Chiaia N L, Zhang S, Crissman R S, Rhoades R W
Department of Anatomy and Neurobiology, Medical College of Ohio, Toledo 43614-5804, USA.
Somatosens Mot Res. 2000;17(3):273-83. doi: 10.1080/08990220050117628.
We have previously shown that attenuation of axoplasmic transport by application of vinblastine to the developing infraorbital nerve (ION) results in a loss of central vibrissae-related patterns that is not accompanied by changes in the receptive field sizes for the V primary afferents innervating the whisker follicles. The present study examines the relationship between the loss of central vibrissae-related patterns and alterations in the response properties of neurons in the V principal sensory nucleus (PrV) of adult rats that sustained application of vinblastine to the ION at birth. Absence of histochemically demonstrable vibrissae-related patterns in PrV resulted in only modest changes in the receptive fields and response properties of vibrissae-sensitive neurons in this nucleus that projected to the contralateral thalamus. Response latencies to electrical activation of the V ganglion were similar in treated and untreated animals. The mean receptive field size was significantly increased from 1.3 +/- 0.7 vibrissae in controls to 1.7 +/- 0.9 vibrissae in vinblastine-treated animals, and the percentage of cells yielding a tonic response to vibrissae deflection was markedly reduced (p < 0.01 for both measures). Phasically responding cells recorded in vinblastine-treated animals showed a significant reduction in the mean number of spikes per stimulus following deflection of the vibrissae in either the preferred or non-preferred direction relative to cells recorded in normal animals (p < 0.05). The present results indicate that disruption of the normal vibrissae-related aggregates of neurons in PrV by application of vinblastine to the ION has limited effects on the functional representation of the vibrissae in this nucleus.
我们之前已经表明，在发育中的眶下神经（ION）上应用长春花碱会导致轴浆运输减弱，进而导致中央触须相关模式的丧失，而支配触须毛囊的V初级传入神经元的感受野大小并未发生变化。本研究探讨了中央触须相关模式的丧失与成年大鼠V主感觉核（PrV）中神经元反应特性改变之间的关系，这些成年大鼠在出生时持续对ION应用长春花碱。PrV中缺乏组织化学可证实的触须相关模式，仅导致该核中投射到对侧丘脑的触须敏感神经元的感受野和反应特性发生适度变化。在治疗组和未治疗组动物中，对V神经节进行电激活的反应潜伏期相似。平均感受野大小从对照组的1.3±0.7根触须显著增加到长春花碱治疗组动物的1.7±0.9根触须，并且对触须偏转产生紧张性反应的细胞百分比显著降低（两项测量均p<0.01）。在长春花碱治疗组动物中记录到的相位反应细胞，相对于正常动物中记录的细胞，在触须向偏好或非偏好方向偏转后，每个刺激的平均峰值数量显著减少（p<0.05）。目前的结果表明，通过对ION应用长春花碱破坏PrV中正常的触须相关神经元聚集，对该核中触须的功能表征影响有限。
