title: Excessive nitrite affects zebrafish valvulogenesis through yielding too much NO signaling.
abstract: Sodium nitrite, a common food additive, exists widely not only in the environment but also in our body. Excessive nitrite causes toxicological effects on human health; however, whether it affects vertebrate heart valve development remains unknown. In vertebrates, developmental defects of cardiac valves usually lead to congenital heart disease. To understand the toxic effects of nitrite on valvulogenesis, we exposed zebrafish embryos with different concentrations of sodium nitrite. Our results showed that sodium nitrite caused developmental defects of zebrafish heart dose dependently. It affected zebrafish heart development starting from 36 hpf (hour post fertilization) when heart initiates looping process. Comprehensive analysis on the embryos at 24 hpf and 48 hpf showed that excessive nitrite did not affect blood circulation, vascular network, myocardium and endocardium development. But development of endocardial cells in atrioventricular canal (AVC) of the embryos at 48 hpf was disrupted by too much nitrite, leading to defective formation of primitive valve leaflets at 76 hpf. Consistently, excessive nitrite diminished expressions of valve progenitor markers including bmp4, has2, vcana and notch1b at 48 hpf. Furthermore, 3', 5'-cyclic guanosine monophosphate (cGMP), downstream of nitric oxide (NO) signaling, was increased its level significantly in the embryos exposed with excessive nitrite and microinjection of soluble guanylate cyclase inhibitor ODQ (1H-[1], [2], [4]Oxadiazolo[4,3-a] quinoxalin-1-one), an antagonist of NO signaling, into nitrite-exposed embryos could partly rescue the cardiac valve malformation. Taken together, our results show that excessive nitrite affects early valve leaflet formation by producing too much NO signaling.
authors.affiliation: Model Animal Research Center, Ministry of Education Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China.
authors.forename: Junbo
authors.initials: J
authors.lastname: Li
authors.affiliation: Model Animal Research Center, Ministry of Education Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China.
authors.forename: Wenshuang
authors.initials: W
authors.lastname: Jia
authors.affiliation: Model Animal Research Center, Ministry of Education Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China.
authors.forename: Qingshun
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D006330:Heart Defects, Congenital / Q000139:chemically induced; D006351:Heart Valves / Q000196:embryology / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000494:pharmacology*; D038081:Organogenesis / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism*
chemical_list: D009573:Nitrites; D009569:Nitric Oxide; D006152:Cyclic GMP