Induction of Milk Protein Synthesis by Placental Lactogen and Prolactin in Vitro
1968; Oxford University Press; Volume: 82; Issue: 3 Linguagem: Inglês
10.1210/endo-82-3-575
ISSN1945-7170
Autores Tópico(s)Digestive system and related health
ResumoHuman placental lactogen (HPL) and ovine prolactin each induce the synthesis of casein, α-lactalbumin and β-lactoglobulin in mammary epithelial cells formed during organ culture on synthetic medium containing insulin and hydrocortisone. After 96 hr of incubation on such medium, neither the differentiated cells originally formed in vivo nor the post-mitotic daughter cells formed in vitro synthesize detectable amounts of the major casein components. Casein synthesis is induced by the addition of HPL or prolactin, and experiments with colchicine demonstrated that this new synthetic activity is present only in the progeny of undifferentiated cells. The post-mitotic induction of milk protein synthesis by HPL or prolactin depends upon the continuing presence of insulin in the medium. Addition of HPL or prolactin in the post-mitotic period stimulates RNA synthesis by mammary epithelial cells, and the induction of milk protein synthesis is prevented by actinomycin D. These results suggest that the induction of milk protein synthesis by HPL and prolactin may require new DNA-directed RNA synthesis. HPL and prolactin are nearly equally effective in inducing alveolar development and casein synthesis in nonpregnancy mammary tissue. These studies further demonstrate the similarity between the actions of HPL and prolactin on mouse mammary gland in vitro. (Endocrinology82: 575, 1968)
Referência(s)