Objective

There is an increasing interest concerning the contribution of astrocytes to the intrinsic bioremediation of ischemic brain injury. The aim of this work was to disclose the effects and mechanism of dexmedetomidine (DEX) on the apoptosis of astrocytes under oxygen glucose deprivation (OGD) condition.

Methods

Primary cultured astrocytes separated from Sprague-Dawley (SD) rats were subjected to OGD treatment. Astrocytes were transfected with si-JMJD3 or pcDNA3.1-JMJD3 and then treated with DEX or JAK/STAT inhibitor (WP1066) before cell apoptosis was detected by TUNEL apoptosis kit. Western blot was applied to assess the level of apoptosis-related proteins Caspase-3, Bax and Bcl-2. Astrocyte cell viability was assessed by measuring the lactate dehydrogenase (LDH) level using a LDH assay kit.

Results

Astrocytes received OGD treatment had increased LDH and elevated apoptotic rate (P < 0.05). DEX could suppress OGD induced cytotoxic effect on astrocytes, as evidenced by decreased LDH release and suppressed cell apoptosis rate (P < 0.05). Meanwhile, DEX and WP1066 treatment were also found to inhibit the phosphorylation level of STAT1 and STAT3 (P < 0.05), indicating the DEX could suppress the activation of JAK/STAT signal pathway. JMJD3 overexpression in astrocytes could suppress the anti-apoptotic function of WP1066 in OGD treated astrocytes and hamper the protective effect of DEX in cell apoptosis (P < 0.05), suggesting that DEX and JAK/STAT signal pathway inhibits OGD induced apoptosis in astrocytes by down-regulating JMJD3.

Conclusion

DEX protects astrocytes against apoptosis via inhibiting JAK2/STAT3 signal pathway and downregulating JMJD3 expression in vitro.

中文翻译：

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右美托咪定通过靶向JAK/STAT3信号通路抑制氧糖剥夺诱导的星形胶质细胞凋亡

客观的

星形胶质细胞对缺血性脑损伤的内在生物修复的贡献越来越受到关注。本工作的目的是揭示右美托咪定（DEX）在氧糖剥夺（OGD）条件下对星形胶质细胞凋亡的影响和机制。

方法

从 Sprague-Dawley (SD) 大鼠中分离出来的原代培养的星形胶质细胞进行 OGD 治疗。星形胶质细胞用si-JMJD3或pcDNA3.1-JMJD3转染，然后用DEX或JAK/STAT抑制剂（WP1066）处理，然后用TUNEL凋亡试剂盒检测细胞凋亡。应用蛋白质印迹来评估凋亡相关蛋白 Caspase-3、Bax 和 Bcl-2 的水平。通过使用 LDH 测定试剂盒测量乳酸脱氢酶 (LDH) 水平来评估星形胶质细胞的活力。

结果

接受OGD处理的星形胶质细胞具有增加的LDH和升高的凋亡率（P  < 0.05）。DEX 可以抑制 OGD 对星形胶质细胞的细胞毒作用，这可以通过减少 LDH 释放和抑制细胞凋亡率来证明（P  < 0.05）。同时，DEX 和 WP1066 处理也被发现抑制 STAT1 和 STAT3 的磷酸化水平（P  < 0.05），表明 DEX 可以抑制 JAK/STAT 信号通路的激活。星形胶质细胞中过表达 JMJD3 可抑制 WP1066 在 OGD 处理的星形胶质细胞中的抗凋亡功能，并阻碍 DEX 对细胞凋亡的保护作用（P  < 0.05），表明 DEX 和 JAK/STAT 信号通路通过向下抑制 OGD 诱导的星形胶质细胞凋亡- 调节 JMJD3。

结论

DEX 在体外通过抑制 JAK2/STAT3 信号通路和下调 JMJD3 表达来保护星形胶质细胞免受凋亡。