Ca2 -dependent recruitment of voltage-gated sodium channels underlies bilirubin-induced overexcitation and neurotoxicity
Ca2 -dependent recruitment of voltage-gated sodium channels underlies bilirubin-induced overexcitation and neurotoxicity
复制标题
电压门控钠通道的 Ca2 依赖性募集是胆红素诱导的过度兴奋和神经毒性的基础
DOI：
10.1038/s41419-019-1979-1
复制
发表时间：
2019
影响因子：
9
通讯作者：
Yin Shan-Kai
中科院分区：
文献类型：
--
作者：
Shi Hao-Song;Lai Ke;Yin Xin-Lu;Liang Min;Ye Hai-Bo;Shi Hai-Bo;Wang Lu-Yang;Yin Shan-Kai
新生儿黄疸在新生儿中很普遍，可导致严重的神经功能障碍，特别是感觉运动功能障碍。先前的研究表明，胆红素（BIL）增强中枢神经元的内在兴奋性，这可能有助于它们的过度兴奋，Ca2+超载和神经毒性。然而，神经元兴奋性升高的细胞机制尚不清楚。通过对大鼠内侧前庭核（MVN）的新生神经元进行膜片夹记录，我们发现BIL （3 μM）通过上调电流介导的电压门控钠通道（VGSCs）而显著增加自发放电率，同时将其电压依赖性激活转向更高的超极化电位。免疫荧光标记和抗nav1.1抗体的western免疫印迹显示，BIL通过促进VGSCs向细胞膜募集来提高VGSCs的表达。此外，我们发现这种vgsc运输过程依赖于Ca2+，因为用Ca2+缓冲剂BAPTA-AM或胞外分泌抑制剂dat - nsf700预加载MVN神经元，可以阻止BIL的作用，这表明功能性VGSCs的活性和密度上调是负责的核心机制。最重要的是，用低剂量的VGSC阻滞剂利多卡因纠正这种过度兴奋可显著减轻bil诱导的细胞死亡。我们认为，VGSC电流的增强直接导致新生儿大脑易受高胆红素血症的影响，暗示在严重黄疸的情况下，NaV1.1通道的活动和运输是神经保护的潜在靶点。
Neonatal jaundice is prevalent among newborns and can lead to severe neurological deficits, particularly sensorimotor dysfunction. Previous studies have shown that bilirubin (BIL) enhances the intrinsic excitability of central neurons and this can potentially contribute to their overexcitation, Ca2+overload, and neurotoxicity. However, the cellular mechanisms underlying elevated neuronal excitability remain unknown. By performing patch-clamp recordings from neonatal neurons in the rat medial vestibular nucleus (MVN), a crucial relay station for locomotor and balance control, we found that BIL (3 μM) drastically increases the spontaneous firing rates by upregulating the current-mediated voltage-gated sodium channels (VGSCs), while shifting their voltage-dependent activation toward more hyperpolarized potentials. Immunofluorescence labeling and western immunoblotting with an anti-NaV1.1 antibody, revealed that BIL elevates the expression of VGSCs by promoting their recruitment to the membrane. Furthermore, we found that this VGSC-trafficking process is Ca2+dependent because preloading MVN neurons with the Ca2+buffer BAPTA-AM, or exocytosis inhibitor TAT-NSF700, prevents the effects of BIL, indicating the upregulated activity and density of functional VGSCs as the core mechanism accountable for the BIL-induced overexcitation of neonatal neurons. Most importantly, rectification of such overexcitation with a low dose of VGSC blocker lidocaine significantly attenuates BIL-induced cell death. We suggest that this enhancement of VGSC currents directly contributes to the vulnerability of neonatal brain to hyperbilirubinemia, implicating the activity and trafficking of NaV1.1 channels as a potential target for neuroprotection in cases of severe jaundice.