Stimulation of adrenal cell proliferation in normal rats by carcinogen-induced serum factors

The mitotic activity of the adrenal cortex shows diurnal variations. Irrespective of these fluctuations, single doses of 2-acetylaminofluorene selectively stimulate cell division in the zona fasciculata. The serum from 2-acetylaminofluorene-treated rats also acts mitogenically after transfer to intact recipients. After simultaneous administration of 3-methylcholanthrene and 2-acetylaminofluorene the mitotic action of the serum is lost. The proliferative response of the adrenal cortex is supposed to be systemically mediated by growth factors which are induced by the carcinogen.