Abstract:OBJECTIVE: To study the mechanism of LPS, IL 1β and TNF α induced apoptosis of astrocytes in rats. METHODS: The astrocytes of the neonatal rat were cultured in vitro and randomely assigned into the inflammation group (treated with LPS, IL 1β and TNF α), pre treatment group (L NMMA was administrated half an hour before treatment with LPS, IL 1β and TNF α) and normal control group. The cell viability was assayed by MTT; apoptosis was evaluated by electron microscope and flow cytometry; nitric oxide (NO) content was measured by spectrophotometer; cytochrome C content in cytoplasm was measured by Western Blot and Caspase 3 mRNA expression was detected by hybridization in situ. RESULTS: The cell viability in the pre treatment group was significantly higher than that of the inflammation group ( 0.81 ± 0.29 vs 0.46 ± 0.15 ), P< 0.01 . There was a negative correlation between the cell viability and NO content produced by astrocytes in the inflammation group (r= -0.604 , P< 0.05 ). The apoptosis rate of the pre treatment group was lower than that of the inflammation group [( 15.2 ± 7.9 ) % vs ( 29.7 ± 10.4 )%; P< 0.05 ]. The cytochrome C content in cytoplasm of astrocytes of the pre treatment group (14 784±2 096) decreased compared with that of the inflammation group (31 049±3 784) (P< 0.01 ). The expression of Caspase 3 mRNA in the inflammation group was intensified compared with that of the pre treatment group. CONCLUSIONS: Cytokines may lead to decrease of viability of astrocytes through increasing NO content produced by astrocytes. The increase of NO content can induce astrocyte apoptosis, which is related to the release of the cytochrome C from mitochondria to cell plasma, and activating the expression of Caspase 3 mRNA.
