Effects of protein kinase C on aquaporin-4 over-expression induced by ammonia in astrocytes of rats
AIM: To examine the effects of protein kinase C (PKC) on the expression of aquaporin-4 ( AQP-4) in ammonia-treated astrocytes. METHODS: Cultured astrocytes were randomly divided into 5 groups: Control group: cultured with normal medium for 24 h;NH_4Cl group: Incubated in culture medium with 5 mmol/L NH_4C1 for 24 h; DMSO group: Pretreated with 10 g/L dimethyl sul-foxide(DMSO) for 30 min,and then treated as NH_4C1 group;TPA group: Pretreated with 12-o-tetradecanoylphorbol 13-acetate (TPA) (1μmol/ L) , a PKC activator, for 30 min, subsequently treated as NH_4C1 group. RT group: Pretreated with a PKC inhibitor Ro31-8220(1μmol/L) for 30 min,and then treated as the TPA group; Cell morphology was assessed by light microscopy, and Western Blot analysis was used to detect AQP-4 expression. RESULTS: The AQP-4 expression in NH_4C1 group and DMSO group was(0. 69 ± 0. 03)and(0. 67±0. 03) , compared with the Control group, they increase significantly respectively( P <0. 05) ,but there is no differ ences between them, and the astrocytes in these 2 group swell notably. The expression of AQP-4 in TPA group was (0. 40 ± 0.02) ,compared with the NH_4CI group, it decrease significantly ( P <0. 05 ) . And there was no difference in AQP-4 expression between RT group and NH_4C1 group. CONCLUSION: The expression of AQP-4 in astrocytes was increased following treatment of ammonia and the activation of protein kinase C could attenuate this AQP-4 over-expression.
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