Funahashi Makoto, Mitoh Yoshihiro, Akaike Tadashi, Matsuo Ryuji
Department of Oral Physiology and Cellular Function, Hokkaido University, Graduate School of Dental Medicine, North 13 West 7 Kita-ku, Sapporo 060-8586, Japan.
Neurosci Res. 2006 Jan;54(1):43-8. doi: 10.1016/j.neures.2005.10.005. Epub 2005 Nov 15.
Whole-cell recordings were performed to examine the morphological properties of electrophysiologically classified area postrema (AP) neurons in rat brain slices. Using electrophysiological criteria, AP neurons were subdivided into three groups: (1) cells displaying both the hyperpolarization-activated cation current (I(h)) and the fast transient outward current (fast I(to)); (2) cells displaying only the fast I(to); (3) cells displaying only the slow I(to). All AP neurons had a single axon that was distinctly thinner than the cells' dendrites. No systematic differences, across groups, in the orientation of dendrites or axons were identified. Mean values of cell size and capacitance of neurons from group 3 were significantly larger than those of the other groups. Interestingly, a number of cells from groups 1 and 3 but not group 2 were found to extend their dendrites into the nucleus tractus solitarius (NTS), suggesting that AP neurons could receive vagal afferent inputs at their dendritic termini within the NTS. Although the AP has been implicated to contain uniformly shaped neurons, this study indicates the presence of significantly different subpopulations of AP neurons, which were characterized not only electrophysiologically but also morphologically.
采用全细胞记录法研究大鼠脑片上电生理分类的最后区（AP）神经元的形态学特性。根据电生理标准，将AP神经元分为三组：（1）同时表现出超极化激活阳离子电流（I(h)）和快速瞬时外向电流（快速I(to)）的细胞；（2）仅表现出快速I(to)的细胞；（3）仅表现出慢速I(to)的细胞。所有AP神经元都有一条明显比细胞树突细的单轴突。未发现各组之间在树突或轴突方向上存在系统性差异。第3组神经元的细胞大小和电容平均值显著大于其他组。有趣的是，发现第1组和第3组的许多细胞（而非第2组）将其树突延伸至孤束核（NTS），这表明AP神经元可能在NTS内的树突末端接收迷走神经传入输入。尽管以往认为AP包含形状一致的神经元，但本研究表明存在明显不同的AP神经元亚群，这些亚群不仅在电生理上，而且在形态学上都有特征。
