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1.
A mixture ofcis-9-[1-14C] octadecenol and [1-14C] docosanol was injected into the brains of 19-day-old rats, and incorporation of radioactivity into brain lipids was determined
after 3, 12, and 24 hr. Both alcohols were metabolized by the brain but at different rates; each was oxidized to the corresponding
fatty acid, but oleic acid was more radily incorporated into polar lipids. Substantial amounts of radioactivity were incorporated
into 18∶1 alkyl and alk-1-enyl moieties of the ethanolamine phosphoglycerides and into 18∶1 alkyl moieties of the choline
phosphoglycerides. Even after the disappearance of the 18∶1 alcohol from the substrate mixture (12 hr), the 22∶0 alcohol was
not used to any measurable extent for alkyl and alk-1-enyl glycerol formation. 相似文献
2.
A fat-deficient diet was initiated in mice before birth and at different ages during development and maturation. The induction
of an essential fatty acid deficiency in brain was most effective when the deficient diet was initiated prenatally. With increasing
time on the deficient diet, there was an increase in 20∶3(n−9) and a decrease in 20∶4(n−6) in the phosphoglycerides of subcellular
brain fractions. The highest ratio of 20∶3(n−9) to 20∶4(n−6) observed was 1.5 for both diacyl and alkenylacyl glycerophosphorylethanolamines
in the synaptosome-rich fraction from mice on the deficient diet from before birth to 7 months of age. The acyl groups of
brain ethanolamine plasmalogens are quite susceptible to alteration by the fat-deficient diet. Elongated products of 20∶3(n−9),
tentatively identified as 22∶3(n−9) and 22∶5(n−9), also were present in brain during essential fatty acid deficiency. These
fatty acids were preferentially linked to the alkenylacyl glycerophosphorylethanolamines. It further was observed that, even
when the deficient diet was initiated after maturation, similar changes in fatty acid composition occurred in both myelin
and synaptosomerich fractions, but at a slower rate. For mice on the deficient diet from 12–18 months of age, the highest
ratio of 20∶3(n−9) to 20∶4(n−6) was 0.6 for the alkenylacyl glycerophosphorylethanolamines from the myelin. 相似文献
3.
The acyl composition of ethanolamine and choline phosphoglycerides from a series of human brain tumors was determined and
compared to that of normal human gray matter. Six glioblastomas, one astrocytoma, one oligodendroglioma, and one meningioma
were analyzed. The total fatty acid composition of ethanolamine phosphoglycerides generally had a higher percentage of 18∶1,
18∶2ω6, and 22∶5ω3 and a lower percentage of 22∶6ω3 than that of normal gray matter. Choline phosphoglycerides from the tumors
also contained a higher than normal percentage of 18∶2ω6. Separate analysis of the acyl groups at the 2 position of the diacyl
and ether-linked components of the phosphoglycerides revealed that the diacyl component of ethanolamine phosphoglyceride from
the tumors had lower than normal amount of 22∶6ω3 and a higher than normal amount of 18∶1 and 18∶2ω6. The acyl composition
of ether-linked ethanolamine phosphoglycerides genearally contained a higher percentage of 20∶4ω6 and a lower percentage of
18∶1 compared to the corresponding fraction from normal gray matter. The astrocytoma analyzed had fatty acid profiles similar
to those of the control with the exception of a greater 18∶2ω6 content. These data demonstrate that the composition of the
acyl moiety at the 2 position of diacyl and ether-linked phosphoglycerides of brain tumors differs from the corresponding
component from normal gray matter and that the ether-linked ethanolamine phosphoglycerides provide an important pool of polyunsaturated
fatty acids from brain tumor phospholipids. 相似文献
4.
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
5.
Analysis of phospholipids in porcine, bovine and rat adipose tissue revealed a relatively high level of plasmalogens (O-alk-1-enyl lipids). About 50% of the ethanolamine phospholipids in the pig and beef samples consisted of alk-1-enylacylglycerophosphorylethanolamine,
and the corresponding value for the rat sample was near 35%. In the ethanolamine and choline phospholipid fractions, theO-alk-1-enyl moieties were almost exclusively 16∶0, 18∶0 and 18∶1, whereas the acyl moieties had chain lengths ranging from
16 to 22 carbon atoms with a high degree of unsaturation. 相似文献
6.
Edward N. Lambremont 《Lipids》1972,7(8):528-533
When14C-labeled acetate, fatty acids or fatty alcohols were injected into or fed to the tobacco budworm, acyl, alkyl and alk-1-enyl
moieties of the phospholipids incorporated radioactivity. Fatty acids were the principal precursor in acyl bond formation
and fatty alcohols in the synthesis of alkyl and alk-1-enyl glyceryl ethers. Detailed analysis of the etherlinked phosphoglycerides
revealed that most of the radioactivity was in the ethanolamine phosphoglycerides, and very little14C was found in the choline phosphoglycerides. In experiments of a short duration, the alkyl glyceryl ethers incorporated more
radioactivity than the alk-1-enyl glyceryl ethers. The reverse was found with long term experiments, when the alk-1-enyl ethers
had higher radioactivity. In addition to demonstrating the synthesis of ether-linked ethanolamine phosphoglycerides, the data
suggested that fatty alcohols and acids were interconverted by insects and that the alk-1-enyl ethers were derived from the
alkyl ethers.
Presented at the AOCS Meeting, Houston, May 1971.
The following abbreviations and terminology will be used: PE, PC, PI and PS for the generic terms ethanolamine, choline, inositol
and serine phosphoglycerides, respectfully. Alkyl glyceryl ether for 1-alkyl-2-acyl-sn-glycerol-3-phosphoryl-, and alk-1-enyl glyceryl ether for 1-alk-1′-enyl-2-acyl-sn-glycerol-3-phosphoryl-(commonly called plasmalogen). These are adapted from the tentative rules published inJ. Lipid Res. 8:522–528 (1967). 相似文献
7.
Grace Y. Sun 《Lipids》1979,14(11):918-924
The phospholipid composition and their acyl group profiles from subcellular fractions of guinea pig adrenal gland and the
same fractions from the cortex and medulla of the bovine gland were compared. The phospholipids of guinea pig adrenal were
enriched in diacyl-glycerophosphocholines (GPC) which comprised over 50% of the total phospholipids, but the proportions of
ethanolamine and choline plasmalogens, sphingomyelin and diacyl-glycerophosphoserine (GPS) were lower in guinea pig adrenals
as compared to the bovine adrenals. In the bovine adrenal, sphingomyelin and diacyl-GPS were enriched in the medulla, whereas
diacyl-glycerophosphoinositol (GPI) were enriched in the cortex. Although lysolecithin was present (up to 4.5%) in the bovine
adrenal, only trace amounts of this lipid were detected in the guinea pig adrenal. Characteristic acyl group profiles were
found associated with each type of the phosphoglycerides in adrenal membranes. However, acyl group profiles of the phosphoglycerides
were not greatly different either between the bovine and guinea pig adrenal or with respect to the type of subcellular membranes
isolated. Diacyl-GPC were enriched in 16∶0 and 18∶1, but also contained considerable amounts of 18∶0, 18∶2 and 20∶4. Diacyl-GPE
were enriched in 18∶0, 18∶1 and 20∶4, while diacyl-GPI, diacyl-GPS, as well as alkenylacyl-GPE, were enriched in 20∶4. The
lysolecithin from bovine adrenal membranes contained mainly 16∶0, 18∶0 and 18∶1 with only trace amounts of the polyunsaturated
fatty acids. Other polyunsaturated fatty acids, such as 22∶4 and 22∶6, are apparently not prominent in the phosphoglycerides
from either the bovine or the guinea pig adrenal gland. 相似文献
8.
HeLa cells exposed to trace amounts of pentadecan-2-one showed changes in metabolism of 1-14C-palmitate. These changes consisted of an increased incorporation of radioactivity into the triglycerides and free fatty
acids and a decreased14C incorporation into the ether moiety of alk-1-enyl acyl phosphoglycerides. Chemical analysis of the several lipid fractions
showed a threefold increase in triglyceride content but no change in the amount of alk-1-enyl acyl or diacyl phosphoglycerides
in the treated cells. Pentadecan-2-one added to the culture medium apparently gains entrance to the cell since both pentadecan-2-one
and pentadecan-2-ol were detected in the ketone-treated cells and their culture medium. 相似文献
9.
The lipid composition of Yoshida ascites hepatoma cells was analyzed together with that of ascitic plasma and of livers and
blood plasma from host and normal rats. In comparison to normal livers, host livers showed no significant differences in the
content of the various lipid classes, but contained a higher percentage of palmitic acid and a lower proportion of arachidonic
acid in the major phospholipid classes. In addition, tumor growth induced a marked hypertriglyceridemia in host animals; changes
in the concentration of other plasma lipid classes were not statistically significant. The ascitic plasma contained small
amounts of lipids mainly constituted by cholesteryl esters and phospholipids. Yoshida hepatoma cells contained less phospholipids
in comparison to both host and normal liver, while the increased level of triglycerides and the decrease of free fatty acids
were not statistically significant. Hepatoma cells showed appreciable amounts of ether-linked lipids associated in part to
neutral lipids (as glyceryl ether diesters) and, in part, to ethanolamine and choline phosphoglycerides. The alkyl groups
in GEDE as well as in ethanolamine and choline phosphoglycerides were mainly constituted by C16∶0 and C18∶0 followed by C18∶1. The alk-1-enyl groups in ethanolamine and choline phosphoglycerides were C16∶0 and C18∶0 with only a minor proportion of C18∶1. In comparison to both host and normal liver, Yoshida hepatoma cells showed significant changes in the fatty acid composition
of neutral lipids and phospholipids. Some of the major changes consisted of an increase of monoenoic acids associated with
a decrease of arachidonic and docosahexaenoic acids in phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol. 相似文献
10.
Lipid and fatty acyl composition of rat brain capillary endothelia isolated by a new technique 总被引:7,自引:0,他引:7
A method is described for the isolation of pure capillary endothelia from rat brain and the phospholipid composition of these
cells is reported. This method is rapid and requires only a small amount of starting material. It involves: (a) tissue disruption
by high speed homogenization, (b) separation of the capillary endothelia from other brain structures using sucrose gradients,
and (c) a final purification using a glass bead column. Choline and ethanolamine phosphoglycerides were found to be the predominant
lipid classes of these cells amounting to 31.9% and 24.4%, respectively, of total phospholipids. The choline phosphoglycerides
consisted almost exclusively of 1,2-diacyl glycerophosphorylcholine, whereas the ethanolamine phosphoglycerides consisted
of approximately equal amounts of 1,2-diacyl and 1-alk-l’-enyl-2-acyl glycerophosphorylethanolamine. The composition of the
constituent fatty acids of both choline and ethanolamine phosphoglycerides and the alk-1-enyl composition of ethanolamine
phosphoglycerides is reported. Saturated fatty acids accounted for 45% of the total fatty acids in choline phosphoglycerides
and for 53% in ethanolamine phosphoglycerides. Arachidonic acid accounted for approximately 48% of the total fatty acids in
alk-1-enyl ethanolamine phosphoglyceride. 相似文献
11.
Ether lipid content and fatty acid distribution in rabbit polymorphonuclear neutrophil phospholipids
This study was undertaken to determine if rabbit neutrophils contain sufficient ether-linked precursor for the synthesis of
1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activatin factor) by a deacylation-reacylation pathway. The phospholipids from rabbit
peritoneal polymorphonuclear neutrophils were purified and quantitated, and the choline-containing and ethanolamine-containing
phosphoglycerides were analyzed for ether lipid content. Choline-containing phosphoglycerides (37%), ethanolamine-containing
phosphoglycerides (30%), and sphingomyelin (28%) were the predominant phospholipid classes, with smaller amounts of phosphatidylserine
(5%) and phosphatidylinositol (<1%). The choline-linked fraction contained high amounts of 1-O-alkyl-2-acyl-(46%) and 1,2-diacyl-sn-glycero-3-phosphocholine (54%), with a trace of the 1-O-alk-1′-enyl-2-acyl species. The ethanolamine-linked fraction contained high amounts of 1-O-alk-1′-enyl-2-acyl-(63%) and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (34%), and a low quantity of the 1-O-alkyl-2-acyl species (3%). The predominant 1-O-alkyl ether chains found in thesn-1 position of the choline-linked fraction were 16∶0 (35%), 18∶0 (14%), 18∶1 (26%), 20∶0 (16%), and 22∶0 (9%). The major 1-O-alk-1′-enyl ether chains found in thesn-1 position of the ethanolamine-linked fraction were 14∶0 (13%), 16∶0 (44%), 18∶0 (27%), 18∶1 (12%) and 18∶2 (3%). The major
acyl groups in thesn-1 position of 1,2-diacyl-sn-glycero-3-phosphocholine and 1,2-diacyl-sn-glycero-3-phosphoethanolamine were 16∶0, 18∶0 and 18∶1. The most abundant acyl group in thesn-2 position of all classes of choline- and ethanolamine-linked phosphoglycerides was 18⩺2. Although this work does not define
the biosynthetic pathway for platelet activating factor, it does show that there is ample precursor present to support its
synthesis by a deacylation-reacylation pathway. 相似文献
12.
Lipids from bovine optic nerve were analyzed. The total content of 16.5% by weight included 27.2% nonpolar lipids, 26.1% glycolipids,
and 46.7% phospholipids by weight. Free cholesterol was the major component of the nonpolar lipid fraction. The cerebrosides,
73.5% of total glycolipids, were separated by thin layer chromatography (TLC) into two bands (upper and lower) that were present
in equal proportion. Cerebroside sulfates comprised about 27.5% of total glycolipids. Gangliosides were also detected in the
glycolipid fraction. In order of predominance, choline glycerophospholipids, ethanolamine glycerophospholipids, ethanolamine
plasmalogens, serine glycerophospholipids, sphingomyelins, and inositol glycerophospholipids were the major phospholipids.
Palmitoyl (16∶0), stearoyl (18∶0), and oleoyl (18∶1) groups were the major acyl groups in all neutral and phospholipid classes.
However, ethanolamine glycerophospholipids, serine glycerophospholipids, and inositol glycerophospholipids contained a large
percentage of 22∶6 (docosahexaenoyl) group. The major alk-1-enyl groups of the plasmalogens were 16∶0, 18∶0, and 18∶1. Steroyl
(18∶0), lignoceroyl (24∶0), and nervonoyl (24∶1) were the major acyl groups in all sphingolipids. Lower cerebroside band and
cerebroside sulfates contained large amount of hydroxylignoceroyl (cerebronoyl) and hydroxynervonoyl groups.
This investigation was supported by Grants DE-03191 and 2S06-RR-08037 from the National Institutes of Health, Bethesda, MD. 相似文献
13.
Yu-Yan Yeh 《Lipids》1988,23(12):1114-1118
A restricted maternal dietary intake (40% of ad libitum intake) is known to cause myelin deficit that is accompanied by decreased
amounts of individual phospholipids and sphingolipids in brain myelin of suckling rats. This communication reports the effects
of the same nutritional stress on the fatty acid composition of brain myelin lipids. In myelin of 19-day-old normally fed
rats, palmitate (16∶0), stearate (18∶0) and oleate (18∶1) accounted for 80–90% of all fatty acids in phosphatidylcholine,
phosphatidylethanolamine and phosphatidylserine. Maternal dietary restriction resulted in deficits of total fatty acid content,
but did not affect the proportional distribution of individual fatty acids among phospholipids. By contrast, longer chain
(22- and 24-carbon) fatty acids accounted for more than half the fatty acid content of myelin cerebroside and sulfatide from
the 19-day-old control rat pups. In undernourished rats of that age, proportions of lignocerate (24∶0) and nervonate (24∶1)
in cerebroside and sulfatide were 40–50% lower than those in control rats. This, together with higher proportions of 16∶0,
18∶0 and 18∶1 and a higher ratio of C16−C20 to C22−C24 in under-nourished than in control rats, suggests an impairment in fatty acid chain elongation. Ten days of nutritional rehabilitation
failed to restore the fatty acid imbalances; however, after an additional 5 days of ad libitum feeding, the experimental and
control values were similar. The undernutrition results in hypomyelination, which is characterized by a proportional decrease
in lignoceric and nervonic acids of sphingolipids. 相似文献
14.
Hsiang Ju Lin M. S. F. Lie Ken Jie Clara Lai Hing Lee Daniel Hong Seng Lee 《Lipids》1977,12(7):620-625
A comparison of human adult and fetal adrenals with respect to their levels of glyceryl ether lipids and other lipid components
is reported. Fetal glands contained significantly lower levels of alk-1-enyl phosphoglycerides and of cholesterol. Neutral
glyceryl ether diesters, and ethanolamine and choline phosphoglycerides were isolated from adult adrenal tissue. The composition
of theO-alkyl glycerol groups in these lipid fractions was obtained by means of gas chromatography of the trimethylsilyl ethers and
diacetyl derivatives;O-alk-1-enyl glycerols were analyzed as their diacetates. About one-half of the alkyl and alk-1-enyl glycerol moieties present
in glyceryl ether diesters contained hydrocarbon side chains with 20, 22, or 24 carbon atoms. Long hydrocarbon chains (C19–24) were also found in theO-alkyl glycerol moieties present in the total lipids of fetal adrenals. 相似文献
15.
In this study, the 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine content of human platelets was determined. The distribution of arachidonate among the 1,2-diacyl,
1-O-alkyl-2-acyl, and 1-O-alk-l′-enyl-2-acyl classes of choline- and ethanolamine-containing phosphoglycerides was also assessed. The major platelet
phospholipids were choline-containing phosphoglycerides (38%), ethanolamine-containing phosphoglycerides (25%) and sphingomyelin
(18%), with smaller amounts of phosphatidylserine (11%) and phosphatidylinositol (4%). In addition to the diacyl class, the
choline-linked fraction was found to contain both 1-O-alkyl-2-acyl (10%) and 1-O-alk-l′-enyl-2-acyl (9%) species. The ethanolamine-linked fraction, on the other hand, had an elevated level of the 1-O-alk-l′-enyl-2-acyl (60%) species and a small amount of the 1-O-alkyl-2-acyl component (4%). The major fatty acyl residues found in all classes of the choline and ethanolamine phospholipids
were 16∶0, 18∶0, (Δ9), 18∶2(n−6) and 20∶4(n−6). The 1-O-alk-l and 1-O-alk-l′-enyl fraction of the ethanolamine-linked phospholipids also contained substantial amounts of 22∶4(n−6), 22∶5(n−3)
and 22∶6(n−3) acyl chains. Arachidonate comprised 44% of the acyl residues in thesn-2 position of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine. Corresponding values for the diacyl and 1-O-alk-l′-enyl-2-acyl species were 23% and 25%, respectively, based on all 20∶4(n−6) being linked to thesn-2 position of all classes. In the ethanolamine-linked phosphoglycerides, arachidonate constituted 60%, 20% and 68% of the
acyl groups in thesn-2 position of the 1,2-diacyl, 1-O-alkyl-2-acyl and 1-O-alk-l′-enyl-2-acyl classes, respectively. The content of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine appears sufficient to support the synthesis of platelet activating factor by a deacylation-reacylation
pathway in platelets. Our findings also demonstrate that human platelets contain a significant amount of 1-O-alkyl-2-arachidonyl-sn-glycero-3-phosphocholine that could possibly serve as a precursor of both platelet activating factor and bioactive arachidonate
metabolites. 相似文献
16.
Grace Y. Sun 《Lipids》1977,12(8):661-665
The metabolism of a polyunsaturated and a saturated fatty acid in brain membrane phosphoglycerides was examined by injecting
simultaneously a mixture of14C-arachidonate and3H-stearate into the mouse brain and isolating the microsomal and synaptosomal fractions at 1–40 min after injections. Both
types of labeled fatty acids were utilized more readily in the microsomal than the synaptosomal fractions in brain. However,
labeled arachidonate was incorporated more rapidly into membrane phosphoglycerides than was stearate. In both subcellular
fractions, the relative specific radioactivity (3H and14C) of diacyl-glycerophosphorylinositol (diacyl-GPI) was higher than other types of phosphoglycerides such as diacyl-glycerophosphorylcholine
(diacyl-GPC) and diacyl-glycerophosphorylethanolamine (diacyl-GPE). Furthermore, the apparent rates of incorporation of radioactivity
into diacyl-GPI was more rapid for the14C-arachidonate than for the3H-stearate. Results of the experiment have demonstrated obvious differences in metabolism between stearate and arachidonate
in brain. The more rapid transfer of arachidonate to diacyl-GPI is probably due to the presence of an acyl transferase system
specially active for the transfer of arachidonyl groups to diacyl-GPI. 相似文献
17.
Mesenteric fat tissue obtained at autopsy from 6 patients with mesenteric panniculitis (MP) were found to contain significant
amounts of cholesteryl esters (CE). In addition, samples from 3 of these cases were found to contain 0.5–1.3% free cholesterol,
0.9–1.9% free fatty acids (FFA), 0.6–2.5% 1-alkyl glyceryl ether diesters and small amounts of squalene. Two of these tissues
also contained alk-1-enyl glyceryl ether diesters. The fatty acid compositions of the CE, FFA, triacylglycerides and glyceryl
ether diesters (GEDE) were determined and oleic acid (18∶1) was found to be the major fatty acid. The alkyl group composition
of the GEDE consisted essentially of 16∶0 and 18∶0 and 18∶1 carbon atoms in both types of ethers. 相似文献
18.
The lipids of liver mitochondria prepared from normal rats and from rats made hypothyroid by thyroidectomy and injection with131INa contained similar amounts, per mg protein, of total lipids, phospholipids, neutral lipids and lipid phosphorus. Hypothyroidism
caused a doubling of the relative amounts of mitochondrial cardiolipins (CL; to 20.5% of the phospholipid P) and an accompanying
trend (although statistically not significant) toward decreased amounts of both phosphatidylcholines (PC) and phosphatidylserines
(PS), with phosphatidylethanolamines (PE) remaining unchanged. The pattern of elevated 18∶2 fatty acyl content and depleted
20∶4 acyl groups of the mitochondrial phospholipids of hypothyroid preparations was reflected to varying degrees in the resolved
phospholipids, with PC showing greater degrees of abnormality than PE, and CL showing none. Hypothyroidism produced the same
abnormal pattern of fatty acyl distributions in liver microsomal total lipids as was found in the mitochondria. Hypothyroid
rats, when killed 6 hr after injection of [1-14C] labeled linoleate, showed the following abnormalities: the liver incorporated less label into lipids, and converted 18∶2
not exclusively to 20∶4 (as normals do) but instead incorporated the label mainly into saturated fatty acids. These data,
together with the known decrease in β-oxidation, suggest that hypothyroidism involves possible defective step(s) in the conversion
of 18∶2 to 20∶4.
These studies were initiated during a leave at the University of California, Los Angeles. 相似文献
19.
Starting three weeks before mating, 12 groups of female rats were fed different amounts of linoleic acid (18∶2n−6). Their
male pups were killed when 21-days-old. Varying the dietary 18∶2n−6 content between 150 and 6200 mg/100 g food intake had
the following results. Linoleic acid levels remained very low in brain, myelin, synaptosomes, and retina. In contrast, 18∶2n−6
levels increased in sciatic nerve. In heart, linoleic acid levels were high, but were not related to dietary linoleic acid
intake. Levels of 18∶2n−6 were significantly increased in liver, lung, kidney, and testicle and were even higher in muscle
and adipose tissue. On the other hand, in heart a constant amount of 18∶2n−6 was found at a low level of dietary 18∶2n−6.
Constant levels of arachidonic acid (20∶4n−6) were reached at 150 mg/100 g diet in all nerve structures, and at 300 mg/100g
diet in testicle and muscle, at 800 mg/100 g diet in kidney, and at 1200 mg/100 g diet in liver, lung, and heart. Constant
adrenic acid (22∶4n−6) levels were obtained at 150, 900, and 1200 mg/100 g diet in myelin, sciatic nerve, and brain, respectively.
Minimal levels were difficult to determine. In all fractions examined accumulation of docosapentaenoic acid (22∶5n−6) was
the most direct and specific consequence of increasing amounts of dietary 18∶2n−6. Tissue eicosapentaenoic acid (20∶5n−3)
and 22∶5n−3 levels were relatively independent of dietary 18∶2n−6 intake, except in lung, liver, and kidney. In several organs
(muscle, lung, kidney, liver, heart) as well as in myelin, very low levels of dietary linoleic acid led to an increase in
20∶5n−3. Dietary requirements for 18∶2n−6 varied from 150 to 1200 mg/100 g food intake, depending on the organ and the nature
of the tissue fatty acid. Therefore, the minimum dietary requirement is estimated to be about 1200 mg/100 g (i.e., the level
that ensures stable and constant amounts of arachidonic acid). 相似文献
20.
The distribution of phospholipids as well as their fatty acid compositions of rat mammary tissues were examined during pregnant,
lactating, and post-weaning periods. There was no apparent change in phospholipids and their acyl groups during the early
and late pregnant periods. However, tissue phospholipid composition was different during pregnant, early, and late lactating
periods. After parturition, there was a marked increase in the proportion of diacyl-glycerophosphorylcholine in the phospholipids
of mammary tissue, but this proportion decreased gradually during lactation. The decrease in diacyl-glycerophosphorylcholine
during lactation was marked by a corresponding increase in diacyl-glycerophosphorylethanolamine. Although the shorter chain
fatty acids of triglycerides were increased during lactation, only a small proportion of these fatty acids was found in the
phosphoglycerides. Marked changes in acyl group composition of individual phospholipids are found during these different physiological
stages. In general, there was a rapid decrease in 20∶4 and an increase in 18∶2 in the major phosphoglycerides during parturition.
The proportion of 20∶4 in the phosphoglycerides remained low throughout the entire lactating period, while that of 18∶2 continued
to increase 2–3 fold. Most of the changes in acyl group of the phosphoglycerides during lactation returned to normal ca. 10
days after weaning. A possible relationship of the variation of phospholipid and acyl group compositions in mammary tissue
to changes in hormonal pattern during different physiological stages is discussed. 相似文献