人参皂苷Rg1和Rb1促进PC12细胞释放谷氨酸的作用机制

目的研究人参皂苷(ginsenosides)Rg1和Rb1促进PC12细胞释放谷氨酸作用的机制。方法HPLC法测量PC12细胞释放谷氨酸的含量。细胞免疫染色法和Western blotting法检测人参皂苷Rg1和Rb1对突触蛋白(synapsins)磷酸化水平的影响。结果人参皂苷Rg1(10 μmol·L^-1)和Rb1(10 μmol·L^-1)均可明显促进PC12细胞中谷氨酸的释放。加入蛋白激酶A(PKA)抑制剂H89可抑制Rb1诱导的谷氨酸释放增加；但H89不能抑制Rg1诱导的谷氨酸释放增加。Rb1可升高PC12细胞中突触蛋白的磷酸化水平，H89可抑制这种作用；而Rg1对突触蛋白磷酸化水平无明显作用。结论Rb1可介导PKA活化以诱导突触蛋白磷酸化升高，进而引起谷氨酸释放增加；并提示Rg1促进谷氨酸释放的作用可能与突触蛋白磷酸化无关。

The mechanism of ginsenosides Rg1 and Rb1 promoting glutamic acid release from PC12 cells

AIM: To study the mechanism of ginsenosides Rg1 and Rb1 promoting glutamic acid release from PC12 cells. METHODS: The amount of glutamic acid released from PC12 cells was measured by high performance liquid chromatography (HPLC). The effect of Rg1 and Rb1 on the phosphorylation of synapsins was detected with immunofluorescent staining and Western blotting. RESULTS: Both Rg1 (10 micromol x L(-1)) and Rb1 (10 micromol x L(-1)) increased glutamic acid release from PC12 cells. The release of glutamic acid was decreased by pre-incubating with the PKA inhibitor H89. H89 inhibited the release of glutamic acid induced by Rb1, but had no effect on the release of glutamic acid induced by Rg1. Moreover, Rb1 enhanced the phosphorylation of synapsins via PKA pathway, Rg1 was out of touch with this. CONCLUSION: Rb1 may promote release of neurotransmitters by increasing the phosphorylation of synapsins via PKA pathway, whereas the up-regulation of neurotransmitters release induced by Rg1 is independent of the phosphorylation of synapsins.