[The sex dependence of the expression of the particular estrogen-binding protein in the hepatocytes in rat ontogeny].

Formation of dependence on sex of the unusual estrogen-binding protein (UEBP) expression in rat liver during postnatal development was studied using radioligand and immunohistochemical techniques. UEBP was shown to appear in the male and female liver by day 45 to 50 of postnatal life. In females, UEBP remained at a low level until day 75 to 80, corresponding to faint UEBP-specific staining of a single layer of hepatocytes surrounding the central vein. Thereafter UEBP level decreased below the resolving capacity of the method. In males, UEBP content progressively increased during subsequent stages of ontogenesis. This is accompanied by formation of a stable descending centrolobular-periportal gradient of UEBP-positive hepatocytes. High UEBP expression in the male liver was found to result from the programming effect of androgens exerted between days 1-3 and 12 of postnatal development. The formation of hepatic lobuli is not a condition sufficient for switching on the androgen program of UEBP expression. The absence of testicular androgens in males after day 12 of life does not affect the androgen-programmed ontogenetic time course of UEBP expression at high levels. Experimental programming of UEBP expression in hepatocytes of immature females with the use of androgens results in lower UEBP levels than in males. These levels are comparable to those found in male liver at early stages of regeneration (96 h) after partial hepatectomy. It is suggested that androgens determine not only UEBP-producing capacity of hepatocytes but also the system of its control.