Luteolin Attenuates Liver Injury Induced By Mercuric Chloride Via The Nrf2/NF-κB/P53 Pathway

Mercury is a widespread environmental and industrial pollutant,which induces severe alterations in the tissues of both animals and humans.It is still a worldwide problem ever since the outbreak of its poisoning in Minamata Japan in the 1950 s and in Iraq in the 1970 s.About 100 tons of inorganic mercury and organic mercury are produced every year from pesticides in agriculture,smelting industry,air emissions,cosmetics etc.Mercury exposure is a common cause of metal poisoning which is biotransformed to highly toxic metabolites thus eliciting biochemical alterations and oxidative stress.Liver as the body’s detoxification organs,is particularly serious damage.Luteolin（Lut）is a phenolic compound found in many natural products and has the anti-inflammatory,anti-apoptotic and antioxidant properties.Our study was aimed to explore the biological effects of Lut in a liver injury model induced in rats by Hg Cl₂.In vivo experiments,twenty-eight male wistar rats of 6-8-week old with the weights ranging from 110 to 130 g were divided into 4 groups as follows: Control group,Lut group,Hg Cl₂ group,and Hg Cl₂⁺Lut group,7 rats each group,which lasted for thirty days.In the control group,the rats received water freely and gavage 1% DMSO（1 m L/kg·day）;Lut group drank water freely and gavaged Lut solution（80 mg/kg·day）;Hg Cl₂ group drank Hg Cl₂ solution freely and gavaged 1% DMSO（1 m L/kg·day）;Hg Cl₂⁺Lut group drank Hg Cl₂ solution freely and gavage 1% DMSO（1 m L/kg·day）,and Lut was gavaged to rats once daily for the last two weeks at dose levels of 80 mg/kg in 1% DMSO.After breeding,the blood and tissue of the experimental animals were collected.Criteria for injury included the levels of ALT,AST,GSH and MDA,histopathology changes,TUNEL assay.In addition,we used gene detection（RT-PCR）and western blot to detect the Nrf2/NF-κB/P53 pathway and related factors.In vitro experiments,primary hepatocytes from rats were cultured in vitro,hepatocytes were incubated with Hg Cl₂ and Lut.The groups are as followed: contro group,Lut（20 μM）group,Hg Cl₂（5 μM）group,and Hg Cl₂（20 μM）+Lut（20 μM）group,incubating Lut for 2 h later,adding Hg Cl₂ to incubate for 24 h.Cell viability and ROS were were determined with commercial kits.The results showed that:（1）Lut can reduce the accumulation of Hg in the body.（2）Values for erythrocytes and platelets were significantly increased,however,values for parameters were significantly decreased in Hg Cl₂ group;AST and ALT levels were significantly increased in Hg Cl₂ group;Histopathological examination were observed that histological structure had changed in Hg Cl₂ group.These datas indicated that Hg Cl₂ caused severe liver injury,however,in Hg Cl₂⁺Lut group,these changes had been significantly alleviated,so we determined that Lut can attenuate Hg Cl₂-induced liver injury.（3）In Hg Cl₂⁺Lut group,MDA,ROS and TUNEL decreased,in addition,GSH,GSH/GSSG and CCK-8 increased,these results showed that Lut can attenuate Hg Cl₂-induced oxidative stress and apoptosis.（4）The expression of Nrf2,NQO1 and HO-1 protein in Hg Cl₂⁺Lut group were significantly higher than that in Hg Cl₂ group.Compared with Hg Cl₂ group,Lut reduced the expression of Bax,NF-κB and P53 protein,and increased the expression of Bcl-xl and Bcl-2 protein.Taken together,our data suggested that decreasing oxidative stress is an important mechanism that Lut attenuates Hg Cl₂-induced liver injury.Lut has potential efficacy in prevention and treatment of Hg Cl₂-induced liver injury,through regulation of the Nrf2 / NF-κB / P53 pathway in rats.