Different modulation of aromatase activity in frog testis in vitro by ACE and ANG II.

The aim of the present research was to study the role of angiotensin-converting enzyme (ACE) and ANG II in amphibian ( Rana esculenta) testicular steroidogenesis and prostaglandin production. Hormonal effects of ACE, ACE inhibitors, synthetic bullfrog ANG I, and [Val5]ANG II were determined in frog testis of prereproductive period. Production of 17β-estradiol, progesterone, androgens, and PGE2 and PGF2α was determined by incubating frog testes with ACE (2.5 mU/ml), captopril (0.1 mM), lisinopril (0.1 mM), [Val5]ANG II (1 μM), and synthetic bullfrog ANG I (1 μM). The analysis of the data showed an independent modulation of 17β-estradiol and androgen production by ACE and ANG II. The ACE pathway caused a decrease of 17β-estradiol production and an increase of androgen production in frog testes; on the other hand, the ANG II pathway increased 17β-estradiol production and decreased androgen production. The determination of testicular aromatase activity showed a positive regulation by ANG II and a negative regulation by ACE. As for prostaglandin production, only ANG II influenced PGF2α. These results suggest a new physiological role of ACE and ANG II in modulating steroidogenesis and prostaglandin production.