Department of Anesthesiology, the Third Affiliated Hospital of Guangxi University of Traditional Chinese Medicine, Liuzhou, Guangxi 545001, PR China.
Department of Pain, the Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, PR China.
Brain Res. 2021 Jan 1;1750:147141. doi: 10.1016/j.brainres.2020.147141. Epub 2020 Oct 2.
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.
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.
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.
DEX protects astrocytes against apoptosis via inhibiting JAK2/STAT3 signal pathway and downregulating JMJD3 expression in vitro.
星形胶质细胞在缺血性脑损伤的内在生物修复中具有重要作用，这一作用受到越来越多的关注。本研究旨在揭示右美托咪定（DEX）对氧葡萄糖剥夺（OGD）条件下星形胶质细胞凋亡的作用及其机制。
分离 Sprague-Dawley（SD）大鼠原代培养的星形胶质细胞，用 OGD 处理，然后用 si-JMJD3 或 pcDNA3.1-JMJD3 转染，DEX 或 JAK/STAT 抑制剂（WP1066）处理，用 TUNEL 凋亡试剂盒检测细胞凋亡。用 Western blot 检测凋亡相关蛋白 Caspase-3、Bax 和 Bcl-2 的水平。用乳酸脱氢酶（LDH）检测试剂盒检测星形胶质细胞活力。
OGD 处理的星形胶质细胞 LDH 升高，凋亡率增加（P<0.05）。DEX 可抑制 OGD 诱导的星形胶质细胞毒性作用，表现为 LDH 释放减少，细胞凋亡率降低（P<0.05）。同时，DEX 和 WP1066 处理还抑制了 STAT1 和 STAT3 的磷酸化水平（P<0.05），表明 DEX 可抑制 JAK/STAT 信号通路的激活。星形胶质细胞中 JMJD3 的过表达可抑制 WP1066 在 OGD 处理的星形胶质细胞中的抗凋亡作用，并阻碍 DEX 在细胞凋亡中的保护作用（P<0.05），表明 DEX 和 JAK/STAT 信号通路通过下调 JMJD3 抑制 OGD 诱导的星形胶质细胞凋亡。
DEX 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于凋亡。
