Manns Martina, Güntürkün Onur
Biopsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr-University Bochum, Germany.
Brain Res Bull. 2005 Sep 15;66(4-6):475-8. doi: 10.1016/j.brainresbull.2005.03.003. Epub 2005 Apr 7.
The optic tectum of vertebrates bears a set of visual neurons which can be differentiated by the expression of distinct calcium-binding proteins (CaBPs). Using immunohistochemistry, we mapped the distribution of the CaBPs calbindin (CB) and parvalbumin (PV) in the pigeon's optic tectum and examined if their differentiation is affected by retinal brain-derived neurotrophic factor (BDNF)-injections. CB-immunoreactive (ir) and PV-ir cells displayed a lamination pattern which differed from other birds. While PV-ir cells were present in several retinorecipient tectal laminae, CB-ir cells were confined to layer 3 and 5 and - as a specialization of pigeons - were also detected in a subpopulation of layer 13 neurons. Comparison of saline- and BDNF-injected animals revealed that this general expression pattern was not affected by ocular BDNF-injections. In contrast, the size of tectal cells was differentially modulated. While CB-ir cells in layers 3 and 13 were unaffected by retinal BDNF, cells in layer 5 developed enlarged cell bodies. The PV-ir cells displayed smaller soma sizes within both tectal hemispheres suggesting also an indirect effect of retinal BDNF. These data indicate a differential sensitivity of tectal cell types to retinal BDNF, which might be one mechanism by which retinal input modulates tectal circuitries.
脊椎动物的视顶盖含有一组视觉神经元，这些神经元可通过不同钙结合蛋白（CaBPs）的表达来区分。我们利用免疫组织化学方法绘制了钙结合蛋白钙视网膜蛋白（CB）和小白蛋白（PV）在鸽视顶盖中的分布，并研究了视网膜源性脑源性神经营养因子（BDNF）注射是否会影响它们的分化。CB免疫反应性（ir）细胞和PV-ir细胞呈现出一种与其他鸟类不同的分层模式。虽然PV-ir细胞存在于几个视网膜接受性顶盖层中，但CB-ir细胞局限于第3层和第5层，并且作为鸽子的一个特殊特征，在第13层神经元的一个亚群中也被检测到。对注射生理盐水和BDNF的动物进行比较发现，这种一般表达模式不受眼内BDNF注射的影响。相反，顶盖细胞的大小受到不同程度的调节。虽然第3层和第13层中的CB-ir细胞不受视网膜BDNF的影响，但第5层中的细胞胞体增大。PV-ir细胞在两个顶盖半球内的胞体尺寸较小，这也表明视网膜BDNF有间接作用。这些数据表明顶盖细胞类型对视网膜BDNF具有不同的敏感性，这可能是视网膜输入调节顶盖回路的一种机制。
