Mason P, Floeter M K, Fields H L
Department of Neurology, University of California-San Francisco 94143-0114.
J Comp Neurol. 1990 Nov 1;301(1):23-43. doi: 10.1002/cne.903010104.
The rostral ventromedial medulla (RVM) contains two classes of physiologically defined neurons, on-cells and off-cells, that are implicated in nociceptive modulation. In a continuing effort to detail the neural circuitry that underlies the activity of these two distinct neuronal types, the somatodendritic morphology of on- and off-cells was studied in the cat, rat, and ferret. In lightly anesthetized animals, on-cells increased and off-cells decreased their discharge rate during a withdrawal reflex evoked by noxious stimuli. Following their physiological characterization by using intracellular recording, on- and off-cells were injected with either horseradish peroxidase or biocytin and their somatodendritic arborizations were examined. Labeled on- and off-cells included fusiform and stellate cells of all sizes as well as large multipolar neurons. Although the somatic shape of both on- and off-cells in RVM was heterogeneous, off-cells tended to be fusiform neurons whose long axis was oriented mediolaterally. The dendritic domains of both on- and off-cells extended bilaterally past the lateral edge of the trapezoid body or pyramid and ventrally to, and sometimes including, the trapezoid body or pyramid. In contrast to their extensive mediolateral spread, the dendritic domains of both cell types were limited to the ventral half of the reticular formation and were compressed along the rostrocaudal axis. The dendritic arbor of individual on- and off-cells extended well beyond the cytoarchitectonic boundaries of any single nuclear region, within the domain delineated as the RVM. The spatial domains of the dendritic arbors of on- and off-cells are further evidence that the on- and off-cells throughout the RVM constitute an integrated unit in the modulation of nociceptive transmission.
延髓头端腹内侧区（RVM）包含两类经生理学定义的神经元，即开细胞和关细胞，它们与伤害性调制有关。为了持续详细了解这两种不同神经元类型活动背后的神经回路，我们研究了猫、大鼠和雪貂中开细胞和关细胞的树突状形态。在轻度麻醉的动物中，在有害刺激诱发的退缩反射期间，开细胞放电率增加，关细胞放电率降低。在通过细胞内记录对它们进行生理学特征描述后，向开细胞和关细胞注射辣根过氧化物酶或生物胞素，并检查它们的树突状分支。标记的开细胞和关细胞包括各种大小的梭形细胞和星形细胞以及大型多极神经元。尽管RVM中开细胞和关细胞的体细胞形状各不相同，但关细胞倾向于为梭形神经元，其长轴呈内外侧取向。开细胞和关细胞的树突域双侧延伸超过梯形体或锥体的外侧边缘，并向腹侧延伸至梯形体或锥体，有时还包括梯形体或锥体。与其广泛的内外侧扩展形成对比的是，这两种细胞类型的树突域仅限于网状结构的腹侧半部分，并沿前后轴被压缩。单个开细胞和关细胞的树突分支延伸到RVM所划定区域内任何单个核区域的细胞构筑边界之外。开细胞和关细胞树突分支的空间域进一步证明，整个RVM中的开细胞和关细胞在伤害性传递调制中构成一个整合单元。
