title: Excessive apoptosis and defective autophagy contribute to developmental testicular toxicity induced by fluoride.
abstract: Fluoride, a ubiquitous environmental contaminant, is known to impair testicular functions and fertility; however the underlying mechanisms remain obscure. In this study, we used a rat model to mimic human exposure and sought to investigate the roles of apoptosis and autophagy in testicular toxicity of fluoride. Sprague-Dawley rats were developmentally exposed to 25, 50, or 100 mg/L sodium fluoride (NaF) via drinking water from pre-pregnancy to post-puberty, and then the testes of offspring were excised on postnatal day 56. Our results demonstrated that developmental NaF exposure induced an enhanced testicular apoptosis, as manifested by a series of hallmarks such as caspase-3 activation, chromatin condensation and DNA fragmentation. Further study revealed that fluoride exposure elicited significant elevations in the levels of cell surface death receptor Fas with a parallel increase in cytoplasmic cytochrome c, indicating the involvement of both extrinsic and intrinsic apoptotic pathways. Intriguingly, fluoride treatment also simultaneously increased the number of autophagosomes and the levels of autophagy marker LC3-II but not Beclin1. Unexpectedly, the expression of p62, a substrate that is degraded by autophagy, was also significantly elevated, suggesting that the accumulated autophagosomes resulted from impaired autophagy degradation rather than increased formation. Importantly, these were associated with marked histopathological lesions including spermatogenic failure and germ cell loss, along with severe ultrastructural abnormalities in testes. Taken together, our findings provide deeper insights into roles of excessive apoptosis and defective autophagy in the aggravation of testicular damage, which could contribute to a better understanding of fluoride-induced male reproductive toxicity.
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Shun
authors: S
authors: Zhang
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Qiang
authors: Q
authors: Niu
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Hui
authors: H
authors: Gao
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Rulin
authors: R
authors: Ma
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Rongrong
authors: R
authors: Lei
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Cheng
authors: C
authors: Zhang
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Tao
authors: T
authors: Xia
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Pei
authors: P
authors: Li
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Chunyan
authors: C
authors: Xu
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Chao
authors: C
authors: Wang
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Jingwen
authors: J
authors: Chen
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Lixing
authors: L
authors: Dong
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China.
authors: Qian
authors: Q
authors: Zhao
authors: Department of Environmental Health and MOE Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, Hubei, PR China. Electronic address: wangaiguo@mails.tjmu.edu.cn.
authors: Aiguo
authors: A
authors: Wang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D000071186:Beclin-1 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D005260:Female; D005298:Fertility / Q000187:drug effects*; D005459:Fluorides; D006801:Humans; D008297:Male; D046529:Microscopy, Electron, Transmission; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D023421:Models, Animal; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000378:metabolism; D010710:Phosphates; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071456:Sequestosome-1 Protein / Q000378:metabolism; D012969:Sodium Fluoride / Q000633:toxicity*; D013737:Testis / Q000378:metabolism / Q000473:pathology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000071186:Beclin-1; D053148:Caspase 3; D045304:Cytochromes c; D005459:Fluorides; D008869:Microtubule-Associated Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D010710:Phosphates; D000071456:Sequestosome-1 Protein; D012969:Sodium Fluoride; C528558:Daxx protein, rat; C526109:Anxa3 protein, rat; C491079:Sqstm1 protein, rat; C012980:fluorophosphate
keywords: Apoptosis; Autophagy; Fluoride; Reproductive toxicity; Testis