Examination of steroid-induced changes in LHRH gene transcription using 33P-and 35S-labeled probes specific for intron 2.
We previously demonstrated that estrogen, but not progesterone, induces a increase in LHRH messenger RNA levels between 0800 and 1200 h in numerous of the rostral preoptic area/organum vasculosum of the lamina terminalis (rPOA/OVLT). To determine whether these changes are a result of increased transcription, we used in situ hybridization histochemistry to examine the temporal effects of estradiol (E2) and progesterone on cellular levels of intron-2-containing LHRH heteronuclear RNA transcripts. To make our method sufficiently sensitive to detect changes in these levels, we used 33P/35S probes to minimize both background and grain stacking over labeled cell nuclei. We found that levels of LHRH heteronuclear RNA rose between 0800 and 1000 in OVX, E2-treated rats, remained elevated at 1200 h, and declined by 1400 h. Progesterone did not affect these E2-induced changes. Our results suggest that an E2-dependent signal initiates LHRH gene transcription in neurons of the rPOA/OVLT hours before LHRH release begins and that progesterone does not affect this signal.
Petersen
S L
SL
Department of Anatomy, University of Missouri School of Medicine, Columbia 65211, USA.
Gardner
E
E
Adelman
J
J
McCrone
S
S
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D007438:Introns; D010761:Phosphorus Radioisotopes; D011301:Preoptic Area / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013462:Sulfur Radioisotopes; D014158:Transcription, Genetic / Q000187:drug effects*
D010761:Phosphorus Radioisotopes; D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol