Effect of long-term ovariectomy and estrogen replacement on the expression of estrogen receptor gene in female rats.
OBJECTIVE
Estrogen exerts a wide variety of actions involving many target tissues. We studied the effects of long-term ovariectomy (OVX) and OVX with 17beta-estradiol treatment (OVXE2) on the level of estrogen receptor (ER) gene expression in target tissues of female rats.


METHODS
Three groups of Sprague-Dawley female rats were utilized in this study: sham operated (SO), OVX and OVXE2.


METHODS
SO and OVX were performed 2 weeks before starting the 17beta-estradiol treatment. All groups were maintained on liquid diet for 12 weeks from the time of estradiol treatment. Total RNA was prepared from the tissues of the rats and relative quantitative reverse transcription PCR was utilized to compare the ER alpha-subtype (ERalpha) mRNA level in the three groups for each target tissue.


RESULTS
Following long-term OVX, the levels of ERalpha expression showed a significant increase in the uterus, kidney and cerebral cortex and no significant change in the liver, cerebellum, brainstem, heart and thoracic and abdominal aorta compared with their SO levels. On the other hand, a 12-week treatment of OVX rats with 17beta-estradiol restored the previously upregulated ERalpha mRNA to near SO levels except for the liver where the 17beta-estradiol treatment resulted in a significant increase in the ERalpha mRNA level compared with that in SO rats.


CONCLUSIONS
We conclude that the regulation of ERs by its ligand is tissue specific.
Mohamed
M K
MK
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina, USA.
Abdel-Rahman
A A
AA
D000818:Animals; D002540:Cerebral Cortex / Q000737:chemistry; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood; D004967:Estrogens / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D007668:Kidney / Q000737:chemistry; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000737:chemistry; D015430:Weight Gain
D004967:Estrogens; D011960:Receptors, Estrogen; D004958:Estradiol