AGE-RELATED-CHANGES OF ALPHA-TOCOPHEROL TRANSFER PROTEIN EXPRESSION IN RAT-LIVER

Developmental changes in expression of alpha-tocopherol transfer prote in (alpha-TTP) after birth were investigated using rats with respect t o plasma changes of tocopherols. The expression of alpha-TTP in the ne onatal rat liver, which was very low immediately after birth, increase d steadily during the two weeks of life before weanling and reached th e adult level at four weeks. During the suckling period, the plasma ra tio of alpha-tocopherol to gamma-tocopherol linearly increased, becaus e plasma alpha-tocopherol which was low immediately after birth, incre ased rapidly during the period, while gamma-tocopherol remained unchan ged. The increase in the ratio seemed to correlate with the developmen tal expression of alpha-TTP in the liver during this period. The ratio also reached the adult level after four weeks. The expression of alph a-TTP was investigated using primary cultured rat hepatocytes. The exp ression of alpha-TTP was found to be extremely low after 20 h of cultu re. The decrease in alpha-TTP expression was exacerbated by adding epi dermal growth factor to the culture medium and was inhibited by adding dexamethasone. These observations suggest that expression of alpha-TT P may be affected by the state of hepatic differentiation.