Seay-Lowe S L, Claiborne B J
Division of Life Sciences, University of Texas, San Antonio 78249.
J Comp Neurol. 1992 Oct 1;324(1):23-36. doi: 10.1002/cne.903240104.
Although many aspects of the morphological development of interneurons in the dentate gyrus have been described, the full extent of their dendrites and local axon projections in immature rodents has not been examined. Here intracellular labeling was used to assess the branching patterns of interneurons in the dentate gyrus of rat pups between 7 and 9 days of age. Labeled neurons were located within or just below the granule cell layer, and most were classified as GABAergic basket neurons on the basis of their dendritic morphologies. All labeled interneurons exhibited immature characteristics. Spines were present on cell bodies and dendrites, and growth cones were visible on some dendrites and axons. In spite of these immature features, the dendrites and axon arbors of the labeled neurons were extensive. Many apical dendrites reached the top of the molecular layer, and a number of basal dendrites extended to the CA3 pyramidal cell layer of the hippocampus. Elaborate axon plexuses were present within the dentate gyrus itself, and axon collaterals of several neurons extended beyond the dentate gyrus to branch within regions CA3 and CA1 of the hippocampus. These results indicate that the dendrites and axon collaterals of dentate interneurons are extensive at a time when the principal neurons, the granule cells, are still proliferating. These data are consistent with the idea that GABAergic interneurons may influence granule cell development in the dentate gyrus, as well as pyramidal cell maturation in the hippocampus proper.
尽管齿状回中抑制性中间神经元形态发育的许多方面已被描述，但在未成熟啮齿动物中其树突和局部轴突投射的完整范围尚未得到研究。在此，采用细胞内标记法评估7至9日龄大鼠幼崽齿状回中抑制性中间神经元的分支模式。标记的神经元位于颗粒细胞层内或其下方，根据其树突形态，大多数被归类为γ-氨基丁酸能篮状神经元。所有标记的抑制性中间神经元均表现出未成熟的特征。细胞体和树突上存在棘突，一些树突和轴突上可见生长锥。尽管有这些未成熟的特征，但标记神经元的树突和轴突分支广泛。许多顶树突延伸至分子层顶部，一些基树突延伸至海马体的CA3锥体细胞层。在齿状回本身内存在复杂的轴突丛，几个神经元的轴突侧支延伸至齿状回之外，在海马体的CA3和CA1区域内分支。这些结果表明，在主要神经元颗粒细胞仍在增殖的时候，齿状回抑制性中间神经元的树突和轴突侧支就已经广泛存在。这些数据与γ-氨基丁酸能抑制性中间神经元可能影响齿状回颗粒细胞发育以及海马体本身锥体细胞成熟的观点一致。
