Ethanol alters calcium signaling in axonal growth cones.
Ethanol alters calcium signaling in axonal growth cones.
复制标题
乙醇改变轴突生长锥中的钙信号传导。
DOI：
10.1016/j.neuroscience.2011.05.042
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发表时间：
2011
期刊：
影响因子：
3.3
通讯作者：
Lindsley,TA
中科院分区：
文献类型：
--
作者：
Mah,SJ;Fleck,MW;Lindsley,TA
钙离子通道对乙醇敏感，钙离子信号是轴突生长和导向的关键调节因子。急性和慢性暴露于乙醇（22，43，或87 mM）的电压门控钙通道（VGCC）在整个细胞，和KCl诱导的轴突生长锥中的钙瞬变的影响，进行了检查使用解离海马文化。全细胞膜片钳分析与新形成的轴突（阶段3）的神经元显示，快速失活，低电压激活（LVA）和非失活，高电压激活（HVA）电流都抑制急性乙醇的剂量依赖性方式，与相对更大的抑制HVA电流。当通过Fluo-4-AM成像进行评估时，与没有轴突的神经元相比，第3阶段神经元中对乙醇的基线荧光和Ca 2+响应是相似的，但是响应于浴施加KCl的峰值Ca 2+瞬态振幅在第3阶段神经元中更大，并且通过急性乙醇降低。由KCl的局部应用引起的轴突生长锥中特异性的Ca 2+瞬变的幅度也被急性暴露于中高浓度的乙醇（43或87 mM）抑制，而较低浓度（22 mM）则没有影响。当43或87 mM的乙醇存在于培养基中连续，KCl诱发的Ca 2+瞬态振幅也减少在生长锥。相反，Ca 2+瞬变增加，连续暴露于22 mM乙醇。可视化使用荧光二氢吡啶类似物显示，神经元连续暴露于乙醇表达增加量的L-型Ca 2+通道，轴突生长锥比细胞体更大的增加。因此，急性乙醇减少钙电流和KCl诱导的钙反应，在整个细胞和轴突生长锥，分别和慢性曝光也普遍抑制，尽管明显上调L型通道的表达。这些结果是一致的作用，改变生长锥Ca 2+信号异常神经形态发生与胎儿酒精谱系障碍。
Calcium (Ca2+) channels are sensitive to ethanol and Ca2+signaling is a critical regulator of axonal growth and guidance. Effects of acute and chronic exposure to ethanol (22, 43, or 87 mM) on voltage-gated Ca2+channels (VGCCs) in whole cells, and KCl-induced Ca2+transients in axonal growth cones, were examined using dissociated hippocampal cultures. Whole-cell patch-clamp analysis in neurons with newly-formed axons (Stage 3) revealed that rapidly inactivating, low-voltage activated (LVA) and non-inactivating, high-voltage activated (HVA) currents were both inhibited in a dose-dependent manner by acute ethanol, with relatively greater inhibition of HVA currents. When assessed by Fluo-4-AM imaging, baseline fluorescence and Ca2+response to ethanol in Stage 3 neurons was similar compared to neurons without axons, but peak Ca2+transient amplitudes in response to bath-applied KCl were greater in Stage 3 neurons and were decreased by acute ethanol. The amplitude of Ca2+transients elicited specifically in axonal growth cones by focal application of KCl was also inhibited by acute exposure to moderate-to-high concentrations of ethanol (43 or 87 mM), whereas a lower concentration (22 mM) had no effect. When 43 or 87 mM ethanol was present continuously in the medium, KCl-evoked Ca2+transient amplitudes were also reduced in growth cones. In contrast, Ca2+transients were increased by continuous exposure to 22 mM ethanol. Visualization using a fluorescent dihydropyridine analog revealed that neurons continuously exposed to ethanol expressed increased amounts of L-type Ca2+channels, with greater increases in axonal growth cones than cell bodies. Thus, acute ethanol reduces Ca2+current and KCl-induced Ca2+responses in whole cells and axonal growth cones, respectively, and chronic exposure is also generally inhibitory despite apparent up-regulation of L-type channel expression. These results are consistent with a role for altered growth cone Ca2+signaling in abnormal neuromorphogenesis associated with fetal alcohol spectrum disorders.