精氨酸加压素对星形胶质细胞水孔蛋白-4表达的调节及脑水肿形成影响的研究

Study on mechanism of arginine vasopressin inducing expression of aquaporin-4 and brain edema formation

目的研究精氨酸加压素(AVP)对星形胶质细胞水孔蛋白-4(AQP4)表达的调节,以及p38 MAPK信号通路在AQP4表达过程的作用,明确AVP及AQP4在脑水肿发生过程中的作用。方法大鼠大脑皮质分离星形胶质细胞,星形胶质细胞经分别用AVP、V1a受体(V1aR)拮抗剂和SB 203580进行处理,采用免疫组织化学技术及RT-PCR对AQP4 mRNA进行检测,Western blot检测p38 MAPK信号通路在AVP诱导AQP4表达中的活化程度。结果500nmol/L的AVP处理6h后,AQP4 mRNA表达开始升高(P<0.01),到12h达高峰(P<0.01),24h后仍维持在较高的水平(P<0.05)。加入p38 MAPK抑制剂SB 203580干预后,AQP4 mRNA表达水平与对照组比较差异不显著(P>0.05);AVP处理15min后p38 MAPK磷酸化水平开始增加,30min达高峰,持续到60min开始下降。V1aR拮抗剂处理后p38 MAPK磷酸化水平整个时间段均未出现明显变化。结论AVP通过激活V1aR引起p38MAPK信号通路活化从而诱导AQP4 mRNA高表达,从基因水平对AQP4进行调节,可能在脑水肿发生中,尤其是在星形胶质细胞水肿形成中起重要作用。V1aR拮抗剂及p38 MAPK抑制剂能抑制AQP4 mRNA的表达,避免星形胶质细胞肿胀。

Objective To determine the role of p38 MAPK in the aquaporin-4 （AQP4） expression and brain edema induced by arginine vasopressin （AVP） in cultured rat astrocytes. Methods Primary cultured astrocytes were treated with AVP, V1 aR antagonist and SB 203580, harvested for determination of AQP4 mRNA expression by reverse transcription polymerase chain reaction（RT-PCR）, p38 MAPK phosphorylation were assessed by Western blot analysis. Results After astrocytes treated with 500nmol/L AVP for 6h,the expression of AQP4 mRNA began to increase（ P 〈 0.01 ） ,at 12h,reached expression peak（P 〈0.01 ） ,while at 24h, the AQP4 mRNA still maintained the high expression（P 〈 0.01 ）. This course were not exhibited after SB 203580 treatment, p38 MAPK phosphorylation increased 15min after AVP treatment,remained elevated level even at 120min. Conclusions AVP may induce higher expression of AQP4 mRNA through activating VlaR which stimulate p38 MAPK in astrocytes, which may lead to brain edema. SB 203580 and V1aR antagonist could inhibit up- regulation of AQP4 mRNA in the AVP environment, prevent astrocytes from swelling.