Peripubertal Exposure to Silver Nanoparticles (AgNPs) Triggers Follicle Activation, Probably Leading to "Burnout" by Stimulating the PI3K/AKT/mTOR/AMPK Signaling Pathway.

Despite the widespread use of silver nanoparticles (AgNPs) in consumer, industrial, and biomedical products, their potential effects on female reproductive health, particularly during critical developmental periods, remain insufficiently understood. The present study was therefore designed to investigate in vivo the dose-dependent effects of AgNP exposure on ovarian function and reproductive health in pubertal female rats. Pubertal Wistar albino female rats were divided into control and two AgNP groups (0.05 and 0.50 mg/kg/day). After one month of therapy, the females in the different groups were euthanized, and ovarian samples were collected. The results indicated that administration of AgNPs significantly increases the number of primordial follicles and significantly increases the number of growing follicles. Western blot analysis revealed that aromatase (Cyp19) and proliferating cell nuclear antigen (PCNA) were upregulated in both treatment groups. Similarly, the number of mRNA transcripts associated with folliculogenesis and steroidogenesis increased significantly in the high-dose treatment group. In addition, the level of growth differentiation factor 9 (GDF9) mRNA increased significantly in a dose-dependent manner. However, the levels of anti-Müllerian hormone (Amh) mRNA were considerably higher in the low-dose group and lower in the high-dose group, demonstrating that the detailed regulation of this gene is affected by AgNP dose. Analysis of the phosphatidylinositol 3-kinase signaling pathway revealed that compared to a 0.05 mg/kg, a AgNP exposure at 0.5 mg/kg significantly enhanced the PI3K/AKT/mTOR pathway and impacted Ampk signaling in a distinct manner. These findings suggest that AgNPs increase follicular development and deplete the follicular reserve, resulting in a phenomenon known as "burnout".