Final answer:
Aromatase inhibitors block the synthesis of estrogen by inhibiting the enzyme aromatase, rather than converting estrogen into testosterone. They are mainly used to treat certain types of breast cancer. Antagonists that bind to plasma membrane receptors would prevent testosterone from binding, thereby inhibiting its signaling.
Step-by-step explanation:
Aromatase inhibitors are compounds that reduce estrogen levels by inhibiting the activity of aromatase, the enzyme responsible for converting androgens to estrogen. These inhibitors do not convert estrogen to testosterone; instead, they prevent the synthesis of estrogen, which can reduce the growth of estrogen-dependent cancer cells, particularly in postmenopausal women with breast cancer.
Notably, steroidal hormones like testosterone and estrogen generally initiate their action by crossing plasma membranes due to their lipid nature and binding to internal receptors within target cells, which then influences gene expression in the nucleus. In the context of new antagonist molecules, if an antagonist binds to plasma membrane receptors, it would likely block testosterone from binding to its receptor, thus inhibiting testosterone-mediated signaling.