Neonatal exposure to estrogen in the Wistar rat decreases estrogen receptor-beta and induces epithelial proliferation of the prostate in the adult.
OBJECTIVE
The effects of environmental endocrine disruptors on the male reproductive system have received much attention. We attempted to assess the responsible reproduction period vulnerable to decrease in ER beta mRNA by exposing neonate rats to disruptors.


METHODS
Each of 64 male Wistar rats was given an injection of estradiol at a dose of 25 mug or oil on days 1, 3 and 5 after birth. These rats were sacrificed on days 80, 120, 160 and 180 and then subjected to measurements of both serum and tissue testosterone levels. Real-time quantitative polymerase chain reaction (PCR) was used to measure the levels of androgen receptor (AR) and estrogen receptor-beta (ER beta) mRNA of the ventral prostate. Histological compositions were analyzed by quantitative morphometry. Immunohistochemical analysis of proliferating cell nuclear antigen (PCNA) was determined.


RESULTS
The incidence of epithelial components by histomorphometry and the expression of PCNA was significantly higher in the estrogen group in the mature adult (day 160). Levels of AR and ER beta mRNAs in the estrogen group were significantly lower in middle-aged rats (day 180).


CONCLUSIONS
Estrogen exposure in the neonatal period to Wistar rats decreases the number of ER beta in the mature adult and accelerates cell proliferation.
Un-no
Toshiyuki
T
Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Hayami
Shinsuke
S
Nobata
Shunsuke
S
Sudoko
Hiroshi
H
Honma
Seijiro
S
Fujita
Kimio
K
Ozono
Seiichiro
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology; D047629:Estrogen Receptor beta / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D016133:Polymerase Chain Reaction; D011336:Probability; D011467:Prostate / Q000187:drug effects* / Q000473:pathology*; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012680:Sensitivity and Specificity; D013739:Testosterone / Q000378:metabolism
D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D013739:Testosterone; D004958:Estradiol