The effect of dietary menhaden,olive, and coconut oil fed with three levels of vitamin E on plasma and liver lipids and plasma fatty acid composition in rats

The effect of dietary fats with varying degrees of unsaturation in the presence of different concentrations of vitamin E on tissue lipid levels was studied in rats. Rats were fed either menhaden oil, olive oil or coconut oil at 15% levels with either 0.1, 0.3 or 0.6 mg/g of vitamin E as alpha-tocopherol for four weeks. Rat serum and liver were analyzed for total cholesterol, HDL-cholesterol, triacylglycerol and phospholipids. In addition, fatty acid composition of serum lipids was also analyzed. Serum total cholesterol and triacylglycerol were significantly lower in rats fed menhaden oil than in those fed olive or coconut oil, while the HDL-cholesterol was significantly higher in serum of rats fed menhaden and olive oil than in those fed coconut oil. Levels of vitamin E in the diet had only a significant effect on serum cholesterol and liver phospholipids. The Pearson correlation coefficient showed a significant positive relationship between serum triacylglycerol and total cholesterol, and a negative correlation between triacylglycerol and HDL-cholesterol, and between total and HDL-cholesterol.In the liver, total cholesterol was significantly higher in rats fed coconut oil than in rats fed menhaden oil. Total liver phospholipids were lower in rats fed either coconut oil or olive oil compared to those fed menhaden oil, especially with higher levels of vitamin E intake. Higher levels of vitamin E in the diet appear to increase triacylglycerol and phospholipids in livers of rats fed menhaden oil. In the liver a significant negative correlation was observed between phospholipids and cholesterol. The type and degree of unsaturation (polyunsaturated fatty acids in menhaden oil, monounsaturated fatty acids in olive oil and saturated fatty acids in coconut oil) significantly affected plasma and tissue lipids.     

The lipid composition of human testis in testicular feminization syndrome

Testicular tissues obtained from 12 cases of testicular feminization syndrome were subjected to lipid analyses. The total lipids formed 2.75% of the total wet weight of the testicular tissue. Total cholesterol represented 30%, glycerides 33% and phospholipids 37% of the total lipids, respectively. Fractionation studies revealed that free cholesterol formed 66.7% and esterified cholesterol 33.3% of the total cholesterol. Triglycerides represented 89.89% and monoglycerides 10.11% of the total glycerides. Separation of phospholipids showed that phosphatidly choline (46.54%) and phosphatidly ethanolamine (24.89%) to be the major phosphoipid classes.     

Gastrocnemius Muscle Lipids in Relation to Diet in Two Mouse Mutants, 129Re-dy and A2G-adr, with Abnormal Muscle Function

The lipids of gastrocnemius muscle from normal and dystrophic (dy) mice of the Bar Harbor, 129Re strain were studied. Animals were fed diets containing either 3.1% or 1.1% of total calories as linoleic acid. Lipid analyses were also done on muscle from a new mouse mutant, A2G-adr, which has abnormal muscle function, characterised by an arrested development of the righting response. These animals were fed the "high" linoleic acid diet only. Total lipid, triacylglycerol, and cholesterol were elevated in the 129Re-dy irrespective of the diet, whereas A2G-adr possessed significantly higher levels of cholesterol. Total phosphorus (micrograms P/g muscle) and cholesterol/phospholipid ratios were elevated in the dy strains only. Cardiolipin was raised in the dy ("low" linoleic diet) and adr muscle, whereas phosphatidylcholine was lower in the adr strain only. Linoleic acid esterified to phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine was elevated whereas arachidonic acid in phosphatidylserine was decreased in both mutants. Docosahexanoic acid (22:6) in all three dy phospholipids was decreased, independent of dietary treatment. The adr strain possessed normal levels of this fatty acid. The results specifically point to an abnormality in long-chain polyunsaturated fatty acid metabolism in gastrocnemius muscle in the 129Re-dy mutant; in the adr mutant they could reflect an abnormal increase in the number of muscle mitochondria.     

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.     

ISOLATION AND CHARACTERIZATION OF LUMINAL MEMBRANES FROM URINARY BLADDER

A method is reported for the isolation of a highly purified fraction of urinary bladder membranes containing hexagonal plaques. The method uses zonal centrifugation as the final step of fractionation. The purified fraction was characterized by its electron microscopic morphology, by its enzymatic profile, by quantitative and qualitative analysis of lipids and by the protein pattern obtained by electrophoresis in polyacrylamide sodium dodecyl sulfate gels. The fraction contains 65% lipids and 35% proteins. The major protein component has a molecular weight of 27,000 daltons. Phospholipids are more than the 54% of the total lipid weight. Phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol are the major phospholipids with 50%, 30%, and 7% of the total lipid phosphorus, respectively. The glycolipid fraction is 10% of the total lipid weight and is formed by only two components, both sulfatides. Total cholesterol makes up 36% of the total neutral lipid fraction of which cholesterol esters constitute 6%. Glycoproteins are also found to be present in the fraction.     

Pattern of neutral and phospholipids in the semen of normospermic, oligospermic and azoospermic men

Total lipid concentration was elevated in the seminal plasma of oligo- and azoospermic men. The total cholesterol content was comparatively more in the seminal plasma of azoospermic men than in that of normo- and oligospermic men. In general, infertility was associated with increased seminal concentrations for most of the neutral lipid classes. However, total phospholipids and most of the phospholipid classes were diminished in the seminal plasma of oligo- and azoospermic men and in the spermatozoa of oligospermic men. We suggest that there is a positive correlation between seminal phospholipids and fertility and a negative correlation between seminal neutral lipids and fertility.     

Different response to choline deficiency of the serum ornithine carbamoyltransferase activity in four strains of rats

Rats of the Donryu, Wistar, Fischer, and Sprague-Dawley strains were examined for the effects of choline deficiency on liver lipids, serum lipids, and serum ornithine carbamoyltransferase. The liver total lipid, triacylglycerol, cholesterol and phospholipid contents in the choline-deficient rats were significantly higher than those in choline-sufficient rats. The contents of total lipids and phospholipids in the liver of the Wistar and Fischer rats fed on a choline-deficient diet were significantly higher than those of the Donryu and Sprague-Dawley rats. The levels of triacylglycerol, cholesterol and phospholipids in the serum were significantly decreased by feeding with the choline-deficient diet. The serum ornithine carbamoyltransferase activity was increased in the Wistar and Fischer strains by feeding with the choline-deficient diet. The Wistar and Fischer strains were consequently the most sensitive to both lipid accumulation and liver lesions induced by the choline deficiency.     

Lipid composition of liver microsomes in rats fed a high monounsaturated fatty acid diet

The fatty acid and cholesterol contents of tissue membranes are the determinants of membrane stability and functionality. This study was designed to evaluate the influence of a high monounsaturated fatty acid diet on the fatty acid composition of rat liver microsomes and on their cholesterol and lipid phosphorus content. Weanling animals were fed for 5 weeks with high fat diets containing olive oil or corn oil. Saturated fatty acids were increased and oleic acid decreased in microsomal total phospholipids and in the three major phosphoglycerides, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI), of rats fed corn oil as compared to the olive oil group. The percentage of linoleic acid was higher in the corn oil group, but only for total phospholipids and PC. Linoleic and alpha-linolenic metabolites were significantly increased in total phospholipids of olive oil-fed animals with respect to those fed corn oil. These changes were responsible for the low unsaturation index found in microsomal phospholipids of the corn oil group. The diet did not affect the microsome cholesterol or the lipid phosphorus content. These results show that, in olive oil-fed rats, the cholesterol content and the degree of unsaturation of liver microsomes was similar to that observed in weanling animals; this probably suggests an adequate maintenance of functionality of membranes in olive oil-fed animals.     

Role of thyroid on testicular lipids in prepubertal, pubertal and adult rats. I. Hyperthyroidism

The influence of thyroxine-induced hyperthyroidism on testicular neutral and phospholipids was studied in prepubertal, pubertal and adult rats. Thyroxine treatment (25 micrograms/100 g body weight) for 1 month decreased testicular total lipids, total glyceride glycerols, total cholesterol and total phospholipids. Different classes of glyceride glycerol, cholesterol and phospholipid were also diminished due to thyroxine treatment. All classes of lipids returned to the euthyroid level after the withdrawal of thyroxine treatment. The data obtained in the present study suggest that thyroid hormones have a definite influence on testicular lipid metabolism in rats.     

Shedding off specific lipid constituents from sperm cell membrane during cryopreservation

Membrane damage is one of the main reasons for reduced motility and fertility of sperm cells during cryopreservation. Using a model system of sperm cryopreservation developed in our laboratory, we have investigated the detailed changes due to cryopreservation in the plasma membrane lipid composition of the goat epididymal sperm cells. Total lipid and its components, i.e., neutral lipids, glycolipids and phospholipids decreased significantly after cryopreservation. Among neutral lipids sterols, steryl esters and 1-O-alkyl-2,3-diacyl glycerols decreased appreciably, while among phospholipids, major loss was observed for phosphatidyl choline and phosphatidyl ethanolamine. Unsaturated fatty acids bound to the phospholipids diminished while the percentage of saturated acids increased. The cholesterol:phospholipid ratio enhanced and the amount of hydrocarbon, which was unusually high, increased further on cryopreservation. The data indicates that profound increase of the hydrophobicity of the cell membrane is one of the major mechanisms by which spermatozoa acquire potential to resist or combat stress factors like cryodamage. The results are compatible with the view that for survival against cryodamage, sperm cells modulate the structure of their outer membrane by shedding off preferentially some hydrophilic lipid constituents of the cell membrane.     

Lipid composition of heteroploid cells in culture: effects of prednisolone

Prednisolone-induced alterations in the content and composition of the total lipids, cholesterol, phospholipids and fatty acids were studied in HeLa S3 cells. After relatively long exposure of the cell cultures to the hormone analog (24 to 72 hours), total cell lipid content was decreased. Partial inhibition of cholesterol and phospholipid metabolism resulted in a shift in the molar ratio of these two lipid constituents. Total fatty acid content was unaffected by prednisolone but there were minor changes in the relative distribution of the individual fatty acids. The observed decrease in cholesterol turnover after addition of prednisolone was primarily due to the reduced uptake of intact cholesterol from the culture medium. This was compensated, in part, by an increased de novo synthesis of cholesterol from acetate and glucose.     

Changes in cellular composition during magnesium deficiency.

1. Concentrations and compositions of liver, serum and milk lipids of cows were measured during 6 days' starvation and serum lipids during 60 days' re-feeding. 2. The concentration of free fatty acid in serum increased fivefold during starvation. 3. The content of total lipid in liver (g/100g of liver dry matter) doubled owing to a 20-fold increase in triglyceride, an eightfold increase in cholesterol ester, a three fold increase in free fatty acid and a 20% increase in cholesterol. There were no changes in the content or composition of liver phospholipids. 4. Starvation lowered the concentrations of total lipid, phospholipid and cholesterol ester of dextran sulphate-precipitable serum lipoproteins. Total lipid and cholesterol ester concentrations in lipoproteins of d greater than 1.055 and in lipoproteins not precipitable by dextran sulphate decreased from day 4 of the starvation period and during the first 20 days' re-feeding. 5. During starvation there were decreases in percentages of stearic acid and increases in oleic acid in serum free fatty acids and triglycerides and in liver neutral lipid. 6. Throughout starvation total milk lipid yield decreased, yields and percentages of C4-14 fatty acids decreased and percentages of C18 fatty acids increased. 7. It is suggested that accumulation of triglyceride in liver may be caused by increased uptake of plasma free fatty acids without corresponding increase in lipoprotein secretion.     

Schistosoma mansoni: a comparative study of plasma and erythrocyte lipid alterations in the experimentally infected mouse and in selected human patients

Alterations of plasma and erythrocyte lipids associated with hepatosplenic schistosomiasis mansoni were studied in the mouse and in human patients. Qualitative and quantitative differences were observed between the two species which indicated that the experimentally infected mouse should not be used as a model for altered lipid metabolism associated with Schistosoma mansoni infections in man. Also blood lipid values should not be used as prophylactic indicators for experimental therapeutical studies in the infected mouse, although lipid determinations could have clinical value in studies of human patients. In infected mice plasma cholesterol and phospholipid were significantly reduced (40 and 25%, respectively), but proportions of individual plasma phospholipids were unchanged. In contrast, only plasma cholesterol was reduced in human patients with compensated or decompensated hepatosplenic schistosomiasis (16 and 29%, respectively); of the individual phospholipids, lecithin was significantly increased and lysolecithin was decreased. The percentage of plasma total cholesterol was reduced in infected mice and patients suggesting that hypocholesterolemia is due mainly to decreased cholesteryl ester. Lipid changes also occurred in erythrocytes. Those of infected mice had significantly elevated membrane phospholipid content and no changes in cholesterol or in the proportions of the individual phospholipid fractions. In marked contrast, the erythrocytes of two groups of human patients had significantly higher levels of cholesterol without a raised total phospholipid concentration. Moreover, decreased proportions of lysolecithin and increased proportions of lecithin were apparent although only the increased membrane lecithin associated with compensated patients was statistically significant.     

Changes during hibernation in different phospholipid and free and esterified cholesterol serum levels in black bears

During hibernation, fat is known to be the preferred source of energy. A detailed analysis of different phospholipids, as well as free and esterified cholesterol, was conducted to investigate lipid abnormalities during hibernation. The levels of total phospholipids and total cholesterol in the serum of black bears were found to increase significantly in hibernation as compared with the active state. Both free and esterified cholesterol were increased in the hibernating state in comparison with the active state (P < 0.05). The percentage increase during hibernation was more in free cholesterol (57%) than in esterified cholesterol (27%). Analysis of subclasses of serum phospholipids showed that choline containing phospholipids, i.e., sphingomyelin (SPG) (14%) and phosphatidylcholine (PC) (76%), are the major phospholipids in the serum of bear. The minor phospholipids included 8% of phosphatidylserine (PS) + phosphatidylinositol (PI), while phosphatidylethanolamine (PE) was only 2% of the total phospholipids. A comparison of phospholipid subclasses showed that PC, PS + PI and SPG were significantly increased, while PE was significantly decreased (P < 0.05) in the hibernating state as compared with the active state in black bears. These results suggest that the catabolism of phospholipids and cholesterol is decreased during hibernation in black bears, leading to their increased levels in the hibernating state as compared with the active state. In summary, our results indicate that serum cholesterol and phospholipid fractions (except PE) are increased during hibernation in bears. It is proposed that the increase of these lipids may be due to the altered metabolism of lipoproteins that are responsible for the clearance of the lipids.     

Variation in polar-group content in lipids of cowpea (Vigna unguiculata) Cell cultures as a mechanism of haloadaptation

Callus and cell suspension cultures of cowpea (Vigna unguiculata) were induced with 2,4-dichlorophenoxyacetic acid and grown at different NaCl concentrations. The cell biomass yield and its total lipid content decreased with increasing salinity. However, while the hexose content in lipids was higher, the amount of lipid phosphorus was significantly lower in both agar and cell suspension cultures. Ion-transport rates with artificial membranes prepared with different lipid fractions showed that lipids from cells grown in a saline medium were less permeable to Na⁺ and to Cl^- than those grown in a non-saline medium. Also the permeability of membranes prepared with glycolipids was lower than those prepared with phospholipids and whole lipids. Apparently, the increase of hexose/phosphorus ratio in membrane lipids is induced in response to the halo-adaptation process.     

Sterol metabolism and oral epithelial cell growth

Summary Previous studies have demonstrated that as the density of cultured oral epithelial cells increases, there is a concomitant increase in phospholipids and cholesterol ester synthesis and a decrease in that of cholesterol and sterol precursors. Other studies have suggested that the effects of exogenous cholesterol sulfate may be similar to growth responses and influence metabolic steps related to cell density. To further examine this possibility, in the present study lipid synthesis was monitored in hamster cheek pouch epithelial cells in cultures established at different cells densities and in the presence of varying amounts of exogenous cholesterol sulfate. Cell [¹⁴C]acetate incorporation into lipids was measured in cultures established at four densities ranging from very subconfluent to very dense (postconfluent) in two media, Dulbecco’s modified Eagle’s medium (DMEM) with 5% fetal bovine serum and KSFM, a non-serum containing keratinocyte medium. Results indicated that the relative proportion of radiolabel incorporated into different lipid classes changed with cell density. In DMEM, the percentage of radiolabel incorporated into total phospholipids and fatty acids increased significantly with increasing cell density whereas percent incorporation into cholesterol, sterol precursors, and cholesterol esters significantly decreased. In KSFM cultures, proportionate phospholipids labeling was significantly increased in more dense cultures whereas cholesterol and cholesterol esters labeling was significantly decreased. In subconfluent and confluent cultures exposed to 10 or 25μM cholesterol sulfate, the relative proportions of phospholipid labeling also increased significantly compared to dimethyl sulfoxide (solvent) controls, whereas sterol precursors, fatty acids, and cholesterol esters labeling was signifcantly decreased. These results indicate that cholesterol sulfate can affect cellular lipid synthesis in a manner similar to that which occurs with increasing cell density, and strengthen the hypothesis that cholesterol sulfate may regulate lipid metabolic pathways related to growth and differentiation.     

Age-related changes of lipid fractions and total fatty acids in the serum of female and male rats aged from 37 to 1200 days

1. Total lipids and the lipid fractions cholesterol ester, triacylglycerols, free cholesterol, free fatty acids and phospholipids as well as the fatty acid patterns of total lipids were measured in the serum of female and male rats (Wistar SPF, strain Hannover) aged 37-1213 days. 2. All parameters were monitored every 49th day. Five female and five male animals were used in each experiment. 3. All lipid fractions showed a significant positive linear regression vs age in both sexes. There were multiple significant differences in lipid fractions between the sexes. 4. Among the fatty acids only docosahexaenoic acid shows a significant correlation with age in both sexes.     

Myelin development in infant brain

Myelin was isolated from subcortical areas of ten human brains, with ages ranging from 24 days to 350 days-of-age; samples were subsequently analyzed for lipid composition. Eight infants were victims of Sudden Infant Death Syndrome, and two infants were accident cases. Gray and white matter samples from each brain were also dissected and analyzed. Galactolipids were only 12% of the total lipids in white matter from brains of infants that were 24 days-of-age, a time when myelination was just starting in the subcortical areas. At 175 and 350 days of age, myelination was well underway and galactolipids measured 22% of the total lipids. Total phospholipids decreased (65% to 54%) in white matter during development, with the decrease mostly in phosphatidylcholine (23% to 15%). Even though there was little white matter present at early ages, myelin could be isolated. Surprisingly, the lipid composition of myelin, from the 24-day-infant brain was similar to that from adult brain. Galactolipids were 22% of the total lipids, cholesterol, 23%, and phospholipids, 52%. These results suggest that only subtle remodeling of myelin occurs in humans once myelination commences. All four major gangliosides were present in myelin during this first year of development. Interestingly, the yield of myelin from the 350-day-old infant subcortical white matter was similar to that from an adult. Thus major tracts in this area may have acquired most of the myelin by one year-after-birth. Since the control samples blend quite well into the developmental pattern obtained, it is believed there are no abnormalities in myelin lipids from SIDS infants.     

Effects of probucol on lipid metabolism and secretion in long-term cultures of adult rat hepatocytes

To study the effects of probucol on hepatic lipid metabolism, we used adult rat hepatocytes cultured on a feeder layer of 3T3 cells lethally treated with mitomycin C. These cultures synthesize and secrete for at least 2 weeks various lipids from [14C]acetate and [14C]oleate precursors. Treatment with 20 micrograms/ml of probucol for 7 and 14 days decreased the secretion of various radiolabeled lipid species to the culture medium and produced an intracytoplasmic accumulation of triacylglycerol droplets. The lipids whose secretion was most decreased were free and esterified cholesterol (50-70% reduction). Secretion of triacylglycerols and phospholipids was also reduced but to a lower extent. Intracytoplasmic triacylglycerols accumulated and the activity of glycerol phosphate dehydrogenase, a marker enzyme of glycerolipid synthesis, also increased (35-56%). The total incorporation of both radioactive precursors into free and esterified cholesterol and phospholipids was reduced 20-60%. Our data show that 2-week treatment of 3T3-hepatocyte cultures with pharmacological concentrations of probucol reduces significantly lipid secretion and suggest that at least part of the in vivo hypolipidemic effect of probucol could be attributed to a decrease in the secretion of lipids (i.e., lipoproteins) by hepatocytes.     

Radiation changes in the lipid levels in liver and thymus chromatin of gamma-irradiated rats

A study was made of the lipid content of liver and thymus chromatin of intact and gamma-irradiated (10 Gy) rats 10 and 40 min after irradiation. The composition of the chromatin-bound phospholipids was shown to differ from that of phospholipids of intact nuclei and a nuclear membrane by a much larger content of cardiolipin and sphingomyelin. A decrease in the lipid phosphorus level, increase in the amount of total cholesterol, and a 1.7-fold increase in the cholesterol/phospholipids ratio were observed after irradiation: 40 min after exposure these indices were normalized. The opposite changes were noted in the lipid content of the thymus chromatin: 10 min after irradiation no changes were detected while after 40 min more than a 1.5-fold increase in the cholesterol amount and the cholesterol/phospholipids ratio was registered. The content of cardiolipin was reliably decreased in the chromatin of both organs throughout the entire period of observation.