The effect of phenobarbital and carbon tetrachloride on fatty acid content and composition of phospholipids from the endoplasmic reticulum of rat liver
Ilyas, M.S.; de la Iglesia, F.A.; Feuer, G.
Toxicology and Applied Pharmacology 44(3): 491-504
1978
ISSN/ISBN: 0041-008X PMID: 684743 Document Number: 129016
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 CCl4. Both test compounds significantly altered the fatty acid composition of the endoplasmic reticulum. The total amount was significantly raised by phenobarbital and reduced by CCl4. Phenobarbital enhanced palmitic, stearic, arachidic, palmitoleic, linoleic, eicosenoic, eicosadienoic, eicosatrienoic, eicosapentenoic, docosatrienoic and docosahexenoic acids. CCl4 diminished all these, excluding palmitic and palmitoleic acids. The fatty acid content of rough microsomes was significantly increased by phenobarbital and decreased by CCl4, while in smooth microsomes fatty acids were raised by phenobarbital but mainly unaffected by CCl4. In microsomal phosphatidylcholine fractions, phenobarbital significantly elevated oleic, linoleic, eicosatrienoic, arachidonic, eicosapentenoic, docosapentenoic and docosahexenoic acids, whereas all these were significantly reduced with CCl4. In phosphatidylethanolamine fractions, phenobarbital increased palmitoleic, oleic, linoleic and arachidonic acids; CCl4 elicited opposite effects on these acids. Phenobarbital increased and CCl4 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 CCl4. The fatty acid content of phosphatidylethanolamine was increased by phenobarbital, mainly manifesting in palmitoleic, oleic, linoleic, arachidonic, docosapentenoic and docosahexenoic acids. CCl4 elicited no major change in this fraction. Phenobarbital increased the production of unsaturated fatty acids, whereas CCl4 elevated the relative amount of saturated fatty acids. The saturated/unsaturated fatty acids ratio was reduced by phenobarbital and increased by CCl4 and may indicate a selective difference between an inducer and hepatotoxin on fatty acid synthesis of the hepatic endoplasmic reticulum.