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.     

Effect of benzyl viologen on the fatty acid composition of rat liver

The influence of subacute treatment with benzyl viologen (a stimulator of free radical production in cells) on the fatty acid content of rat liver has been analyzed. Lipid storage, essentially characterized by lamellated inclusions, developed as we reported previously (Muriana et al., Exp. Pathol., 32 (1987) 65-72). A substantial increase in liver total lipid, phospholipids and triacylglycerols was found during viologen treatment in rats. The composition in fatty acids was profoundly influenced by the experimental conditions, but to different degrees in different lipid classes.     

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

The fatty acid content and composition of hepatic microsomes of separated smooth and rough components and of isolated phosphatidylcholine and phosphatidylethanolamine fractions were studied in male albino rats treated with phenobarbital or carbon tetrachloride. Both test compounds significantly altered the fatty acid composition of the endoplasmic reticulum. The total amount was significantly raised by phenobarbital and reduced by carbon tetrachloride. Phenobarbital enhanced palmitic, stearic, arachidic, palmitoleic, linoleic, eicosenoic, eicosadienoic, eicosatrienoic, eicosapentenoic, docosatrienoic, and docosahexenoic acids. Carbon tetrachloride diminished all these, excluding palmitic and palmitoleic acids. The fatty acid content of rough microsomes was significantly increased by phenobarbital and decreased by carbon tetrachloride, while in smooth microsomes fatty acids were raised by phenobarbital but mainly unaffected by carbon tetrachloride. In microsomal phosphatidylcholine fractions, phenobarbital significantly elevated oleic, linoleic, eicosatrienoic, arachidonic, eicosapentenoic, docosapentenoic, and docosahexenoic acids, whereas all these were significantly reduced with carbon tetrachloride. In phosphatidylethanolamine fractions, phenobarbital increased palmitoleic, oleic, linoleic, and arachidonic acids; carbon tetrachloride elicited opposite effects on these acids. Phenobarbital increased and carbon tetrachloride reduced the fatty acid content in the phosphatidylcholine fraction of rough membranes. Opposite effects were seen in oleic, linoleic, arachidonic, and eicosapentenoic acids. Both test compounds brought about similar changes in the fatty acid composition of the phosphatidylethanolamine fractions of rough microsomes. In smooth microsomes, phosphatidylcholine fatty acids were significantly enhanced by phenobarbital and reduced by carbon tetrachloride. The fatty acid content of phosphatidylethanolamine was increased by phenobarbital, mainly manifesting in palmitoleic, oleic, linoleic, arachidonic, docosapentenoic, and docosahexenoic acids. Carbon tetrachloride elicited no major change in this fraction. Phenobarbital increased the production of unsaturated fatty acids, whereas carbon tetrachloride elevated the relative amount of saturated fatty acids. The saturated/unsaturated fatty acids ratio was reduced by phenobarbital and increased by carbon tetrachloride, and thus may indicate a selective difference between an inducer and hepatotoxin on fatty acid synthesis of the hepatic endoplasmic reticulum.     

Microsomal and peroxisomal fatty acid oxidation in streptozotocin diabetic rat liver

Microsomal lauric acid hydroxylation and fatty acid peroxisomal β-oxidation were studied in hepatic subcellulant preparations from streptozotocin-induced diabetic and diabetic insulin-treated rats.

• 1.2. The liver microsomes of the streptozotocin diabetic rats displayed a similar activity to hydroxylate lauric acid as the control microsomes.
• 2.3. Diabetic insulin-treated rats showed lower (ω1) and ω-lauric acid hydroxylase activities than diabetic and control rats.
• 3.4. Streptozotocin-induced diabetes and diabetic insulin-treated rats exhibited no significant changes on peroxisomal palmitoyl CoA β-oxidation compared to the control rats.
• 4.5. Both microsomal and peroxisomal fatty acid oxidation responded in a similar way in this model of experimental diabetes.

     

Combined n-benzoyl-d-phenylalanine and metformin treatment reverses changes in the fatty acid composition of streptozotocin diabetic rats

The present investigation was carried out to evaluate the effect of N-benzoyl-D-phenylalanine (NBDP) and metformin on blood glucose, plasma insulin, and on the fatty acid composition of total lipids in the livers and kidneys of control and experimental diabetic rats. When compared with nondiabetic control rats, neonatal streptozotocin (nSTZ) diabetic rats showed a significant increase in blood glucose and decreased plasma insulin. Analysis of fatty acids revealed a significant increase in the concentration of palmitic, stearic, and oleic acids in liver and kidney, whereas linolenic and arachidonic acids were significantly decreased. In diabetic rats, the oral administration of combined NBDP/metformin for 6 wk decreased the high concentrations of palmitic, stearic, and oleic acids and elevated the low levels of linolenic and arachidonic acids. The results suggest that the NBDP/metformin combination exhibits both antidiabetic and antihyperlipidemic effects in nSTZ diabetic rats and prevents the fatty acid changes produced during diabetes.     

非酒精性脂肪肝形成过程中肝型脂肪酸结合蛋白的表达

目的：通过检测非酒精性脂肪肝形成过程中肝型脂肪酸结合蛋白的表达变化探讨其发病机制。方法：雄性大鼠60只，体重（180±10）g，随机分为饮食基础饲料的正常对照组和饮食高脂饲料（基础饲料87．8％、猪油10％、胆固醇2％、胆盐0．2％）的实验组；各组又随机分为2、4、8、12用4个时相纽。用Western-blot方法进行L—FABP蛋白质的动态检测并探讨其发病机制。结果：L—FABP在高脂饮食后的第2周开始升高，与正常饮食组相比升高有显著性（1．31±0．02vs0．67±0．03，P〈0．01）。第8周时升至最高（1．67±0．07vs0．67±0．03，P〈0．01），第12周有所降低，但与第8周相比没有统计学意义。结论：随着高脂饮食时间的延长．L-FABP的表达逐渐上升，一定程度上说明其和脂肪肝的进展有密切关系，有望成为脂肪肝治疗药物的靶点。     

Characterization of the drug binding specificity of rat liver fatty acid binding protein

Liver-fatty acid binding protein (L-FABP) is found in high levels in enterocytes and is involved in the cytosolic solubilization of fatty acids during fat absorption. In the current studies, the interaction of L-FABP with a range of lipophilic drugs has been evaluated to explore the potential for L-FABP to provide an analogous function during the absorption of lipophilic drugs. Binding affinity for L-FABP was assessed by displacement of a fluorescent marker, 1-anilinonaphthalene-8-sulfonic acid (ANS), and the binding site location was determined via nuclear magnetic resonance chemical shift perturbation studies. It was found that the majority of drugs bound to L-FABP at two sites, with the internal site generally having a higher affinity for the compounds tested. Furthermore, in contrast to the interaction of L-FABP with fatty acids, it was demonstrated that a terminal carboxylate is not required for specific binding of lipophilic drugs at the internal site of L-FABP.     

Changes of fatty acid composition of brain synaptosomal phospholipids in isoflurane exposure rat]

We examined effects of inhalational anesthetic drug, isoflurane, on phospholipid and fatty acid in brain synaptosome. Wistar strain male rat was treated by inhalation of isoflurane. Rats were divided into 3 groups each 6 rats, one was 1 minimum alveolar concentration (MAC) exposure group, 1MAC group, and another was 2 times of MAC exposure group, 2MAC group, and the other was non exposure group, control group. The animals were kept in to box (0.343 m3) and the gas flow rate was set in 4 L/min by anesthetic instrument. After 60 minutes of exposure, rats were decapitated. Immediately, cerebrums were removed and fraction of synaptosome was sampled. In 2MAC group, C14:0 of phosphatidylcholine (PC) increased significantly as compared to the control group, but C16:1, C18:0, C18:2 and C20:3 decreased significantly. And also, C18:2 and C20:3 decreased significantly in 1MAC group. In terms of phosphatidylethanolamine(PE), C18:1 in 1MAC group, C14:0 and C16:1 in 2MAC group increased, but C20:3, C20:4 and C22:5 in 2MAC group decreased significantly as compared to the control group. Regarding phosphatidylserine + phosphatidylinositol, C14:0 in 2MAC group increased, but C22:5 decreased. In lysophosphatidylcholine, C12:0 and C14:0 in 2MAC group and C18:0, C20:4 in 1MAC group increased significantly, but C18:1 in 2MAC decreased. The changes of phospholipids and fatty acid in synaptosome were due to the metabolism of phospholipids of basic matrix and this was caused by effects of isoflurane on neural cellular membrane. The results indicated the suppression of membrane activity. Isoflurane has physiological activity on metabolism of phospholipid of cellular membrane. Thus, it has effects on neural cellular functions in brain.     

Protective effect of Coccinia indica on changes in the fatty acid composition in streptozotocin induced diabetic rats

The present study was undertaken to investigate the effect of Coccinia indica, an indigenous plant used in Ayurvedic Medicine in India, on blood glucose, plasma insulin, cholesterol, triglycerides, free fatty acids and phospholipids and fatty acid composition of total lipids in liver, kidney and brain of normal and streptozotocin (STZ) diabetic rats. Oral administration of the ethanolic extract of Coccinia indica leaves (200 mg/kg body weight, CLEt) for 45 days to diabetic rats decreased the concentrations of blood glucose, lipids and fatty acids, viz., palmitic, stearic, and oleic acid whereas linolenic and arachidonic acid and plasma insulin were elevated. These results suggest that CLEt exhibits hypoglycaemic and hypolipidaemic effects in STZ induced diabetic rats. It also prevents the fatty acid changes produced during diabetes. The effect of CLEt at 200 mg/kg body weight was better than that of glibenclamide.     

Hippocampal and striated skeletal muscle changes in fatty acid composition induced by ethanol in alcohol-preferring rats

Chronic ethanol intake affects various organ systems of the body. The present study evaluated modifications of fatty acid concentrations both in brain and striated skeletal muscles of rats genetically selected for voluntary high ethanol intake. Three groups of rats were tracked for 10 weeks of access to ethanol only as fluid (group 1) to free choice of ethanol and water (group 2) or to water only (group 3). At the end of the period, the animals were sacrificed and their brain hippocampus and striated skeletal muscles were removed and fatty acid content of these tissues was determined. Long-chain fatty acid content increased in the hippocampus while it decreased in the striated skeletal muscles. Short chain fatty acid content decreased in the hippocampus while short chain fatty acid content increased in the striated skeletal muscles. The data show that brain and striated skeletal muscles differently modulate fatty acid content perhaps because these areas utilize different cell membrane functionality regulation systems.     

Determination of the antioxidant activity based on the content changes in fatty acid methyl esters in vegetable oils

Free radicals, which are generated in several biochemical reactions in the body, have been implicated as mediators of many diseases, including cancer, atherosclerosis and heart diseases. Although the endogenous antioxidants can scavenge these free radicals, they are often insufficient to maintain the in vivo redox balance. The antioxidant activity（AOA） was examined by addition of each tested antioxidants [alpha-tocopherol（α-T）, beta-tocopherol（β-T）, gamma-tocopherol（γ-T）, delta-tocopherol（δ-T）, butylated hydroxyanisole（BHA）, 2,6-di-tert-butyl-4-methylphenol（BHT）, and ascorbyle palmitate（AP）] to four types of different vegetable oils（sunflower oil, soybean oil, corn oil and olive oil）. Moreover, content changes in fatty acids were then investigated every 3 months during the storage period. The results showed that the AOA was different among the tested antioxidants. The AOA for BHA was the most for different types of oil compared with other antioxidants, whereas the δ-T possessed the lowest AOA.     

Microsomal oxidation of dodecylthioacetic acid (a 3-thia fatty acid) in rat liver.

[1-14C]Dodecylthioacetic acid (DTA), a 3-thia fatty acid, is omega (omega-1)-hydroxylated and sulfur oxygenated at about equal rates in rat liver microsomes. In prolonged incubations DTA is converted to omega-hydroxydodecylsulfoxyacetic acid. omega-Hydroxylation of DTA is catalysed by cytochrome P450IVA1 (or a very closely related isoenzyme in the same gene family), the fatty acid omega-hydroxylating enzyme. It is absolutely dependent on NADPH and inhibited by CO, and lauric acid is a competing substrate. omega-Hydroxylation of DTA is increased by feeding tetradecylthioacetic acid (TTA), a 3-thia fatty acid, for 4 days to rats. omega-Hydroxylation of [1-14C]lauric acid is also induced by TTA and other 3-thia carboxylic acids. A close relationship was observed between induction of microsomal omega-hydroxylation of fatty acid and palmitoyl-CoA hydrolase activity. DTA is omega-hydroxylated at about the same rate as the physiological substrate lauric acid. The sulfur oxygenation of DTA is catalysed by liver microsomal flavin-containing monooxygenase (FMO) (EC 1.14.13.8). It is dependent on either NADH or NADPH. The Km value for NADH was approx. five times larger than the Km value for NADPH. It is inhibited by methimazole and not affected by CO. It is not induced by TTA.     

海参磷脂型EPA对血清及肝脏脂肪酸组成的改善作用

目的 本文研究了海参磷脂型EPA(Eicosapntemacnioc acid-enriched phosphatidylcholine from sea cucumber,EPA-PC) 对非酒精性脂肪肝(Nonalcoholic fatty live disease, NAFLD)大鼠血清和肝脏脂肪酸组成的改善作用。方法 以NAFLD大鼠为模型,灌胃EPA-PC 4w,检测血清中和肝脏中脂质水平及脂肪酸组成。结果 EPA-PC显著降低模型大鼠血清和肝脏总脂中甘油三酯(Triglyceride,TG)和总胆固醇(Total cholesterol,TC)水平,显著升高血清高密度脂蛋白(High density lipoprotein cholesterol,HDLC)/TC水平;显著升高血清和肝脏中多不饱和脂肪酸(Polyunsaturated fatty acids,PUFA)的比例,降低n6/n3PUFA比例,升高DHA比例,降低肝脏总脂和磷脂去饱和C18：1/C18：0指数的比例,改善脂肪酸组成。结论 EPA-PC可以使血清和肝脏脂质水平下降,改变血清和肝脏脂肪酸组成,使NAFLD大鼠脂质水平紊乱状态得到改进。     

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.     

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.     

Inhibitory effect of cholephilic anions on fatty acid uptake by the perfused rat liver

The mechanisms of uptake and intracellular transport of plasma free fatty acids by the liver cell are poorly known. A cytosolic protein, termed Z protein, has been identified in the liver, intestine and other tissues; in vitro studies show a high affinity of fatty acid and organic anions for this protein and suggest that it could be involved in the cellular transport of fatty acids in vivo. The present experiments demonstrate an inhibitory effect of various organic cholephilic anions (B.S.P., D.B.S.P., flavaspidic acid, bilirubin, etc) on fatty acid uptake by the isolated perfused rat liver. This inhibition is rapidly reversible when the liver is perfused with a medium lacking cholephilic anions, which together with the absence of any functional or ultrastructural damage to the organ, excludes any hepatotoxic effect. Such an inhibition of fatty acid uptake could be due to a competition for binding either to membrane sites and/or to intracellular carriers common to both fatty acids and cholephilic anions. These data are consistent with the involvement of carrier-mediated processes in fatty acid transport in the liver. Finally, simultaneous uptake of radioactive fatty acid and cholephilic anions does not interfere with further fatty acid utilization by the cell.     

Effects of long-term administration of clofibric acid on stearoyl-CoA desaturase, 1-acylglycerophosphorylcholine acyltransferase and fatty acyl composition of microsomal phosphatidylcholine in rat liver

Long-term effects of p-chlorophenoxyisobutyric acid (clofibric acid) on inductions of stearoyl-CoA desaturase and 1-acylglycerophosphorylcholine (1-acyl-GPC) acyltransferase, and on changes in fatty acyl composition of microsomal lipid in rat liver were studied. Male rats were fed clofibric acid at a dietary concentration of 0.25% for 2 or 22 weeks. Inductions of stearoyl-CoA desaturase and 1-acyl-GPC acyltransferase lasted throughout the long-term treatment and were the same as those of either young or aged rats which were treated with clofibric acid for 2 weeks. The long-term treatment of rats with clofibric acid scarcely affected components of stearoyl-CoA desaturation system other than terminal desaturase. In accordance with the induction of stearoyl-CoA desaturase, the increase in the proportion of octadecenoic acid in hepatic lipid lasted throughout the 22-week treatment. In the case of both of the long-term treatment and the short-term treatment of rats, the increase in the proportion of octadecenoic acid in microsomal phosphatidylcholine was due to the marked increase in the proportion of octadecenoic acid in position 2, but not position 1, of phosphatidylcholine. These changes in fatty acyl composition of phosphatidylcholine were not due to the alteration of the content of phosphatidylcholine in liver.     

Effects of lipoic acid and n-3 long-chain polyunsaturated fatty acid on the liver ovariectomized rat model of menopause

Background

Bilateral ovariectomy is an experimental model used to analyse the effects of menopause and develop strategies to mitigate the deleterious effects of this condition. Supplementation of the diet with antioxidants has been used to reduce potential oxidative stress caused by menopause. The purpose of the study was to analyse the effects of α-lipoic acid (LA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), dietary supplementation on oxidative stress in the livers of ovariectomized rats.

高脂饲料中胆固醇含量对大鼠非酒精性脂肪肝动物模型建立的影响

目的观察大鼠非酒精性脂肪肝动物模型构建中肝脏脂变程度与高脂饲料内胆固醇含量和造模时间的动态关系,以找到合适的非酒精性脂肪肝的造模方法。方法 SD雄性大鼠70只,饲喂不同胆固醇含量的高脂饲料,分别检测14,21和28d大鼠血清ALT,AST,TC,TG,LDL-C和HDL-C,并观察肝脏脂变情况。结果造模2,3和4周后高脂饲料中胆固醇质量分数1%组与1.5%组大鼠的肝脏脂肪变性均无显著区别。其中21d后,所有的大鼠均发生了肝脏脂肪变性;28d后,大部分大鼠发生了肝脏重度脂肪变性,质量分数1.5%胆固醇组大鼠肝脏发生了炎症浸润和点状坏死。结论实验较好再现了高脂饮食引起的非酒精性脂肪肝发展的全过程,其中高胆固醇的质量分数为1%和1.5%的高脂饲料对大鼠肝脏脂变程度的影响无明显差别。