Developmental changes in the expression of alpha-tocopherol transfer protein during the neonatal period of rat

It is well known that the cellular concentration of alpha-tocopherol (alpha-toc) is about 10-fold greater than that of gamma-tocopherol (gamma-toc) despite the ingestion of a large amount of gamma-toc in the diet. Recently, this discrimination of tocopherol is considered to be attributed to alpha-tocopherol transfer protein (alpha-TTP) which binds to alpha-toc in preference to the other forms of tocopherol in the liver. In the present study, developmental changes in expression of alpha-TTP after birth were investigated using rats with respect to plasma changes of tocopherols. The expression of alpha-TTP in the neonatal rat liver, which was very low immediately after birth, increased steadily during the two weeks of life before weanling and reached the adult level at four weeks. During the suckling period, the plasma ratio of alpha-toc to gamma-toc linearly increased, because plasma alpha-toc which was low immediately after birth, increased rapidly during the period, while gamma-toc remained unchanged. The increase in the ratio seemed to correlate with the developmental expression of alpha-TTP in the liver during this period.