Veenman C L, Albin R L, Richfield E K, Reiner A
Department of Anatomy and Neurobiology, University of Tennessee, Memphis 38163.
J Comp Neurol. 1994 Jun 8;344(2):161-89. doi: 10.1002/cne.903440202.
Autoradiographic and immunohistochemical methods were used to study the distributions of GABAA, GABAB and benzodiazepine (BDZ) receptors in the pigeon fore- and midbrain. GABAA, GABAB and BDZ binding sites were found to be abundant although heterogeneously distributed in the telencephalon. The primary sensory areas of the pallium of the avian telencephalon (Wulst and dorsal ventricular ridge) tended to be low in all three binding sites, while the surrounding second order belt regions of the pallium were typically high in all three. Finally, the outermost rind of the pallium (termed the pallium externum by us), which surrounds the belt regions and projects to the striatum of the basal ganglia, was intermediate in all three GABAergic receptors types. Although both GABAA and benzodiazepine receptors were abundant within the basal ganglia, GABAA binding sites were densest in the striatum and BDZ binding sites were densest in the pallidum. Among the brainstem regions receiving GABAergic basal ganglia input, the anterior and posterior nuclei of the ansa lenticularis showed very low levels of all three receptors, while the lateral spiriform nucleus and the ventral tegmental area/substantia nigra complex contained moderate abundance of the three binding sites. The dorsalmost part of the dorsal thalamus (containing nonspecific nuclei) was rich in all three binding sites, while the more ventral part of the dorsal thalamus (containing specific sensory nuclei), the ventral thalamus and the hypothalamus were poor in all three binding sites. The pretectum was also generally poor in all three, although some nuclei displayed higher levels of one or more binding sites. The optic tectum, inferior colliculus, and central gray were rich in all three sites, while among the isthmic nuclei, the parvicellular isthmic nucleus was conspicuously rich in BDZ sites. The results show a strong correlation of the regional abundance of GABA binding sites with previously described distributions of GABAergic fibers and terminals in the avian forebrain and midbrain. The regional distribution of these binding sites is also remarkably similar to that in mammals, indicating a conservative evolution of forebrain and midbrain GABA systems among amniotes.
采用放射自显影和免疫组织化学方法研究了家鸽前脑和中脑中GABAA、GABAB和苯二氮䓬（BDZ）受体的分布。发现GABAA、GABAB和BDZ结合位点丰富，尽管在端脑分布不均一。禽端脑皮质的主要感觉区（视叶和背侧室嵴）这三种结合位点的含量往往较低，而皮质周围的二级带状区域这三种结合位点的含量通常较高。最后，皮质的最外层（我们称为皮质外区），围绕带状区域并投射到基底神经节的纹状体，在这三种GABA能受体类型中含量处于中等水平。虽然基底神经节内GABAA和苯二氮䓬受体都很丰富，但GABAA结合位点在纹状体中最密集，BDZ结合位点在苍白球中最密集。在接受GABA能基底神经节输入的脑干区域中，豆状袢前核和后核这三种受体的水平都非常低，而外侧螺旋状核和腹侧被盖区/黑质复合体这三种结合位点含量适中。背侧丘脑最背侧部分（包含非特异性核团）这三种结合位点都很丰富，而背侧丘脑更腹侧部分（包含特异性感觉核团）、腹侧丘脑和下丘脑这三种结合位点都很少。顶盖前区这三种结合位点通常也很少，尽管一些核团一种或多种结合位点的水平较高。视顶盖、下丘和中央灰质这三种位点都很丰富，而在峡核中，小细胞峡核BDZ位点明显丰富。结果表明，GABA结合位点的区域丰度与先前描述的禽前脑和中脑中GABA能纤维和终末的分布密切相关。这些结合位点的区域分布也与哺乳动物非常相似，表明羊膜动物前脑和中脑GABA系统的进化具有保守性。
