Gold nanoparticles induced histological, ultrastructural, and functional changes of the adult rat testis. Is it nano-size dependent?

Gold nanoparticles (AuNPs) have diverse medical applications, but concerns rose about toxicity. The goal of this work was to evaluate the harmful effects of AuNPs (15-nm and 40-nm) on adult rat testes. Twenty-one male rats were assigned into three groups and received the following treatments via gavage: distilled water as a control, 15-nm AuNPs group, and 40-nm AuNPs group. After 28 days, animals were sacrificed. Testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were measured. Testicular tissue's levels of malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) were measured. Sperm morphology and count were assessed. Testicular histology was assessed using toluidine blue stain, periodic acid-Schiff (PAS), and hematoxylin and eosin (H&E). Transmission electron microscopy was used to evaluate the testicular ultrastructure. The findings showed that both AuNPs groups saw a substantial (p ≤ .05) rise in FSH, a drop in testosterone, an increase in MDA, and a decrease in GSH. The 15-nm AuNPs group saw a substantial decrease in sperm count. Histological findings showed that the 15-nm AuNPs group had more atrophic seminiferous tubules and a substantial (p ≤ .05) reduction in seminiferous epithelial height. Electron microscopy showed germ cells with degraded mitochondria and cytoplasmic vacuoles. Testicular structure and function were both negatively impacted by AuNPs, with the effects being more pronounced for 15 nm AuNPs.