of fatty acids in CL is similar in both tissues. 相似文献
20.
Streptozotocin diabetes in the rat alters liver microsomal membrane fatty acid composition. The present study was undertaken
to determine if such changes in fatty acid composition were due to changes in the amount of individual phosphoglycerides or
to disproportionate changes in fatty acid composition in any of the individual phosphoglycerides. The diabetic animals showed
a small increase in total microsomal phospholipid, which is due to a selective increase in the phosphatidylethanolamine fraction.
The changes in fatty acid composition in the total lipid extract (decreased palmitoleic, oleic and arachidonic acids and increased
linoleic and docosahexaenoic acids) from the diabetic animals were present in both the major phosphoglycerides, phosphatidylcholine
and phosphatidylethanolamine, with very little change in fatty acid composition in the phosphatidylserine and inositol fraction.
Further studies are necessary to delineate the cause of the abnormal membrane phospholipid composition in the diabetic animal.
Abbreviations: The abbreviated fatty acid nomenclature refers to the number of carbon atoms in the chain, the number of unsaturated
bonds, and the position of the first unsaturated bond counting from the terminal methyl group; thus arachidonic acid, 5,8,11,14-eicosatetraenoic
acid, is 20∶4ω6. 相似文献