Ovarian-Specific Cyp17A1 Overexpression in Female Mice: A Novel Model of Endogenous Testosterone Excess

Excessive androgen levels can severely affect female health. However, most existing models of androgen excess rely on exogenous androgen administration, which does not fully capture the effect of elevated local ovarian testosterone on reproductive and metabolic functions. Here, we report the development of a novel hyperandrogenic mouse model, Cyp17TM-625, generated by combining CRISPR-Cas9 and a Tet-On doxycycline system to induce Cyp17A1 overexpression in ovarian theca-interstitial cells. As a result, Cyp17TM-625 mice exhibited significantly elevated Cyp17A1 messenger RNA and protein levels, accompanied by increased testosterone concentrations without alterations in basal levels of estradiol, progesterone, luteinizing hormone, or follicle-stimulating hormone. These mice demonstrated subfertility, evident by smaller and fewer litters, prolonged estrous cycles, and an increased number of unhealthy follicles with abnormally shaped oocytes. Despite these marked reproductive changes, body weight and glucose homeostasis remained comparable to Con-625 mice. Notably, withdrawal of doxycycline reversed testosterone overexpression and restored fertility over time. This model recapitulates reproductive dysfunction but not the metabolic disturbances, commonly observed in exogenous androgen models. The Cyp17TM-625 mouse line is a unique model for investigating the effects of local excess androgens on ovarian function. It also serves as a valuable tool for studying fertility restoration following the withdrawal of testosterone.