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大鼠视皮层神经元中低电压激活钙通道表达的发育变化

Developmental changes in the expression of low-voltage-activated Ca2+ channels in rat visual cortical neurones.

作者信息

Tarasenko A N, Isaev D S, Eremin A V, Kostyuk P G

机构信息

Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, National Academy of Sciences, Bogomoletz Street 4, Kiev-24, 252024 Ukraine.

出版信息

J Physiol. 1998 Jun 1;509 ( Pt 2)(Pt 2):385-94. doi: 10.1111/j.1469-7793.1998.385bn.x.

Abstract
  1. The functional properties of low-voltage-activated (LVA) Ca2+ channels were studied in pyramidal neurones from different rat visual cortical layers in order to investigate changes in their properties during early postnatal development. Ca2+ currents were recorded in brain slices using the whole-cell patch-clamp technique in rats from three age groups: 2, 3 and 12 days old (postnatal day (P) 2, P3 and P12). 2. It was demonstrated that LVA Ca2+ currents are present in neurones from superficial (I-II) and deep (V-VI) visual cortex layers of P2 and P3 rats. No LVA Ca2+ currents were observed in neurones from the middle (III-IV) layers of these rats. The LVA Ca2+ currents observed in P2 and P3 neurones from both superficial and deep layers could be completely blocked by nifedipine (100 microM) and were insensitive to Ni2+ (25 microM). 3. The density of LVA Ca2+ currents decreased rapidly during the early stages of postnatal development, while the density of high-voltage-activated (HVA) Ca2+ currents progressively increased up to the twelfth postnatal day. No LVA Ca2+ currents were found in P12 neurones from any of the layers. Only HVA Ca2+ currents with high sensitivity to F- applied through the patch pipette were observed. 4. The kinetics of LVA Ca2+ currents could be well approximated by the m2h Hodgkin-Huxley equation with an inactivation time constant of 24 +/- 6 ms. The steady-state inactivation curve fitted by a Boltzmann function had the following parameters: membrane potential at half-inactivation, -86.9 mV; steepness coefficient,3.4 mV. 5. It is concluded that, in visual cortical neurones, LVA Ca2+ channels are expressed only in the neurones of deep and superficial layers over a short period during the earliest postnatal stages. These channels are nifedipine sensitive and similar in functional properties to those in the laterodorsal (LD) thalamic nucleus. However, the cortical neurones do not express another ('slow') type of LVA Ca2+ channel, which is permanently present in LD thalamic neurones after the second postnatal week, indicating that the developmental time course of cortical and thalamic cells is different.
摘要
  1. 为了研究出生后早期发育过程中低电压激活(LVA)Ca2+通道特性的变化,我们对来自不同大鼠视觉皮层层的锥体神经元的功能特性进行了研究。使用全细胞膜片钳技术在来自三个年龄组(出生后第2、3和12天,即P2、P3和P12)的大鼠脑片中记录Ca2+电流。2. 结果表明,P2和P3大鼠的浅层(I-II)和深层(V-VI)视觉皮层层的神经元中存在LVA Ca2+电流。在这些大鼠的中层(III-IV)神经元中未观察到LVA Ca2+电流。在P2和P3大鼠浅层和深层神经元中观察到的LVA Ca2+电流可被硝苯地平(100 microM)完全阻断,且对Ni2+(25 microM)不敏感。3. 在出生后发育的早期阶段,LVA Ca2+电流密度迅速下降,而高电压激活(HVA)Ca2+电流密度在出生后第12天之前逐渐增加。在P12大鼠的任何层神经元中均未发现LVA Ca2+电流。仅观察到通过膜片电极施加的对F-高度敏感的HVA Ca2+电流。4. LVA Ca2+电流的动力学可以用m2h霍奇金-赫胥黎方程很好地拟合,失活时间常数为24±6毫秒。用玻尔兹曼函数拟合的稳态失活曲线具有以下参数:半失活时的膜电位,-86.9 mV;陡度系数,3.4 mV。5. 研究得出结论,在视觉皮层神经元中,LVA Ca2+通道仅在出生后最早阶段的短时间内在深层和浅层神经元中表达。这些通道对硝苯地平敏感,其功能特性与后外侧(LD)丘脑核中的通道相似。然而,皮层神经元不表达另一种(“慢”)类型的LVA Ca2+通道,这种通道在出生后第二周后在LD丘脑神经元中永久存在,这表明皮层和丘脑细胞的发育时间进程不同。

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