Prolactin-like actions of phospholipase C on RNA and casein synthesis in mouse mammary gland explants.

Phospholipase C stimulated the rate of [3H]-uridine incorporation into RNA in cultured mouse mammary gland explants. This effect was similar to that elicited by prolactin in that the time-course and magnitude of response were the same. In addition, the effects of prolactin and phospholipase C were non-additive when these agents were tested together. Although phospholipase C, by itself, had no effect on the rate of [3H]-leucine incorporation into casein, it was found to stimulate casein synthesis when the explants were simultaneously exposed to 0.5 mM spermidine. These observations are compatible with the idea that at least certain of the actions of prolactin in the mammary gland may be carried out via phospholipase C.