![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai 981-8555, Japan
1To whom correspondence should be addressed.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
-tocopherol level was reduced concomitantly (21–73% of control
rats). Consistent with these results, rats fed DHA-containing oils
had more thiobarbituric reactive substances in these organs than the
controls. Thus, high incorporation of (n-3) fatty acids (mainly DHA)
into plasma and tissue lipids due to DHA-containing oil ingestion
may undesirably affect tissues by enhancing susceptibility of membranes
to lipid peroxidation and by disrupting the antioxidant system.
KEY WORDS: • chemiluminescence • fish oil • lipid peroxidation • phospholipid hydroperoxide • -tocopherol • rats
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
, Harris 1996
, Kinsella et al. 1990
, Reddy et al. 1991
,
Sakaguchi et al. 1990
). Increased intake of DHA may
ameliorate lipid abnormalities such as hyperlipidemia and imbalances of
(n-6) and (n-3) fatty acids (Lands 1990
, Lees and Karel 1986
). However, because DHA has six double bonds and five
methylene carbons, it is highly susceptible to peroxidation. DHA is
more readily oxidized and results in more toxic oxidation products than
linoleic, linolenic and arachidonic acids (Cho et al. 1987
, Witting and Horwitt 1964
). Furthermore,
polyunsaturated oil intake decreases the concentration of vitamin E in
animal tissues (Leibowitz 1990
, Miyazawa 1993
). There are several different opinions about whether DHA
ingestion in mammals affects the oxidative state of organs. In this study, we tested the effect of DHA-enriched oils as triacylglycerols (TG), ethyl esters (EE) and phospholipids (PL) with identical constituent fatty acids, on lipid profiles and peroxidative status in rat plasma, liver and kidney. These are critical organs in the regulation and synthesis of lipids, and their constituent fatty acids are influenced by the oils ingested.
The phospholipid on the surface of membranes of tissues should be
an ideal target for peroxidation. To evaluate peroxidation in vivo, a
chemiluminescence-HPLC (CL-HPLC) system was developed previously as
a method for the quantitative analysis of hydroperoxide in biomembranes
(Miyazawa 1989
). This method was shown to be highly
sensitive and specific for phospholipid hydroperoxide (PLOOH)
(Miyazawa et al. 1992
). In this study, we used the
CL-HPLC assay to determine the concentrations of PLOOH as key
products for oxidative injury in the plasma, liver and kidney of rats.
Given the important structural and functional roles of fatty acids in
tissue membranes, alterations in fatty acid composition may contribute
to the peroxidative effect of DHA.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Male Sprague-Dawley rats (4 wk old; Funabashi Farm, Chiba, Japan),
weighing 79–82 g, were divided into four groups (n
= 6 rats/group). They were kept in an air-conditioned room
(22–23°C) with a 12-h light:dark cycle. The experimental protocols
were approved by Tohoku University Animal Care Committee. Rats in the
experimental groups were fed a diet containing 15 g/100 g of different
types of lipids (
8.31 g total food mass/100 g rat mass containing
1.25 g fat including 90 mg DHA) for 3 wk according to a
paired-feeding protocol to ensure similar energy intakes in the
groups (30.6% of the total energy). Briefly, another group of rats
(n = 6) was allowed to consume the control oil diet
ad libitum; food consumption was monitored daily. Experimental rats
were fed corresponding amounts the next day. The diet composition was
based on the AIN-76A formula for rats (AIN 1997). The
composition of the diet (g/100 g diet) was as follows: vitamin-free
casein, 20; -cornstarch, 45; sucrose, 10; cellulose, 5; oil, 15;
mineral mixture (AIN-76), 3.5; vitamin mixture (AIN-76, free of
-tocopherol), 1.2; and DL-methionine, 0.3. All dietary
components were purchased from Oriental Yeast (Tokyo, Japan) except for
the DHA oils, which were a kind gift from the Bizen Chemical (Okayama,
Japan). The DHA oils in the form of TG, EE and PL, which contained
similar fatty acid compositions and equal amounts of DHA content in
their constituent fatty acids, were used. The fatty acid compositions
of DHA oils as TG and EE were quite similar to each other; the DHA
concentration was 7.0 mol/100 mol total fatty acids as given in
Table 1
. The peroxidizability index (PI) of DHA oil in these three forms (PI,
95.1–112.2) was 5 times that of the control oil (PI, 20.4). The
test oils contained -, 
- and 
-tocopherols, among which
-tocopherol was predominant in the TG and EE oils. The total
tocopherols in DHA oils and control oils were equivalent. The control
group received palm oil supplemented with 20% soybean oil (i.e.,
80 g palm oil mixed with 20 g soybean oil), which contained
no DHA. The diets were freshly prepared every 5 d and stored at
-25°C. During the feeding period, the rats received fresh food
daily. The peroxide value of test oil in the diet was kept below 6.0
mequiv/kg throughout the animal trial (Song and Miyazawa 1997
).
|
Lipid analysis.
Plasma total lipid was extracted with a mixture of chloroform/methanol
(2:1, v/v) as previously described (Kates 1986
,
Miyazawa 1993
). Briefly, 5 mL of chloroform/methanol
(2:1, v/v) containing 10 mg BHT was added to 1 mL of plasma, which was
obtained by the centrifugation of heparinized rat blood. The mixture
was centrifuged at 1000 x g for 10 min. The lower
chloroform layer was concentrated in a rotary evaporator and dried
under a nitrogen stream. Liver and kidney total lipids were extracted
as described (Miyazawa 1993
). Then, 2 mL of 0.15 mol/L
saline containing 20 mg BHT was added to 200 mg tissue, and the mixture
was homogenized in a teflon-glass homogenizer with ice cooling. The
homogenate obtained was added to 5 mL of chloroform/methanol (2:1, v/v)
and was centrifuged at 1000 x g for 10 min. The
lower chloroform layer was concentrated in a rotary evaporator and
dried under a nitrogen stream.
Fatty acid composition of the total lipids was analyzed by
gas-liquid chromatography (Song and Miyazawa 1997
).
Fatty acid methyl esters (FAME) derived from total lipid in the
presence of 1 mmol/L pentadecanoic acid (15:0) as internal standard
were prepared by incubation with 10% methanolic-HCl in sealed
vials at 85°C for 1 h. Methyl esters were extracted with hexane
and were analyzed using a GC 380 gas chromatograph (GL Sciences, Tokyo,
Japan) equipped with a flame ionization detector and a CP-SIL 88
capillary column (0.25 mm x 50 m, Chrompack, Bergen
op Zoom, The Netherlands). The column temperature was increased from
170 to 225°C at 2°C/min. FAME were identified by comparison of
their retention times with those of standards.
Total cholesterol, free cholesterol, TG and HDL cholesterol were
analyzed enzymatically using cholesterol E-test, free cholesterol
E-test, triacylglycerol E-test and HDL-cholesterol E-test
(Wako Pure Chemical, Osaka, Japan), respectively. Phospholipid
phosphorus was determined by the method of Bartlett (1959)
.
Tissue -tocopherol (-TOC) was determined by the fluorescence
detection-HPLC method (Ave 1975
), using
2,2,5,7,8-pentamethyl-6-hydroxychroman (Wako Pure Chemical) as an
internal standard.
PLOOH determination.
Phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine
hydroperoxide (PEOOH) in total lipid extracts from plasma and tissue
homogenates were determined by the CL-HPLC method using a
chemiluminescence cocktail consisting of cytochrome c and luminol
(Miyazawa et al. 1992 and 1994
). Briefly, the
column was a JASCO Finepak SIL NH2-5 (250 x 4.6 mm, 5
µm; JASCO, Tokyo, Japan). The column mobile phase was
hexane/2-propanol/methanol/water (5:7:2:1, v/v/v/v), and the flow rate
was maintained at 1 mL/min by a JASCO 880PU pump. The luminescent
reagent was prepared by dissolving cytochrome c (from horse heart, type
IV; Sigma, Tokyo, Japan) and luminol (3-aminophytaloyl
hydrazine; Wako Pure Chemical) in an alkaline borate buffer (pH 10) and
was added at a flow rate of 1.2 mL/min. The column eluate was mixed
with the luminescent reagent at a postcolumn mixing joint (Y-type;
Kyowa Seimitsu, Japan) with the temperature controlled at 40°C in a
JASCO 860 column oven. The chemiluminscence generated by the reaction
of the hydroperoxide with the luminescent reagent at the postcolumn was
measured with a CLD-110 chemiluminescence detector (Tohoku Electronic
Industries, Sendai, Japan). Because antioxidants and neutral lipids
elute earlier, these components did not interfere with the assay.
Calibrations of PCOOH and PEOOH were done with an authentic standard
PCOOH according to the method of Miyazawa et al. (1992)
.
Thiobarbituric acid reactive substances (TBARS) were measured as a
marker of lipid peroxidation in plasma by fluorometric determination
(Yagi 1976
) and tissues by colorimetric determination
(Buege and Aust 1978
). Two different methods were
applied for determining TBARS in plasma and in tissues to avoid
interference by iron ions and to use a sufficiently sensitive assay to
obtain a quantitative measure of the lower levels of lipid peroxide in
plasma.
Statistical analysis.
Differences among the four groups were identified using a one-way ANOVA (StatView, version 4.5, Abacus Concepts, Berkeley, CA) and the significance of differences was evaluated by Duncan’s multiple range test. For comparisons between two groups, Student’s t test was used. Differences of P < 0.05 were considered to be significant.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
). Although plasma TG concentration was reduced in all DHA-fed
groups, it was most dramatically affected in the rats fed the EE diet
(Table 2)
. The major constituent fatty acids in total plasma lipids of
all groups were as follows: 16:0 (26.9–32.9 mol/100 mol); 20:4(n-6)
(14.4–26.0 mol/100 mol); 18:2(n-6) (11.8–15.1 mol/100 mol); 18:1(n-9)
(10.0–15.1 mol/100 mol); and 18:0 (12.2–13.0 mol/100 mol)
(Table 3
). Plasma DHA concentrations of rats fed DHA-containing oil as TG
and EE were 1.5–1.9 times that of control oil–fed rats. The PI values
of TG and EE DHA-fed rats were not different from controls (Table 3)
. The DHA oil–fed rats had more than three times the control
concentration of 20:5(n-3) in plasma total lipids.
|
|
. The DHA concentration in the liver total lipids was
higher in the DHA oil—fed groups, and the PI values of fatty acid were
1.9–2.7 times the control group (Table 3)
. Regardless of the dietary
oil ingested, the arachidonic acid [20:4(n-6)] concentration in the
liver was lower than that in plasma.
Kidney lipids did not differ among groups (Table 2)
. DHA in kidney
lipids of the DHA oil–fed rats was 4.8–5.4 mol/100 mol of the total
fatty acids, higher than that in the control oil–fed rats (Table 3)
.
PI values of kidney lipids of DHA oil–fed rats were 1.1–1.3 times
those of the control oil-fed rats.
Plasma -TOC concentrations were significantly lower in all three DHA
oil–fed groups, decreasing 44–70% (21.3 ± 2.8
µmol/L plasma, Fig. 1
). The plasma TBARS levels of the DHA groups were 107–131% greater
than those of the control group [4.0 ± 0.2 µmol
malondialdehyde (MDA)/L plasma]. Similarly, the plasma PCOOH
concentration was 90% greater in DHA oil–fed rats than that of
control oil–fed rats (46.7 ± 8.4 nmol/L plasma). No significant
differences were observed among the rats fed the DHA oil–containing
diets (Fig. 1)
.
|
-TOC concentrations were 40–74% lower among the DHA oil–fed
groups relative to the control group (48.8 ± 3.3 nmol/g liver,
Fig. 2
). The concentrations of liver TBARS were 22–35% greater in DHA
oil–fed rats relative to control rats (397 ± 12 nmol MDA/g
liver). Liver PCOOH levels were also higher among the DHA-fed
groups (70–110%) relative to the control, although no significant
difference was found among liver PEOOH levels (Fig. 2)
.
|
-tocopherol concentrations were 21–28% lower in DHA-fed
rats than in control rats (27.1 ± 1.5 nmol/g kidney, Fig. 3
). Kidney TBARS levels were slightly higher in DHA oil–fed rats,
whereas PCOOH levels were higher by 63–156% in DHA oil–fed rats
relative to control rats (TBARS, 529 ± 16 nmol MDA/g kidney;
PCOOH, 265 ± 40 pmol/g kidney). PEOOH levels in kidney were
higher (93–223%) in the DHA-fed rats than in controls (PEOOH, 203
± 20 pmol/g kidney).
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
, Song and Miyazawa 1997
). From these results, we expected beneficial
resistance of tissue membrane lipids toward oxidative stress when DHA
oil was ingested in the form of PL. Therefore, we examined whether
dietary DHA oil in the form of TG, EE and PL affected lipid metabolism
and tissue lipid peroxidation differently in rats.
Treatment with DHA oils changed the PUFA pattern of the tissue
membranes by increasing DHA [(n-3) fatty acid] content and by
decreasing concomitantly arachidonic acid [(n-6) fatty acid]. We
confirmed the findings of others that increases in (n-3) fatty acids
such as DHA and EPA in total plasma lipids occur in rats supplemented
with DHA oil in the form of TG, EE and PL (Table 3)
(Arbuckle et al. 1991
, Innis et al. 1995
). DHA [22:6(n-3)]
incorporation into plasma and liver was lower in DHA-PL–fed relative
to DHA-TG– and DHA-EE–fed rats. It is possible that DHA oil in the
form of PL was absorbed in the intestine less efficiently than DHA oil
in the form of TG and EE as a result of differences in the enzyme
activities of pancreatic lipases for TG and EE and of phospholipase for
PL. DHA-PL administration increased the oxidative stress of cell
membranes to the same extent as did DHA-TG or DHA-EE, even
though it did not increase (n-3) fatty acids relative to other DHA
oils. Perhaps there is a tissue concentration of DHA that is sufficient
for increased oxidative stress vulnerability.
Plasma TG are generally accepted as an independent risk factor for
heart disease (Davignon and Cohn 1996
). The previously
described hypotriacylglycerolemic effect of DHA-containing oil is
thought to be mediated by its inhibition of VLDL synthesis and
secretion in the liver (Herold and Kinsella 1986
,
Simopoulos 1991
, Thiery and Seidel 1987
,
Tremoli et al. 1995
, Vidgren et al. 1997
)
and by its enhancement of ß-oxidation of fatty acids in the liver
(Sanders et al. 1985
, Surette et al. 1992
). We found that dietary DHA oils exerted a significant
hypotriacylglycerolemic effect in the rats whose diets were
supplemented with DHA (2.14% of total energy intake), although kidney
lipid profiles were not affected (Table 2)
. When DHA was ingested in
the form of EE-type oil, plasma TG concentration was lowered more
than it was when it was ingested as TG- or PL-type oil. This may be
due to differences in rates of hydrolysis of DHA-containing oil by
lipases in the intestinal digest. Imaizumi et al. (1982)
suggested that dietary PL absorption may be inhibited by an increase in
the particle size of chylomicrons in the intestine. Ikeda et al. (1995)
reported that digestion and lymphatic transport of DHA
were influenced by lipid types in rats. We found that plasma free
cholesterol levels were decreased in rats fed the DHA oil diets
relative to those fed the control oil diet. This is not surprising
because the (n-3) fatty acid content of the DHA oil was higher than
that of the control oil. Dietary (n-3) fatty acids have previously been
demonstrated to reduce the amount of free cholesterol through its
conversion to cholesterol ester (Sugano et al. 1997
).
These results indicate that reduction of plasma TG and free cholesterol
by DHA oil is an important intervention in reducing the risk of
atherosclerosis, in view of the relationship to cardiovascular disease.
Although the ingestion of highly unsaturated oils such as fish and
DHA-containing oils may be part of interesting therapeutic
approaches for the prevention of this disease, there is the potential
to cause tissue membrane PL peroxidation and exhaust -TOC in
mammals. In our examination of oxidative stress, results in plasma,
liver and kidney showed no significant differences in lipid
peroxidation among the three different DHA oil forms, even though the
PL-type DHA oil had a lower PI value than TG- or EE-type DHA
oils. The PI values may not necessarily correlate with the lipid
peroxidation values. These discrepancies may be due to different
concentrations of the (n-3) and (n-6) fatty acids in the DHA oil–fed
groups and the control oil–fed group. The PI value is obtained from
both (n-3) and (n-6) fatty acids values; however, the (n-3) fatty acids
contribute a greater portion of those oxidized. There was a close
correlation between DHA oil–fed groups and the control oil–fed group
associated with corresponding amounts of DHA (plasma, r =
0.980, P < 0.05; liver, r = 0.969,
P < 0.05; kidney, r = 0.965, P < 0.05) or values of PLOOH (plasma, r = 0.985, P
< 0.05; liver, r = 0.971, P < 0.05;
kidney, r = 0.984, P < 0.05) or TBARS
(plasma, r = 0.966, P < 0.05; liver,
r = 0.965, P < 0.05; kidney, r =
0.986, P < 0.05). These results are consistent with
our previous observation that a fish oil diet increased the PLOOH
concentration of liver and plasma more than safflower oil, perilla oil
and olive oils, supporting the idea that a diet rich in DHA oils
significantly affects lipid peroxidation in vivo (Miyazawa et al. 1993
).
The incorporation of PUFA into tissue membranes after DHA oil ingestion
increases their susceptibility to free radical attack, -TOC
exhaustion and subsequent peroxidation in the digestive tract, blood
and tissue organelles (Alexander-North et al. 1994
,
Buckingham 1985
, Mouri et al. 1984
).
These results suggest that PUFA and tocopherol levels influence tissue
membrane susceptibility to lipid peroxidation. However, the different
forms of DHA oil did not cause different degrees of lipid peroxidation.
Thus, tissue peroxidative susceptibilities in oil-fed rats were
related to increases in corresponding tissue membrane
unsaturation as a result of dietary oil ingestion. Our present
results showed that the -TOC concentration in plasma, liver and
kidney of DHA oil–fed groups and the control oil–fed group was
inversely associated with corresponding amounts of DHA (plasma, r
= 0.746, P < 0.05; liver, r =
0.700, P < 0.05; kidney, r = 0.605,
P < 0.05) or values of PCOOH (plasma, r =
0.700, P < 0.05; liver, r = 0.650, P < 0.05; kidney, r = 0.678,
P < 0.05) or TBARS (plasma, r = 0.771,
P < 0.05; liver, r = 0.857, P < 0.05; kidney, r = 0.524, P < 0.05).
The similarity of -TOC reductions and the degree of lipid
peroxidation resulting from the ingestion of different forms of DHA oil
suggest that the decrease in -TOC or other changes in antioxidant
activity may be central to the increased lipid peroxidation in DHA
oil–fed rats. These observations are consistent with a study in which
a fish oil– supplemented diet increased the activities of catalase,
glutathione peroxidase and glutathione-S-transferase and
decreased glutathione levels in rat tissues, whereas vitamin E
cosupplementation with fish oil decreased antioxidant enzyme activities
(Atalay et al. 2000
). These data suggest that dietary
oils significantly affect the antioxidant defense in biomembranes,
which in turn was caused by a decrease of -TOC. Ando et al. (2000)
also observed that intake of fish oil (50 g/kg diet)
when supplemented with vitamin E (4.3 g/kg fish oil) did not increase
lipid peroxidation in rat organs, compared with rats fed safflower oil,
which was rich in (n-6) fatty acids. These results support the
hypothesis that feeding DHA-containing oil is sufficient to change
tissue membrane lipid content to high amounts of (n-3) fatty acids,
which can enhance the production of hydroperoxides and decrease the
antioxidant -TOC in target membranes. In addition, (n-3) fatty
acids, mainly DHA, are more likely targets for peroxidation than (n-6)
fatty acids. Therefore, the degree of DHA incorporation affects the
extent of lipid peroxidation, which is consistent with an increased
susceptibility to an oxidative stress found when certain cells were
cultured with DHA in the absence of -TOC (Igarashi and Miyazawa 2000
). Moreover, other clinical studies have
demonstrated that high doses of DHA-rich fish oil in the human
diet, as well as long-term treatments, affected serum, LDL and
erythrocyte susceptibility to lipid peroxidation by increasing levels
of (n-3) fatty acids and by decreasing the tocopherol content in these
organs (Korpela et al. 1999
, Palozza et al. 1996
).
Although dietary supplementation with DHA oil has shown preventive
value in relation to cardiovascular disease by a reduction in plasma TG
levels and possibly by inhibiting platelet function by reducing
arachidonic acid levels in tissue lipids, it may also be a health risk
because it substantially increases lipid peroxidation. This elevated
lipid peroxidation was seen in conjunction with increased DHA
incorporation and decreased levels of -TOC. Further studies will be
required to clarify the effects of long-term administration of DHA
oil on lipid metabolism and peroxidation. We conclude, therefore, that
DHA is able to exert a beneficial effect with regard to reducing the
risk of atherosclerosis, only if antioxidative protection against
oxidative stress is sufficient. Thus, our results suggest that DHA oil
interventions should be coupled with antioxidant therapy to minimize
the peroxidative damage of tissue lipids.
|
FOOTNOTES |
|---|
-TOC, -tocopherol; CL,
chemiluminescence; DHA, docosahexaenoic acid; EE, ethyl ester; FAME,
fatty acid methyl esters; MDA, malondialdehyde; PCOOH,
phosphatidylcholine hydroperoxide; PEOOH, phosphatidylethanolamine
hydroperoxide; PI, peroxidizability index; PL, phospholipid; PLOOH,
phospholipid hydroperoxide; PUFA, polyunsaturated fatty acid; TBARS,
thiobarbituric acid reactive substance; TG, triacylglycerol. 
Manuscript received July 31, 2000. Initial review completed August 15, 2000. Revision accepted September 11, 2000.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
1. Alexander-North L. S., North J. A., Kiminyo K. P., Buettner G. R., Spector A. A. Polyunsaturated fatty acids increase lipid radical formation induced by oxidant stress in endothelial cell. J. Lipid Res. 1994;35:1773-1785[Abstract]
2. American Institute of Nutrition Report of the American Institute of Nutrition ad hoc committee on standards for nutritional studies. J. Nutr. 1977;107:1340-1348
3. Ando K., Nagata K., Yoshida R., Kikugawa K., Suzuki M. Effect of n-3 polyunsaturated fatty acid supplementation on lipid peroxidation of rat organs. Lipids 2000;35:401-407[Medline]
4. Arbuckle L. D., Rioux F. M., Mackinnon M. J., Hrboticky N., Innis S. M. Response of (n-3) and (n-6) fatty acids in brain, liver, and plasma of piglets fed formula with increasing, but low levels of fish oil supplementation. J. Nutr. 1991;121:1536-1547
5. Atalay M., Laaksonen D. E., Khanna S., Kaliste-Korhonen E., Hanninen O., Sen C. K. Vitamin E regulates changes in tissue antioxidants induced by fish oil and acute exercise. Med. Sci. Sports Exerc. 2000;32:601-607[Medline]
6. Ave K. Quantitative determination of tocopherols by high-speed liquid chromatography. J. Nutr. Sci. Vitaminol. 1975;21:183-188
7.
Bartlett G. R. Phosphorus assay in column chromatography. J. Biol. Chem. 1959;234:466-468
8. Boreson C. E., Pardini L., Pardini R. S., Reitz R. C. Effects of dietary fish oil on human mammary carcinoma and on lipid-metabolizing enzymes. Lipids 1989;24:290-295[Medline]
9. Buckingham K. W. Effect of dietary polyunsaturated/saturated fatty acid ratio and dietary vitamin E on lipid peroxidation in the rat. J. Nutr. 1985;115:1425-1435
10. Buege J., Aust S. D. Microsomal lipid peroxidation. Methods Enzymol 1978;52:302-310[Medline]
11. Cho S.-Y., Miyashita K., Miyazawa T., Fujimoto K., Kaneda T. Autoxidation of ethyl eicosapentaenoate and docosahexaenoate. J. Am. Oil Chem. Soc. 1987;64:876-879
12. Davignon J., Cohn J. S. Triglycerides: a risk factor for coronary heart disease. Atherosclerosis 1996;124:S57-S64
13. Harris W. S. n-3 Fatty acids and lipoproteins: comparison of results from human and animal studies. Lipids 1996;31:243-252[Medline]
14.
Herold P. M., Kinsella J. E. Fish oil consumption and decreased risk of cardiovascular disease: a comparison of findings from animal and human feeding trials. Am. J. Clin. Nutr. 1986;43:566-598
15. Igarashi M., Miyazawa T. Do conjugated eicosapentaenoic acid and conjugated docosahexaenoic acid induce apoptosis via lipid peroxidation in cultured human tumor cells?. Biochem. Biophys. Res. Commun 2000;270:649-656[Medline]
16. Ikeda I., Sasaki E., Yasunami H., Nomiyama S., Nakayama M., Sugano M., Imaizumi K., Yazawa K. Digestion and lymphatic transport of eicosapentaenoic and docosahexaenoic acids given in the form of triacylglycerol, free acid and ethyl ester in rats. Biochim. Biophys. Acta 1995;1259:297-304[Medline]
17. Imaizumi K., Murata M., Sugano M. Effect of dietary polyunsaturated phospholipid on the chemical composition of mesenteric lymph chylomicrons and the excretion of steroids into bile and feces in rat. J. Nutr. Sci. Vitaminol. 1982;28:265-280
18. Innis S. M., Rioux F. M., Auestad N., Ackman R. G. Marine and freshwater fish oil varying in arachidonic, eicosapentaenoic and docosahexaenoic acids differ in their effects on organ lipids and fatty acids in growing rats. J. Nutr. 1995;125:2286-2293
19. Kates M. Techniques of lipidology. Burdon R. H. Knippenberg P. H. eds. Laboratory Techniques in Biochemistry and Molecular Biology 1986 Elsevier Amsterdam, The Netherlands.
20.
Kinsella J. E., Lokesh B., Stone R. A. Dietary n-3 polyunsaturated fatty acids and amelioration of cardiovascular disease: possible mechanisms. Am. J. Clin. Nutr. 1990;52:1-28
21. Korpela R., Seppo L., Laako J., Lilja J., Karjala K., Lahteenmaki T., Solatunturi E., Vapaatalo H., Tikkanen M. J. Dietary habits affect the susceptibility of low-density lipoprotein to oxidation. Eur. J. Clin. Nutr. 1999;53:802-807[Medline]
22. Lands W.E.M. Fish and Human Health 1990 Marcel Dekker New York, NY.
23. Lees R. S., Karel M. Omega-3 Fatty Acids in Health and Disease 1986 Academic Press New York, NY.
24. Leibowitz B. E., Hu M.-L., Tappel A. L. Lipid peroxidation in rat tissue slices: effect of dietary vitamin E, corn oil-lard and menhaden oil. Lipids 1990;25:125-129[Medline]
25. Miyazawa T. Determination of phospholipid hydroperoxides in human blood plasma by a chemiluminescence-HPLC assay. Free Radic. Biol. Med. 1989;7:209-217[Medline]
26. Miyazawa T. Membrane phospholipid hydroperoxides as estimated by chemiluminescence: the effect of dietary polyunsaturated fatty acids. Essential Fatty Acids and Eicosanoids 1993 American Oil Chemists’ Society Champaign, IL.
27. Miyazawa T., Fujimoto K., Suzuki T., Yasuda K. Determination of phospholipid hydroperoxide using luminol chemiluminescence-high performance liquid chromatography. Methods Enzymol 1994;233:324-332[Medline]
28. Miyazawa T., Suzuki T., Fujimoto K. Age-dependent accumulation of phosphatidylcholine hydroperoxide in the brain and liver of the rat. Lipids 1993;28:789-793[Medline]
29. Miyazawa T., Suzuki T., Fujimoto K., Yasuda K. Chemiluminescent simultaneous determination of phosphatidylcholine hydroperoxide and phosphatidylethanolamine hydroperoxide in the river and brain of the rat. J. Lipid Res. 1992;33:1051-1059[Abstract]
30.
Mouri K., Ikesu H., Esuka T., Igarashi O. Influence of marine oil intake upon levels of lipids, -tocopherol and lipid peroxidation in serum and liver of rats. J. Nutr. Sci. Vitaminol. 1984;30:307-318
31.
Palozza P., Sgarlata E., Luberto C., Piccioni E., Anti M., Marra G., Armelao F., Franceschelli P., Bartoli G. M. n-3 fatty acids induce oxidative modifications in human erythrocytes depending on dose and duration of dietary supplementation. Am. J. Clin. Nutr. 1996;64:297-304
32.
Reddy B. S., Burill C., Rigotty J. Effect of diets high in 
-3 and -6 fatty acids on initiation and postinitiation stages of colon carcinogenesis. Cancer Res 1991;51:487-491
33. Sakaguchi M., Imray C., Davis A., Rowley S., Jones C., Lawson N., Keighley M.R.B., Baker P. R., Neoptolemos J. P. Effects of dietary n-3 and saturated fats on growth rates of the human colonic cancer cell lines SW-620 and LS 174T in vivo in relation to tissue and plasma lipids. Anticancer Res 1990;10:1763-1768[Medline]
34. Sanders T. A., Sullivan D. R., Reeve J., Thompson G. R. Triglyceride-lowering effect of marine polyunsaturates in patients with hypertriglyceridemia. Atherosclerosis 1985;5:459-465
35.
Simopoulos A. P. Omega-3 fatty acids in health and disease and in growth and development. Am. J. Clin. Nutr. 1991;54:438-463
36. Song J. H., Inoue Y., Miyazawa T. Oxidative stability of docosahexaenoic acid-containing oils in the form of phospholipids, triacylglycerols, and ethyl esters. Biosci. Biotechnol. Biochem. 1997;61:2085-2088[Medline]
37. Song J. H., Miyazawa T. Superior oxidative stability of docosahexaenoic-enriched oils in the form of phospholipids. J. Food Lipids 1997;4:109-117
38. Sugano M., Makino N., Yanaga T. Effect of dietary omega-3 eicosapentaenoic acid supplements on cholesteryl ester transfer from HDL in cholesterol-fed rabbits. Biochim. Biophys. Acta 1997;1346:17-24[Medline]
39. Surette M. E., Whelan J., Broughton K. S., Kinsella J. E. Evidence for mechanisms of the hypotriglyceridemic effect of n-3 polyunsaturated fatty Acids. Biochim. Biophys. Acta 1992;1126:199-205[Medline]
40. Thiery J., Seidel D. Fish oil feeding results in an enhancement of cholesterol-induced atherosclerosis in rabbits. Atherosclerosis 1987;63:53-56[Medline]
41.
Tremoli E., Maderna P., Marangoni F., Colli S., Eligini S., Catalano I., Angeli M. T., Pazzucconi F., Gianfranceschi G., Davi G., Stragliotto E., Sirtori C. R., Galli C. Prolonged inhibition of platelet aggregation after n-3 fatty acid ethyl ester ingestion by healthy volunteers. Am. J. Clin. Nutr. 1995;61:607-613
42. Vidgren H. M., Agren J. J., Schwab U., Rissanen T., Hanninen O., Uusitupa M. I. Incorporation of n-3 fatty acids into plasma lipid fractions, and erythrocyte membranes and platelets during dietary supplementation with fish, fish oil, and docosahexaenoic acid-rich oil among healthy young men. Lipids 1997;32:697-705[Medline]
43. Witting L. A., Horwitt M. K. Effect of degree of fatty acid unsaturation in tocopherol deficiency-induced creatinuria. J. Nutr. 1964;82:19-23[Medline]
44. Yagi K. A simple fluorometric assay for lipoperoxide in blood plasma. Biochem. Med. 1976;15:212-216[Medline]
This article has been cited by other articles:
|
|
 |
|
  P. Nieminen, A.-M. Mustonen, V. Karja, J. Asikainen, and K. Rouvinen-Watt Fatty Acid Composition and Development of Hepatic Lipidosis During Food Deprivation--Mustelids as a Potential Animal Model for Liver Steatosis Experimental Biology and Medicine, March 1, 2009; 234(3): 278 - 286. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-F. Xiao, D. C. Sigg, M. R. Ujhelyi, J. J. Wilhelm, E. S. Richardson, and P. A. Iaizzo Pericardial delivery of omega-3 fatty acid: a novel approach to reducing myocardial infarct sizes and arrhythmias Am J Physiol Heart Circ Physiol, May 1, 2008; 294(5): H2212 - H2218. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Tsuzuki, Y. Tokuyama, M. Igarashi, and T. Miyazawa Tumor growth suppression by {alpha}-eleostearic acid, a linolenic acid isomer with a conjugated triene system, via lipid peroxidation Carcinogenesis, August 1, 2004; 25(8): 1417 - 1425. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Tsuzuki, M. Igarashi, and T. Miyazawa Conjugated Eicosapentaenoic Acid (EPA) Inhibits Transplanted Tumor Growth via Membrane Lipid Peroxidation in Nude Mice J. Nutr., May 1, 2004; 134(5): 1162 - 1166. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. P. Rotstein, L. E. Politi, O. L. German, and R. Girotti Protective Effect of Docosahexaenoic Acid on Oxidative Stress-Induced Apoptosis of Retina Photoreceptors Invest. Ophthalmol. Vis. Sci., May 1, 2003; 44(5): 2252 - 2259. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Moreno, T. Carbonell, T. Sanchez, S. Miret, and M. T. Mitjavila Olive Oil Decreases both Oxidative Stress and the Production of Arachidonic Acid Metabolites by the Prostaglandin G/H Synthase Pathway in Rat Macrophages J. Nutr., August 1, 2001; 131(8): 2145 - 2149. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
