The Expression of Oestrogen, Prolactin and Progesterone Receptors in mammary gland land liver of Female Rats during different reproductive states: Regulation by Thyroid Hormones.

VARAS, SILVIA M; JAHN, GRACIELA A

ENDOCRINE RESEARCH

Taylor & Francis

Año: 2005 vol. 31 p. 357 - 370

0743-5800

The aim of this study was to examine, using semiquantitative RT-PCR the changes in mRNA expression of the two estrogen receptor (ER) subtypes, ERa and ERb, prolactin receptor, long (PRL-RL) and short (PRL-Rs) forms, and progesterone receptor (PgR) in liver and mammary gland during gestation, early lactation and weaning in hyperthyroid (HT) and normal rats. Pregnancy increased PRL-RL and ERa mRNAs in liver and PRL-RL in mammary gland. Lactation decreased PRL-RL in liver and ERb and PgR in mammary gland. HT decreased PRL-RL at the end of pregnancy (G21), ERa (in G21 and L1) in liver and PRL-RL in L1 as well as PRL-RS (G7, L1) and ER b (G7, G14, L4) in mammary gland. In conclusion, our data indicated that: 1) PRL-RL and ERa expression levels are differentially regulated in the liver, and PgR and ERb in mammary gland during pregnancy and lactation; 2) ERb is variably expressed depending on the state of thyroid hormones, however the ERa gene expression remained constant in mammary gland; and 3) PRL-RL mRNA expression is highly induced in the mammary gland during late pregnancy and abruptly declines on the first day of lactation for the HT rats.