[Enhanced sensitivity of pituitary cells to corticosteroids in neonatal rats].

The effects of corticosteroids on pituitary cells, obtained from developing rats of different ages, were studied during long-term (3-4 days) incubation. Dexamethasone, cortisol and aldosterone inhibited the rate of DNA synthesis in primary cultures of pituitary cells from neonatal and pup rats more efficiently than in cell cultures of prepubertal and adult animals. Moreover, the above mentioned corticosteroids inhibited total protein biosynthesis in pituitary cells of infantile rats and did not change significantly this index of functional activity in cells of prepubertal and adult animals. In separate experiments steroid specificity of glucocorticoid action was examined in detail: estradiol and testosterone did not change the rates of macromolecule synthesis in neonatal pituitary cells whereas progesterone possessed a weak inhibitory effect that was, however, far less marked as compared to the effect of corticosterone. It has been concluded that neonatal rat pituitary cells demonstrate enhanced sensitivity to anti-proliferative and catabolic action of corticosteroids.