Vitellogenin synthesis via androgens in primary cultures of tilapia hepatocytes.
Involvement of androgens in vitellogenin (VTG) synthesis was investigated using the primary hepatocyte cultures of tilapia, Oreochromis mossambicus. Concentration of VTG in the medium was assessed by enzyme-linked immunosorbent assay. When the hepatocytes of females were treated with testosterone (T), 17 alpha-methyltestosterone (MT) and 5 alpha-dihydrotestosterone (DHT), VTG concentration in the medium slightly increased or maintained. DHT, but not T and MT, increased VTG in the medium of male hepatocyte cultures. However, VTG production in the male hepatocytes, which were previously treated with estradiol-17 beta (E(2)), maintained high level by treatment of T. Similarly, co-treatment of E(2) and the androgens to the male hepatocytes enhanced VTG concentration in the medium. These results suggest that the androgens have some roles in VTG synthesis in the hepatocytes. Tamoxifen, a nonsteroidal antiestrogen, reduced VTG synthesis by the androgens. On the other hand, co-treatment of T and fadrozole, an aromatase inhibitor, failed to inhibit the effect of VTG synthesis by T alone. Analysis with RT-PCR did not demonstrate expression of the brain and the ovarian types of aromatase mRNA in the liver. These results suggest that the possibility of local aromatization of the androgens in the tilapia liver is low and that androgens bind estrogen receptor and, consequently, exert estrogenic action. Treatment of cyproterone acetate, an antiandrogen reagent, increased production of VTG with DHT. Involvement of androgens might not be ignored in regulation of VTG synthesis in the liver.
Kim
Byung-Ho
BH
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan.
Takemura
Akihiro
A
Kim
Se Jae
SJ
Lee
Young-Don
YD
D000726:Androgen Antagonists / Q000494:pharmacology; D059002:Androgen Receptor Antagonists; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D001141:Aromatase / Q000378:metabolism; D002478:Cells, Cultured; D017373:Cyproterone Acetate / Q000494:pharmacology; D013196:Dihydrotestosterone / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D005260:Female; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008777:Methyltestosterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology; D013739:Testosterone / Q000494:pharmacology; D045165:Testosterone Congeners / Q000494:pharmacology; D017210:Tilapia / Q000378:metabolism*; D014819:Vitellogenins / Q000096:biosynthesis*
D000726:Androgen Antagonists; D059002:Androgen Receptor Antagonists; D000728:Androgens; D004965:Estrogen Antagonists; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D045165:Testosterone Congeners; D014819:Vitellogenins; D013196:Dihydrotestosterone; D013629:Tamoxifen; D013739:Testosterone; D017373:Cyproterone Acetate; D004958:Estradiol; D001141:Aromatase; D008777:Methyltestosterone