Song W J, Murakami F
Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University, Japan.
Brain Res Dev Brain Res. 1990 Oct 1;56(1):75-85. doi: 10.1016/0165-3806(90)90166-v.
Hemicerebellectomy has been reported to induce aberrant ipsilateral projection from the nucleus interpositus (IN) of the remaining hemisphere to the red nucleus (RN) in the kitten but not in adult cats. The cellular mechanisms for this age-at-lesion effect were investigated. The experiments were designed to compare interpositorubral (IN-RN) projections in normal kittens and in kittens hemicerebellectomized at corresponding ages. A sparse ipsilateral IN-RN projection was found in normal kittens aged 7-16 postnatal days (PND) with the PHA-L method, but was not found in those aged 26-43 PND. Among the hemicerebellectomized kittens, ipsilateral IN-RN projections were observed only in those which received the lesion on PND 17 or earlier. Such temporal coincidence between the two events strongly suggests that the exuberant ipsilateral IN-RN projection in normal kittens is related to the establishment of the aberrant ipsilateral IN-RN projection observed after hemicerebellectomy. This notion is strengthened by other lines of evidence; the fibers projecting to the ipsilateral RNs appeared to enter the nucleus from the contralateral one by recrossing the midline between them in both the normal and the lesioned animals. In kittens in which hemicerebellectomy induced the aberrant ipsilateral projection, labeling of fibers within the ipsilateral RNs was much more extensive than that in the normal kittens, while labeling on the pathway of the projection was comparable to that in the normal animals. These observations support the interpretation for aberrant projections observed after a neonatal lesion as being terminal proliferations of pre-existing exuberant projections.
据报道，小脑半球切除术可诱导幼猫剩余半球的间位核（IN）向红核（RN）发出异常的同侧投射，而成猫则不会。本研究调查了这种损伤年龄效应的细胞机制。实验旨在比较正常幼猫和在相应年龄进行小脑半球切除的幼猫的间位核 - 红核（IN - RN）投射。采用PHA - L法发现，出生后7 - 16天（PND）的正常幼猫存在稀疏的同侧IN - RN投射，而26 - 43 PND的幼猫则未发现。在接受小脑半球切除的幼猫中，仅在出生后第17天或更早接受损伤的幼猫中观察到同侧IN - RN投射。这两个事件之间的时间巧合强烈表明，正常幼猫中旺盛的同侧IN - RN投射与小脑半球切除后观察到的异常同侧IN - RN投射的建立有关。其他证据也支持了这一观点；在正常和损伤动物中，投射到同侧RN的纤维似乎都是通过在它们之间重新穿过中线从对侧进入该核的。在小脑半球切除术诱导异常同侧投射的幼猫中，同侧RN内的纤维标记比正常幼猫广泛得多，而投射路径上的标记与正常动物相当。这些观察结果支持将新生期损伤后观察到的异常投射解释为先前旺盛投射的终末增殖。
