AMH/MIS as a contraceptive that protects the ovarian reserve during chemotherapy

Significance

All current reversible hormonal contraceptives rely on modulating gonadotropins or sex steroids by acting on the hypothalamic–pituitary–gonadal axis. Primordial follicle activation, the first step of folliculogenesis, is independent of gonadotropins or steroids. In this study we show that Müllerian inhibiting substance (MIS) can completely block primordial follicle activation, representing a unique mechanism of contraception that spares the pool of quiescent primordial follicles (ovarian reserve). Chemotherapy is thought to cause the over-recruitment of primordial follicles. Here we show that treatment with MIS during cycles of carboplatin, doxorubicin, or cyclophosphamide can significantly protect the ovarian reserve in mice. Thus, MIS may provide a paradigm of a reversible contraceptive that could mitigate damage to the ovarian reserve associated with gonadotoxic chemotherapeutics.

Abstract

The ovarian reserve represents the stock of quiescent primordial follicles in the ovary which is gradually depleted during a woman’s reproductive lifespan, resulting in menopause. Müllerian inhibiting substance (MIS) (or anti-Müllerian hormone/AMH), which is produced by granulosa cells of growing follicles, has been proposed as a negative regulator of primordial follicle activation. Here we show that long-term parenteral administration of superphysiological doses of MIS, using either an adeno-associated virus serotype 9 (AAV9) gene therapy vector or recombinant protein, resulted in a complete arrest of folliculogenesis in mice. The ovaries of MIS-treated mice were smaller than those in controls and did not contain growing follicles but retained a normal ovarian reserve. When mice treated with AAV9/MIS were paired with male breeders, they exhibited complete and permanent contraception for their entire reproductive lifespan, disrupted vaginal cycling, and hypergonadotropic hypogonadism. However, when ovaries from AAV9-MIS–treated mice were transplanted orthotopically into normal recipient mice, or when treatment with the protein was discontinued, folliculogenesis resumed, suggesting reversibility. One of the important causes of primary ovarian insufficiency is chemotherapy-induced primordial follicle depletion, which has been proposed to be mediated in part by increased activation. To test the hypothesis that MIS could prevent chemotherapy-induced overactivation, mice were given carboplatin, doxorubicin, or cyclophosphamide and were cotreated with AAV9-MIS, recombinant MIS protein, or vehicle controls. We found significantly more primordial follicles in MIS-treated animals than in controls. Thus treatment with MIS may provide a method of contraception with the unique characteristic of blocking primordial follicle activation that could be exploited to prevent the primary ovarian insufficiency often associated with chemotherapy.