Silverman J D, Kruger L
Department of Anatomy, UCLA Center for the Health Sciences 90024.
J Comp Neurol. 1990 Feb 22;292(4):575-84. doi: 10.1002/cne.902920407.
Primary gustatory neurons and their peripheral and central processes were evaluated histochemically in the geniculate and petrosal cranial nerve ganglia, lingual fungiform taste buds, and the nucleus of the solitary tract (NST) using 1) the plant lectin Griffonia simplicifolia I-B4, which binds specifically to D-galactose residues and selectively labels primarily nonpeptide-containing peripheral somatosensory neurons, and 2) calcitonin gene-related peptide immunoreactivity (CGRP-IR), which labels most peptidergic somatosensory neurons. Lectin reactivity was expressed by the vast majority of geniculate and petrosal ganglion cells, while CGRP-IR labeled very few cells. Peripherally, gustatory intragemmal axons penetrating fungiform taste buds were labeled only by the lectin and were depleted following chorda tympani transection. However, both lectin-labeled and CGRP-IR subpopulations of somatosensory perigemmal axons surrounding the taste buds were observed and were eliminated by section of the lingual nerve. The differing brainstem projection patterns of lectin-reactive vs. CGRP-IR central axons reflected their distinct ganglionic origins and the differential distributions of lectin reactivity and CGRP-IR among taste buds. Central lectin-reactive terminals were found throughout the entire rostrocaudal extent of the NST, including its rostral lateral "gustatory" zone; the extensive lectin-reactive visceral afferent projection can be presumed to have originated mainly from the large proportion of lectin-labeled neurons in the nodose ganglion. The lectin also prominently and selectively labeled the area postrema. CGRP-IR central terminals, however, was relatively sparse and restricted primarily to the caudal and medial "visceral" divisions of the NST. The results are discussed with respect to the possible functional implications of cell surface glycoconjugate expression by gustatory axons innervating taste bud receptor cells of the tongue.
利用1）植物凝集素格里菲斯豆凝集素I-B4，其特异性结合D-半乳糖残基并选择性标记主要不含肽的外周躯体感觉神经元，以及2）降钙素基因相关肽免疫反应性（CGRP-IR），其标记大多数含肽的躯体感觉神经元，对膝状和岩状脑神经节、舌菌状味蕾以及孤束核（NST）中的初级味觉神经元及其外周和中枢突进行了组织化学评估。绝大多数膝状和岩状神经节细胞表现出凝集素反应性，而CGRP-IR标记的细胞很少。在周围，穿透菌状味蕾的味觉芽内轴突仅被凝集素标记，并且在鼓索横断后消失。然而，观察到味蕾周围的躯体感觉芽周轴突的凝集素标记和CGRP-IR亚群，并且通过切断舌神经将其消除。凝集素反应性与CGRP-IR中枢轴突不同的脑干投射模式反映了它们不同的神经节起源以及凝集素反应性和CGRP-IR在味蕾中的差异分布。在NST的整个前后范围内都发现了中枢凝集素反应性终末，包括其前端外侧的“味觉”区；广泛的凝集素反应性内脏传入投射可以推测主要起源于结节神经节中大部分凝集素标记的神经元。凝集素还显著且选择性地标记了最后区。然而，CGRP-IR中枢终末相对稀疏，主要局限于NST的尾侧和内侧“内脏”部分。讨论了支配舌味蕾受体细胞的味觉轴突细胞表面糖缀合物表达的可能功能意义。
