Ion channels in spinal cord astrocytes in vitro. III. Modulation of channel expression by coculture with neurons and neuron-conditioned medium.
Ion channels in spinal cord astrocytes in vitro. III. Modulation of channel expression by coculture with neurons and neuron-conditioned medium.
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体外脊髓星形胶质细胞的离子通道。
DOI：
10.1152/jn.1993.69.3.819
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发表时间：
1993
影响因子：
2.5
通讯作者：
H. Sontheimer
中科院分区：
文献类型：
--
作者：
C. Thio;S. Waxman;H. Sontheimer
1.从大鼠脊髓培养的星形胶质细胞表达高密度的电压激活的Na+通道（高达8个通道/微米2）。星状星形胶质细胞表达Na+电流在体外的所有时间。在扁平星形胶质细胞中，Na+通道表达显示出不同的时间模式，在体外（DIV）1-3天不存在通道表达，并且在7-8 DIV时达到峰值Na+通道密度。2.脊髓星形胶质细胞与背根神经节（DRG）神经元的共培养大大降低了两种脊髓星形胶质细胞类型中电压激活的Na+通道的表达。在扁平脊髓星形胶质细胞中，表达Na+通道的细胞百分比和Na+通道表达细胞中的通道密度均显著降低。在星状脊髓星形胶质细胞中，Na+通道表达细胞的百分比不变，但在共培养中每个细胞的Na+通道密度显著降低。3.在神经元条件培养基中培养脊髓星形胶质细胞可将两种脊髓星形胶质细胞类型中的Na+通道表达降低至共培养和对照之间的中间水平，这表明，至少部分地，神经元对Na+通道表达的影响是由神经元分泌到培养基中的可溶性因子介导的。4.与电压激活的Na+通道的表达一样，电压激活的K+通道的表达在与DRG神经元共培养的两种脊髓星形胶质细胞类型中减少。在神经元条件培养基中培养细胞不能模拟这种效应，这表明对K+通道表达的影响是由不太稳定且更容易降解的因子介导的。5.与DRG神经元共培养或在神经元条件培养基中培养不会改变煎饼脊髓星形胶质细胞中电压激活的Na+电流的生物物理特性。因此，稳态活化、稳态失活以及活化和失活的时间常数在各种培养条件下几乎不变。
1. Astrocytes cultured from rat spinal cord express voltage-activated Na+ channels in high densities (up to 8 channels per microns2). Stellate astrocytes express Na+ currents at all times in vitro. In pancake astrocytes, Na+ channel expression shows a distinct temporal pattern, an absence of channel expression at 1-3 days in vitro (DIV), and peak Na+ channel density at 7-8 DIV. 2. Coculture of spinal cord astrocytes with dorsal root ganglion (DRG) neurons substantially reduces the expression of voltage-activated Na+ channels in both spinal cord astrocyte types. In pancake spinal cord astrocytes, both the percentage of cells expressing Na+ channels and the channel density in Na+ channel-expressing cells are markedly reduced. In stellate spinal cord astrocytes, the percentage of Na+ channel-expressing cells is unchanged, but the Na+ channel density per cell is markedly reduced in coculture. 3. Culturing spinal cord astrocytes in neuron-conditioned media reduces Na+ channel expression in both spinal cord astrocyte types to levels intermediate between coculture and control, suggesting that, at least in part, neuronal effects on Na+ channel expression are mediated by a soluble factor secreted into the media by neurons. 4. As with the expression of voltage-activated Na+ channels, the expression of voltage-activated K+ channels is reduced in both spinal cord astrocyte types cocultured with DRG neurons. The effect is not mimicked by culturing cells in neuron-conditioned media, suggesting that effects on K+ channel expression are mediated by a less stable and more readily degradable factor. 5. Coculture with DRG neurons or culture in neuron-conditioned media do not alter the biophysical properties of voltage-activated Na+ currents in pancake spinal cord astrocytes. Thus steady-state activation, steady-state inactivation, and the time constants of activation and inactivation are virtually unchanged under the various culture conditions.