Moriyama Naoki, Taniguchi Makoto, Miyano Kanako, Miyoshi Michio, Watanabe Tatsuo
Division of Integrative Physiology, Department of Functional, Morphological and Regulatory Science, Tottori University Faculty of Medicine, Yonago, Tottori 683, Japan.
Biochem Biophys Res Commun. 2006 Nov 17;350(2):322-8. doi: 10.1016/j.bbrc.2006.09.034. Epub 2006 Sep 18.
Atrial natriuretic peptide (ANP) contributes to the inhibition of such causes of inflammation as the lipopolysaccharide (LPS)-induced productions of nitric oxide (NO) and proinflammatory cytokines [including interleukin-1 (IL-1)] in macrophages. In the present study we used primary cultures of rat brain macrophage-like cells (i.e., microglial cells) to investigate whether ANP binding to its receptors inhibits LPS-induced microglial activation via effects on the activation of the proinflammatory transcription factors NF-kappaB and AP-1. The productions of NO and IL-1, as well as morphological changes, were examined to assess LPS-induced activation of microglial cells. Our RT-PCR study revealed that rat microglial cells express the mRNAs for ANP receptors (types A, B, and C) and that for the ANP molecule. LPS (100 ng/ml)-stimulated microglial cells showed increases in nitrite (a relatively stable metabolite of NO) and IL-1 concentrations, and in the expression of IL-1 mRNA, as well as a morphological change from an amoeboid shape to a multipolar (mostly bipolar, but sometimes tripolar) rod shape. These effects were all significantly inhibited by treatment with ANP (at 10(-6)M or less). The inhibition by ANP of the LPS-induced nitrite response was abrogated by a NP-receptor antagonist, HS-142-1 (100 ng/ml). NF-kappaB and AP-1 activities were enhanced in LPS-stimulated microglial cells, and these enhancements were significantly suppressed by ANP (10(-6)M). These results suggest that ANP inhibits LPS-stimulated activities in microglial cells through activation of microglial ANP receptors, leading to inhibitions of NF-kappaB and AP-1.
心房利钠肽（ANP）有助于抑制诸如脂多糖（LPS）诱导巨噬细胞产生一氧化氮（NO）和促炎细胞因子[包括白细胞介素 -1（IL -1）]等炎症原因。在本研究中，我们使用大鼠脑巨噬细胞样细胞（即小胶质细胞）的原代培养物来研究ANP与其受体结合是否通过影响促炎转录因子NF -κB和AP -1的激活来抑制LPS诱导的小胶质细胞活化。检测了NO和IL -1的产生以及形态变化，以评估LPS诱导的小胶质细胞活化情况。我们的逆转录聚合酶链反应（RT -PCR）研究表明，大鼠小胶质细胞表达ANP受体（A、B和C型）的信使核糖核酸（mRNA）以及ANP分子的mRNA。LPS（100纳克/毫升）刺激的小胶质细胞显示亚硝酸盐（NO的一种相对稳定的代谢产物）和IL -1浓度增加，IL -1 mRNA表达增加，并且形态从阿米巴样变为多极（主要是双极，但有时是三极）杆状。用ANP（10^(-6)M或更低浓度）处理可显著抑制这些效应。NP受体拮抗剂HS -142 -1（100纳克/毫升）可消除ANP对LPS诱导的亚硝酸盐反应的抑制作用。在LPS刺激的小胶质细胞中，NF -κB和AP -1活性增强，而ANP（10^(-6)M）可显著抑制这些增强作用。这些结果表明ANP通过激活小胶质细胞ANP受体来抑制小胶质细胞中LPS刺激的活性，从而导致NF -κB和AP -1受到抑制。
