Nabors L B, Mize R R
Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis 38163.
J Neurosci. 1991 Aug;11(8):2460-76. doi: 10.1523/JNEUROSCI.11-08-02460.1991.
The pretectum is an important center for visual reflexes. However, the location, boundaries, and connections of individual nuclei of the pretectum are incompletely understood. In cat, the traditionally defined nuclear boundaries have been placed in doubt by recent evidence showing that the retinal input to the pretectum forms four continuous projection zones that do not match the cytoarchitectural boundaries of individual pretectal nuclei defined by previous studies. We now show that antibodies to the calcium-binding protein calbindin-D 28K (CaBP) label clusters of neurons within the pretectum that match the zones of retinal termination. Four obvious cell clusters within the pretectum were labeled by CaBP antisera. Computer three-dimensional reconstruction of these cell clusters revealed that they form four distinct but continuous zones that run the rostrocaudal length of the pretectum in a medial-to-lateral direction. By combining anterograde HRP labeling of retinal terminals with CaBP immunocytochemistry, these CaBP-labeled cell clusters were found virtually to overlap the retinal projection zones. The CaBP-labeled neurons included both multipolar and fusiform morphologies, and most were medium- to large-sized cells. HRP retrograde transport studies showed that many CaBP-labeled neurons in the clusters projected to the LGN, while none projected to the inferior olive (IO). GABA-immunoreactive neurons were also found within the CaBP cell clusters, but these neurons were smaller than most CaBP-labeled neurons, and none were retrogradely labeled following HRP injections into the LGN or IO. Two-color antibody double-labeling experiments did not reveal any GABA neurons within the clusters that colocalized CaBP. In summary, calbindin is a precise marker of neuron clusters that overlap the retinal projection zones in the cat pretectum. Many of these CaBP neurons project to the LGN, and none contain GABA.
顶盖前区是视觉反射的重要中枢。然而，顶盖前区各个核团的位置、边界及连接情况尚未完全明确。在猫中，传统定义的核边界受到了近期证据的质疑，该证据表明，视网膜向顶盖前区的输入形成了四个连续的投射区，这与先前研究定义的各个顶盖前核的细胞构筑边界并不匹配。我们现在发现，针对钙结合蛋白钙视网膜蛋白-D 28K（CaBP）的抗体标记了顶盖前区内与视网膜终末区相匹配的神经元簇。CaBP抗血清标记了顶盖前区内四个明显的细胞簇。对这些细胞簇进行计算机三维重建显示，它们形成了四个不同但连续的区域，在顶盖前区的前后长度上从内侧向外侧延伸。通过将视网膜终末的顺行HRP标记与CaBP免疫细胞化学相结合，发现这些CaBP标记的细胞簇实际上与视网膜投射区重叠。CaBP标记的神经元包括多极和梭形形态，大多数是中大型细胞。HRP逆行运输研究表明，簇内许多CaBP标记的神经元投射到外侧膝状体（LGN），而没有一个投射到下橄榄核（IO）。在CaBP细胞簇内也发现了GABA免疫反应性神经元，但这些神经元比大多数CaBP标记的神经元小，并且在将HRP注射到LGN或IO后没有一个被逆行标记。双色抗体双重标记实验未在簇内发现任何与CaBP共定位的GABA神经元。总之，钙视网膜蛋白是猫顶盖前区内与视网膜投射区重叠的神经元簇的精确标记物。这些CaBP神经元中的许多投射到LGN，并且都不含有GABA。
