Behan Mary, Steinhacker Kate, Jeffrey-Borger Susan, Meredith M Alex
Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin 53706-1102, USA.
J Comp Neurol. 2002 Oct 28;452(4):334-59. doi: 10.1002/cne.10378.
gamma-Aminobutyric acid (GABA)ergic neurons are thought to play a key role both in visual processing and in the complex sensory-motor transformations that take place in the mammalian superior colliculus. To understand the organization of GABAergic neurons in the ferret superior colliculus, we applied antisera to several markers of GABAergic function, including GABA, two isoforms of its synthetic enzyme glutamic acid decarboxylase (GAD-65 and GAD-67), and the GABA transporter, GAT-1. We also applied antisera to several calcium binding proteins (calbindin [CB], calretinin [CR], and parvalbumin [PV]) and neuronal nitric oxide synthase (NOS), chemical markers that colocalize with GABA in some areas of the central nervous system. The distribution of GABAergic neurons in the ferret is similar to that of other mammalian species. GABAergic neurons in the ferret superior colliculus were small, morphologically diverse, and widely distributed throughout all layers of the colliculus. As has been shown in other mammalian species, neurons expressing PV, CB, CR, and NOS were differentially distributed in layers and patches throughout the ferret colliculus. None of these markers, however, showed a distribution that mirrored that of GABAergic neurons. Furthermore, few GABAergic neurons colocalized these neurochemical markers. Only 14% of GABAergic neurons in the superficial layers and 18% of neurons in the deeper layers colocalized PV, 14% of GABAergic neurons in the superficial layers and 10% in the deeper layers colocalized CB, and only 1% of GABAergic neurons in both the superficial and deep layers colocalized nitric oxide synthase. Thus, the arrangement of GABAergic neurons in the ferret superior colliculus is broadly distributed and is distinct from other recognized organizational patterns in the superior colliculus.
γ-氨基丁酸（GABA）能神经元被认为在视觉处理以及哺乳动物上丘发生的复杂感觉运动转换中都起着关键作用。为了了解雪貂上丘中GABA能神经元的组织结构，我们将抗血清应用于几种GABA能功能标记物，包括GABA、其合成酶谷氨酸脱羧酶的两种同工型（GAD - 65和GAD - 67）以及GABA转运体GAT - 1。我们还将抗血清应用于几种钙结合蛋白（钙结合蛋白[CB]、钙视网膜蛋白[CR]和小白蛋白[PV]）以及神经元型一氧化氮合酶（NOS），这些化学标记物在中枢神经系统的某些区域与GABA共定位。雪貂中GABA能神经元的分布与其他哺乳动物物种相似。雪貂上丘中的GABA能神经元体积小，形态多样，广泛分布于上丘的所有层。正如在其他哺乳动物物种中所显示的那样，表达PV、CB、CR和NOS的神经元在雪貂上丘的各层和斑块中分布不同。然而，这些标记物均未显示出与GABA能神经元分布相对应的分布情况。此外，很少有GABA能神经元与这些神经化学标记物共定位。在上丘浅层，只有14%的GABA能神经元与PV共定位，深层为18%；在上丘浅层，14%的GABA能神经元与CB共定位，深层为10%；在上丘浅层和深层，只有1%的GABA能神经元与一氧化氮合酶共定位。因此，雪貂上丘中GABA能神经元的排列广泛分布，且与上丘中其他公认的组织模式不同。
