Is the androgen-dependent increase in preoptic estradiol-17 beta formation due to aromatase induction?
Aromatization of testosterone in the preoptic area of the male ring dove is required for the expression of specific estrogen-sensitive sexual behavior. Estradiol metabolism and/or binding of the aromatization product(s) to the preoptic estrogen receptors (ER) could interfere with the apparent increase in estradiol formation that occurs after androgen administration to castrated males. Therefore, we have re-examined the induction mechanism using a direct in vitro assay of aromatase activity. Since levels of aromatase activity and enzyme kinetics were similar irrespective of the assay used, we can conclude that increased estradiol formation after androgen stimulation is mainly due to enzyme induction and that estrogen binding and/or metabolism do not interfere significantly with the induction process.
Steimer
T
T
Division of Biology of Growth and Reproduction, Faculty of Medicine, University of Geneva, Switzerland.
Hutchison
J B
JB
D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D001717:Birds / Q000378:metabolism* / Q000502:physiology; D004958:Estradiol / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy; D011301:Preoptic Area / Q000187:drug effects / Q000201:enzymology*; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism* / Q000494:pharmacology
D013739:Testosterone; D004958:Estradiol; D001141:Aromatase