Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
J Neuroinflammation. 2011 Jun 17;8:68. doi: 10.1186/1742-2094-8-68.
Peripheral-type benzodiazepine receptor (PBR) expression levels are low in normal human brain, but their levels increase in inflammation, brain injury, neurodegenerative states and gliomas. It has been reported that PBR functions as an immunomodulator. The mechanisms of action of midazolam, a benzodiazepine, in the immune system in the CNS remain to be fully elucidated. We previously reported that interleukin (IL)-1β stimulates IL-6 synthesis from rat C6 glioma cells and that IL-1β induces phosphorylation of inhibitory kappa B (IκB), p38 mitogen-activated protein (MAP) kinase, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2, and signal transducer and activator of transcription (STAT)3. It has been shown that p38 MAP kinase is involved in IL-1β-induced IL-6 release from these cells. In the present study, we investigated the effect of midazolam on IL-1β-induced IL-6 release from C6 cells, and the mechanisms of this effect.
Cultured C6 cells were stimulated by IL-1β. IL-6 release from C6 cells was measured using an enzyme-linked immunosorbent assay, and phosphorylation of IκB, the MAP kinase superfamily, and STAT3 was analyzed by Western blotting.
Midazolam, but not propofol, inhibited IL-1β-stimulated IL-6 release from C6 cells. The IL-1β-stimulated levels of IL-6 were suppressed by wedelolactone (an inhibitor of IκB kinase), SP600125 (an inhibitor of SAPK/JNK), and JAK inhibitor I (an inhibitor of JAK 1, 2 and 3). However, IL-6 levels were not affected by PD98059 (an inhibitor of MEK1/2). Midazolam markedly suppressed IL-1β-stimulated STAT3 phosphorylation without affecting the phosphorylation of p38 MAP kinase, SAPK/JNK or IκB.
These results strongly suggest that midazolam inhibits IL-1β-induced IL-6 release in rat C6 glioma cells via suppression of STAT3 activation. Midazolam may affect immune system function in the CNS.
外周型苯二氮䓬受体（PBR）在正常人大脑中的表达水平较低，但在炎症、脑损伤、神经退行性状态和神经胶质瘤中其水平会升高。据报道，PBR 作为一种免疫调节剂发挥作用。咪达唑仑（一种苯二氮䓬类药物）在中枢神经系统中的免疫系统中的作用机制仍有待充分阐明。我们之前曾报道过，白细胞介素（IL）-1β刺激大鼠 C6 神经胶质瘤细胞合成 IL-6，IL-1β诱导抑制性 κB（IκB）、p38 丝裂原激活蛋白（MAP）激酶、应激激活蛋白激酶（SAPK）/c-Jun N-末端激酶（JNK）、细胞外信号调节激酶 1/2 和信号转导和转录激活因子（STAT）3 的磷酸化。已经表明 p38 MAP 激酶参与了这些细胞中由 IL-1β 诱导的 IL-6 释放。在本研究中，我们研究了咪达唑仑对 C6 细胞中由 IL-1β 诱导的 IL-6 释放的影响，以及这种作用的机制。
用 IL-1β 刺激培养的 C6 细胞。通过酶联免疫吸附试验测定 C6 细胞中 IL-6 的释放，并用 Western blot 分析 IκB、MAP 激酶超家族和 STAT3 的磷酸化。
咪达唑仑而非丙泊酚抑制了 C6 细胞中由 IL-1β 刺激的 IL-6 释放。IL-1β 刺激的 IL-6 水平被 wedelolactone（IκB 激酶抑制剂）、SP600125（SAPK/JNK 抑制剂）和 JAK 抑制剂 I（JAK1、2 和 3 的抑制剂）抑制，但 PD98059（MEK1/2 抑制剂）对 IL-6 水平没有影响。咪达唑仑显著抑制了由 IL-1β 刺激的 STAT3 磷酸化，而不影响 p38 MAP 激酶、SAPK/JNK 或 IκB 的磷酸化。
这些结果强烈表明，咪达唑仑通过抑制 STAT3 激活来抑制大鼠 C6 神经胶质瘤细胞中由 IL-1β 诱导的 IL-6 释放。咪达唑仑可能会影响中枢神经系统中的免疫系统功能。
