OBJECTIVETo explore the mechanisms of aluminum (Al)-induced neurotoxicity by studying the effect of aluminum on lipid peroxidation in rat's brain and its sex related difference.

METHODSForty SD rats, both male and female, were exposed to aluminum through intraperitoneal injection of AlCl3 solution for 60 days at different dose. After exposure, the step down test was performed to examine the learning and memory abilities of rats, and the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in rat's cerebrum were detected by chemical method. The changes of ultrastructure in cortex were observed by transmission electron microscopy.

RESULTSThe differences between the changes of all indexes of female and male rats in the same dose-group wasn't statistically significant (P > 0.05). Compared with the rats in the control group, the learning and memory abilities of the Al-exposed rats were significantly decreased (P < 0.05). The content of MDA was increased (P < 0.01) while the activity of SOD was decreased (P < 0.05). The membrane structure of neurons in cerebrum cortex of the Al-exposed rats were broken, dissolved and gone.

CONCLUSIONAluminum can accelerate lipid peroxidation in rat's brain, which may be one of the important intoxication mechanisms of aluminum. However, the sex-related difference of this effect have not yet been observed.

Aluminum ; toxicity ; Animals ; Brain ; drug effects ; metabolism ; ultrastructure ; Dose-Response Relationship, Drug ; Female ; Learning ; drug effects ; Lipid Peroxidation ; drug effects ; Male ; Malondialdehyde ; metabolism ; Memory ; drug effects ; Rats ; Rats, Sprague-Dawley ; Sex Factors ; Superoxide Dismutase ; metabolism

OBJECTIVETo find the optimal design of small interfering RNA compounds, transfection concentration and transfection time to reduce the Al-induced apoptosis in SH-SY5Y cells.

METHODSThree siRNA sequences on bak gene were designed and transfected into SH-SY5Y cells, which were treated at various concentrations of aluminum. Cell viability was detected by CCK-8 kit on different siRNA sequences, various transfection concentrations, and diverse transfection courses. Transfection efficiency was determined by fluorescent staining of CY3, and interference efficiency was measured by QRT-PCR. Besides, immunohistochemical staining was used to express Bak protein content. Finally, apoptotic rate and necrotic rate in Al treated SH-SY5Y cells transfecting by the selected bak siRNA 1 were detected.

RESULTSBased on the viability of siRNA sequences, siRNA 1 was selected as the optimal siRNA sequences. The optimal transfection concentration was 10 nmol/L, and the optimal time course was 24 h after transfection. The transfection efficiency was above 90% and the interference efficiency with bak gene was 57.76%. Furthermore, there was significant transfection effect on Bak protein. The apoptotic rate in Al treated SH-SY5Y cells were significantly decreased by bak siRNA 1 transfection.

CONCLUSIONApoptosis is one of the major cell death pathways in SH-SY5Y cells induced by aluminum. When chemically synthesized siRNA is inducted to neural cells, it can significantly reduce bak gene level, decrease Bak protein expression and apoptotic rate, which may serve as the basis for preventing neural cells apoptosis and inhibiting the development of neurodegenerative diseases.

Aluminum ; pharmacology ; Apoptosis ; drug effects ; genetics ; Cell Line, Tumor ; Cell Survival ; drug effects ; genetics ; Humans ; Neuroblastoma ; genetics ; metabolism ; pathology ; RNA, Small Interfering ; genetics ; Transfection ; bcl-2 Homologous Antagonist-Killer Protein ; genetics ; metabolism

OBJECTIVETo study the role of Bcl-2 and Bax protein contents and their gene expression in Al-induced neurons apoptosis.

METHODSNeurons from 0 - 3 day rats were cultured and treated with different concentrations of AlCl(3 x 6) H2O. The cell apoptosis was observed by the TUNEL method and under the scan electron microscope. Bcl-2 and Bax protein contents were detected by the immunochemistry method while their gene expressions were measured by the RT-PCR method.

RESULTS(1) DNA fractions in the TUNEL method increased with the rising aluminum concentration. Blebbings and apoptosis bodies on the surface of the neurons were clearly observed under the scan electron microscope. (2) Bcl-2 protein contents and their gene expression decreased with the rising aluminum concentration (P < 0.01, r = -0.695; P < 0.05, r = -0.647), while Bax increased at the same time (P < 0.01, r = 0.676; P < 0.01, r = 0.794), the value of Bcl-2/Bax was related with the aluminum concentration (P < 0.01, r = -0.655; P < 0.01, r = -0.777).

CONCLUSIONThe aluminum may induce neurons apoptosis. Bcl-2 and Bax protein contents and their gene expression may play an important role in Al-induced apoptosis.

Aluminum ; toxicity ; Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Cells, Cultured ; Dose-Response Relationship, Drug ; Gene Expression ; drug effects ; Neurons ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; biosynthesis ; genetics

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide ; toxicity ; Carcinogens ; toxicity ; Cell Line, Tumor ; DNA Damage ; drug effects ; Dose-Response Relationship, Drug ; HSP70 Heat-Shock Proteins ; biosynthesis ; Humans