Loay K. Age peculiarities of the lipid turnover involved in the processes of signal transduction.

The object of the study. It has been determined that sphingolipid turnover increased in the liver at the old age of rats as compared with the young animals. The increased sphingolipid turnover in the liver is associated with the increased production and contents of the ceramide and sphingosine. The ceramide content in the brain structures (hyppocampus and cortex) of the 24-month-old rats was significantly higher than that in the brain of the 3-month-old animals. The significant increase has been determined in the diacylglycerol (DAG) and fatty acid (FFA) masses in the liver, the hippocampus, and the brain cortex of the old rats as compared to the young animals. The results demonstrate that the thyroxin plays an important role in the rapid non-genomic regulation of the sphingo- and glicerolipid turnover in the target cells. The hormone effect on the hepatocytes is found to be dependent on the animal age and could be modulated by the dietary compounds (vitamin E and FFA). It has been determined that the vitamin E reduces the ceramide and the DAG levels in the hepatocytes of the old rats and the ceramide content in the palmitate-treated cells and enhances cell sensitivity to the thyroxin action. In summary, the combination of these observations indicate that the enhanced basal levels of the ceramide and the DAG play an important role in the age-dependent decrease of the cell sensitivity to the non-genomic thyroxin action on the cells.