Scicolone Gabriel, Ortalli Ana Laura, Alvarez Gabriela, López-Costa Juan José, Rapacioli Melina, Ferrán José Luis, Sanchez Viviana, Flores Vladimir
Institute of Cell Biology and Neurosciences "Prof. E. De Robertis," School of Medicine, University of Buenos Aires, 1121 Buenos Aires, Argentina.
J Comp Neurol. 2006 Feb 20;494(6):1007-30. doi: 10.1002/cne.20878.
The chick retinotectal system is a suitable model to investigate the mechanisms involved in the establishment of synaptic connections in whose refinement nitric oxide was implicated. The purpose of this work was to describe the developmental pattern of the nitric oxide synthase (NOS)-positive neurons as well as to determine if it is sensitive to changes in visual stimulation. The NADPH-diaphorase histochemical method was used to describe and quantify NOS neurons in normally stimulated and subnormally stimulated chickens. Nine types of NOS neurons were identified; seven of them express NOS until adulthood, while two of them show only a transient expression. The developmental pattern of NOS neurons follows the process of laminar segregation. It can be divided into three phases. The first includes the onset of NOS expression in periventricular neurons and the formation of a deep network of NOS fibers during early development. These neurons do not show any significant change in subnormally stimulated animals. The second phase includes the appearance of two transient NOS populations of bipolar neurons that occupy the intermediate layers during the optic fibers ingrowth. One of them significantly changes in subnormally stimulated chicks. The third phase occurs when the transitory expression of bipolar neurons decreases. It includes NOS expression in six neuronal populations that innervate the superficial retinorecipient layers. Most of these cells suffer plastic changes in subnormally stimulated chicks. The diversity of neuronal types with regard to their morphology, location, and sensitivity to visual stimulation strongly suggests that they serve different functions.
鸡视网膜-脑顶盖系统是研究突触连接建立机制的合适模型，其中一氧化氮参与了突触连接的精细化过程。本研究的目的是描述一氧化氮合酶（NOS）阳性神经元的发育模式，并确定其是否对视觉刺激的变化敏感。采用NADPH-黄递酶组织化学方法对正常刺激和刺激不足的鸡的NOS神经元进行描述和定量。共鉴定出9种NOS神经元；其中7种在成年前持续表达NOS，而另外2种仅表现出短暂表达。NOS神经元的发育模式遵循层状分离过程。可分为三个阶段。第一阶段包括早期发育过程中室周神经元中NOS表达的开始以及NOS纤维深部网络的形成。在刺激不足的动物中，这些神经元没有表现出任何显著变化。第二阶段包括在视神经纤维向内生长期间出现的两个占据中间层的双极神经元的短暂NOS群体。其中一个在刺激不足的雏鸡中有显著变化。第三阶段发生在双极神经元的短暂表达减少时。它包括支配视网膜浅层接受层的六个神经元群体中的NOS表达。在刺激不足的雏鸡中，这些细胞中的大多数会发生可塑性变化。神经元类型在形态、位置和对视觉刺激的敏感性方面的多样性强烈表明它们具有不同的功能。
