BACKGROUND: Studies show that the dexamethasone (DEX) can induce the apoptosis of astrocytes. However, the mechanism is not clear. There are

no reports related to the interference of DEX on cyclin expression of astrocytes.
OBJECTIVE: To study the relationship between apoptosis and the expression of cyclin in astrocytes of rats induced by DEX.
METHODS: Pure cultured astrocytes from rat cerebral cortex were incubated with different concentrations (0, 10-5, 10-4,      10-3 mol/L) of DEX for 24 hours. The cell cycle of the astrocytes was examined by the flow cytomete. Then the expressions of cyclin A and cyclin E in astrocytes were measured by immunocytochemistry.
RESULTS AND CONCLUSION: The cell index of G1 phase was obviously increased in the 10-5 and 10-4 mol/L groups (P < 0.05, P < 0.01), and the cell index of S phase was obviously increased in 10-3 mol/L group compared with the control group (P < 0.01). The expression of cyclin A was decreased with the increasing of DEX concentration. The expression of cyclin E was decreased with the increasing of DEX concentration in the 10-5 and 10-4 mol/L groups (P < 0.05), and increased in the 10-3 mol/L group     (P < 0.01). The attenuated expression of cyclin A and cyclin E may contribute to the cell cycle arrest at G1 phase in the 10-5 and 10-4 mol/L groups, while the cell cycle arrest at S phase in 10-3 mol/L group may mainly attribute to the attenuated expression of cyclin A.