Miguel-Hidalgo J J, Senba E, Takatsuji K, Tohyama M
Second Department of Anatomy, Osaka University Medical School, Japan.
J Comp Neurol. 1991 Jan 1;303(1):63-74. doi: 10.1002/cne.903030107.
The fine structure of substance P (SP) and adenosine deaminase (ADA) immunoreactive structures in synaptic contacts localized to the superficial layers of the superior colliculus of the rat was investigated by means of immunoelectron microscopy. We also examined the possibility of retinal innervation of SP- and ADA- containing neurons by immunohistochemistry after degeneration of retinal terminals caused by enucleation. SP-like immunoreactive presynaptic terminals of the stratum griseum superficiale (SGS) formed both asymmetric and symmetric synaptic contacts. Presynaptic dendritelike structures were also observed. SP immunoreactive postsynaptic elements made contacts with terminals showing diverse features. ADA-like immunoreactive structures were seen only as postsynaptic elements to different kinds of nonimmunoreactive terminals and were mostly localized in the ventral third of the SGS and the dorsalmost stratum opticum (SO). After enucleation, degenerating retinal terminals were found to form synaptic contacts with SP and ADA immunoreactive structures. The highest number of such degenerating terminals on ADA immunoreactive structures was observed 2 days after retinal denervation, very few being seen after 5 days. These degenerating terminals were restricted to the ventral SGS and dorsal SO. SP immunoreactive structures postsynaptic to degenerating retinal terminals were most numerous 5 days after enucleation and mainly localized in the dorsal SGS. Occasionally, SP immunoreactive dendritelike processes forming synapses with degenerating retinal terminals were simultaneously presynaptic to other nonimmunoreactive profiles, defining, therefore, serial synapses. The present results suggest that SP-I and ADA-I collicular neurons may be part of distinct channels carrying visual information to the lateral posterior and lateral geniculate nuclei of the thalamus, respectively.
采用免疫电子显微镜技术，研究了大鼠上丘表层突触接触中P物质（SP）和腺苷脱氨酶（ADA）免疫反应性结构的精细结构。我们还通过免疫组织化学方法，在摘除眼球导致视网膜终末变性后，检查了含SP和ADA神经元的视网膜神经支配的可能性。浅灰质层（SGS）中SP样免疫反应性突触前终末形成了不对称和对称的突触接触。还观察到突触前树突状结构。SP免疫反应性突触后成分与具有不同特征的终末形成接触。ADA样免疫反应性结构仅作为不同类型非免疫反应性终末的突触后成分出现，主要位于SGS的腹侧三分之一和最背侧的视层（SO）。摘除眼球后，发现变性的视网膜终末与SP和ADA免疫反应性结构形成突触接触。在视网膜去神经支配后2天，观察到ADA免疫反应性结构上此类变性终末的数量最多，5天后则很少见到。这些变性终末局限于腹侧SGS和背侧SO。摘除眼球后5天，与变性视网膜终末突触后的SP免疫反应性结构数量最多，主要位于背侧SGS。偶尔，与变性视网膜终末形成突触的SP免疫反应性树突状突起同时作为其他非免疫反应性轮廓的突触前成分，因此定义为串联突触。目前的结果表明，含SP-I和ADA-I的上丘神经元可能分别是将视觉信息传递到丘脑外侧后核和外侧膝状体核的不同通道的一部分。
