Abstract
Dispersed monkey pituitary cells were cultured on extracellular matrix and in serum-free medium for up to 1 month, with medium changes every other day. The cells were treated with ethanol vehicle or 10 nM 17 beta-estradiol (E2 beta), 17 alpha-estradiol (E2 alpha), progesterone (P4), pregnenalone (P5), 17 alpha-hydroxyprogesterone (17OH P4), and E2 beta plus P4. Immunoreactive PRL (IR-PRL) levels in 48 h medium samples were first determined with a homologous human PRL RIA and then with a heterologous monkey PRL RIA. On the last day of culture, the cells were incubated with [35S]methionine for 4 h, and 35S-labeled PRL in the medium and cells was determined and compared to 4 h IR-PRL. Differences between control and treated groups in 48 h IR-PRL were greater with the heterologous monkey RIA. E2 beta, E2 alpha, and E2 beta plus P4 significantly elevated IR-PRL in 48 h medium samples an average of 73%, as determined with the monkey RIA. P4, P5, or 17OH P4 had no effect on IR-PRL in 48 h medium samples. Secreted and intracellular [35S]PRL were consistently elevated by E2 beta and E2 beta plus P4, but less consistently elevated by E2 alpha. P4, P5, or 17OH P4 had little effect on [35S]PRL in medium or cells. IR-PRL in the 4 h medium sample and cells generally paralleled [35S]PRL, although E2 alpha caused a more consistent elevation in IR-PRL than in [35S]PRL. In summary, E2 beta and E2 alpha directly stimulate PRL synthesis by monkey pituitary cells on extracellular matrix in long term serum-free culture. Nanomolar levels of progestins have little direct effect on PRL synthesis, nor does 10 nM P4 block the stimulatory effect of E2 beta.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have