Takakusaki K, Shiroyama T, Yamamoto T, Kitai S T
Department of Anatomy and Neurobiology, University of Tennessee, College of Medicine, Memphis 38163, USA.
J Comp Neurol. 1996 Jul 29;371(3):345-61. doi: 10.1002/(SICI)1096-9861(19960729)371:3<345::AID-CNE1>3.0.CO;2-2.
Morphological features of rat pedunculopontine projection neurons were investigated in in vitro preparation by using intracellular labeling with biocytin combined with choline acetyltransferase (ChAT) immunohistochemistry. These neurons were classified into two types (Type I and II), based on their electrical membrane properties: Type I had low-threshold Ca2+ spikes, and Type II had A-current. All Type I neurons (n = 17) were ChAT immunonegative (ChAT-). Type II neurons were either ChAT immunopositive (ChAT+; n = 49) or ChAT- (n = 20). In terms of topography in the tegmental pedunculopontine nucleus (PPN), Type I neurons were dispersed throughout the extent of the nucleus, whereas Type II neurons tended to be located more in the rostral and middle sections. Both Type I and II neurons consisted of small (long axis < 20 microns), medium (20-35 microns), and large (> 35 microns) cells. The small cells were round or oval; medium cells were round, triangular, or fusiform; and the large cells were primarily fusiform in shape. In terms of the soma size, there was a difference in Type I (15-38 microns) and Type II (11-50 microns) neurons, but no significant difference was found between Type II ChAT+ and ChAT- cells. Both types of neurons had three to six primary dendrites, but the dendritic field was more prominent in Type II neurons. Most of the axons originated from one of the primary dendrites, which gave off axon collaterals, some of which projected out of the nucleus. The intrinsic collaterals were thin and branched partly within the dendritic field of the parent cell. The extrinsic collaterals were thicker and could be grouped into three categories: 1) collaterals arborizing in the substantia nigra; 2) collaterals ascending mainly toward the thalamus, pretectal, and tectal area; and 3) collaterals descending toward the mesencephalic and/or pontine reticular formation. It was noted that the collaterals of both ChAT+ and ChAT-neurons were traced into the substantia nigra. There was no significant difference in antidromic latencies between Type I (m = 1.47 msec) and Type II (m = 1.36 msec) neurons following electrical stimulation of the substantia nigra.
采用生物胞素细胞内标记结合胆碱乙酰转移酶（ChAT）免疫组织化学方法，在体外制备中研究大鼠脚桥核投射神经元的形态学特征。根据其电膜特性，这些神经元分为两种类型（I型和II型）：I型具有低阈值Ca2+尖峰，II型具有A电流。所有I型神经元（n = 17）ChAT免疫阴性（ChAT-）。II型神经元要么ChAT免疫阳性（ChAT+；n = 49），要么ChAT阴性（n = 20）。在被盖脚桥核（PPN）的拓扑结构方面，I型神经元分散在整个核范围内，而II型神经元倾向于更多地位于嘴侧和中间部分。I型和II型神经元均由小（长轴<20微米）、中（20 - 35微米）和大（>35微米）细胞组成。小细胞呈圆形或椭圆形；中细胞呈圆形、三角形或梭形；大细胞主要呈梭形。就胞体大小而言，I型（15 - 38微米）和II型（11 - 50微米）神经元存在差异，但II型ChAT+和ChAT-细胞之间未发现显著差异。两种类型的神经元都有三到六个初级树突，但II型神经元的树突野更明显。大多数轴突起源于其中一个初级树突，该初级树突发出轴突侧支，其中一些投射出核外。内在侧支较细，部分在母细胞的树突野内分支。外在侧支较粗，可分为三类：1）在黑质分支的侧支；2）主要向上丘脑、顶盖前区和顶盖区上升的侧支；3）向中脑和/或脑桥网状结构下降的侧支。值得注意 的是，ChAT+和ChAT-神经元的侧支都追踪到了黑质。在对黑质进行电刺激后，I型（m = 1.47毫秒）和II型（m = 1.36毫秒）神经元的逆向潜伏期没有显著差异。
