Regulation of ovine pituitary glycoprotein hormone alpha subunit mRNA by 17 beta-estradiol in cell culture

Messenger RNA (mRNA) activity for the alpha glycoprotein subunit in ovine pituitary cell cultures was quantified using a wheat germ translation assay. [35S] Cysteine alpha translation product normally accounted for 0.3-0.9% of total 35S-product in translations of total culture RNA. Treatment of cultures with 1 nM 17 beta-estradiol (E2) decreased alpha mRNA activity by 50% and 92% after 1.8 and 8 days, respectively. Alpha mRNA activity decreased by 1/2 in 51 h, which is about three times slower than the rate of decrease reported for follicle-stimulating hormone (FSH) beta mRNA activity in similarly treated cultures (Alexander and Miller, 1982). The effective dose (ED50) for E2 in vitro was 30 pM (8 pg/ml), which is within the physiological range for ewes. These results indicate that E2 can act directly on the ovine pituitary to decrease alpha mRNA activity coordinately with mRNA activity for FSH beta.