Rat Liver Phospholipid Research Articles

НОРМАЛІЗАЦІЯ ФІТОПРЕПАРАТОМ «КВЕРТУЛІН» ОБМІНУ ЕСЕНЦІАЛЬНИХ ЖИРНИХ КИСЛОТ ФОФСОЛІПІДІВ ПЕЧІНКИ ЩУРІВ, ЯКІ ОТРИМУВАЛИ ПАЛЬМОВУ ОЛІЮ НА ТЛІ ДИСБІОЗУ

Keywords: liver, phospholipids, essential fatty acids, palm oil, dysbiosis, herbal medicine. Aim. To study the effect of the phytopreparation kvertulin on the processes of biosynthesis of PUFA of liver phospholipids in rats treated with palm oil against the background of dysbiosis. Methods. Rats consumed a fat-free diet (group 1), a diet with 15 % palm oil (group 2), a diet with 15 % palm oil on the background of experimental dysbiosis (group 3) and a diet with 15 % palm oil on background of dysbiosis + kvertulin. The duration of the experiment is 40 days. The content of fatty acids in liver phospholipids was determined by gas chromatography. The ratio of the PUFA content was used to calculate the “activity” of ω-3-desaturase, the intensity of synthesis of arachidonic acid, and the intensity of synthesis of docosahexaenoic acid. Results: In rats of the 3rd group, which received palm oil against the background of dysbiosis, there was a decrease in the content of ω-3 PUFA, an increase in the ratio of ω-6 / ω-3 PUFA, and a decrease in the “activity” of ω-3-desaturase. In rats of the 4th group, which received kvertulin, the content of PUFA was completely restored and the “activity” of enzymes of their biosynthesis was normalized. Conclusion. The use of the phytopreparation kvertulin normalizes the endogenous biosynthesis of PUFA of liver phospholipids in rats consuming palm oil against the background of dysbiosis.

Antioxidant Activity of Flavonoid Rich Fraction of Ligaria cuneifolia (Loranthaceae).

Ligaria cuneifolia (Ruiz & Pav.) Tiegh. (Loranthaceae), the 'Argentine mistletoe', is a hemiparasite species largely used in folk medicine. The aim of this study was to evaluate the antioxidant activity using in vitro, ex vivo, and in vivo methods. A screening of phenolics was performed by UV spectroscopy on different fractions. The antioxidant capacity was evaluated in vitro by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH. ) assay on a crude extract (CE), ethyl acetate fraction (EAF), and aqueous fraction (AF). The results suggest that EAF concentrates the antioxidant capacity and was selected for further analysis. Capillary electrophoresis was employed to monitor the individual antioxidant capacity and the potential contributors to this effect. Ex vivo assays showed an efficient inhibition of tert-butyl hydroperoxide-induced rat liver phospholipid oxidation, as well as rat brain autoxidation, and H2 O2 -induced DNA damage in blood monocytes. In vivo, the topical application of EAF significantly decreased skin chemiluminescence in a mice model.

Liver phospholipids fatty acids composition in response to different types of diets in rats of both sexes

BackgroundDietary intake influence changes in fatty acids (FA) profiles in liver which plays a central role in fatty acid metabolism, triacylglycerol synthesis and energy homeostasis. We investigated the effects of 4-weeks treatment with milk- and fish-based diet, on plasma biochemical parameters and FA composition of liver phospholipids (PL) in rats of both sexes.MethodsAdult, 4 months old, Wistar rats of both sexes, were fed with different types of diets: standard, milk-based and fish-based, during 4 weeks. Analytical characterization of different foods was done. Biochemical parameters in plasma were determined. Fatty acid composition was analyzed by gas-chromatography. Statistical significance of FA levels was tested with two-way analysis of variance (ANOVA) using the sex of animals and treatment (type of diet) as factors on logarithmic or trigonometric transformed data.ResultsOur results showed that both, milk- and fish-based diet, changed the composition and ratio of rat liver phospholipids FA, in gender-specific manner. Initially present sex differences appear to be dietary modulated. Although, applied diets changed the ratio of total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), and effects were gender specific. Milk-based diet lowered SFA and elevated MUFA in males and increased PUFA in females vs. standard diet. The same diet decreased n-3, increased n-6 and n-6/n-3 ratio in males. Fish-based diet increased n-3, decreased n-6 and n-6/n-3 ratio vs. standard and milk-based diet in females. However, the ratio of individual FA in liver PL was also dietary-influenced, but with gender specific manner. While in females fish-based diet decreased AA (arachidonic acid) increased level of EPA (eicosapentaenoic acid), DPA (docosapentaenoic acid) and DHA (docosahexaenoic acid), the same diet elevated only DHA levels in males.ConclusionGender related variations in FA composition of rat liver PL were observed, and results have shown that those initial differences could be significantly modulated by the type of diet. Furthermore, the modulatory effects of milk- and fish-based diets on liver phospholipids FA profiles appeared to be sex-specific.

Elucidation of phosphatidylcholine isomers using two dimensional liquid chromatography coupled in-line with ozonolysis mass spectrometry

In this study, two dimensional (2D) liquid chromatography (LC) was coupled in-line with ozonolysis-mass spectrometry (O3-MS) for the elucidation of phosphatidylcholine (PC) structures in phospholipid extracts. In O3-MS, PC molecules carried by mobile phase pass through a length of gas-permeable tubing surrounded by ozone vapor resulting in oxidative cleavage of double bonds. The characteristic aldehyde products are then directly analyzed by eletrospray ionization (ESI)-MS, allowing assignment of the double bond positions within the PC fatty acyl chains. The on-line 2D-LC method employs hydrophilic interaction chromatography as the first dimension to separate phospholipid classes and reversed phase chromatography in the second dimension to further separate PC molecular species. Thus, by combing the separation power of 2D-LC with in-line O3-MS (2D-LC/O3-MS), PC species in complex mixtures can be identified including the detailed structure of their two fatty acid chains. When the 2D-LC/O3-MS method was applied to a rat liver phospholipid extract, 19 PC molecular species were identified with fatty acid isomers unambiguously assigned.

Жирнокислотний склад фосфоліпідів плазми крові, печінки і скелетних м’язів щурів за експериментальної гіперхолестеринемії та впливу риб’ячого жиру

Fatty acid composition of phospholipids which are the main structural elements of the cytoplasmic and cell membranes studied. It was established that in the fatty acid composition of blood plasma, liver, skeletal muscles phospholipids in rats with experimental hyperсholesterinemia an increase in saturated fatty acids with even and odd number of carbon atoms in chain and monounsaturated fatty acids of family n-9 took place. However, the relative content of polyunsaturated fatty acids of families n-3 and n-6 decreased. Inverse patterns due to the above fatty acids in fatty acid composition of blood plasma, liver, skeletal muscles phospholipid in rats with experimental hypercholesterinemia corrected by fish oil. It decreased the relative content of saturated fatty acids with even and odd number of carbon atoms in chain and monounsaturated fatty acids of family n-9, and increased the relative content of polyunsaturated fatty acids of families n-3 and n-6. Feeding with fish oil corrected fatty acid composition of blood plasma, liver and skeletal muscle phospholipids in rats with experimental hypercholesterolemia. Keywords: fatty acid composition, phospholipids, experimental hiperсholeste­rinemia, fish oil, rats.

A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics

A shotgun lipidomics approach that allowed the analysis of eight lipid classes directly from crude extracts of the soil bacterium Sinorhizobium meliloti is presented. New MS-MS transitions are reported for the analysis of monomethylphosphatidylethanolamines, dimethylphosphatidylethanolamines, and three bacterial non-phosphorus-containing lipid classes [sulfoquinovosyldiacylglycerols, ornithines, and diacylglyceryl-(N,N,N-trimethyl)-homoserines]. Unique MS-MS transitions allowed the analysis of isomeric species from various lipid classes without chromatography. Analyses required small sample amounts and minimal preparation; thus, this methodology has excellent potential to be used as a screening tool for the analysis of large numbers of samples in functional genomics studies. FA distributions within lipid classes of S. meliloti are described for the first time, and the relative positions of fatty acyl substituents (sn-1, sn-2) in phospholipids are presented. FA distributions in diacylglyceryl-(N,N,N-trimethyl)-homoserines were identical to those of phospholipids, indicating a common biosynthetic origin for these lipids. The method was applied to the analysis of mutants deficient in the PhoB regulator protein. Increased lipid cyclopropanation was observed in PhoB-deficient mutants under P(i) starvation.

Incorporation of valproic acid into phospholipids in rat liver and brain

The mechanism of action of valproic acid’s (VPA) mood stabilizing, anti-epileptic, and migraine prevention properties is still not clearly understood. Its incorporation into phospholipids may play a role in its diverse biological effects. To study in vivo incorporation, rats were injected intraperitoneally with 178 g/kg of VPA twice daily for 2 weeks. After sacrifice, total lipids were extracted from rat liver and brain with chloroform:methanol (2:1) and NaCl for phase separation. Phospholipids were separated from free VPA and other neutral lipids by TLC. Then, methylesters were prepared from fatty acids (including VPA) using 14% BF3 in methanol or alternatively using sodium methoxide. VPA-methylesters were analyzed using GC/chemical ionization MS with positive ion detection. Of 9 rats treated with VPA, VPA phospholipids were found in livers of all 9 animals and in brains of 2 of the animals. These results demonstrate that VPA is incorporated into phospholipids in rat liver and rat brain after two weeks of i.p. injections. Alteration of phospholipid signaling pathways by VPA phospholipids may be part of the mechanism of action of sodium valproate’s mood stabilizing, anti-epileptic, and migraine prevention properties.

Absorption and metabolism of conjugated α-linolenic acid given as free fatty acids or triacylglycerols in rats

BackgroundConjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids which have been extensively studied in the past two decades. However, conjugated octadecatrienoic acid such as cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15, recently identified, have not been extensively investigated. This work presents bioavailability and tissue incorporation of a mixture of conjugated octadecatrienoic (CLnA) acids ingested as free fatty acids (FFA) and triacylglycerols (TAG).ResultsMale Wistar rats were fed rumenic acid (RA: cis-9,trans-11 18:2) and a CLnA mixture (cis-9,trans-11,cis-15 18:3 and cis-9,trans-13,cis-15 18:3) as FFA and TAG for 8 days. RA and CLnA were both totally absorbed when given as FFA as well as TAG. Both isomers of CLnA as FFA or TAG were incorporated into neutral lipids. Metabolites up to 22:6 conjugated isomers were present in liver and plasma phospholipids of rats fed the CLnA diets.ConclusionFinally, CLnA are as well absorbed as RA in vivo and their incorporation into tissues and bioconversion are similar when ingested as FFA or as TAG.

Effects of oral androstenedione on phospholipid fatty acids, ATP, caspase-3, prostaglandin E 2 and C-reactive protein in serum and livers of pregnant and non-pregnant female rats

Androstenedione, a steroidal dietary supplement taken to enhance athletic performance, could affect serum and liver lipid metabolism, induce liver toxicity or alter inflammatory response depending on dose and duration of exposure. Pregnancy could further exaggerate these effects. To examine this, mature female rats were gavaged with 0, 5, 30 or 60 mg/kg/day androstenedione beginning two weeks prior to mating and continuing through gestation day 19. Non-pregnant female rats were gavaged over the same time frame with 0 or 60 mg/kg/day androstenedione. Serum was collected and livers were removed from dams on gestation day 20 and from non-pregnant rats after 5 weeks of treatment. Androstenedione had no effect on serum total cholesterol, triglycerides or HDL-cholesterol, but significantly decreased C-reactive protein in pregnant rats and prostaglandin E 2 in serum of both pregnant and non-pregnant rats. There were treatment related decreases in liver ATP and, to a lesser degree, caspase-3 and no change in alkaline phosphatase of pregnant female rats. Androstenedione decreased docosahexaenoic acid in both serum and liver phospholipids of pregnant female rats. In conclusion, oral androstenedione did not result in overt hepatotoxicity in pregnant female rats, but produced modest changes in lipid metabolism and may impair regeneration of injured hepatic cells or tissue.

ESI-MS quantitation of increased sphingomyelin in Niemann-Pick disease type B HDL

HDLs have been proposed to have antiatherogenic properties because of their role in reverse cholesterol transport as lipid acceptors. To elucidate the phospholipid profile of these particles, we used electrospray ionization mass spectrometry to examine the phosphatidylcholine (PC) and sphingomyelin (SM) composition of HDLs purified from plasma and nascently generated in vitro from fibroblasts. We also quantitatively compared the phospholipids present in these lipoproteins between normal and Niemann-Pick disease type B (NPD-B) subjects characterized by sphingomyelinase (SMase) deficiency. We demonstrated that plasma HDLs from NPD-B were significantly enriched in SM by an average of 28%, particularly the palmitoyl SM (with an increase of 95%), which accounted for approximately 25-44% of total SM molecular species. Similarly, we observed an increase of approximately 63% in total SM levels in nascent HDLs prepared from NPD-B fibroblasts. Although PC levels in nascent HDLs were comparable between control and NPD-B cells, there was a 95% increase in total PC levels similar to that of SM in plasma HDLs extracted from NPD-B subjects. These data provide insight into the structure of HDLs and identify potential new roles for SMase in lipoprotein metabolism.

Effect of linseed oil supplementation on concentrations of (n‐3) polyunsaturated fatty acids in liver phospholipids of rats fed diets containing either an oil rich in conjugated linoleic acids, sunflower oil or high‐oleic acid sunflower oil

This study investigated the metabolism of alpha-linolenic acid and the formation of eicosanoids in rats fed diets with three different dietary fats (30 g/kg diet): either a conjugated linoleic acid (CLA) preparation with a high concentration of cis-9, trans-11 CLA (32.2 g/100 g) and trans-10, cis-12 CLA (33.3 g/100 g) and a low concentration of linoleic acid (0.5 g/100 g), sunflower oil (SFO) with a high concentration of linoleic acid or high-oleic acid sunflower oil (HO-SFO) with a high concentration of oleic acid. Basal diets with those oils were fed for 4 weeks. In the fifth week, the same diets supplemented with 50 g of linseed oil/kg as a source of alpha-linolenic acid were fed. To study the effect of the oils on the metabolism of alpha-linolenic acid, the amounts of individual (n-3) polyunsaturated fatty acids (PUFA) in liver phospholipids (phosphatidyl choline and phosphatidyl ethanolamine) were determined; to study the effect on eicosanoid formation, the concentrations of various two-series eicosanoids in liver and plasma, the activity of the secretory phospholipase A2 and the relative mRNA concentrations of cyclooxygenases-1 and 2 in the liver were measured. Rats fed the CLA diets had the highest concentrations of long chain (n-3) PUFA deriving from delta6, delta5 and 14-desaturation of alpha-linolenic acid in liver phospholipids; rats fed the SFO diet had the lowest concentrations of those fatty acids. The concentration of arachidonic acid in liver phospholipids and the concentrations of eicosanoids in liver and plasma were lowest in rats fed the CLA diet and highest in the rats fed the SFO diet. Moreover, rats fed the CLA diet had a higher gene expression of delta6-desaturase in the liver than the other two groups of rats. The results show that feeding the CLA oil reduced the formation of arachidonic acid and eicosanoids but enhanced the formation of long chain (n-3) PUFA and their incorporation into tissue lipids when compared with feeding SFO or HO-SFO.

Effects of dietary linseed, evening primrose or fish oils on fatty acid and prostaglandin E 2 contents in the rat livers and 7,12-dimethylbenz[ a]anthracene-induced tumours

We examined the influence of diets supplemented with fish and vegetable oils on fatty acid and prostaglandin E 2 (PGE 2) contents in livers of non-7,12-dimethylbenz[ a]anthracene (DMBA)- and DMBA-treated rats, and in DMBA-induced tumours. Decreased concentrations of saturated fatty acids and increased unsaturated fatty acid levels were observed in liver phospholipids of rats fed these oils. There was a marked difference in the concentrations of fatty acids found in the tumours and those present in liver lipids. Oleic acid was the main unsaturated fatty acid found in the tumour tissue. Both liver and tumour PGE 2 contents were clearly correlated to the diet. The PGE 2 concentrations were decreased in livers and tumours of rats fed fish (FO) and linseed oils (LO).

Molecular species composition of rat liver phospholipids by ESI-MS/MS: the effect of chromatography

Using electrospray ionization tandem mass spectrometry (ESI-MS/MS) this study shows that the loss of glycerophospholipid (GPL) after chromatography was unevenly distributed across the GPL molecular species. Both TLC and HPLC caused a preferential loss of GPL with 0 to 3 double bonds: 20% and 7.2% for choline glycerophosphates (PC) and 19.7% and 7.5% for ethanolamine glycerophosphates (PE), respectively. A consequence of these losses was that GPLs containing fatty acids with four or more double bonds had a greater contribution to the total after chromatography. ESI-MS/MS analysis also showed that PC molecular species with four or more double bonds migrated at the front of the TLC band of PCs. GPLs extracted from TLC plates occasionally contained PCs that were smaller than those in the original extract. These low molecular mass PCs were easily reduced to alcohols and formed derivatives with 2,4-dinitrophenylhydrazine, suggesting that aldehydes were generated by the oxidation of unsaturated fatty acids. Directly analyzing lipid extracts by ESI-MS/MS without preliminary chromatographic separation gives an accurate distribution of GPL molecular species in lipid mixtures. However, the ionization of the phospholipids in the electrospray jet maximized at relatively low concentrations of GPL. There was a linear response between phospholipid mass and ion intensity for concentrations around 1-2 nmol/ml for both PC and PE. The total ion intensity continued to increase with concentrations above 1-2 nmol/ml, but the response was non-linear.

Supplementation of orotic acid to the casein, but not to egg protein, soy protein, or wheat gluten diets, increases serum ornithine carbamoyltransferase activity

Effects of dietary supplementation of orotic acid to a diet containing the casein protein were compared with diets containing egg protein, soy protein, or wheat gluten on lipid levels in the liver and serum and activities of ornithine carbamoyltransferase (OCT) and alanine aminotransferase in the serum of rats. We found that supplementation of orotic acid to each diet increased the contents of the liver total lipids, triacylglycerol, and phospholipids compared with those not supplemented. The contents of liver total lipids, triacylglycerol, cholesterol, and phospholipids in rats fed the casein diet were significantly higher than those of rats fed the other three diets when orotic acid was supplemented. The levels of triacylglycerol, cholesterol, and phospholipids in the serum of rats fed the casein diet were markedly decreased by addition of orotic acid. The supplementation of orotic acid significantly increased the activities of both serum OCT and alanine aminotransferase in rats fed the casein diet, but not in rats fed the other diets. In conclusion, liver lipid accumulation induced by dietary orotic acid depends on the type of dietary protein. The enhancement of serum OCT activity may result from liver lipid accumulation in rats fed the casein diet supplemented with orotic acid, demonstrating hepatic damage.

Effect of long term fluoride exposure on lipid composition in rat liver

Chronic fluorosis can severely damage many systems of human body, but its pathogenesis is unclear. Normal composition and structure of cellular membrane lipids are a basic factor to maintain cell function. In this investigation, cellular membrane lipids of the liver were analysed after a long term fluoride treatment for rats and the results are discussed in order to give an explanation for the pathogenesis of this disease. Wistar rats were supplied with drinking water containing either 30 or 100 ppm fluoride (NaF) for seven months. Contents of phospholipid and neutral lipid in rat liver were analyzed by high-performance liquid chromatography, and fatty acid composition from individual phospholipids was measured by gas chromatography. Results showed that the total liver phospholipid content decreased in the rats treated with high dose of fluoride due to a lower content of phosphatidylethanolamine (PE), phosphatidylcholine (PC) and phosphatidylserine (PS). Among the fatty acid compositions of PE and PC in the livers of fluoride poisoned animals, the proportion of polyunsaturated fatty acids (20:4 and 22:6) decreased, whereas saturated fatty acids (16:0 and 18:0) increased. No changes could be detected in the amounts of liver cholesterol and dolichol. Total ubiquinone contents in rat liver were reduced by 11% in the group treated with 30 ppm fluoride and by 42% in the group treated with 100 ppm fluoride. In the subclasses of ubiquinone, both ubiquinone-9 and ubiquinoine-10 amounts decreased after fluoride treatment. These modifications of membrane lipids might be induced by oxidative stress, which might be an important factor in the pathogenesis of chronic fluorosis.

Folate Administration Increases n-3 Polyunsaturated Fatty Acids in Rat Plasma and Tissue Lipids

It has been shown that folic acid deficiency can modify polyunsaturated fatty acid (PUFA) metabolism and thus could contribute to the development of cardiovascular diseases. We have studied the effect of folate administration on fatty acid composition of plasma, platelet, erythrocyte, intestinal and liver lipids. Two groups of rats were daily injected with either saline solution (control group) or 5-methyl-tetrahydrofolate (MTHF) solution (MTHF group) for 15 days. Changes induced by folate treatment on n-6 PUFA were not very significant. Linoleic acid only decreased in liver and intestinal phospholipids of MTHF rats whereas arachidonic acid was unaffected by folate administration. However, n-3 PUFA significantly increased in plasma lipid fractions and in platelet, erythrocyte and intestinal phospholipids. It is well known that n-3 PUFA show antithrombotic properties. Thus, the increase of n-3 PUFA observed after MTHF administration might contribute to the prevention of vascular disorders.

Alterations of Rat Liver Phospholipid Composition Induced by Oral Thalidomide

In an attempt to elucidate the effects of oral thalidomide on liver phospholipid composition, doses of 1 and 3 mg/kg/day of thalidomide were orally administered to two groups of female Wistar rats (7 animals each), respectively, over a period of 60 days. Control animals (n = 7) received corresponding quantities of the vehicle alone. Chromatographic analysis and quantitative determination of the isolated phospholipid classes revealed statistically significant alterations of phospholipid fractions in the liver of the animals treated with the higher thalidomide dose (3 mg/kg/day). These alterations may be associated with changes in the metabolic activity, ionic transport and cell-cell interactions of the hepatic cellular components.

Diphenylacetaldehyde-generated excited states promote damage to isolated rat liver mitochondrial DNA, phospholipids, and proteins

This work studies damage to rat liver mitochondrial protein, lipid, and DNA caused by electronically excited states generated by cytochrome c-catalyzed diphenylacetaldehyde enol oxidation to triplet benzophenone. The extension of lipid peroxidation was estimated by production of thiobarbituric acid–reactive substances and by formation of Schiff bases with membrane proteins, evaluated by SDS-polyacrylamide gel electrophoresis. Concomitant with DPAA-driven mitochondrial permeabilization, extensive mtDNA fragmentation occurred and DNA adducts with aldehydes—products of fatty acid oxidation—were observed. The degree of lipid peroxidation and mtDNA alterations were significantly decreased by butylated hydroxytoluene, a potent peroxidation chain breaker. The lipid peroxidation process was also partially inhibited by the bioflavonoid rutin and urate totally prevented the mitochondrial transmembrane potential collapse. In all cases, the mitochondrial damage was dependent on the presence of phosphate ions, a putative bifunctional catalyst of carbonyl enolization. These data are consistent with the notion that triplet ketones may act like alkoxyl radicals as deleterious reactive oxygen species on biologic structures. Involvement of singlet dioxygen formed by triplet-triplet energy transfer from benzophenone in the model reaction with DPAA/cytochrome c in the presence of DCP liposomes was suggested by quenching of the accompanying chemiluminescence upon addition of histidine and lycopene.

A comparison of the metabolism of [3- 14C]-labeled 22- and 24-carbon ( n−3) and ( n−6) unsaturated fatty acids by rat testes and liver

The unsaturated fatty acid composition of phospholipids from different tissues frequently varies. Rat liver phospholipids contain esterified 22:6( n−3) while 22:5( n−6) is the major esterified 22-carbon acid in testes phospholipids. Both testes and liver synthesize polyunsaturated fatty acids. Microsomes, particularly from liver, have been used extensively to measure reaction rates as they relate to polyunsaturated fatty acid and phospholipid biosynthesis. None of these rate studies explain why specific acids are synthesized and subsequently esterified. In this study we compared the metabolism of [3- 14C]-labeled ( n−3) and ( n−6) acids when injected via the tail vein, as a measure of hepatic metabolism, versus when they were injected directly into the testes. Liver preferentially metabolizes [3- 14C]-labeled 24:5( n−3) and 24:6( n−3) to yield esterified 22:6( n−3), when compared with the conversion of [3- 14C]-labeled 24:4( n−6) and 24:5( n−6) to yield 22:5( n−6). Both 24-carbon ( n−3) acids were also converted to 22:5( n−3) but no labeled 22:4( n−6) was detected after injecting the two 24-carbon ( n−6) acids. Differences in the hepatic metabolism of 24-carbon ( n−3) and ( n−6) acids to 22:6( n−3) and 22:5( n−6), versus their partial β-oxidation to 22:5( n−3) and 22:4( n−6), are important in vivo controls. Surprisingly, in testes a higher percentage of radioactivity was found in esterified 22:6( n−3) versus 22:5( n−6) following injections, respectively, of [3- 14C]-labeled 22:5( n−3) versus 22:4( n−6), which is the corresponding metabolic analog. Corresponding pairs of 24-carbon ( n−3) and ( n−6) acids, as they relate to metabolism, were processed in similar ways by testes. The relative absence of esterified 22-carbon ( n−3) fatty acids, versus the abundance of 22- and 24-carbon ( n−6) acids in testes phospholipids, does not appear per se to be due to differences in the ability of testes to metabolize ( n−3) and ( n−6) fatty acids. It remains to be determined if there is selective uptake of specific fatty acids by testes for use as precursors to synthesize polyunsaturated fatty acids.

Effect of dietary fish oil (active EPA-30) on liver phospholipids in young and aged rats

We explored the uses of fish oil (active EPA-30) as a source of eicosapentaenate (EPA; 20:5 n-3), to young and old rats. We treated three subgroups of rats each comprising 20 young or old rats, respectively. The first group was kept on the basal ration (lab-pellet) as control diet, the second group was fed semi-purified diets contained 5% pig-fat (n-3 fatty acids deficient diet). The third group was fed a modified diet in which 50% of pig-fat was replaced by active EPA-30. Livers of young rats fed pig-fat had a drastic decrease in the amount of phosphatidylethanolamine (PE) and omega-3 polyunsaturated fatty acids (EPA, 20:5 n-3 and docosahexaenoic, DHA, 22:6 n-3) and compensatory increase of phosphatidylcholine, saturated fatty acids and n-6 polyunsaturated fatty acids in the liver phospholipids. In contrast, the liver of young rats fed active EPA-30 had large amounts of PE and concomitant enrichment in polyunsaturated fatty acids. The liver of old rats, fed on active EPA-30 supplemented diet had lower amounts of PE and there were no significant changes in the phospholipid fatty acid composition.