Study On The Disorder Of Mitochondrial Dynamics In Kidney Injury Induced By Chronic Inorganic Mercury Exposure In Mice

Mercury as a toxic heavy metal is widely present in the atmosphere,water,and soil.China is one of the largest country which is producing and discharging mercury.Although China has been signed the"Minamata Convention"and strictly abides the relevant provisions,the mercury still exists in the environment cannot be quickly removed.Mercury in the environment is ubiquitou s.Livestock and poultry ingest the drinking water and/or feed which is mercury-containing will cause inorganic mercury accumulate in the body.Kidney is the most important organ for mercury excretion and is one of the main targets of mercury toxicity.The decline of the quality and production of animal-derived foods caused by kidney damage may induce serious economic losses,and chronic mercury poisoning of livestock and poultry is a more serious threat to animal-derived food safety.Therefore,it is of great significance to study the renal injury induced by inorganic mercury exposure and the molecular mechanism.The test is divided into in vivo test and in vitro test.In vivo experiments,twenty-eight healthy male Kunming mice were randomly divided into 4 groups,7 in each group.Different concentrations of HgCl₂ were added to drinking water every day,namely control group?0 mg/L?,low-dose group?20 mg/L?,medium-dose group?40 mg/L?and high-dose group?80 mg/L?.The test period is 16 weeks.After the test period,blood and kidney tissues were collected.HE staining,biochemical indicators CREA and BUN,transmission electron microscopy,renal tissue ATP concentration detection,oxidative stress indicators,comet test,TUNEL,q-PCR and western blot detection assay were used.In vitro test,renal cell lines were devided into 4 groups,including control group?0?mol/L?,low-dose group?1.25?mol/L?,medium-dose group?5?mol/L?,and high-dose group?20?mol/L?.Cell viability test,active oxygen test and q-PCR test were performed to further study the molecular mechanism of chronic inorganic mercury exposure induced kidney damage in mice.Test results:?1?HE section results showed that inorganic mercury exposure induced kidney damage.?2?The results of biochemical indicators indicate d that inorganic mercury exposure leads to the increase of CREA and BUN level.?3?Transmission electron microscopy results showed that inorganic mercury exposure caused mitochondrial damage.?4?The results of renal tissue ATP concentration showed that inorganic mercury exposure induced renal energy homeostasis destruction.?5?The oxidative stress index results indicate that inorganic mercury exposure leads to renal oxidative stress.?6?The comet test results showed that inorganic mercury exposure induced DNA damage in the mice kidney.?7?The TUNEL results showed that inorganic mercury exposure induced apoptosis of kidney in mice.?8?q PCR and western blot showed that inorganic mercury exposure inhibited the gene and protein expression of silent information regulator1-1?Sirt1?,peroxisome proliferator-activated receptor-?coactivator-1??PGC-1??,and mitochondrial fusion protein 2,and increased the gene and protein expression of dynamin-related protein 1.The results showed that inorganic mercury exposure inhibited Sirt1/PGC-1?signaling pathway induces dysfunction of mitochondrial dynamics in mice;inorganic mercury exposure inhibits the expression of genes and/or proteins of nuclear factor erythroid 2-related factor 2?Nrf2?,NAD?P?H:quinone oxidoreductase l?NQO1?,and heme oxygenase-1?HO-1?.The results indicated that inorganic mercury exposure induced kidneys oxidative stress via inhibiting Nrf2 signaling pathway in mice;Inorganic mercury exposure inhibited B-cell lymphoma gene 2?Bcl-2?protein expression and increased Bax protein expression.The results show that inorganic mercury exposure induced renal cell apoptosis in mice.?8?In vitro test results showed that inorganic mercury exposure induced the decrease of renal cell viability and increased ROS production in vitro.The results of q PCR verified the homeostasis of renal mitochondria induced by inorganic mercury.In summary,HgCl₂ exposure induces disorder of mitochondrial dynamics and oxidative stress via inhibiting Sirt1/PGC-1?and Nrf2 signaling pathways,and ultimately leads torenal cell apoptosis.Sirt1/PGC-1?signaling pathway may be a potential target for reducing renal damage induced by inorganic mercury exposure.