Cheung S, Ballew J R, Moore K E, Lookingland K J
Department of Pharmacology and Toxicology, B-432 Life Sciences Building, Michigan State University, East Lansing, MI 48824, USA.
Brain Res. 1998 Oct 19;808(2):174-81. doi: 10.1016/s0006-8993(98)00809-9.
Results of previous studies suggested that incertohypothalamic dopamine (IHDA) neurons located in the medial zona incerta (MZI) project to the central nucleus of the amygdala (cAMY), horizontal diagonal band of Broca (HDB), and paraventricular nucleus (PVN). The overall goal of the present study was to determine the relative contribution of IHDA neurons to the DA innervation of these brain regions. A combined fluorescent and in situ hybridization histochemical procedure was employed to localize the retrograde tracer fluoro-gold (FG) in cells expressing tyrosine hydroxylase (TH) mRNA in the MZI following its iontophoretic injection into either the cAMY, HDB or PVN. For comparison, the numbers of dual labeled FG/TH mRNA neurons in the midbrain were also determined. One week after unilateral injection of FG into the cAMY, cells containing FG+TH mRNA were found in the ipsilateral MZI, substantia nigra zona compacta (SNC) and ventral tegmental area (VTA). The total numbers of cells labeled with FG varied with the size of the injection site, but the ratio of dual labeling in the MZI to that of the SNC-VTA remained constant across animals at approximately 1:6. FG injections into the HDB resulted in a ratio of dual labeled cells in the ipsilateral MZI and VTA of approximately 1:2, but no dual labeled cells were found in the SNC. Dual labeled cells were only found in the ipsilateral MZI in animals receiving FG injections in the PVN. Thus, DA terminals in the PVN originate exclusively from IHDA neurons in the MZI, whereas these neurons provide only a portion of the DA innervation of the cAMY and HDB. The similar distribution of dual labeled cells in the MZI following FG injections into the cAMY, HDB and PVN suggests that perikarya of IHDA neurons projecting to these regions are not organized into distinct groups.
以往研究结果表明，位于未定带内侧（MZI）的未定带下丘脑多巴胺（IHDA）神经元投射至杏仁核中央核（cAMY）、布罗卡水平斜带（HDB）和室旁核（PVN）。本研究的总体目标是确定IHDA神经元对这些脑区多巴胺神经支配的相对贡献。采用荧光和原位杂交组织化学联合方法，在将荧光金（FG）离子电渗注入cAMY、HDB或PVN后，定位MZI中表达酪氨酸羟化酶（TH）mRNA的细胞中的逆行示踪剂FG。为作比较，还测定了中脑双标记FG/TH mRNA神经元的数量。在将FG单侧注入cAMY一周后，在同侧MZI、黑质致密部（SNC）和腹侧被盖区（VTA）发现了含有FG+TH mRNA的细胞。用FG标记的细胞总数随注射部位大小而变化，但MZI中双标记细胞与SNC-VTA中双标记细胞的比例在各动物间保持恒定，约为1:6。向HDB注射FG导致同侧MZI和VTA中双标记细胞的比例约为1:2，但在SNC中未发现双标记细胞。在PVN接受FG注射的动物中，仅在同侧MZI中发现双标记细胞。因此，PVN中的多巴胺终末仅起源于MZI中的IHDA神经元，而这些神经元仅提供cAMY和HDB多巴胺神经支配的一部分。将FG注入cAMY、HDB和PVN后，MZI中双标记细胞的分布相似，这表明投射至这些区域的IHDA神经元的胞体并未组织成不同的组。
