Net @entity172 sensitivity in target tissues critically depends on the regulated expression of full-length and alternately processed @entity172 receptor (ER) isoforms. However, the molecular mechanisms for the control of pituitary responsiveness to @entity172 remain partially unknown. In the present communication, we report the ability of different ligands, with distinct agonistic or antagonistic properties at the ER, to modulate the expression of the transcripts encoding @entity7605 and @entity12209 isoforms, as well as those for the truncated @entity7605 product (TERP), and the variant ERbeta2, in pituitaries from ovariectomized @entity35 , i.e., a background devoid of endogenous @entity172 . Compared with expression levels at the morning of proestrus, ovariectomy (OVX) resulted in increased pituitary expression of @entity12209 and ERbeta2 mRNAs, whereas it decreased TERP-1 and -2 levels without affecting those of @entity7605 . Administration of @entity4520 (as potent agonist for alpha and beta forms of ER) or the selective @entity7605 agonist, @entity31850 , fully reversed the responses to OVX, while the @entity12209 ligand, @entity21914 , failed to induce any significant effect except for a partial stimulation of TERP-1 and -2 mRNA expression levels. To note, the @entity12209 agonist was also ineffective in altering pituitary expression of @entity1420 receptor-B mRNA, i.e., a major @entity172 -responsive target. In all parameters tested, @entity440 , a selective ER modulator with mixed agonist/antagonist activity, behaved as @entity7605 agonist, although the magnitude of @entity440 effects was significantly lower than those of the @entity7605 ligand, except for TERP induction. In contrast, the pure antiestrogen @entity62673 did not modify the expression of any of the targets under analysis. Overall, our results indicate that endogenous @entity172 differentially regulates pituitary expression of the mRNAs encoding several ER isoforms with distinct functional properties, by a mechanism that is mostly conducted through @entity7605 . Differential regulation of ER isoforms may represent a relevant system for the self-tuning of @entity172 responsiveness in female pituitary.

Regulation of XXXX receptor (ER) isoform messenger RNA expression by different ER ligands in female @entity35 pituitary.

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity440 :: ('MESH:D013629', 'Chemical') :: ['tamoxifen'] @entity35 :: ('10116', 'Species') :: ['rats'] @entity1420 :: ('MESH:D011374', 'Chemical') :: ['progesterone'] @entity7605 :: ('24890(Tax:10116)', 'Gene') :: ['ERalpha'] @entity21914 :: ('MESH:C492519', 'Chemical') :: ['diarylpropionitrile'] @entity12209 :: ('25149(Tax:10116)', 'Gene') :: ['ERbeta'] @entity62673 :: ('MESH:C086511', 'Chemical') :: ['RU-58668'] @entity31850 :: ('MESH:C467746', 'Chemical') :: ['propyl pyrazole triol'] @entity4520 :: ('MESH:C074283', 'Chemical') :: ['estradiol benzoate']
@entity172 :: (MESH:D004967,Chemical) :: ['estrogen']
