Levine R L, Dethier S
Department of Biology, McGill University, Montréal, Québec, Canada.
Exp Neurol. 1988 Nov;102(2):153-66. doi: 10.1016/0014-4886(88)90089-1.
We have used retrograde labeling with horseradish peroxidase (HRP) and a wheat germ agglutinin conjugate of HRP (WGA:HRP) to investigate the projections of the nucleus postglomerulosus (nPg) both in normal goldfish and in animals which had undergone retinal removal. In normal animals, our evidence indicates that nPg projects only to the optic tectum. Using small HRP and WGA:HRP application sites in the tectum, we have shown that nPg cells have broadly spread terminals in the tectal neuropil and that there is no obvious correspondence between the rostrocaudal axis of the nPg and the deployment of the terminal arbors of its cells along the rostrocaudal axis of the tectum. In addition, we found no evidence for an nPg projection to the eye in normal animals. After retinal removal we found that nPg cells were more readily backfilled from small tectal applications of HRP. However, our most interesting observation was that at 4-6 weeks and more after ocular surgery, we could retrogradely label the cells of the nPg with intraocular or retroocular injections of WGA:HRP. At the same postoperative times, we were also able to label neurites in the atrophied optic nerve by microinjecting WGA:HRP into the contralateral midbrain tegmentum. Finally, we found that the cells of the nPg undergo a hypertrophic response, similar to that seen in other neurons after axotomy, following retinal removal or section of the dorsomedial brachium of the optic tract. Thus, these cells respond to retinal denervation of the tectum with a response characteristic of axotomized cells although their axons have not been cut. Similar changes were also seen in the nucleus isthmi on both sides of the brain following retinal removal. We interpret our data to indicate that cells of the nPg can respond to optic (and thus heterotypic) denervation of their terminal field by sprouting processes which grow away from the terminal field, through denervated optic pathways, to the retinaless eye. This interpretation requires that the sprouted processes grow for several millimeters.
我们使用辣根过氧化物酶（HRP）以及HRP与小麦胚凝集素的结合物（WGA:HRP）进行逆行标记，以研究正常金鱼以及视网膜切除动物中肾小球后核（nPg）的投射。在正常动物中，我们的证据表明nPg仅投射至视顶盖。通过在顶盖中使用小的HRP和WGA:HRP应用位点，我们发现nPg细胞在顶盖神经毡中具有广泛分布的终末，并且nPg的前后轴与其细胞终末分支沿顶盖前后轴的分布之间没有明显的对应关系。此外，我们在正常动物中未发现nPg投射至眼睛的证据。视网膜切除后，我们发现从顶盖小剂量应用HRP更容易使nPg细胞被逆向填充。然而，我们最有趣的观察结果是，在眼部手术后4 - 6周及更长时间，通过眼内或眼后注射WGA:HRP，我们能够逆向标记nPg的细胞。在相同的术后时间，我们还能够通过将WGA:HRP微量注射到对侧中脑被盖中来标记萎缩视神经中的神经突。最后，我们发现nPg的细胞在视网膜切除或视束背内侧臂切断后会发生肥大反应，类似于其他神经元在轴突切断后所见的反应。因此，尽管这些细胞的轴突未被切断，但它们对顶盖的视网膜去神经支配的反应具有轴突切断细胞的特征。视网膜切除后，在脑两侧的峡核也观察到了类似的变化。我们对数据的解释表明，nPg的细胞可以通过从终末场长出的芽生过程对其终末场的视觉（因此是异型的）去神经支配做出反应，这些芽生过程通过去神经的视觉通路生长到无视网膜的眼睛。这种解释要求芽生过程生长数毫米。
