Estrogen receptors in the inner ear during different stages of pregnancy and development in the rat.
CONCLUSIONS
ERalpha and ERbeta are present in the inner ear and are up- and down-regulated depending on the stage of maturation, development and pregnancy, suggesting that estrogen may have an effect on the cochlea during various stages of life. No estrogen receptors (ERs) were found in the cochlea of the developing fetus, which suggests that estrogen does not have an effect on the cochlea during gestation.


OBJECTIVE
To investigate the distribution of ERs in the cochlea during pregnancy, maturation and development in a female rat model.


METHODS
The cochleas of 24 rats in 4 groups in different time periods of maturation (21 and 56 days old) and pregnancy (day 8 and 18 of pregnancy) and 16 fetuses at gestational ages of 8 and 18 days were collected. All specimens were stained for ERs using standard immunohistochemical techniques.


RESULTS
ERs are present in the cochlea of the rat and vary during maturation and pregnancy. No ERs were found in the fetal cochleas. Of the non-fetal time points measured, the expression levels of ERs in the rat cochlea were highest at the postnatal age of 21 days and were lowest during late pregnancy (day 18).
Simonoska
Rusana
R
Department of Otorhinolaryngology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden. rusana.simonoska@karolinska.se
Stenberg
Annika
A
Masironi
Britt
B
Sahlin
Lena
L
Hultcrantz
Malou
M
D000367:Age Factors; D000818:Animals; D003051:Cochlea / Q000033:anatomy & histology* / Q000196:embryology; D005260:Female; D005865:Gestational Age; D007124:Immunoenzyme Techniques; D008297:Male; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011959:Receptors, Estradiol / Q000032:analysis*; D012016:Reference Values; D012737:Sex Factors; D012741:Sexual Maturation / Q000502:physiology*
D011959:Receptors, Estradiol