Study On Sodium Nitrite Affections On Gametes And Reproduction In Female Mice

Sodium nitrite is an industrial chemical and often used as a food additive to prevent botulism and enhance glossiness.It has been found human in some area undertake excessive nitrite and nitrate through groundwater containing overproof nitrite and nitrate.Lots of studies demonstrated large doses sodium nitrite may increase incidences of cancer,methemoglobinemia,oxidative stress and even death.However,less is known about the toxic effect of nitrite on female fertility or fetal development.In this study,ICR mice used for control were fed with saline,mice used for low dose group were fed with sodium nitrite at the dosage of 60 mg/kg/day,mice used for high dose group were fed with sodium nitrite at the dosage of 120 mg/kg/day.Each group were continuously fed for up to 21 days.After feeding,the oocyte morphology,spindle-chromosome complex dynamics,mitochondria distribution,adenosine triphosphate(ATP)content,cell apoptosis,DNA damage,histone modification,reactive oxygen species(ROS)level and the birth of offspring were tested.The results showed that uptake of nitrite induced declined oocyte number,impaired polar body extrusion,increased zona pellucida thickness in GV oocyte.Nitrite also induced disordered MII spindle integrity,abnormal mitochondria distribution,declined ATP content.In addition,ROS level as well as histone H3K4me2 methylation were also increased in IIM oocytes in nitrite treated mice.Moreover,the frequency of oocytes early stage apoptosis and DNA damage increased in nitrite treated mice.Significantly,decreased offspring numbers were monitored in female mice after nitrite administration.Our results for the first time illustrates the negative effect of sodium nitrite on female reproductive ability in mice,which provide the basic knowledge about the human reproductive infect by nitrite supplemented in industry material.