Humphrey M F, Renshaw G M, Kitchener P D, Beazley L D
Department of Psychology, University of Western Australia, Nedlands.
J Comp Neurol. 1995 Apr 3;354(2):295-305. doi: 10.1002/cne.903540210.
Extensive regeneration of the optic nerve takes place in adult Amphibia. In this study, we have determined whether one aspect of retinotectal organisation, namely immunoreactive laminae in the retinorecipient layers of the optic tectum, is restored after optic nerve regeneration. To do so, the distributions of substance-P, bombesin, and leucine-enkephalin immunoreactivities were examined in the optic tectum of the frog Litoria (Hyla) moorei. Results of a normal series were compared with those at intervals up to 84 days and at 196 days after either unilateral deafferentation or optic nerve crush. In the normal series, distinct neuropeptide immunoreactive laminae were located within the retinorecipient tectal layers. There were two major laminae with substance-P, two with bombesin, and one with leucine-enkephalin immunoreactivities. Additional faint laminae of both substance-P and bombesin immunoreactivity were present in the tectal region that receives input from the visual streak. In addition, labelling of cell bodies and dendrites was seen elsewhere in the tectum. All except one immunoreactive lamina changed after deafferentation. The deeper of those with substance-P immunoreactivity, along with both bombesin laminae, were eventually lost; the lamina with leucine-enkephalin immunoreactivity was halved in intensity. We assume that these laminae are wholely or, in the case of the leucine-enkephalin lamina, partially associated with primary optic input. By contrast, the more superficial lamina with substance-P immunoreactivity remained unchanged and is presumably not directly related to visual input. During nerve regeneration, the intensity of all laminae associated with optic input initially fell as in the deafferentation series but, in the long term, recovered to approximately 80% of normal intensities. We conclude that ganglion cells associated with each of the immunoreactivities tested had successfully regenerated. The reduced intensity of immunoreactivities after regeneration is due presumably in part to the cell loss from the ganglion cell population. Furthermore, we discuss the findings of similar studies for Rana pipiens (Kuljis and Karten [1983] J. Comp. Neurol. 217:239-251 and [1985] 240:1-15) in light of the present findings. We argue that some of the previous observations can be reinterpreted to indicate that regeneration was not limited to ganglion cells associated with substance-P immunoreactivity as first thought.
成年两栖动物的视神经会发生广泛再生。在本研究中，我们确定了视顶盖组织的一个方面，即视顶盖视网膜接受层中的免疫反应性板层，在视神经再生后是否会恢复。为此，我们检测了摩尔雨滨蛙（Litoria (Hyla) moorei）视顶盖中P物质、蛙皮素和亮氨酸脑啡肽免疫反应性的分布。将正常系列的结果与单侧去传入或视神经挤压后长达84天以及196天的不同时间间隔的结果进行了比较。在正常系列中，不同的神经肽免疫反应性板层位于视网膜接受性顶盖层内。有两个主要的P物质免疫反应性板层、两个蛙皮素免疫反应性板层和一个亮氨酸脑啡肽免疫反应性板层。在接受来自视觉条纹输入的顶盖区域还存在P物质和蛙皮素免疫反应性的额外微弱板层。此外，在顶盖的其他部位还可见细胞体和树突的标记。除了一个免疫反应性板层外，所有板层在去传入后都发生了变化。P物质免疫反应性较深的板层以及两个蛙皮素板层最终消失；亮氨酸脑啡肽免疫反应性板层的强度减半。我们假设这些板层全部或（就亮氨酸脑啡肽板层而言）部分与初级视觉输入相关。相比之下，P物质免疫反应性较浅的板层保持不变，大概与视觉输入没有直接关系。在神经再生过程中，与视觉输入相关的所有板层的强度最初如在去传入系列中一样下降，但从长期来看，恢复到正常强度的约80%。我们得出结论，与所测试的每种免疫反应性相关的神经节细胞已成功再生。再生后免疫反应性强度降低可能部分归因于神经节细胞群体中的细胞损失。此外，我们根据目前的研究结果讨论了对豹蛙（Rana pipiens）的类似研究结果（Kuljis和Karten [1983]《比较神经学杂志》217:239 - 251以及[1985] 240:1 - 15）。我们认为，之前的一些观察结果可以重新解释，以表明再生并不局限于最初认为的与P物质免疫反应性相关的神经节细胞。
