The effect of phenobarbital and carbon tetrachloride on fatty acid content and composition of phospholipids from rat liver

The administration of phenobarbital or carbon tetrachloride to rats caused various changes in hepatic fatty acid content and composition. Phenobarbital elicited no effect on the total amount of fatty acids but significantly decreased myristic, pentadecanoic, and arachidonic acids and increased eicosatrienoic, eicosapentenoic, lignoceric, and docosatrienoic acid. In contrast, carbon tetrachloride enhanced significantly the total content and several components such as pentadecanoic, palmitic, palmitoleic, oleic, linoleic, arachidic, eicosenoic, eicosadienoic, eicosatrienoic, docosapentenoic, lignoceric and docosahexenoic acids. It elicited no effect on arachidonic acid. Unsaturated fatty acid moieties participating in the structure of these phosphatides were increased by phenobarbital and diminished by carbon tetrachloride. Phenobarbital caused a reduction in the ratio of saturated/unsaturated fatty acids mainly because of the decreased palmitic and increased oleic, linoleic, eicosatrienoic, arachidonic, docosapentenoic, and docosahexenoic acids. The significant variation brought about by phenobarbital and carbon tetrachloride on tissue fatty acids and in particular on fatty acid composition of phosphatidylcholine and phosphatidylethanolamine fractions reflects the opposing effects of these compounds on the liver cell. The major action of phenobarbital and carbon tetrachloride is associated with changes of the endoplasmic reticulum. Thus, their contrasting effect on fatty acid composition and metabolism may suggest that the disposition of lipid constituents plays a determinant role in the hepatic action of foreign compounds.     

Effects of progesterone metabolites on fatty acids of the hepatic endoplasmic reticulum membranes

The effect of 2 selected progesterone metabolites on the phospholipid fatty acid composition of the liver and microsomal function was studied in the female rat. 16α-Hydroxyprogesterone significantly increased microsomal phospholipid content and the total amount of fatty acids esterified to phospholipids parallel with aminopyrine N-demethylase activity. Phospholipid changes were attributable to phosphatidylcholine and phosphatidylethanolamine. Both saturated and unsaturated fatty acids were enhanced. In contrast, 5β-pregnane-3α-ol-20-one caused a reduction of microsomal phospholipids, phosphatidycholine, together with decreased aminopyrine N-demethylase activity and total microsomal fatty acid content. Pregnanolone decreased both saturated and unsaturated fatty acids and its action on unsaturated acyl components was greater than on the saturated ones. Changes in fatty acids were manifested in palmitic, stearic and lignoceric acids among saturated fatty acids and in palmitoleic, oleic, linoleic, eicosaenoic, eicosadienoic, eicosatrienoic, arachidonic, eicosapentenoic, docosatrienoic, docosapentenoic and docosahexenoic acids among unsaturated ones. Total liver phospholipids were unaltered by either 16α-hydroxyprogesterone or 5β-pregnane-3α-ol-20-one. These test compounds, however, modified total hepatic fatty acid content. 16α-Hydroxyprogesterone increased total fatty acids and both saturated and unsaturated acyl components, whereas 5β-pregnane-3α-ol-20-one decreased these parameters. Major changes were manifested in saturated fatty acids such as stearic, arachidic and lignoceric acids, and in unsaturated ones such as palmitoleic, linoleic, eicosatrienoic and docosapentenoic acids. The action of these compounds on phospholipid fatty acids of hepatic microsomes may be causally related to their effect on drug-metabolizing activity of the endoplasmic reticulum.     

Fatty acid content and composition of phospholipids bound to the hepatic endoplasmic reticulum of the rat: effect of pregnancy

Phospholipid and fatty acid content were decreased and fatty acid composition of hepatic microsomes was altered in the rat during pregnancy. These changes were reversible 2 to 3 weeks after parturition. Pregnancy-related fatty acid changes were mainly localized in phosphatidylcholine and -ethanolamine fractions. Both saturated and unsaturated fatty acids were altered, but the reduction of the unsaturated fraction was more pronounced. Saturated acyl components, such as palmitic, stearic, and lignoceric acids, and unsaturated ones, including palmitoleic, oleic, linoleic, eicosatrienoic, arachidonic, and eicosapentaenoic acids, were significantly decreased, whereas only docosahexaenoic acid was elevated. Fatty acid changes were greater in the unsaturated components in phosphatidylcholine and -ethanolamine fractions. The largest reduction was in palmitic, palmitoleic, stearic, oleic, linoleic, arachidonic, and eicosahexaenoic acid content. Pregnancy-related changes in fatty acid distribution and content, and in phospholipid fractions reflect a modified organization and disposition of the hepatic endoplasmic reticulum membranes. These membrane changes represent essentially topographical factors influencing the function and enzymatic activity of these membranes.     

Differential effects of fibrates on the acyl composition of microsomal phospholipids in rats.

1. The time-course and comparative effects of treatment with clofibrate (CFB), bezafibrate (BFB), and gemfibrozil (GFB) on the acyl composition of the main microsomal phospholipids, i.e. phosphatidylcholine and phosphatidylethanolamine, have been studied in male Sprague-Dawley rats. 2. The administration of the three fibrates caused a strong peroxisomal induction and a hypolipidaemic effect. Concerning the changes in acyl composition, CFB and BFB behaved in a similar way, with differences which could be attributed to their different potency as peroxisome inducers, whereas GFB showed a somewhat distinct profile. 3. The three drugs increased the relative content of palmitic, palmitoleic and oleic acids, whereas the levels of stearic acid and also those of long chain, highly unsaturated fatty acids docosatetraenoic, docosapentaenoic and docosahexaenoic acids were reduced. In general, these effects appeared from the first day of treatment and were highly correlated with peroxisomal proliferation. In addition, they were more evident in the phosphatidylcholine than in the phosphatidylethanolamine fraction. 4. Fibrates increased total monounsaturated fatty acids, whereas a decrease in total polyunsaturated fatty acids in the phosphatidylcholine fraction was observed in CFB- and BFB-, but not in GFB-treated rats. Clear differences appeared between CFB and BFB on the one hand, and GFB on the other when the influence of fibrate treatment on the molar percentages of linoleic, eicosatrienoic, arachidonic and mead acids was analyzed. 5. GFB increased linoleic acid content in phosphatidylethanolamine, whereas CFB and BFB decreased its level in both phospholipid fractions. In contrast, CFB and BFB enhanced eicosatrienoic and mead acids in both fractions and arachidonic acid in phosphatidylethanolamine, whereas GFB had practically no effect.     

Phospholipids in the liver of the pregnant rat: changes in fatty acid content and composition

Pregnancy in the rat was associated with changes in hepatic phospholipids. All changes returned to the prepregnancy levels 2 to 3 weeks postpartum. The total phospholipid content was reduced significantly, mainly representing a reduction of phosphatidylcholine, -ethanolamine, and lysophosphatidylcholine fractions. Hepatic fatty acid content was also reduced and the composition was modified since both saturated and unsaturated acyl components were decreased with more pronounced changes in unsaturated acids. Total liver saturated fatty acids with 14 to 16 carbon atoms remained unaltered; stearic acid was reduced and arachidic and lignoceric acids were elevated. Among unsaturated fatty acids, palmitoleic, oleic, eicosatrienoic, arachidonic, eicosapentaenoic, and docosapentaenoic were decreased, docosatrienoic and docosahexaenoic were raised, whereas eicosaenoic and eicosadienoic did not change. In the phosphatidylcholine and -ethanolamine fractions, unsaturated acyl components also showed significant reduction. By and large they reflected the fatty acid changes occurring in total liver with the exception of the docosahexaenoic acid which was diminished in both fractions. The overall effect of pregnancy thus indicated a modification in unsaturated fatty acid content leading to the construction of less fluid membranes which may be responsible for the reduced enzyme activity of the endoplasmic reticulum.     

Phenobarbital pretreatment alters the localization of CCl4-induced changes in rat liver microsomal fatty acids

Phenobarbital treatment induces an isozyme(s) of liver microsomal cytochrome P450 susceptible to CCl4 and enhances the latter's lethality. We have now studied phenobarbital's effect on the specificity of phosphatidyl fatty acid changes in rat liver microsomes. Male Sprague-Dawley rats were pretreated with three daily ip doses of phenobarbital (50 mg/kg) or saline and then orally dosed with CCl4 (2.5 ml/kg). Liver microsomes were prepared 7.5 to 180 min after CCl4 treatment, the lipid fraction was extracted, diene conjugate content was determined, and phospholipids were separated by HPLC for fatty acid content determination. Protein, phospholipid, and phosphatidyl fatty acid residue loss occurred early (7.5 to 30 min) and in some cases later (60 to 180 min) in both pretreated groups, suggesting that two phases of CCl4-mediated injury occurred. Phenobarbital pretreatment accelerated the CCl4-induced formation of diene conjugates in the microsomal lipids. In studies on the separated phospholipids, phenobarbital alone altered microsomal fatty acid content, primarily decreasing arachidonic acid in favor of linoleate, particularly in phosphatidylserine. During the early phase of CCl4 injury, phenobarbital pretreatment shifted the major loss of arachidonic acid from phosphatidylserine to phosphatidylethanolamine. During the later phase, arachidonic acid loss was still prominent, but the most extensive CCl4-induced changes in fatty acids occurred in the neutral lipid fraction, regardless of pretreatment. These changes included loss of neutral lipid linoleic and docosahexanoic acids associated with an increase in palmitic acid. These data demonstrate that phenobarbital pretreatment is associated with a shift in the predominant phospholipid locus from phosphatidylserine to phosphatidylethanolamine for the early CCl4-induced fatty acid changes in rat liver microsomes.     

Effect of drugs on progesterone metabolism in the female rat

Various drugs brought about a reduction of serum progesterone level irrespective of whether or not a potent inducer (phenobarbital, 4-methyl-coumarin) or a hepatotoxin (carbon tetrachloride, α-naphthylisothiocyanate, coumarin) has been administered. The decrease by hepatotoxins was highly significant during the estrus phase of the cycle. These treatments affected the hepatic level of progesterone and altered the uptake of [4-¹⁴C]progesterone in vivo. The serum level of progesterone was significantly decreased by phenobarbital and carbon tetrachloride; however, the incorporation into the liver was enhanced by phenobarbital and reduced by carbon tetrachloride. This opposing hepatic action showed selectivity; phenobarbital increased the oxidative pathway of progesterone metabolism (formation of 6β-, 16α-, 20α-hydroxyprogesterone) but the reductive pathway remained unaltered (formation of pregnanediol, pregnanolone). Conversely, carbon tetrachloride diminished oxidation and raised reduction of progesterone. These results have been confirmed by measurements of progesterone metabolism in vitro using isolated microsomes. Phenobarbital brought about an induction of progesterone 16α-, 6β- and 20α-hydroxylase, did not affect progesterone Δ⁴-5α-dehydrogenase, whereas carbon tetrachloride inhibited hydroxylase and raised dehydrogenase activities. The action of these test compounds on serum and liver levels of progesterone and on the variation of progesterone metabolism seemed to be related to changes manifest in the function of the hepatic endoplasmic reticulum. Similar changes might be associated with the development of mild hepatic lesions induced by various steroids.     

Effect of acute nitrogen dioxide exposure on the composition of fatty acids in lung and liver phospholipids

In order to examine the effects of NO₂ on the fatty acid content of the lung and liver phospholipids, the phospholipid fractions of rats exposed to 20 ppm NO₂ for 20 and 40 h were extracted and analyzed using gas chromatography. Among the fatty acid species in the lung, the relative amount of palmitic acid, palmitoleic acid and linoleic acid increased significantly, whereas myristic acid, stearic acid and oleic acid decreased significantly after exposure to NO₂. These changes in the composition of fatty acids are discussed in comparison with the results of acute, subacute and chronic exposure to NO₂ reported by other workers. In the case of the fatty acid species in the liver, a significant increase for stearic acid and arachidonic acid and a decrease in oleic acid were observed.     

Propranolol inhibits accumulation of non-esterified fatty acids in the ischemic dog heart

The effects of propranolol and d-propranolol on the accumulation of non-esterified fatty acids (NEFA) induced by complete occlusion of the left anterior descending coronary artery (LAD) for 90 min, were investigated in dogs anesthetized with pentobarbital. The myocardial levels of eight NEFA (lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic and arachidonic acids) were determined after fluorescent labelling of the NEFA with 9-anthryldiazomethane. LAD occlusion increased the myocardial levels of NEFA, especially those of arachidonic and palmitoleic acids; arachidonic acid increased by 3.5 times and palmitoleic acid by 2.9 times. Pretreatment with propranolol (1 mg/kg) inhibited almost completely the accumulation of NEFA induced by occlusion of the LAD, whereas pretreatment with d-propranolol (1 mg/kg) did not inhibit the accumulation of NEFA, although it tended to inhibit the accumulation of palmitoleic, stearic and arachidonic acids. These results suggest that the inhibitory action of propranolol on the accumulation of NEFA in the myocardium during ischemia is mainly due to its antagonistic effect at beta-adrenoceptors and probably partly due to its effect as a local anesthetic.     

Cholesterol ester hydrolase mediated conjugation of haloethanols with fatty acids

The formation of fatty acid conjugates of haloethanols was studied under in vitro conditions by using purified bovine pancreatic cholesterol ester hydrolase (EC 3.1.1.13). The enzymatic formation of 2-chloroethyl and 2-bromoethyl esters of oleic, linoleic, linolenic, and arachidonic acids was confirmed by proton nuclear magnetic resonance spectroscopy and chemical ionization mass spectrometry. 2-Bromoethanol was a better substrate than 2-chloroethanol for fatty acid esterification using cholesterol ester hydrolase. Among the chloroethanols, 2-chloroethanol was a better substrate than 2,2-dichloroethanol and 2,2,2-trichloroethanol. The saturated fatty acids (palmitic and stearic) showed a small amount of ester formation when cholesterol ester hydrolase was used. The kinetics of haloethanol and oleic acid incorporation into haloethyl oleate catalyzed by cholesterol ester hydrolase were determined. In vitro experiments were also conducted to study the conjugation of haloethanols with fatty acids using rat liver microsomes. The saturated fatty acid (palmitic) was more reactive compared to unsaturated fatty acid (oleic) when haloethanols were used. The results using rat liver microsomes were in contrast to those obtained when cholesterol ester hydrolase was used. The synthesis, purification, and characterization of 2-chloroethyl and 2-bromoethyl esters of oleic, linoleic, linolenic, and arachidonic acids are also described.     

Ranking the toxicity of fatty acids on Jurkat and Raji cells by flow cytometric analysis

The fatty acids have an important role in the control of leukocyte metabolism and function. Higher concentrations of certain fatty acids, particularly polyunsaturated fatty acids (PUFAs) and volatile fatty acids, can cause cell death via apoptosis or, when concentrations are greater, necrosis. In this study, we determined the highest concentrations of various fatty acids that are non-toxic to two human leukemic cell lines, Jurkat (T-lymphocyte) and Raji (B-lymphocyte). Toxicity was evaluated by either loss of membrane integrity and/or DNA fragmentation using flow cytometric analysis. There were no remarkable differences for the toxicity of the fatty acids between B and T cell lines. The cytotoxicity of the fatty acids was related to the carbon chain length and number of double bonds: docosahexaenoic ACID=eicosapentaenoic ACID=arachidonic ACID=γ-linolenic ACID=stearic ACID=palmitic acid > linoleic ACID=palmitoleic acid > vacenic ACID=lauric acid > oleic acid > elaidic acid > capric acid > butyric acid > caprylic ACID=caproic ACID=propionic acid. The proportion of cells undergoing apoptosis or necrosis, induced by the fatty acids tested, remains to be investigated.     

Effect of phenobarbital treatment on carbon tetrachloride-mediated cytochrome P-450 loss and diene conjugate formation.

The effect of phenobarbital treatment on the linkage between carbon tetrachloride-mediated cytochrome P-450 loss and lipid peroxidation in rat liver microsomes was studied. Male Sprague-Dawley rats, pretreated with 3 daily i.p. doses of phenobarbital (50 mg/kg) or saline, were orally dosed with carbon tetrachloride (0.01-2.5 ml/kg), with liver microsomes prepared at 7.5-180 min after carbon tetrachloride treatment. In vivo cytochrome P-450 loss displayed pseudo-first-order kinetics, and the initial rates of diene conjugate formation were saturable with dose. Phenobarbital pretreatment decreased the in vivo t0.5,max from 27.0 to 15.6 min, and increased the Kd,app from 0.78 to 1.30 ml/kg for carbon tetrachloride mediated cytochrome P-450 loss. Phenobarbital had no effect on the in vivo Vmax (1.03 to 1.04 delta OD232 nm/min/mg phospholipid) for carbon tetrachloride mediated diene conjugate formation, but decreased the Km,app from 0.22 to 0.10 ml/kg. These results are consistent with destruction of cytochrome P-450 heme resulting from a metabolite which does not leave the site of generation, and with phenobarbital pretreatment enhancing the initiation of lipid peroxidation.     

In vitro conjugation of ethanolamine with fatty acids by rat liver subcellular fractions

Previous studies from our laboratory have shown the enzymic formation of fatty acid (FA) conjugates of xenobiotic alcohols and amines. In the present study, the formation of FA conjugates of a bifunctional compound, ethanolamine was investigated by incubating [1-14C]oleic acid (1 mM) with ethanolamine (25 mM) at 37 degrees C in the presence of various rat liver subcellular fractions. The resultant product (or products) was separated by thin-layer chromatography (TLC) and the radioactivity corresponding to the relative flow of fatty acid amide was determined. Under similar conditions, formation of ethanolamides of palmitic, stearic, linoleic, linolenic, and arachidonic acids were also examined. The formation of ethanolamine conjugate with oleic acid was found to be 16.3 nmol/h/mg protein as compared to 6.7, 6.2, 8.1, 8.3, and 7.6 nmol/h/mg protein for palmitic, stearic, linoleic, linolenic, and arachidonic acids, respectively. The formation of oleoyl ethanolamide was found to be 18.9, 40.1, 65.9, and 0.3 nmol/h/mg protein in postnuclear, mitochondrial, microsomal, and cytosolic fractions, respectively. Mass spectrometric and nuclear magnetic resonance spectroscopic data of the TLC-purified product confirm the formation of oleoyl ethanolamide, and amidation appeared to be a preferred reaction over esterification. The results of this study suggest that the enzyme responsible for the amidation of fatty acids resides mainly in the microsomal fraction of the liver, and that oleic acid is a better substrate than other fatty acids used in the present study.     

Effect of propranolol on accumulation of NEFA in the ischemic perfused rat heart

The effect of propranolol on the accumulation of non-esterified fatty acids (NEFA) in the isolated, perfused working rat heart was investigated. Ischemia was induced by lowering the afterload pressure to 0 mm Hg for 20 min and for reperfusion, the pressure was raised to the pre-ischemic pressure (60 mm Hg) for 20 min. The heart was frozen for biochemical studies immediately after ischemia or reperfusion. Ischemia decreased mechanical function, increased the levels of palmitoleic, arachidonic and linoleic acids, left oleic, lauric, myristic, palmitic and stearic acids unchanged, decreased the levels of adenosine triphosphate (ATP), creatine phosphate (CrP) and the energy charge potential (ECP), and increased the level of lactate. Propranolol (10(-5) or 3 x 10(-5) M) restored mechanical function and inhibited the changes in NEFA, ATP and ECP caused by ischemia. It is suggested that propranolol inhibits the decrease in mechanical function and high energy phosphates caused by ischemia, and thereby inhibits the accumulation of NEFA, especially of the unsaturated fatty acids such as arachidonic acid, during ischemia.     

Changes in the relative levels of fatty acids in blood and myocardium in the Prague breed of rats with hereditary hypercholesteremia after administration of slow calcium channel blockers]

The present paper describes the effect of six-week oral administration of verapamil and diltiazem (1 mg.kg-1 of weight two times daily in 12 hour intervals) on the content of fatty acids of the serum and myocardium of PHHC rats. A cholesterol diet changes the content of fatty acids of the serum and myocardium of PHHC rats in comparison with control rats without the cholesterol diet. A significant decrease in the content of palmitic acid, a decrease in the content of stearic acid, linoleic acid and arachidonic acid and a significant increase in the content of oleic acid were observed in the serum. Long-term administration of the slow calcium channel blockers produces another decrease in the content of the bound form of arachidonic acid. Changes in the representation of other fatty acids are not marked. Long-term administration of a cholesterol diet produces an increase in the content of palmitic acid and stearic acid and a decrease in the content of oleic acid, linoleic acid and arachidonic acid in the myocardium. Administration of verapamil results in a modification of the above-mentioned changes in all parameters excepting the content of arachidonic acid, the content of which was decreased in an even more marked manner. Administration of diltiazem produced an accumulation of both saturated and mono-unsaturated fatty acids (palmitic, stearic and oleic acids) and produced a significant decrease in the content of linoleic acid and mainly the bound form of arachidonic acid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Profiling of fatty acids released during calcium-induced mitochondrial permeability transition in isolated rabbit kidney cortex mitochondria

Increases in intracellular Ca²⁺ during cellular stress often lead to the mitochondrial permeability transition (MPT). We examined changes in fatty acids (FAs) released from isolated renal cortical mitochondria subjected to Ca²⁺-induced MPT. Exposing mitochondria to Ca²⁺ stimulated mitochondrial swelling and release of FAs such as arachidonic (20:4) and docosahexenoic acids which increased 71% and 32%, respectively, and linoleic (18:2) which decreased 23% compared to controls. Stearic (18:0), oleic (18:1), and linoleic (18:3) acids were unchanged. To elucidate a mechanism for FA release, mitochondria were pre-treated with bromoenolactone (BEL) to inhibit Ca²⁺-independent phospholipase A₂ gamma activity (iPLA₂γ). BEL blocked Ca²⁺-induced release of arachidonic and behenic (22:0) acids. Finally, four FAs were released in the absence of Ca²⁺ in a BEL-sensitive manner, including arachidonic and docosatrienoic acids. Thus, extensive FA release occurs during Ca²⁺-induced MPT, and that mitochondrial iPLA₂γ maintains mitochondrial arachidonic acid homeostasis under both basal and Ca²⁺-induced stress conditions.     

Essential fatty acid status in paediatric Crohn's disease: relationship with disease activity and nutritional status

BACKGROUND: Active paediatric Crohn's disease is associated with nutritional deficiencies and altered nutrient intake. The availability of essential fatty acids (linoleic and alpha-linolenic acids) or their derivatives (arachidonic and eicosapentaenoic acids) may alter in plasma and cell membrane phospholipid in protein-energy malnutrition in children and in Crohn's disease in adults. AIM: To investigate the relationship of fatty acid phospholipid profiles with disease activity and nutritional status in paediatric Crohn's disease. METHODS: The fatty acid (proportionate) composition of plasma and erythrocyte phosphatidylcholine was determined in 30 patients (10.3-17.0 years) stratified into active and quiescent Crohn's disease (paediatric Crohn's disease activity index) and high and low body mass (body mass index centile). RESULTS: In plasma phosphatidylcholine, active disease activity was associated with a lower level of alpha-linolenic acid compared with that in quiescent disease (P < 0.05). A body mass index below the 50th centile was associated with active Crohn's disease, low linoleic and alpha-linolenic acids and high arachidonic acid (P < 0.05) in plasma phosphatidylcholine, and low alpha-linolenic acid in erythrocyte phosphatidylcholine. These findings could not be explained through differences in habitual dietary fat intake. CONCLUSION: In paediatric Crohn's disease, a low body mass index centile and high disease activity are associated with altered profiles of essential fatty acids and their derivatives, which may reflect altered metabolic demand.     

Clofibric acid increases the formation of oleic acid in endoplasmic reticulum of the liver of rats

The effects of 2-(4-chlorophenoxy)-2-methylpropionic acid (clofibric acid) on the formation of oleic acid (18:1) from stearic acid (18:0) and utilization of the 18:1 formed for phosphatidylcholine (PC) formation in endoplasmic reticulum in the liver of rats were studied in vivo. [1?C]18:0 was intravenously injected into control Wistar male rats and rats that had been fed on a diet containing 0.5% (w/w) clofibric acid for 7 days; and the distribution of radiolabeled fatty acids among subcellular organelles, microsomes, peroxisomes, and mitochondria, was estimated on the basis of correction utilizing the yields from homogenates of marker enzymes for these organelles. The radioactivity was mostly localized in microsomes and the radiolabeled fatty acids present in microsomes were significantly increased by the treatment of rats with clofibric acid. The formation of radiolabeled 18:1 in microsomes markedly increased and incorporations of the formed [1?C]18:1 into PC and phosphatidylethanolamine in microsomes were augmented in response to clofibric acid. The [1?C]18:1 incorporated into PC was mostly located at the C-2 position, but not the C-1 position, of PC, and the radioactivity in 18:1 at the C-2 position of PC was strikingly increased by clofibric acid. These results obtained from the in vivo experiments directly link the findings that clofibric acid treatment induces microsomal stearoyl-CoA desaturase and 1-acylglycerophosphocholine acyltransferase in the liver and the findings that the treatment with the drug elevated absolute mass and mass proportion of 18:1 at the C-2 position, but not the C-1 position, of PC in the liver together.     

Structural and functional changes in liver mitochondria of mice fed palmitoylethanolamide (PEA)

Repeated administration of palmitoylethanolamide (PEA) to mice, at a dose of 50 mg/kg body wt, produced a characteristic change in lipid composition of liver mitochondria. The content of the saturated fatty acids, palmitic (16:0) and stearic (18:0), decreased in the fraction of neutral lipids while the content of the unsaturated acids, palmitoleic (16:1), and oleic (18:1) and of the higher saturated acid arachidonic (20:4) increased. In contrast the amount of palmitoleic (16:1) acid decreased and palmitic (16:0) acid increased in mitochondrial phospholipids. Concomitant with these changes in the lipid composition of mitochondria changes occurred in their biochemical properties. The swelling of liver mitochondria induced by orthophosphate and by crude staphylococcal toxin is delayed in PEA-treated mice. Structural changes in mitochondrial phospholipids were confirmed with the fluorescent hydrophobic probe. The mitochondria isolated from mice pretreated with PEA had a lower fluorescence ratio than mitochondria from control animals.     

Effects of drugs or hepatotoxins on the relation between drug-metabolizing activity and phospholipids in hepatic microsomes during choline deficiency

Choline-deficient diet was shown to alter the effects of foreign compounds on the phospholipid composition and enzyme activity of rat liver microsomes. Simultaneous treatment with phenobarbital resulted in much lower levels of individual phospholipids than those obtained from similarly treated animals kept on choline-supplemented diet although the changes were proportionately similar. The effect of carbon tetrachloride on phospholipids was masked by the deficient diet.Choline deficiency caused a decrease of drug-metabolizing activity and reduced all phospholipid fractions with the exception of phosphatidic acid. The induction of drug metabolism by phenobarbital or 4-methylcoumarin was antagonized, whereas the inhibition by carbon tetrachloride or coumarin was potentiated as were their effects on phosphatases. S-Adenosylmethionine microsomal-phospholipid methyltransferase activity was significantly increased in choline-deficient animals.The findings suggested that microsomal phospholipids might play an important role in the induction and activity of drug metabolizing enzymes and that the therapeutic effectiveness of drugs might be seriously altered during conditions of adverse health.