Brooke Ruth E, Atkinson Lucy, Edwards Ian, Parson Simon H, Deuchars Jim
Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK.
Brain Res. 2006 Jan 27;1070(1):101-15. doi: 10.1016/j.brainres.2005.10.102. Epub 2006 Jan 5.
Voltage gated K+ channels (Kv) are a diverse group of channels important in determining neuronal excitability. The Kv superfamily is divided into 12 subfamilies (Kv1-12) and members of the Kv3 subfamily are highly abundant in the CNS, with each Kv3 gene (Kv3.1-Kv3.4) exhibiting a unique expression pattern. Since the localisation of Kv subunits is important in defining the roles they play in neuronal function, we have used immunohistochemistry to determine the distribution of the Kv3.3 subunit in the medulla oblongata and spinal cord of rats. Kv3.3 subunit immunoreactivity (Kv3.3-IR) was widespread but present only in specific cell populations where it could be detected in somata, dendrites and synaptic terminals. Labelled neurones were observed in the spinal cord in laminae IV and V, in the region of the central canal and in the ventral horn. In the medulla oblongata, labelled cell bodies were numerous in the spinal trigeminal, cuneate and gracilis nuclei whilst rarer in the lateral reticular nucleus, hypoglossal nucleus and raphe nucleus. Regions containing autonomic efferent neurones were predominantly devoid of labelling with only occasional labelled neurones being observed. Dual immunohistochemistry revealed that some Kv3.3-IR neurones in the ventral medullary reticular nucleus, spinal trigeminal nucleus, dorsal horn, ventral horn and central canal region were also immunoreactive for the Kv3.1b subunit. The presence of Kv3.3 subunits in terminals was confirmed by co-localisation of Kv3.3-IR with the synaptic vesicle protein SV2, the vesicular glutamate transporter VGluT2 and the glycine transporter GlyT2. Co-localisation of Kv3.3-IR was not observed with VGluT1, tyrosine hydroxylase, serotonin or choline acetyl transferase. Electron microscopy confirmed the presence of Kv3.3-IR in terminals and somatic membranes in ventral horn neurones, but not motoneurones. This study provides evidence supporting a role for Kv3.3 subunits in regulating neuronal excitability and in the modulation of excitatory and inhibitory synaptic transmission in the medulla oblongata and spinal cord.
电压门控钾通道（Kv）是一组多样的通道，在决定神经元兴奋性方面很重要。Kv超家族分为12个亚家族（Kv1 - 12），Kv3亚家族的成员在中枢神经系统中高度丰富，每个Kv3基因（Kv3.1 - Kv3.4）都表现出独特的表达模式。由于Kv亚基的定位对于确定它们在神经元功能中所起的作用很重要，我们利用免疫组织化学来确定Kv3.3亚基在大鼠延髓和脊髓中的分布。Kv3.3亚基免疫反应性（Kv3.3 - IR）广泛存在，但仅存在于特定的细胞群体中，在这些细胞的胞体、树突和突触终末中可以检测到。在脊髓的IV层和V层、中央管区域和腹角观察到有标记的神经元。在延髓中，标记的细胞体在脊髓三叉神经核、楔束核和薄束核中大量存在，而在外侧网状核、舌下神经核和中缝核中较少见。含有自主传出神经元的区域主要没有标记，仅偶尔观察到有标记的神经元。双重免疫组织化学显示，延髓腹侧网状核、脊髓三叉神经核、背角、腹角和中央管区域的一些Kv3.3 - IR神经元对Kv3.1b亚基也有免疫反应性。通过Kv3.3 - IR与突触囊泡蛋白SV2、囊泡谷氨酸转运体VGluT2和甘氨酸转运体GlyT2的共定位，证实了终末中存在Kv3.3亚基。未观察到Kv3.3 - IR与VGluT1、酪氨酸羟化酶、5 - 羟色胺或胆碱乙酰转移酶的共定位。电子显微镜证实腹角神经元的终末和胞体膜中存在Kv3.3 - IR，但运动神经元中没有。这项研究提供了证据，支持Kv3.3亚基在调节神经元兴奋性以及在延髓和脊髓中调节兴奋性和抑制性突触传递方面发挥作用。
