Trophic effect and modulation of ACTH-dependent stimulation of steroidogenesis by prolactin in guinea pig adrenal cortex.

The effect of PRL in intact guinea pig on the incorporation of specific labelled precursors into DNA, RNA, proteins and corticosteroids in adrenocortical tissue of intact guinea pig at different levels of activation of the gland were studied. PRL (2 IU/100 g daily) did not cause any significant changes until 3 days of treatment. PRL administered alone for 3 days caused significant elevation of 3H-thymidine incorporation into DNA in adrenocortical slices and no significant changes in labelling of RNA, protein and corticosteroids. In contrast, PRL administered together with ACTH (0.5 IU/100 g) for 3 days did not affect DNA synthesis but caused increase of 3H-cholesterol incorporation into cortisol and cortisone additionally to the ACTH action. Labelling of 17-deoxycorticosteroids in adrenocortical slices from animals of ACTH+PRL group either did not change significantly (aldosterone) or decreased (corticosterone).