The Mode of Action of Steroid Hormones: Some Recent Findings

Effect of actinomycin D on the inhibition of the pituitary response to LH-RH by oestradiol in rats

“…Oestradiol is known to promote an early increase in protein synthesis at the translational levels with secondary augmentation of RNA polymerase activity and RNA synthesis (Gorski, 1964;Gorski, Noteboom & Nicolette, 1965;Mueller, Vondehaar, Kim & Le Mahieu, 1972). Baulieu (1974) has demonstrated a blocking effect when actinomycin D is given at the same time as oestrogen, indicating localization of the oestrogenreceptor complex at the transcriptional level. It therefore seems possible that the modulating effect of oestradiol on the response to LH-RH, which is itself modified by actinomycin D, probably also indicates an action at the translational level by inhibiting the induced protein, but we are uncertain how these events affect the release of LH.…”

Different effects of inhibitors of protein synthesis on the inhibited and augmented LH response of pituitary glands from ovariectomized rats to LH‐RH in vitro after pretreatment with oestradiol‐17β‐benzoate in vivo

“…The effects of oestrogen on their target organs are mediated through RNA and/or protein synthesis dependent steps [3,4]. With regard to both effects of oestrogen on the pituitary LH response to LH-RH, however, there is little conclusive evidence for the involvement of similar mechanisms of action.…”