Perreault Marie-Claude, Qin Yi, Heggelund Paul, Zhu J Julius
Department of Physiology, University of Oslo, POB 1103, N-0317 Oslo, Norway.
J Physiol. 2003 Jan 1;546(Pt 1):137-48. doi: 10.1113/jphysiol.2002.030643.
Diverse forms of GABAergic inhibition are found in the mature brain. To understand how this diversity develops, we studied the changes in morphology of inhibitory interneurons and changes in interneuron-mediated synaptic transmission in the rat dorsal lateral geniculate nucleus (dLGN). We found a steady expansion of the dendritic tree of interneurons over the first three postnatal weeks. During this period, the area around a thalamocortical cell from which GABA(A) inhibition could be elicited also expanded. Dendritic branching and burst firing in interneurons evolved more slowly. The distal dendrites of interneurons began to branch extensively after the third week, and at the same time burst firing appeared. The appearance of burst firing and an elaborated dendritic tree were accompanied by a pronounced GABA(B) inhibition of thalamocortical cells. Thus, GABA inhibition of thalamocortical cells developed from one type of GABA(A) inhibition (spatially restricted) in the young animal into two distinct types of GABA(A) inhibition (short- and long-range) and GABA(B) inhibition in the adult animal. The close temporal relationships between the development of the diverse forms of inhibition and the postnatal changes in morphology of local GABAergic interneurons in the dLGN suggest that postnatal dendritic maturation is an important presynaptic factor for the developmental time course of the various types of feedforward inhibition in thalamus.
在成熟大脑中发现了多种形式的γ-氨基丁酸（GABA）能抑制作用。为了了解这种多样性是如何形成的，我们研究了大鼠背外侧膝状核（dLGN）中抑制性中间神经元的形态变化以及中间神经元介导的突触传递变化。我们发现，在出生后的前三周，中间神经元的树突不断稳定扩展。在此期间，能引发GABA(A)抑制作用的丘脑皮质细胞周围区域也在扩大。中间神经元的树突分支和爆发式放电进化得较为缓慢。中间神经元的远端树突在第三周后开始广泛分支，与此同时爆发式放电出现。爆发式放电和复杂树突的出现伴随着对丘脑皮质细胞明显的GABA(B)抑制作用。因此，对丘脑皮质细胞的GABA抑制作用从幼小动物中一种类型的GABA(A)抑制作用（空间受限）发展为成年动物中两种不同类型的GABA(A)抑制作用（短程和长程）以及GABA(B)抑制作用。dLGN中不同形式抑制作用的发展与局部GABA能中间神经元出生后形态变化之间紧密的时间关系表明，出生后树突成熟是丘脑各种类型前馈抑制发育时间进程的一个重要突触前因素。
