17 beta-estradiol treatment increases the levels of estrogen receptor and its mRNA in male rat liver.
This study examined estrogen receptor dynamics in the livers of male obese rats (SHHF/Mcc-cp) treated for two weeks with a continuous, low dose of 17 beta-estradiol compared with untreated controls. An increased binding capacity for tritiated 17 beta-estradiol in the cytosol, consistent with binding to the estrogen receptor, was demonstrated in treated males relative to control males (P < 0.01). These observations were confirmed using curve-peeling techniques with saturation analysis, ammonium sulfate precipitation/fractionation of cytosol protein, and chromatographic techniques to isolate the high-affinity binding from other interfering factors. Increased hepatic nuclear estrogen receptor levels in treated males (112.3 +/- 8.3 fmol/g liver) compared with controls (64.1 +/- 6.8 fmol/g liver) suggested that the liver was under estrogenic influences. This interpretation was supported by an increase in serum triglyceride levels, reflecting increased very low density lipoprotein secretion by the liver. Reductions in testosterone levels and in the weights of seminal vesicles and the testes in treated males indicated detrimental effects on reproduction. An interpretation of increased synthesis of estrogen receptor with 17 beta-estradiol treatment was supported by the observation of an increase in the mRNA for estrogen receptor. Taken together, these observations indicate that continuous, low-dose 17 beta-estradiol treatment induces estrogenic action in the livers of male rats and also increases hepatic estrogen receptor, probably indirectly, via an increase in its mRNA.
Fort Wayne Center for Medical Education, Indiana University Medical School 46805, USA.
D R
DR
Koritnik
A
A
Koshy
R C
RC
Hoversland
D000818:Animals; D001483:Base Sequence; D001835:Body Weight / Q000187:drug effects; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000378:metabolism; D004958:Estradiol / Q000627:therapeutic use*; D005260:Female; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D009765:Obesity; D009929:Organ Size / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D012727:Sex Characteristics; D013223:Statistics as Topic
D012333:RNA, Messenger; D011960:Receptors, Estrogen; D004958:Estradiol