Paquet M, Smith Y
Centre de Recherche en Neurobiologie, Hôpital de I'Enfant- Jésus and Université laval, Québec, Canada.
Eur J Neurosci. 1996 Jan;8(1):229-33. doi: 10.1111/j.1460-9568.1996.tb01184.x.
The subthalamic nucleus has long been known as the main source of glutamatergic afferents to the pallidum and the substantia nigra in primates. Recent findings showed that the excitatory effects induced by the subthalamic nucleus in pallidal cells are mediated through the activation of non-NMDA receptors in the rat. The objective of the present study was to analyse the distribution of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) glutamate receptor subunits in the external pallidum (GPe), the internal pallidum (GPi) and the substantia nigra pars reticulata (SNr) in squirrel monkeys (Saimiri sciureus). This was achieved by means of immunohistochemistry using antibodies raised against the GluR1 and the GluR2/3 subunits of the AMPA receptor. Our results show that all neuronal perikarya in GPe and GPi display immunoreactivity for GluR2/3 subunits whereas GluR1 is confined exclusively to cells in the GPe. The proportion of GluR1-immunoreactive neurons is not uniform throughout the rostrocaudal extent of GPe; in the rostral third all GPe cells display GluR1 immunoreactivity, whereas in the caudal third the proportion of GluR1-positive cells decreases to 50%. The intensity of GluR1 immunostaining associated with GPe cells is lower than that associated with neighbouring large-sized neurons in the nucleus basalis of Meynert. In contrast to GPi cells, the neurons in the SNr display immunoreactivity for both GluR1 and GluR2/3 subunits. In conclusion, our results provide the first evidence for a different distribution of the GluR1 subunit of the AMPA receptors in the two segments of the globus pallidus in monkeys. These findings imply that the control of the basal activity of GPe and GPi cells by the subthalamic nucleus is exerted via the activation of AMPA receptors composed of different subunits. These data reinforce the view that the two segments of the globus pallidus are different entities that possess their own functional characteristics in primates.
长期以来，人们一直认为丘脑底核是灵长类动物苍白球和黑质谷氨酸能传入纤维的主要来源。最近的研究结果表明，在大鼠中，丘脑底核在苍白球细胞中诱导的兴奋作用是通过非NMDA受体的激活介导的。本研究的目的是分析松鼠猴（Saimiri sciureus）外侧苍白球（GPe）、内侧苍白球（GPi）和黑质网状部（SNr）中α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）谷氨酸受体亚基的分布。这是通过免疫组织化学方法实现的，使用针对AMPA受体的GluR1和GluR2/3亚基产生的抗体。我们的结果表明，GPe和GPi中的所有神经元胞体对GluR2/3亚基均表现出免疫反应性，而GluR1仅局限于GPe中的细胞。在GPe的整个 rostrocaudal 范围内，GluR1免疫反应性神经元的比例并不均匀；在前三分之一中，所有GPe细胞均表现出GluR1免疫反应性，而在后三分之一中，GluR1阳性细胞的比例降至50%。与GPe细胞相关的GluR1免疫染色强度低于与Meynert基底核中相邻大神经元相关的强度。与GPi细胞不同，SNr中的神经元对GluR1和GluR2/3亚基均表现出免疫反应性。总之，我们的结果首次证明了AMPA受体的GluR1亚基在猴苍白球的两个节段中分布不同。这些发现意味着丘脑底核对GPe和GPi细胞基础活动的控制是通过由不同亚基组成的AMPA受体的激活来实现的。这些数据强化了这样一种观点，即苍白球的两个节段是不同的实体，在灵长类动物中具有各自的功能特征。
