Estrogen and progesterone regulate alpha, beta, and gammaENaC subunit mRNA levels in female rat kidney.
BACKGROUND
Estrogen and progesterone regulate alpha, beta, and gamma amiloride-sensitive epithelial sodium channel (ENaC) subunit mRNA levels in female rat kidney. Renal Na(+) handling differs between males and females. Further, within females Na(+) metabolism changes during the menstrual cycle and pregnancy. Electrolyte homeostasis and extracellular fluid volume are maintained primarily by regulated transport of Na(+) via the amiloride-sensitive Na(+) channel. This study examines the role of the female gender steroids in the regulation of expression of ENaC.


METHODS
We measured ENaC subunit mRNA levels in rat kidney using Northern blotting. Kidneys were taken from male and females at different ages and from adult ovariectomized rats treated with 17-beta-estradiol benzoate (estrogen) and/or progesterone for 8 or 24 hours.


RESULTS
The abundance of alpha, beta, and gammaENaC mRNA was significantly higher in female compared to male rat kidneys from 10 weeks of age (P= 0.001, P= 0.004, and P= 0.02, N= 10, respectively). These differences were abolished in ovariectomized rats. Treatment of ovariectomized rats with estrogen increased alphaENaC mRNA abundance in the kidney at both 8 and 24 hours (P < 0.05, N= 6; and P < 0.05, N= 7, respectively). Progesterone inhibited the effect of estrogen on alphaENaC mRNA at 8 hours but when given alone increased gammaENaC mRNA (P < 0.05, N= 3). Neither hormone, alone or in combination, had any significant effect on betaENaC mRNA levels at 8 or 24 hours.


CONCLUSIONS
Female gonadal steroids differentially modulate expression of ENaC subunit mRNA in the rat kidney.
Gambling
Lorraine
L
Development, Growth and Function Division, Rowett Institute, Aberdeen, Scotland, United Kingdom.
Dunford
Susan
S
Wilson
Catherine A
CA
McArdle
Harry J
HJ
Baines
Deborah L
DL
D000818:Animals; D053503:Epithelial Sodium Channels; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D015222:Sodium Channels / Q000737:chemistry / Q000235:genetics*
D053503:Epithelial Sodium Channels; D021122:Protein Subunits; D012333:RNA, Messenger; D015222:Sodium Channels; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol