Estradiol inhibits prolactin induced alpha-lactalbumin production in normal primate mammary tissue in vitro.

The effect of estradiol on prolactin induced alpha-lactalbumin production in normal primate mammary tissue was studied by maintaining tissues in organ culture with or without various combinations of oPRL and 17 beta-estradiol. As expected alpha-lactalbumin was increased byoPRL. 17 Beta-estradiol was found to have a significant inhibitory effect on oPRL-induced alpha-lactalbumin production. By 9 days in culture estradiol (10(-11) M) caused a mean 31% inhibition of prolactin-induced alpha-lactalbumin; with estradiol (10(-8) M) the inhibition was 40%. In the absence of oPRL, estradiol did not inhibit alpha-lactalbumin production. Thus it appears that estradiol directly antagonizes the lactogenic effect of prolactin on the normal primate mammary gland.