title: Exposure to silica nanoparticles causes reversible damage of the spermatogenic process in mice.
abstract: Environmental exposure to nanomaterials is inevitable, as nanomaterials have become part of our daily life now. In this study, we firstly investigated the effects of silica nanoparticles on the spermatogenic process according to their time course in male mice. 48 male mice were randomly divided into control group and silica nanoparticle group with 24 mice per group, with three evaluation time points (15, 35 and 60 days after the first dose) per group. Mice were exposed to the vehicle control and silica nanoparticles at a dosage of 20 mg/kg every 3 days, five times over a 13-day period, and were sacrificed at 15, 35 and 60 days after the first dose. The results showed that silica nanoparticles caused damage to the mitochondrial cristae and decreased the levels of ATP, resulting in oxidative stress in the testis by days 15 and 35; however, the damage was repaired by day 60. DNA damage and the decreases in the quantity and quality of epididymal sperm were found by days 15 and 35; but these changes were recovered by day 60. In contrast, the acrosome integrity and fertility in epididymal sperm, the numbers of spermatogonia and sperm in the testes, and the levels of three major sex hormones were not significantly affected throughout the 60-day period. The results suggest that nanoparticles can cause reversible damage to the sperms in the epididymis without affecting fertility, they are more sensitive than both spermatogonia and spermatocytes to silica nanoparticle toxicity. Considering the spermatogenesis time course, silica nanoparticles primarily influence the maturation process of sperm in the epididymis by causing oxidative stress and damage to the mitochondrial structure, resulting in energy metabolism dysfunction.
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Department of Laboratory Animal Science, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Wang
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Yan-Bo
authors.initials: YB
authors.lastname: Li
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Yong-Bo
authors.initials: YB
authors.lastname: Yu
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Xian-Qing
authors.initials: XQ
authors.lastname: Zhou
authors.affiliation: Department of Health Toxicology and Health Chemistry, School of Public Health, Capital Medical University, Beijing, China; Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, China.
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Sun
mesh_terms: D000818:Animals; D004249:DNA Damage; D004734:Energy Metabolism; D004781:Environmental Exposure / Q000009:adverse effects; D004822:Epididymis / Q000166:cytology / Q000378:metabolism; D012739:Gonadal Steroid Hormones / Q000097:blood; D008297:Male; D051379:Mice; D053758:Nanoparticles / Q000009:adverse effects* / Q000648:ultrastructure; D018384:Oxidative Stress; D012822:Silicon Dioxide / Q000009:adverse effects*; D013076:Sperm Count; D013081:Sperm Motility; D013091:Spermatogenesis / Q000187:drug effects* / Q000502:physiology*; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism*; D013737:Testis / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure
chemical_list: D012739:Gonadal Steroid Hormones; D012822:Silicon Dioxide