Effects of hypothyroidism on the gene expression of progesterone receptors in the neonatal rat brain.

The effects of neonatal hypothyroidism on the gene expression of progesterone receptors (PRs) in the 8-day-old female rat brain were examined. The levels of PR ('A'+'B')-, PR ('B')-, estrogen receptor (ER)- and beta-actin mRNAs in the cerebral cortex and hypothalamus-preoptic area of propylthiouracil-treated rats (PTU group) or untreated rats (control group) were analyzed using a quantitative reverse transcription-polymerase chain reaction-Southern blotting assay. When the levels of PR mRNAs were calibrated by respective levels of beta-actin mRNA, the levels of PR ('A'+'B')- and PR ('B') mRNAs in the cerebral cortex of the PTU group were markedly less than those in the control group with no significant changes in the levels of PR messages in the hypothalamus-preoptic area of both groups. No significant difference in the calibrated levels of ER mRNA between both groups was found in these tissues. These results on the PR-, and ER mRNAs were essentially similar to those on the levels of PR- and ER proteins previously reported suggesting that thyroid hormones affect the transcriptional machinery of PR in the developing brain, in a region-specific manner.