Molecular species of choline and ethanolamine glycerophospholipids in rat brain myelin during development

The composition of the molecular species of various phospholipid subclasses was examined in myelin isolated from brain of 15-, 21- and 90-day-old rats. The molecular species of diacylglycerophosphocholine (PtdCho), diacylglycerophosphoethanolamine (PtdEtn) and plasmenylethanolamine (PlsEtn) were quantified by high-performance liquid chromatography (HPLC) after phospholipase C treatment and dinitrobenzoyl derivatization. In rat brain myelin, each phospholipid subclass showed a specific pattern of molecular species that changed during development. PtdCho contained large amounts of saturated/monounsaturated and disaturated species and low amounts of saturated/polyunsaturated species. During brain development, the levels of saturated/monounsaturated molecular species increased whereas those of the disaturated and saturated/polyunsaturated species decreased. PtdEtn were characterized by their low levels of disaturated species and a high content of saturated/monounsaturated and saturated/polyunsaturated species, of which those containing fatty acids of the n−3 series decreased, whereas those containing fatty acids of the n−6 series did not change during brain development. The levels of saturated/monounsaturated species increased in PtdEtn. No disaturated molecular species could be detected in PlsEtn. This alkenylacyl subclass contained large amounts of saturated/polyunsaturated, saturated/monounsaturated and dimonounsaturated molecular species. During development, the levels of saturated/polyunsaturated molecular species decreased while those of the two others increased. The data indicated that myelin sheaths undergo phospholipid changes during brain development and maturation.     

Metabolism of chimyl alcohol and phosphatidyl ethanolamine in the rat brain

Following intracerebral injection of¹⁴C-phosphatidylethanolamine and³H-chimyl alcohol into 18 day old rats, the ethanolamine phosphoglycerides were isolated and analyzed. The¹⁴C and³H activities in the dimethyl acetals derived from alkenyl acyl ethanolamine phosphoglycerides and in the glyceryl ethers derived from the alkyl acyl ethanolamine phosphoglycerides were measured. The absence of¹⁴C in the dimethyl acetals indicates that phosphatidyl ethanolamine is not transformed into phosphatidal ethanolamine under these circumstances. The increase with time of the³H content of the glyceryl ethers and dimethyl acetals indicates that chimyl alcohol was a precursor of both types of phospholipids. Abbreviations used: CA, Chimyl alcohol; GLC, gas liquid chromatography; GPE, glyceryl-3-phosphorylethanolamine; PE, phosphatidylethanolamine; TLC, thin-layer chromatography; TFA, trifluoroacetyl.     

The incorporation of ethanolamine into ether-containing lipids in rat brain

After intracerebral injection of C¹⁴-ethanolamine into rats, the ethanolamine phosphoglycerides were isolated and hydrolyzed with mild alkali and acid. The specific radioactivity of the diacyl, acyl alkenyl, and acyl alkyl glyceryl-3-phosphorylethanolamine, the diacyl and acyl alkenyl glyceryl-3-phosphorylcholine, and sphingomyelin was determined at 0.5, 2, 24, and 48 hours. The specific radioactivity-time relationships show that the ethanolamine plasmalogen is not a precursor for the glyceryl ether form but suggest that acyl alkyl glyceryl-3-phosphorylethanolamine is desaturated to form some of the acyl alkenyl glyceryl-3-phosphorylethanolamine. The radioactivity in the choline portion of the choline phospholipids was very low. Presented at the AOCS Meeting, Cincinnati, October 1965.     

Effects of frying and storage on cholesterol oxidation in minced meat products

The presence of cholesterol oxidation products (COP) in the diet is a health concern for their various known adverse effects. It is important that the generation of COP be assessed during different stages of production, handling, and storage of meats and meat products so that relevant measures can be taken to minimize the production of COP. In a preliminary study, we investigated the content of COP in the lipids of raw meatballs (50% prok+50% beef), prefried meatballs (50% pork +50% beef), raw hamburger (100% beef), and prefried burger (50% pork+50% beef). Six of the common COP, viz 7α- and 7β-hydroxycholesterol, 7-ketocholesterol, 5α,6α-epoxycholestanol, 5β,6β-epoxycholestanol, and cholestanetriol, were analyzed by gas chromatography (GC) and GC-mass spectroscopy. The total content of these COP was in the range of 7 to 10 μg/g lipids in raw meatballs, prefried meat balls, and raw hamburger, after frying these samples for consumption. The prefried hamburger had ca. 8μg/g lipids of the total COP before frying, and this amount increased to 29 μg/g lipids after frying. During the storage of this fried sample, the total COP increased to 42 and 50 μg/g lipids, after 1 and 2 wk of storage, respectively. The results of this study show that freshly prepared meat products are a minor source of COP in the diet. However, if semiprepared frozen meat products are fried once and then stored for future consumption, the levels of COP can increase considerably, and this may be of concern for certain groups of consumers. Presented in part as a poster at the 88th AOCS Annual Meeting and Exposeattle, WA, May 11–14, 1997.     

The labeling of brain ethanolamine phosphoglycerides from cytidine diphosphate ethanolamine in vitro

Chicken brain microsomes convert¹⁴C-ethanolamine-labeled cytidine diphosphate ethanolamine (CDPE) to ethanolamine lipids (EPG) at a measurable rate. Mitochondria and particle-free supernatant fractions are almost inactive. On adding saturating amounts of diacyl glycerol to the microsomes, formation of EPG increases 10-fold, and is almost totally confined to the diacylsn-glycero-3-phosphorylethanolamine (GPE), whose synthesis increases 20-fold (from 13.1 to 249 mμmoles/mg protein/hr). The addition of the 1-alkenyl 2-acyl glycerol also produces a noticeable increase in the rate of EPG labeling, which is almost exclusively confined to the alkenyl acyl GPE, whose synthesis is stimulated 30-fold (from 3.1 to 90 mμmoles/mg protein/hr). Synthesis of alkyl acyl GPE from CDPE was not detected in the brain microsomes. Synthesis of EPG from CDPE by chicken brain homogenates has also been examined and results similar to those reported for the brain microsomes were obtained. In addition, small amounts of labeled alkyl acyl GPE are produced from CDPE in the homogenates, but in no case does this synthesis increase on adding various lipid acceptors to the incubation system. Various properties of the phosphorylethanolaminediacyl glycerol phosphotransferase (E.C. 2.7.8.1) of brain microsomes were examined. It is concluded that the enzymic activities which convert CDPE to diacyl GPE and alkenyl acyl GPE, respectively, are similar.     

Fatty acid composition of brain glycerophospholipids in peroxisomal disorders

This paper shows for the first time the differential fatty acid composition of ethanolamine plasmalogens (EP) and phosphatidylethanolamine (PE) in the brains of 12 patients with disorders of peroxisomal biogenesis and compares the results to normal values for the age. Other important glycerophospholipids (GPL), such as phosphatidylserine (PS) and phosphatidylcholine (PC), are also included in this study. GPL were separated by two-dimensional thin-layer chromatography, and their fatty acid composition was determined by capillary column gas-liquid chromatography. Total brain GPL were slightly decreased in peroxisomal disorders (27.98±2.95 μmol/g in the patients against 34.5±6.21 μmol/g in age-matched controls, P=0.005), and the distribution of the different GPL classes was much altered. In confirmation of known data, EP were very much decreased (2.18±1.3 μmol/g in the patients against 6.9±2.3 μmol/g in controls) at the expense of PE, which was increased (8.58±2.17 μmol/g in the patients against 5.97±0.58 μmol/g in controls, P<0.005). PS and PC were both significantly decreased (P=0.0001 and P=0.037, respectively). The polyunsaturated fatty acid (PUFA) composition of all the GPL fractions was markedly abnormal. In absolute terms, docosahexaenoic acid (22∶6n−3) was drastically decreased in all GPL classes (always at the P<0.0001 level) while arachidonic acid (20∶4n−6) was increased in PE and PS (P<0.001 in both cases). In the alkenyl acyl form, EP, 22∶6n−3, and 20∶4n−6 were both very significantly decreased (P<0.0001), although the former was always the most affected. The myelin PUFA adrenic acid (22∶4n−6) was decreased in EP (P<0.0001) and slightly increased in PS (P<0.05). The changes found confirm that 22∶6n−3 deficiency is a predominant defect in the brain in peroxisomal disorders.     

Alk-1-enylacyl,alkylacyl, and diacyl subclasses of native ethanolamine and choline glycerophospholipids can be quantified directly by phosphorus-31 NMR in solution

We show that phosphorus-31 nuclear magnetic resonance spectroscopy can be used to distinguish and to quantify the alk-1-enylacyl, alkylacyl, and diacyl glycerophosphoethanolamine (GPE) subclasses, and the respective glycerophosphocholine (GPC) subclasses, in their native form without prior degradation or derivatization, provided the phospholipids are observed in the nonaggregated state. Monomeric phospholipid distribution is ascertained by recording the spectra, after removal of metal ions, on CDCI₃/CD₃OD/D₂O (50∶50∶15, by vol) solutions. The utility of this approach is exemplified for the ethanolamine glycerophospholipids (EPL) from bovine brain and the choline glycerophospholipids (CPL) from bovine heart. Sharp and well-resolved resonances are obtained for alkylacylGPE (+0.395 ppm; re 1% H₃PO₄), alkenylacylGPE (+0.353 ppm), and diacylGPE (+0.315 ppm), and for alkylacylGPC (−0.383 ppm), alkenylacylGPC (−0.436 ppm) and diacylGPC (−0.451 ppm). Integrated peak reas are shown to closely correlate with dose. Accurate quantitation of EPL and CPL subclasses at submicromolar levels can further be facilitated by use of synthetic dialkylGPE (+0.602 ppm) and dialkylGPC (−0.196 ppm) as internal standards. The method is simple, rapid, sensitive and reproducible, and permits the complete resolution and direct quantitation of all ethanolamine and choline glycerophospholipid subclasses quite independent of fatty chain length and degree of unsaturation. This work was presented at the 85th AOCS Annual Meeting, Atlanta, Georgia, May 1994 (see Ref. 1).     

In vitro oxidation of vitamins C and E,cholesterol, and thiols in rat brain synaptosomes

Free radical-induced oxidation of vitamins C, E, sulfhydryl compounds, and cholesterol in brain synaptosomes from Fisher 344 rats was studied. The synaptosomes were incubated at 37°C with 2,2′-abobis-(2-amidinopropane) dihydrochloride (AAPH), which undergoes thermal decomposition to yield free radicals. After incubation, the synaptosomes were sedimented, saponified, and extracted with hexane to isolate tocopherol and cholesterol. Ascorbate and tocopherol were assayed by liquid chromatography, cholesterol by gas chromatography, and total sulfhydryls by spectrophotometry. Under thein vitro conditions used in this study, the approximate order for the ease of oxidation of the various compounds was: ascorbate ≫tocopherol>sulfhydryl compounds⋙cholesterol. However, tocopherol and sulfhydryl oxidation occurred even before all of the ascorbate had been consumed. Therefore, the fate of a specific antioxidant at a particular cellular location cannot be predicted with complete accuracy using thein vitro order for ease of oxidation shown here. Ascorbate may play a major role in protecting brain against oxidative damage because: (i) ascorbate concentration is high in brain, (ii) it can regenerate vitamin E from its radical oxidation product, and (iii) it is one of the first antioxidants to be consumed during oxidative reactions.     

Molecular species composition of glycerophospholipids from white matter of human brain

The molecular species composition of the major glycerophospholipids from white matter of human brain were determined by high-performance liquid chromatography of the 3,5-dinitrobenzoyl derivatives of the corresponding diradylglycerols. In phosphatidylcholine (PC) and phosphatidylserine (PS), molecular species containing only saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) comprised 85.7 and 82.4% of the respective totals, with 18∶0/18∶1 predominant in PS and 16∶0/18∶1 in PC. These molecular species were also abundant in phosphatidylethanolamine (PE), but in this phospholipid species containing polyunsaturated fatty acids (PUFA), largely 18∶0/22∶6n−3 and 18∶0/20∶4n−6, accounted for over half the total; 18∶1/18∶1 was also abundant in PE. In contrast, 1-O-alk-1′-enyl-2-acylsn-glycero-3-phosphoethanolamine (GPE) had much more SFA- and MUFA-containing species, predominantly 16∶0a/18∶1, 18∶0a/18∶1 and 18∶1a/18∶1, with low amounts of species containing 20∶4n−6 and 22∶6n−3. In alkenylacyl GPE, 22∶4n−6 was the major PUFA and 16∶0a/22∶4n−6 and 18∶1a/22∶4n−6 the main PUFA-containing species. There was six times more 22∶6n−3, twice as much 20∶4n−6 and half the amount of 22∶4n−6 in PE as compared to alkenylacyl GPE. Molecular species are abbreviated as follows:e.g., 16∶0/18∶1 PE is 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine; the corresponding alkenylacyl species, 1-O-hexadec-1′-enyl-2-oleoyl-sn-glycero-3-phosphoethanolamine is 16∶0a/18∶1.     

Effects of colestipol hydrochloride and neomycin sulfate on cholesterol turnover in the rat

Three groups of male rats were fed diets containing the bile acid sequestrant colestipol hydrochloride (1%), neomycin sulfate (0.25%), or basic diet during the test. After 15 days, each rat was injected IV with 3.9 μCi cholesterol-1,2-³H complexed with serum lipoproteins; specific radioactivity of the total serum cholesterol was measured at several time intervals for a period of 7 weeks. Computer analysis of the data indicated that the turnover of cholesterol could best be fitted by a three-pool model. In pool 1, colestipol HCl caused a significant increase in production rate (10.09 to 15.96 mg/day) and the excretion rate constant (0.53 to 0.79 day⁻¹) of cholesterol without significantly altering the size of the pool or serum cholesterol concentrations. These results are compatible with an agent capable of binding bile acids in the rat but do not cause a decrease of the sterol pool because of an adequate compensatory increase in cholesterol biosynthesis. Neomycin SO₄ caused a significant reduction in serum cholesterol (9%) without altering turnover parameters and apparently exerts its hypocholesterolemia by some mechanism other than bile acid sequestration.     

Effects of ketoconazole on cholesterol synthesis and precursor concentrations in the rat liver

Ketoconazole, an antimycotic agent, given to rats for a week as 0.05% food addition had no effect on the hepatic concentrations of free and esterified cholesterol or on the activity of acyl coenzyme A: cholesterol-acyltransferase (ACAT). However, the levels of free methylated cholesterol precursors, especially lanosterols, less markedly Δ^8,24 and Δ⁸-dimethyl sterols and monomethyl sterols, were increased after only one day's treatment, while those of esterified methyl sterols were increased inconsistently, and those of free and esterified Δ⁸-lathosterol, lathosterol and desmosterol were not affected at all. Cholestyramine treatment had no significant effect on ACAT in spite of a decrease in the hepatic content of esterified cholesterol and caused a marked increase in the free cholesterol precursor levels, especially in those of lathosterols. Cholestyramine given to ketoconazole-treated rats increased the hepatic levels of Δ⁸ and Δ⁷-lathosterols but not desmosterol or methylated cholesterol precursors. Ketoconazole increased and cholestyramine markedly decreased plantssterols, sitosterol and campesterol in the liver. In serum, the contents of both lanosterols and lathosterol were increased but that of cholesterol tended to be decreased by ketoconazole (−19%). The results indicate that ketoconazole impairs demethylation processes at C-14 and to some extent at C-4 in the rat liver, resulting in lowered serum cholesterol level.     

Fatty acid and sterol specificity of cholesterol esterifying enzyme in developing rat brain

The properties and fatty acid and sterol specificity of cholesterol-esterifying enzyme (EC 3.1.1.13) in rat brain were studied. The enzyme utilized free fatty acid for esterification, and activity was maximal at pH 5.6. Exogenous ATP and CoA did not stimulate the incorporation of free fatty acids into sterol esters. Substrates dispersed in Tween 20 or Triton X-100 were just as effective as the substrates dissolved in acetone solution, while dispersion in propylene glycol or sodium taurocholate was not as effective. Snake venom phospholipase A₂ (EC 3.1.1.4) increased the esterification of cholesterol in the absence of added fatty acid. The fatty acid specificity data indicated that oleic and palmitic acids were the preferred fatty acids. Little or no esterification occurred in the presence of long chain fatty acids (C₂₀–C₂₄). Esterification of cholesterol with palmitate or stearate was not affected by the presence of oleic acid in the mixture. Thus, the nonrequirement of the brain-esterifying enzyme for a bile acid or for an amphiphile such as an unsaturated fatty acid suggests that micellar solubilization of the substrate is not essential for activity. Although the brain enzyme catalyzed the esterification of desmosterol, cholesterol was the preferred substrate. Neither lanosterol (C₂₉ sterols) nor Δ7-dehydrocholesterol was esterified to any significant extent. The presence of low concentrations of desmosterol increased cholesterol esterification slightly, while there was a concentration-dependent inhibition of demosterol esterification by cholesterol. These data on fatty acid and sterol specificity of the esterifying enzyme correlate well with the composition of sterol esters present in developing rat brain.     

制备工艺、水质及贮存条件等对5%阿维菌素水乳剂稳定性影响

通过测定粒径、跨距等性能指标,考察制备工艺、水质及贮存条件对5%阿维菌素水乳剂的稳定性能的影响。结果表明,采用剪切速率3 000 r/min,剪切4 min可以获得较小的粒径和较窄的跨距,产品对水质有较好的适应性,但当用1 000 mg/L硬水时会影响其稳定性,产品常温贮存、热贮和冷贮均表现良好的稳定性,各项性能符合国家标准要求。     

Fatty acids of cerebrosides in different regions of the developing foetal brain

The fatty acid composition of cerebrosides of developing foetal human brain and regional variations, if any, during intrauterine life were studied. While palmitic and stearic acids were the predominant normal fatty acids throughout intrauterine life, long chain fatty acids, like lignoceric and nervonic acids, which were low at early gestational ages, rapidly accumulated at term. Regional differences were observed in the concentrations of long chain normal fatty acids especially at term. Medulla oblongata showed a greater accumulation of long chain fatty acids as compared to the cerebellum and cerebrum. The distribution of 2-hydroxy fatty acids in different regions showed a pattern predominantly that of long chain carbon units, even at 34 wk of foetal life. A higher ratio of lignoeric to stearic acid in the case of normal fatty acids, probably indicative of chain elongation, was also evident in the case of medulla oblongata and cerebellum as compared to the cerebrum. The significance of these qualitative alterations in relation to rapid growth of brain prior to term and the process of myelination has been discussed.     

Effects of ethanol diets on cholesterol content and phospholipid acyl composition of rat hepatocytes

Chronic treatment of adult male rats with ethanol liquid diets resulted in alterations in phospholipid and cholesterol contents as well as the acyl composition of phosphatidylethanolamine (PE), phosphatidylinositol (PI)-phosphatidylserine (PS) mixture, and phosphatidylcholine (PC) of isolated hepatocytes. The influence of ethanol on these lipids was largely dependent on the proportion of dietary fat. Phospholipid and total cholesterol contents were elevated 23 and 27%, respectively, by ethanol when offered in a low-fat diet (5% corn oil). Only the percentage of arachidonic acid from PI-PS was significantly reduced in the low-fat ethanol group. Exposure to a high-fat (34% corn oil) diet in the presence of ethanol for 4–5 weeks resulted in a significant decrease in arachidonate/linoleate ratios of hepatic PE, PS-PI and PC, while total phospholipid content remained constant. In the high-fat, ethanol-treated group, hepatic cholesterol content was increased 2-fold. These results suggest that the level of dietary fat plays an important role in determining the effects of chronic ethanol consumption on hepatic cholesterol content and phospholipid acyl composition.     

Effects of a single ingestion of sodium taurocholate on esterified cholesterol concentration in liver and cholesterol turnover in the rat

The overall response of the rat’s cholesterol metabolism to a single ingestion of taurocholate (80 mg) was studied with the isotopic equilibrium method. The bile acid production, measured by the daily¹⁴CO₂ output of rats in isotopic equilibrium of [26-¹⁴C]-cholesterol, initially decreased and then increased. Conversely, the hepatic concentration of esterified cholesterol first increased and then decreased. Moreover, the ingestion of taurocholate increasing the intestinal absorption coefficient of dietary cholesterol increased the abosprtion and decreased the fecal excretion and the intestinal biosynthesis of cholesterol. The balance of these last effects is an excess cholesterol inflow. The classical hypothesis of negative feedback regulation of bile acid production fails to explain the observed biphasic effect of taurocholate. This compound, when its origin is exogenous, appears to stimulate the storage of esterified cholesterol in the liver, at the expense of bile acid synthesis. This accumulation rate takes into account not only the decrease in cholesterol transformation into bile acids but also the excess inflow of cholesterol. As the exogenous taurocholate was eliminated from the body, cholesteryl ester hydrolysis occurred and provided a supplementary source of free cholesterol for bile acid synthesis.     

Effects of highly hydrogenated soybean oil and cholesterol on plasma,liver cholesterol,and fecal steroids in rats

We investigated the relationship between dietary highly hydrogenated soybean oil (HSO) and cholesterol transport in rats. In the first study, to examine the effects of cholesterol transport of different concentrations of HSO in dietary oil, rats were given one of the three diets containing 0, 25, or 50% HSO in dietary oil with cholesterol (5 g/kg diet) or a diet without HSO and cholesterol for 22 d. Feeding the high concentration of HSO prevented the increase in plasma total cholesterol, hepatic total lipids, and cholesterol and the decrease in high-density lipoprotein-cholesterol, which were caused by dietary cholesterol. Moreover, HSO increased the fecal excretion, fecal lipids, and steroids in a dose-dependent manner. In the second study, to examine the effects on cholesterol transport of redistribution of stearic acid in the triacylglycerol species contained in HSO, rats were given one of the six diets containing HSO (distearoylmonoacylglycerol and tristearoylglycerol)-rich, monostearoylglycerol-rich, or palmitic acid-rich oil with/without cholesterol (5 g/kg diet), for 30 d. Whereas the accumulation of cholesterol in the body was reduced, cholesterol excretion was enhanced effectively in rats given the HSO-rich diet compared with rats given the monostearoylglycerol-rich diet. These results suggested that not only the high concentration of stearic acid but also its uneven distribution in HSO-triacylglycerol contributed to the reduction in intestinal cholesterol absorption in rats.     

Effects of renal factors on in vitro hepatic cholesterol synthesis in the rat

Two products derived from rat renal tissue have been shown to affect in vitro hepatic cholesterol synthesis. A premevalonate inhibitor of hepatic cholesterol synthesis is associated with the membranes of the renal endoplasmic reticulum. It is stable at −75 C and at 4 C but is heat labile. A pre-mevalonate stimulator of in vitro hepatic cholesterol synthesis is located within renal lysosomes and can be prepared in a nonsedimentable form by extraction with hypotonic buffer. While it is stable at −75 C, it loses activity at 4 C. Both of these products appear to have a molecular weight in excess of 150,000 as determined by gel filtration. Deceased.     

Molecular species composition of the major diacyl glycerophospholipids from muscle,liver, retina and brain of cod (Gadus morhua)

The molecular species composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) from white muscle, liver, retina and brain of cod (Gadus morhua) were determined by high-performance liquid chromatography of the respective 1,2-diacylglycerol 3,5-dinitrobenzoyl derivatives. A minimum of 69 diacyl species was identified. In muscle and liver saturated fatty acid/polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid/PUFA molecular species were predominant, particularly 16∶0/20∶5 and 16∶0/22∶6 in PC, 16∶0/22∶6 and 18∶1/22∶6 in PE and 18∶0/22∶6 and 18∶1/22∶6 in PS. Didocosahexaenoyl species were major components of PC, PE and PS from retina, comprising 29.3, 71.8 and 59.7% of the respective totals. Didocosahexaenoyl species were also abundant in PE and PS from brain, accounting for 13.8 and 24.0% of the totals, respectively. DiPUFA species were important in muscle, totalling 21.2% in PC and 38.3% in PE. PC from all tissues had the largest amounts of species containing only saturated or monounsaturated fatty acids, accounting for 59.8% of PC from brain, including 12.8% of 18∶1/24∶1 plus 24∶1/18∶1.     

Differential trypsin effect upon (1-14C) acetate incorporation into choline and ethanolamine glycerophosphatides of rat brain and liver

Preincubation of rat brain and liver slices in a medium (5% glucose, 5% fructose, 1% albumin, 1% trypsin, 10 mM phosphate buffer pH 6.0) used to pretreat brain tissue for the separation of cell types was found to uncouple the incorporation of (1-¹⁴C) acetate into ethanolamine phosphoglycerides from that of the choline phosphoglycerides. Incorporation into ethanolamine phosphoglycerides was stimulated in both brain (330%) and liver (780%) slices, while the incorporation of (1-¹⁴C) acetate into choline phosphoglycerides was reduced for both brain (71%) and liver (63%) slices, compared to control values from nonpreincubated material. With (1-¹⁴C) linolenic acid as a precursor, no significant differences were found in incorporation into ethanolamine phosphoglycerides and choline phosphoglycerides.