McLaughlin B J, Barber R, Saito K, Roberts E, Wu J Y
J Comp Neurol. 1975 Dec 1;164(3):305-21. doi: 10.1002/cne.901640304.
The GABA synthesizing enzyme, glutamate decarboxylase (GAD), has been localized by light and electron microscopy in the rat lumbosacral spinal cord using a peroxidase-labeling antibody technique. The light microscopic localization shows heavy, punctate reaction product for GAD in the dorsal horn laminae I-III. Moderately heavy reaction product is also seen in the deeper dorsal horn laminae IV-VI, the medial aspect of the intermediate gray (lamina VII) and the region around the central canal (lamina X). A moderately light concentration of GAD reaction product is observed in the ventral horn, and punctate deposits of reaction product also are seen on motoneuron cell bodies. The punctate distribution of reaction product for GAD in both ventral and dorsal horns, as visualized by light microscopy, corresponds to GAD-containing synaptic terminals seen by electron microscopy in comparable regions of the spinal gray. Many more GAD-positive terminals are observed in dorsal horn laminae I-III than in deeper laminae IV-VI. GAD-containing terminals in the dorsal horn are presynpatic to dendrites and cell bodies. Gad-containing terminals presynaptic to other axon terminals are observed also, and they are more numerous in laminae II and III. In the ventral horn motor nuclei, GAD-positive knobs are presynaptic to large and small dendrites and motoneuror cell bodies. In addition, small GAD-containing terminals also are presynaptic to larger axonal terminals which are in turn presynaptic to motoneuron somata. The observation of GAD-containing terminals presynaptic to dendrites and cell bodies in both dorsal and ventral horns is compatible with the evidence suggesting that GABA terminals may mediate postsynaptic inhibition of spinal interneurons and motoneurons. The additional finding of GAD-positive terminals presynaptic to other axonal terminals in the dorsal horn and motor nuclei is consistent with the growing evidence that GABA also may be the transmises mediating presynaptic inhibition via axo-axond synapses in the spinal cord.
利用过氧化物酶标记抗体技术，通过光学显微镜和电子显微镜对大鼠腰骶脊髓中γ-氨基丁酸（GABA）合成酶——谷氨酸脱羧酶（GAD）进行了定位。光学显微镜下的定位显示，在背角I-III层中，GAD呈现出强烈的点状反应产物。在背角更深的IV-VI层、中间带灰质（VII层）内侧以及中央管周围区域（X层）也可见中等强度的反应产物。在腹角观察到GAD反应产物浓度适中，并且在运动神经元细胞体上也可见点状反应沉积物。光学显微镜下所见的腹角和背角中GAD反应产物的点状分布，与电子显微镜在脊髓灰质相应区域所见的含GAD突触终末相对应。在背角I-III层中观察到的含GAD终末比在更深的IV-VI层中更多。背角中含GAD的终末与树突和细胞体形成突触前联系。还观察到含GAD的终末与其他轴突终末形成突触前联系，并且在II层和III层中更为常见。在腹角运动核中，GAD阳性的小结与大小树突以及运动神经元细胞体形成突触前联系。此外，小的含GAD终末也与较大的轴突终末形成突触前联系，而这些较大的轴突终末又与运动神经元胞体形成突触前联系。在背角和腹角中均观察到含GAD的终末与树突和细胞体形成突触前联系，这与GABA终末可能介导脊髓中间神经元和运动神经元突触后抑制的证据相符。在背角和运动核中发现含GAD的终末与其他轴突终末形成突触前联系这一额外发现，与越来越多的证据一致，即GABA也可能是通过脊髓中轴突-轴突突触介导突触前抑制的递质。
