Todd A J
Laboratory of Human Anatomy, University of Glasgow, UK.
Eur J Neurosci. 1996 Dec;8(12):2492-8. doi: 10.1111/j.1460-9568.1996.tb01543.x.
The superficial dorsal horn of rat spinal cord contains two types of synaptic glomerulus, which are centred around the terminals of unmyelinated and myelinated primary afferents respectively. Both types of glomerulus contain GABAergic axons and dendrites, which are thought to originate from local inhibitory interneurons. Some of the dendrites contain synaptic vesicles, and may be presynaptic to the central axon of dendroaxonic synapses. In order to determine whether GABAergic structures in the two types of glomerulus are derived from different populations of interneurons, a quantitative post-embedding immunogold study of GABA- and glycine-immunoreactivity in a rat dorsal horn was performed. In type I glomeruli, all of the peripheral axons and most vesicle-containing dendrites were GABA-immunoreactive, but only one of 32 axons and none of the vesicle-containing dendrites was glycine-immunoreactive. In contrast, most of the peripheral axons and some of the vesicle-containing dendrites in type II glomeruli possessed both GABA- and glycine-immunoreactivity. This strongly suggests that different types of inhibitory interneuron in the dorsal horn are associated with the two types of glomerulus. It is therefore likely that different populations of interneurons mediate presynaptic inhibition of unmyelinated and myelinated primary afferents.
大鼠脊髓浅表背角包含两种类型的突触小球，它们分别以无髓鞘和有髓鞘初级传入神经的终末为中心。两种类型的小球均含有GABA能轴突和树突，这些被认为起源于局部抑制性中间神经元。一些树突含有突触小泡，可能是树突-轴突突触中央轴突的突触前成分。为了确定两种类型小球中的GABA能结构是否源自不同群体的中间神经元，对大鼠背角中GABA和甘氨酸免疫反应性进行了定量包埋后免疫金研究。在I型小球中，所有外周轴突和大多数含小泡树突呈GABA免疫反应性，但32根轴突中只有1根以及含小泡树突均无甘氨酸免疫反应性。相反，II型小球中的大多数外周轴突和一些含小泡树突同时具有GABA和甘氨酸免疫反应性。这有力地表明，背角中不同类型的抑制性中间神经元与两种类型的小球相关。因此，很可能不同群体的中间神经元介导了对无髓鞘和有髓鞘初级传入神经的突触前抑制。
