title: [DIACYLGLYCEROL ACCUMULATION IMPAIRS SHORT-TERM ACTIVATION OF PHOSPHOLIPASE D BY THYROXINE IN THE LIVER CELLS].
abstract: Thyroid hormones (TG) are known modulators of signal transduction. Phospholipase D (PLD) is one of the targets of TG in the stimulated cells. Response of cells to the short-term TG action significantly reduces at old age. Taking into account that diacylglycerol (DAG) accumulation induces the resistance of cells to some of regulatory factors in the target cells the aim of the present study was to determine if DAG content increase in hepatocytes impairs the L-thyroxine (L-T4) short-term action. The experiments were performed in either the [14C]palmitic acid- labeled hepatocytes or [14C]oleic acid-pre-labeled liver cells of 3- and 24-month-old rats. To study the short-term L-T4 action on cells the PLD activation was determined. The DAG production and content in hepatocytes significantly increased at old age and in the young cells pre-treated with palmitic acid. The reduction of DAG level in cells by means of DAG-kinase activator, alfa-tocoferol acetate, or long-term L-T4 treatment improved the short-term hormone action. The above data have indicated that DAG play important role in the L-T4 PLD regulation. The cross-talk between classic and non-genomic pathways of TG regulation of lipid metabolism has been determined.
authors.forename: Loay Kh M
authors.initials: LKh
authors.lastname: Hassouneh
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D019852:Diacylglycerol Kinase / Q000378:metabolism; D004075:Diglycerides / Q000096:biosynthesis*; D004789:Enzyme Activation; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D019301:Oleic Acid / Q000378:metabolism; D019308:Palmitic Acid / Q000378:metabolism; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D061251:Primary Cell Culture; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013974:Thyroxine / Q000494:pharmacology*; D024502:alpha-Tocopherol / Q000494:pharmacology
chemical_list: C011439:1,2-diacylglycerol; D002250:Carbon Radioisotopes; D004075:Diglycerides; D019301:Oleic Acid; D019308:Palmitic Acid; D019852:Diacylglycerol Kinase; D010739:Phospholipase D; D024502:alpha-Tocopherol; D013974:Thyroxine