ABSTRACT
OBJECTIVE To explore the potential neurotoxicity of nano-alu mina (<50 n m)in vivo, we treated the ICR mouse with the nano-alu mina to investigate the mitochondrial da mage of nerve cells on morphology and function.METHODS Adult male mice were exposed to nano-alu mina (<50 n m)of 0,25,50 and 75 mg·kg -1 by nasal instillation for 1 month.Then we observed the mitochondrial ultra-structure of the nerve cells in CA3 region of hippoca mpus,and measured the mean dia meter in every group.The activities of Na +-K +-ATPase and Ca2 +-Mg2 +-ATPase were tested by the determination of the inorganic phosphorus,which was the deco mposition product of ATPase.Western blot analysis was used to detect the expression of COX-Ⅳ,Beclin1 ,LC3Ιand LC3Ⅱ.RESULTS Co mpared with 0 and 25 mg·kg -1 groups exposed to Al2 O3 nanopartilces (Al2 O3 NPs),the mitochondria of CA3 region in hip-poca mpus in 50 mg·kg -1 group beca me ede matous and swollen with sparse and broken cristae sur-rounding the nuclear,and the mean dia meter was higher(0.49 ±0.02 μm,P <0.05).But co mpared with 50 mg·kg -1 group,the mitochondria in 75 mg·kg -1 group beca me s maller with inner cristae of high density,and the mean dia meter was lower(0.36 ±0.02 μm,P<0.05).The enzy me activity of the mito-chondria in cerebral cortex decreased dose-dependently with exposure,the activities of Na +-K +-ATPase in 50 and 75 mg·kg -1 groups(6.37 ±0.22 kU·g -1 protein,5.48 ±1 .53 kU·g -1 protein)and Ca2 +-Mg2 +-ATPase in 50 and 75 mg·kg -1 groups (3.21 ±0.99 kU·g -1 protein,3.28 ±0.15 kU·g -1 protein)were lower than the 0 mg·kg -1 group(P<0.05).Meanwhile,the Ca2 +-Mg2 +-ATPase in 50 and 75 mg·kg -1 groups showed lower activities in co mparison with the 25 mg·kg -1 group.The 75 mg·kg -1 group expressed higher level of the COX-Ⅳ protein 1 .35 ±0.66(P<0.05)than other groups.Both expression of Beclin1 protein and rate of LC3Ⅱ/LC3Ⅰin 75 mg·kg -1 group were more than the 0 mg·kg -1 group. CONCLUSION The mitochondrial dysfunction may be the potential neurotoxicity of nano-alu mina,and the da maged mitochondria were cleared by autophagy.
ABSTRACT
OBJECTIVE To study the effect of nano-alumina(nano-Al2 O3 )on mitophagy in primary cortical neuronal cells from Wistar newborn rats. METHODS The purity of neuronal cells was detected by immunohistochemistry,and the lactate dehydrogenase(LDH)assay was performed to determine the viability of the cells treated with 13 nm nano-Al2 O3 0.5 mmol·L-1 for 12,24 and 48 h,respectively. The mitochondrial membrane potential(MMP)was detected by flow cytometry analysis . The ultrastructure of mitochondria and mitophagy vacuoles was observed by transmission electron microscopy(TEM). Auto-phagic vacuoles were observed by dansylpentanediamine(MDC)staining and the expression of autoph-agy related protein Beclin1 and LC3Ⅱ/ Ⅰ was determined by Western blotting. Mitophagy was observed by Lysotracker and Mitotracker staining respectively. RESULTS More than 95% cells were neuronal cells. The activity of LDH in the supernatant liquid exposed to nano-Al2 O3 for 12 and 24 h groups was sig-nificantly increased compared with the control group(P﹤0.05). After exposure to nano-Al2 O3 ,the mito-chondrial membrane potential was significantly decreased compared with the control group( P ﹤0.01). The results of TEM displayed mitochondrial swelling and the formation of vacuoles and mitophagy in nano-Al2 O3 groups. MDC positive fluorescence particles were observed and the expression of autophagy related protein Beclin1 and LC3Ⅱ/ Ⅰ was increased in nano-Al2 O3 groups compared with the control group( P ﹤ 0. 05 ). The result of Lysotracker and Mitotracker colocalization showed the fusion of mitochondria and lysosomals. CONCULSION Nano-Al2 O3 may induce autophagy and mitochondria damage in neuronal cells while the damaged mitochondria may be removed by mitophagy.