Clements J R, Beitz A J
Department of Veterinary Anatomy, Texas A&M University, College Station 77843-4458.
J Comp Neurol. 1991 Jul 8;309(2):271-80. doi: 10.1002/cne.903090208.
The spinal and principal sensory trigeminal nuclei relay noxious and nonnoxious stimuli from the orofacial region to the thalamus. Physiological studies have implicated glutamate as an important neurotransmitter in this region. Despite its importance as a potential transmitter, few studies have examined the anatomical distribution of glutamate within these nuclei. We therefore chose to use a monoclonal antibody raised against glutamate conjugated to a carrier protein to identify and describe glutamate-like immunoreactive processes at the electron microscopic level. Glutamate-like immunoreactive axon terminals were identified throughout the spinal trigeminal and principal sensory trigeminal nucleus. In subnucleus caudalis glutamate-like immunoreactive terminals occurred frequently in all laminae and were morphologically heterogeneous. In lamina I, glutamate-like immunoreactive terminals were primarily ovoid, contained spherical synaptic vesicles, and participated in synaptic complexes with both dendritic and axonal profiles. In laminae II and III many glutamate-like immunoreactive axon terminals were identified as the central element in synaptic glomeruli. Within discrete patches of lamina II, large numbers of glutamate-like immunoreactive terminals contained dense core vesicles. The majority of glutamate-like immunoreactive terminals in subnucleus interpolaris, subnucleus oralis, and principal sensory trigeminal nucleus were similar in morphology and synaptic interaction to the glutamate-like immunoreactive terminals found in subnucleus caudalis. Glutamate-like immunoreactive terminals that were the central presynaptic element in glomerular complexes were seen in all subnuclei. In sections from subnucleus interpolaris and subnucleus oralis central glutamate-like immunoreactive terminations within glomerular complexes had much smoother profiles, and in subnucleus interpolaris participated primarily in axodendritic synaptic junctions. In the principal sensory trigeminal nucleus central glutamate-like immunoreactive terminations were highly scalloped and participated in numerous axoaxonic synaptic junctions. The above observations are consistent with the hypothesis that glutamate-like immunoreactivity is present in some primary afferent terminations and functions as an important excitatory transmitter involved in the relay of sensory information to the spinal trigeminal and principal sensory trigeminal nucleus.
脊髓三叉神经核和三叉神经主感觉核将来自口面部区域的伤害性和非伤害性刺激传递至丘脑。生理学研究表明谷氨酸是该区域重要的神经递质。尽管谷氨酸作为潜在递质很重要，但很少有研究考察其在这些核内的解剖分布。因此，我们选择使用一种针对与载体蛋白偶联的谷氨酸的单克隆抗体，在电子显微镜水平鉴定和描述谷氨酸样免疫反应性过程。在整个三叉神经脊束核和三叉神经主感觉核中均发现了谷氨酸样免疫反应性轴突终末。在尾侧亚核中，谷氨酸样免疫反应性终末在所有板层中均频繁出现，且形态各异。在I层，谷氨酸样免疫反应性终末主要呈卵圆形，含有球形突触小泡，并与树突和轴突形态共同参与突触复合体。在II层和III层，许多谷氨酸样免疫反应性轴突终末被鉴定为突触小球的中心成分。在II层的离散区域内，大量谷氨酸样免疫反应性终末含有致密核心小泡。极间亚核、口侧亚核和三叉神经主感觉核中的大多数谷氨酸样免疫反应性终末在形态和突触相互作用方面与在尾侧亚核中发现的谷氨酸样免疫反应性终末相似。在所有亚核中均可见到作为突触小球复合体中突触前中心成分的谷氨酸样免疫反应性终末。在极间亚核和口侧亚核的切片中，突触小球复合体内的中央谷氨酸样免疫反应性终末轮廓更为平滑，在极间亚核中主要参与轴-树突触连接。在三叉神经主感觉核中，中央谷氨酸样免疫反应性终末呈高度扇贝状，参与众多轴-轴突触连接。上述观察结果与以下假设一致，即谷氨酸样免疫反应性存在于一些初级传入终末中，并作为一种重要的兴奋性递质，参与感觉信息向三叉神经脊束核和三叉神经主感觉核的传递。
