RESUMO
OBJECTIVE To explore the protective effect and possible mechanism of baicalein on hypoxia-induced cortical neuron injury in rats. METHODS The cortical neurons of rats （RN-C cells） were studied and cultured under hypoxic conditions （5%CO2， 94% N2， 1%O2） for 24 hours； the effects of different concentrations of baicalein （0.01， 0.1， 1， 10， 100 μmol/L） on the survival rate of hypoxic RN-C cells were investigated； the effects of baicalein （0.1 μmol/L） on the activities of lactate dehydrogenase （LDH） and superoxide dismutase （SOD）， the content of malondialdehyde （MDA）， migration rate， apoptotic rate， cell cycle and the expressions of cleaved caspase-3， B-cell lymphoma-2 （Bcl-2） and Bcl-2 X protein （Bax） were all detected. RESULTS Compared with control group， the survival rate of cells in the hypoxia group was significantly reduced （P＜0.01）； 0.01， 0.1 and 1 μmol/L baicalein could reverse survival rate of hypoxia-induced cortical neurons （P＜0.05 or P＜0.01）. Scratch experiments showed that baicalein significantly increased the migration rate of hypoxic RN-C cells （P＜0.01）. Compared with control group， the activity of LDH in the supernatant and the content of MDA in the cells， apoptotic rate and the proportion of cells in G1 phase， were significantly increased in the hypoxia group， while SOD activity and the proportion of cells in G2+S phase was decreased significantly （P＜0.01）. The protein expressions of cleaved caspase-3 were increased significantly， while the ratio of Bcl-2/Bax in cells was significantly reduced （P＜0.05 or P＜0.01）. Compared with hypoxia group， the above indexes were all reversed significantly in baicalein group （P＜0.01）. CONCLUSIONS Baicalein can promote the proliferation and migration of cortical neurons， improve hypoxia-induced cell apoptosis and cell cycle distribution， decrease the activity of LDH in supernatant and the level of cellular lipid peroxidation， and improve antioxidant levels. Its mechanism may be related to regulating the caspase- 3/Bax/Bcl-2 pathway.