Cadmium-induced apoptosis of granulosa cells is mediated by excessive activation of mitophagy and ROS-mediated mitochondrial dysfunction.

Cadmium (Cd), a pervasive environmental and occupational toxicant, has raised significant public health concerns due to its detrimental effects on human health. Emerging evidence highlights its capacity to impair the female reproductive system, notably through induction of follicular cell apoptosis. However, the underlying mechanism of Cd-induced apoptosis of granulosa cells remains unclear. In this study, thirty female mice were randomly allocated into three groups and exposed to CdCl₂ (0, 1.0, or 4.0 mg/kg) for 12 h, while 40 mice were divided into four groups and treated with CdCl₂ (4 mg/kg) for varying durations (0, 6, 12, or 24 h). Ovarian injury, apoptosis and mitophagy were observed in mice. To further elucidate the mechanism, human ovarian granulosa-like tumor cells (KGN cells) were treated with CdCl₂ (0-40 μM). Cd triggered apoptosis and excessive mitophagy in KGN cells, accompanied by reduced adenosine triphosphate (ATP) levels, diminished mitochondrial membrane potential (MMP), and elevated total reactive oxygen species (ROS) and mitochondrial ROS (mtROS). Pharmacological inhibition of autophagy using 3-methyladenine (3-MA) attenuated Cd-induced apoptosis and mitochondrial dysfunction, whereas autophagy activation via rapamycin exacerbated these detrimental effects. Our findings demonstrate that Cd disrupts mitochondrial homeostasis by over activating mitophagy, which subsequently amplifies apoptotic signaling in ovarian granulosa cells. These results provide mechanistic insights into Cd-associated ovarian pathologies and highlight the therapeutic potential of targeting mitophagy to mitigate reproductive toxicity.