Estradiol regulation of alpha 1b-adrenoceptor mRNA in female rat hypothalamus-preoptic area.
Estradiol treatment for 48 h increases the density of alpha 1B-adrenoceptors in the hypothalamus-preoptic area of ovariectomized female rats by five- to six-fold. Present studies tested the hypothesis that estradiol elevation of hypothalamus-preoptic area alpha 1B-adrenoceptor density is correlated with increased levels of mRNA for this receptor. We developed a semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) protocol for measuring brain alpha 1b-adrenoceptor mRNA. The primers chosen yielded the predicted 409 base pair PCR product when used to amplify authentic alpha 1b-adrenoceptor cDNA. The identity of the RT-PCR products from rat brain was confirmed by restriction digest analysis and sequencing. Moreover, there was a good correlation between the levels of alpha 1b-adrenoceptor mRNA measured by RT-PCR in liver, whole brain and cerebellum with previous measurements using Northern blots and RNAse protection assays. We then performed RT-PCR on total RNA from hypothalamic-preoptic area tissue taken from ovariectomized control rats and from ovariectomized rats injected once or twice with 2 micrograms of estradiol benzoate at 24 or 24 and 48 h before sacrifice. Exposure to estradiol for either 24 or 48 h significantly increased levels of alpha 1b-adrenoceptor mRNA by 86-110% in the hypothalamus-preoptic area of ovariectomized female rats when compared to oil-treated controls. We also examined whether estradiol regulates alpha 1b-adrenoceptor mRNA in the cortex. Cortical alpha 1b-adrenoceptor mRNA levels were reduced to approximately 20% of control levels when measured 24 h after hormone injection. A similar decrease in cortical alpha 1b-adrenoceptor mRNA was observed 48 h after estrogen administration. In summary, estradiol treatment significantly increases the level of alpha 1b-adrenoceptor mRNA in the hypothalamus-preoptic area, a brain region involved in the control of reproductive function. In the cortex, a brain region with relatively few estrogen receptors, the same estrogen treatment reduces alpha 1b-adrenoceptor mRNA levels.
Karkanias
G B
GB
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Ansonoff
M A
MA
Etgen
A M
AM
D000818:Animals; D017931:DNA Primers; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D007031:Hypothalamus / Q000378:metabolism*; D010052:Ovariectomy; D016133:Polymerase Chain Reaction; D011301:Preoptic Area / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012194:RNA-Directed DNA Polymerase; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000235:genetics* / Q000378:metabolism
D017931:DNA Primers; D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; D004958:Estradiol; D012194:RNA-Directed DNA Polymerase