Protective Effects And Mechanism Of Nano-selenium Against Nickel-induced Hepatorenal Toxicity And Apoptosis In Rats

Objective:This study aimed to investigate whether selenium nanoparticles（Nano-Se）can reduce Ni-induced hepatorenal toxicity resulted by oxidative damage and apoptosis in Sprague Dawley（SD）rats and explore the potential mechanisms.Methods:（1）Nano-Se was prepared by Laser irradiation in liquids（LIL）technique and the size of Nano-Se was determined by Scanning electron microscope（SEM）.The crystal structure of Nano-Se was analyzed by X-ray diffraction（XRD）and laser Raman spectrometer.（2）Fifty-six healthy male SD rats were exposed to nickel sulfate（Ni SO₄,5.0 mg/kg,i.p.）with or without Nano-Se（0.5,1,and 2 mg/kg,oral gavage）co-administration for 14 days.（3）On the 15th day,all rats were sacrificed after ether anesthesia and the blood samples were collected from the heart.Following a cervical dislocation,livers and kidneys were immediately removed and weighted.Pathological changes were examined under the light microscope after staining with hematoxylin-eosin（H＆E）.（4）We assessed the activiness of alanine aminotransferase（ALT）,alanine aminotransferase（AST）,creatinine（Cr）,and urea nitrogen（BUN）in serum,and we assayed the contents of malondialdehyde（MDA）in the livers and kidneys.（5）The apoptotic cells in the livers and kidneys were determined by TUNEL assay.（6）Western blot was used to detect the expression levels of PI3K,p-PI3K,Akt,p-Akt,Bak,Bcl-2,cytochrome c,caspase-9,caspase-3,GRP78,caspase-12,and GADD153 in the livers and kidneys.Results:Characteristicsn of Nano-Se:A considerable quantity of spherical Nano-Se particles were observed under the SEM,and the size distribution was calculated with the average size of 60±0.15 nm.A signal peak appears in the spectrum around 257 cm^-1corresponded to the A1 symmetric stretching mode of amorphous Se.Moreover,there was no clear,sharp bragg reflection that can be observed in the XRD spectrum.Protective effects and its mechanism of nano-selenium against nickel-induced hepatotoxicity and apoptosis:（1）Compared with the control group,the liver in the Ni SO₄group showed obvious pathological changes charactered by hepatic sinus dilatation,liver lobules unclear,hepatocyte degeneration.After Nano-Se intervention,the pathological injury of the liver was changed.（2）There was no significant change in ALT and AST activities in each group.Nano-Se co-treated with Ni SO₄significantly restrainted the increase of MDA.（3）The results of TUNEL assay showed that Ni-induced excessive apoptosis in the liver was significantly inhibited by Nano-Se.（4）Nano-Se significantly up-regulated the protein level of Bcl-2,p-PI3K,p-Akt,and decreased the level of cytochrome c,caspase-9,caspase-3,and caspase-12 in Ni-treated rat livers.Protective effects and mechanism of nano-selenium against nickel-induced kidney toxicity and apoptosis:（1）Our study found that Nano-Se prevented Ni-induced renal pathological changes.（2）Compared with the Control group,the levels of Cr in serum and MDA in kidney tissues were significantly increased in the Ni SO₄group.Nano-Se co-exposed to Ni SO₄significantly decreased the levels of Cr and MDA.（3）The TUNEL assay showed that Ni-induced excessive apoptosis in the renal cell was significantly inhibited by Nano-Se in the high dose group.（4）Ni significantly increased the protein levels of GRP78,caspase-12,Bak,cytochrome c,caspase-3,and caspase-9,and decreased the protein levels of Bcl-2,p-PI3K,p-Akt in rat kidneys.Nano-Se co-exposed to Ni SO₄significantly up-regulated the protein levels of Bcl-2 and decreased the level of Bak,caspase-3,caspase-9,caspase-12,and cytochrome in rat kidneys.Conclusion:Our study found that Nano-Se could inhibit mitochondria-mediated apoptosis via the activation of PI3K-Akt pathway to attenuate Ni-induced liver injury.In addition,Nano-Se could inhibit endoplasmic reticulum stress and activate PI3K-Akt pathway inhibit mitochondria-mediated apoptosis protected kidney against Nickel-induced injury.