Different Responses of Albumin-Containing and Alpha-Fetoprotein-Containing Cells to Estriol in the Adult Mouse Liver

A single intraperitoneal injection of 10mg estriol (E3) rapidly induced a transient decrease in the serum albumin (ALB) level in 3 to 5 days in adult mice. At a dose of 5mg, E3 showed a remarkable threshold effect on the decline of serum ALB. By immunohistochemistry, two types of ALB-positive cells were found in the liver. Type 1 cells were stained intensely and almost homogeneously throughout all or nearly all their entire cytoplasm, and type 2 cells showed only granular or vesicular cytoplasmic deposits. After administration of 10mg E3, the type 1 cells diminished rapidly and markedly in direct proportion to the fall in serum ALB from the centro- and mediolobular zones, where they had been normally localized either singly or in small groups. Simultaneously, the granular or vesicular deposits that had been normally stained very weakly in the type 2 cells in the centro- and mediolobular zones became intensely stained along with cells in the perilobular zone. Alpha-fetoprotein (AFP)-containing cells in the liver appeared in maximal numbers at 5 to 7 days after E3 administration. These serological and cytological changes after E3 adiministration are here discussed on the basis of a possible inverse relationship between ALB and AFP gene expression.