Veenman C L, Reiner A
Department of Anatomy and Neurobiology, University of Tennessee-Memphis 38163.
J Comp Neurol. 1994 Jan 8;339(2):209-50. doi: 10.1002/cne.903390205.
Immunohistochemical techniques were used to study the distributions of glutamic acid decarboxylase (GAD) and gamma-aminobutyric acid (GABA) in pigeon forebrain and midbrain to determine the organization of GABAergic systems in these brain areas in birds. In the basal ganglia, numerous medium-sized neurons throughout the striatum were labeled for GABA, while pallidal neurons, as well as a small population of large, aspiny striatal neurons, labeled for GAD and GABA. GAD+ and GABA+ fibers and terminals were abundant throughout the basal ganglia, and GABAergic fibers were found in all extratelencephalic targets of the basal ganglia. Most of these targets also contained numerous GABAergic neurons. In pallial regions, approximately 10-12% of the neurons were GABAergic. The outer rind of the pallium was more intensely labeled for GABAergic fibers than the core. The olfactory tubercle region, the ventral pallidum, and the hypothalamus were extremely densely labeled for GABAergic fibers, while GABAergic neurons were unevenly distributed in the hypothalamus. GABAergic neurons and fibers were abundant in the dorsalmost part of thalamus and the dorsal geniculate region, while GABAergic neurons and fibers were sparse (or lightly labeled) in the thalamic nuclei rotundus, triangularis, and ovoidalis. Further, GABAergic neurons were abundant in the superficial tectal layers, the magnocellular isthmic nucleus, the inferior colliculus, the intercollicular region, the central gray, and the reticular formation. GABAergic fibers were particularly abundant in the superficial tectal layers, the parvocellular isthmic nucleus, the inferior colliculus, the intercollicular region, the central gray, and the interpeduncular nucleus. These results suggest that GABA plays a role as a neurotransmitter in nearly all fore- and midbrain regions of birds, and in many instances the observed distributions of GABAergic neurons and fibers closely resemble the patterns seen in mammals, as well as in other vertebrates.
采用免疫组织化学技术研究谷氨酸脱羧酶（GAD）和γ-氨基丁酸（GABA）在鸽前脑和中脑的分布，以确定鸟类这些脑区中GABA能系统的组织情况。在基底神经节，整个纹状体中大量中等大小的神经元被标记为GABA，而苍白球神经元以及一小部分大的、无棘的纹状体神经元被标记为GAD和GABA。GAD+和GABA+纤维及终末在整个基底神经节中丰富，并且在基底神经节的所有脑外靶区都发现了GABA能纤维。这些靶区中的大多数也含有大量GABA能神经元。在脑皮层区域，约10 - 12%的神经元是GABA能的。脑皮层的外层比核心区域被GABA能纤维标记得更强烈。嗅结节区、腹侧苍白球和下丘脑被GABA能纤维标记得极其密集，而GABA能神经元在下丘脑分布不均匀。GABA能神经元和纤维在丘脑最背侧部分和背侧膝状体区域丰富，而在丘脑圆核、三角核和卵圆核中GABA能神经元和纤维稀疏（或标记浅）。此外，GABA能神经元在顶盖浅层、大细胞峡核、下丘、丘间区域、中央灰质和网状结构中丰富。GABA能纤维在顶盖浅层、小细胞峡核、下丘、丘间区域、中央灰质和脚间核中特别丰富。这些结果表明，GABA在鸟类几乎所有的前脑和中脑区域都作为神经递质发挥作用，并且在许多情况下，观察到的GABA能神经元和纤维的分布模式与哺乳动物以及其他脊椎动物中的模式非常相似。
