Molybdenum And Cadmium Co-exposure Induces Spleen Injury In Ducks Via PI3K/AKT Signaling Pathway

To study the effect of molybdenum and cadmium co-exposure on spleen damage in ducks through PI3K/AKT signaling pathway,forty Shaoxing ducks were selected and randomly divided into four groups:the control group（Control group）was fed the basal diet,the molybdenum group（Mo group）was supplemented with 100 mg Mo/kg in the feed,the cadmium group（Cd group）was supplemented with 4 mg Cd/kg in the feed,and the combined molybdenum-cadmium group（Mo+Cd group）was supplemented with 100 mg Mo/kg+4 mg Cd/kg in the feed.（NH₄）₆Mo₇O₂₄·4H₂O and 3Cd SO₄·8H₂O were used as the sources of Mo and Cd,respectively.On the 16^th week,spleen tissues were collected from each group of ducks,and H&E staining,RT-q PCR,ELISA and western blot were applied to calculate spleen index,analyze the pathological histological changes and detect the content of trace elements,oxidative stress indexes,and levels of PI3K/AKT signaling pathway,pyroptosis and autophagy in the spleen.The results were as follows:1.Exposure to Mo and/or Cd could reduce in the spleen index in ducks,but there is no significant difference.2.Exposure to Mo and/or Cd could lead to diffuse hyperplasia of lymphocytes,unclear boundary between white pulp and red pulp,and hemorrhage in white pulp area in duck spleens.And the changes were more serious in Mo+Cd group.3.Exposure to Mo and/or Cd results in a significant increase in Mo and Cd content in the duck spleen tissue,while Ca,Fe,Mg,Zn,Cu,and Se show a significant decrease.And the changes are more pronounced in the Mo+Cd group.4.Mo and/or Cd exposure induced a significant decrease in the activities of T-AOC,T-SOD,GSH-Px and CAT and a significant increase in MDA content in spleen tissues,inducing oxidative stress.And the changes were more obvious in Mo+Cd group.5.Mo and/or Cd exposure remarkably decreased the expression of PI3K/AKT signaling pathway-related factors（PI3K,AKT and p-AKT）.And it was more obvious in the Mo+Cd group.6.Mo and/or Cd exposure notably increased the number of LC3II fluorescence aggregation points and autophagosomes and the expression of autophagy-related factors（LC3A,Beclin-1,LC3B,Atg5 and LC3II/LC3I）,decreased the expression of autophagy-related factors（P62 and Dynein）,and dramatically increased the expression of pyroptosis-related factors（GSDMA,NEK7,NLRP3,GSDME,ASC,Caspase-1,IL-18 and IL-1β）,as well as content of IL-18 and IL-1β.And the changes of the above indexes were more obvious in the Mo+Cd group.Conclusion:Mo and/or Cd exposure caused the imbalance of trace elements homeostasis and oxidative stress,evoked pyroptosis and autophagy by inhibiting PI3K/AKT signaling pathway,finally caused damage to duck spleen tissue,which is exacerbated by the Mo+Cd.