Effect of tetramethylpyrazine pretreatment on the expression of c-fos and heat shock protein 70 during hypoxia-reoxygenation in cultured fetal rat hippocampal neurons

Objective To investigate the effect of tetramethylpyrazine pretreatment on the expression of cfos and heat shock protein （HSP70） during hypoxia-reoxygenation （H/R） in cultured fetal rat hippocampal neurons. Methods After the neurons were cultured and identified, they were randomly divided into 5 groups （ n = 24each）： control group （group C）, H/R group, and low, median and high concentration of tetramethylpyrazine pretreatment groups （group L, M and H）. The neurons were exposed to 2 h of hypoxia followed by 24 h of reoxygenation. Tetramethylpyrazine was added with the final concentrations of 60, 200 and 800 μg/ml in group L, M and H respectively, and then the neurons were incubated for 1 h before H/R. The apoptosis rate, cell viability and expression of c-fos and HSP70 were detected. Results The cell viability was significantly lower, while the apoptosis rate was significantly higher in group A/R, L and H than in group C （P 〈0.01）. The cell viability and HSP70expression were significantly higher, while the apoptosis rate and c-fos expression were significantly lower in group L, M and H than in group A/R, and in group M and H than in group L （P〈 0.05）. The cell viability and HSP70expression were significantly lower, while the apoptosis rate and c-fos expression were significantly higher in group H than in group M （ P 〈 0.01 ）.Conclusion The mechanism by which tetramethylpyrazine pretreatment inhibits the apoptosis in cultured fetal rat hippocampal neurons during H/R may be related to the dowm-regulation of c-fos expression and up-regulation of HSP70 expression. Key words: TETRAMETHYLPYRAZINE;  Ischemic preconditioning;  Oxygen;  Cell hypoxia;  Proto-oncogene proteins c-fos;  HSP70 heat-shock proteins;  Hippocampus;  Neurons