Guthmann A, Fritschy J M, Ottersen O P, Torp R, Herbert H
Department of Animal Physiology, University of Tübingen, Germany.
J Comp Neurol. 1998 Oct 19;400(2):229-43.
In the present study, we investigated the key molecules that determine gamma-aminobutyric acid (GABA)ergic signal transduction in the parabrachial/Kölliker-Fuse complex (PB/KF) by means of immunocytochemistry and in situ hybridization. Our data demonstrate a dense plexus of GABA-immunoreactive (-ir) varicosities throughout the nuclei of the PB and the KF. The number of neurons expressing GAD65 or GAD67 mRNA was fairly low in the PB, whereas caudally in the KF an accumulation of GAD-expressing neurons was observed. The GABA transporter-3 (GAT-3) was detected in all parts of the PB/KF, whereas immunolabeling for GAT1 was not observed. All nuclei of the PB and the KF exhibited immunoreactivity for the gamma2-, alpha2-, and alpha3-subunits of the GABA(A) receptor. Gamma2-ir was strong and similar in all PB/KF nuclei. In contrast, alpha2-labeling was particularly intense in the superior lateral PB, and alpha3-labeling was most prominent in the external lateral and external medial PB, compared with the remaining nuclei. With respect to the subcellular localization, we found gamma2-ir in cell bodies and higher order dendrites, whereas alpha2- and alpha3-ir was predominantly found in cell bodies. Immunolabeling for the beta2/3- and the alpha1-subunit was seen in cell bodies and presumed dendritic profiles. The staining intensity was strongest in the dorsal lateral PB. Most importantly, the external lateral PB and the waist area were totally devoid of beta2/3- and alpha1-ir. Our data suggest that neural processing in the PB/KF is under a strong GABAergic inhibition that is apparently mediated by different types of GABA(A) receptors in functionally different pathways through the PB/KF.
在本研究中，我们通过免疫细胞化学和原位杂交技术，研究了在臂旁核/柯利克-富斯复合体（PB/KF）中决定γ-氨基丁酸（GABA）能信号转导的关键分子。我们的数据显示，在PB和KF的整个核内，有密集的GABA免疫反应性（-ir）曲张体丛。在PB中，表达GAD65或GAD67 mRNA的神经元数量相当少，而在KF的尾部观察到有表达GAD的神经元聚集。在PB/KF的所有部位都检测到了GABA转运体-3（GAT-3），而未观察到GAT1的免疫标记。PB和KF的所有核均对GABA(A)受体的γ2-、α2-和α3-亚基表现出免疫反应性。γ2-ir在所有PB/KF核中都很强且相似。相比之下，与其余核相比，α2标记在PB上外侧特别强烈，α3标记在PB外侧和内侧最突出。关于亚细胞定位，我们在细胞体和高阶树突中发现了γ2-ir，而α2-和α3-ir主要存在于细胞体中。在细胞体和推测的树突轮廓中可见β2/3-和α1-亚基的免疫标记。染色强度在PB背外侧最强。最重要的是，PB外侧和腰部区域完全没有β2/3-和α1-ir。我们的数据表明，PB/KF中的神经处理受到强烈的GABA能抑制，这显然是由功能不同的通过PB/KF的通路中不同类型的GABA(A)受体介导的。
