The conversion of testosterone into oestradiol by ovine Leydig cells
culturedin vitrowas studied using the non-steroidal
aromatase inhibitor CGS 16949A. Additionally, aromatase activity was detected
by immunohistochemical staining of cultured Leydig cells or cryosections. The
cells were obtained from testes of Polish Mountain rams 5–6 months old
(immature) or 12–15 months old (mature). Leydig cells were cultured
alone (controls) or incubated for 6 h in the presence of testosterone.
Aromatase inhibitor was then added to the cultures which were incubated for a
further 18 h. After a 24-h incubation period, testosterone and oestradiol
secretion were determined by testing the culture medium using
radioimmunological methods.
The addition of testosterone to the culture medium enhanced oestradiol
synthesis, suggesting that exogenous testosterone could also be aromatized to
oestradiol by ovine Leydig cells in vitro. In the
presence of CGS 16949A, the conversion of testosterone to oestradiol was
significantly suppressed in a dose-dependent manner. All Leydig cells obtained
from testes of mature rams and stained immunohistochemically were positive for
aromatase, whereas Leydig cells from immature males were negative. The
localization of immunoreactive aromatase appeared to be dependent on the age
of the donor ram. It is suggested therefore, that mature Leydig cells in the
ram are not only the site for testosterone synthesis, they are also capable of
converting androgens into oestrogens.
HC diet inhibited testosterone synthesis by activating endoplasmic reticulum stress in testicular Leydig cells
