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.