Lucier G E, Egizii R
University of Calgary, Faculty of Medicine, Department of Physiology, Alberta, Canada.
Exp Neurol. 1989 Jan;103(1):83-9. doi: 10.1016/0014-4886(89)90189-1.
Stimulation of the nasal mucous membrane can initiate protective reflexes, particularly sneezing and apnea. Very little is known about the receptors in the nasal cavity responsible for initiating these reflexes, which are thought to be mediated by trigeminal rather than olfactory pathways. In the cat, the ethmoidal branch of the ophthalmic division of V carries this afferent information. The objectives of the present study were to determine a set of adequate nasal receptor stimuli capable of initiating these protective reflexes; to characterize the types of information carried in the ethmoidal nerve afferents, by recording from single fibers dissected from the nerve; to determine the conduction velocities of these afferents, by recording from the cell bodies of ethmoidal afferents in the trigeminal ganglion; and to study the second-order neurones in the brain stem on which these afferents make contact. Results of single fiber recording indicated that, in addition to being tactile, approximately half of the neurones studied also responded to noxious chemical stimuli. The conduction velocity of the majority of these afferents were found to be in the A-delta range. Second-order neurones in spinal trigeminal nucleus which had an input from the ethmoidal nerve could be divided into two classifications: (i) low threshold mechanoreceptive (LTM) neurones which received light tactile input and did not respond to noxious chemical or mechanical stimuli applied to the nasal cavity, and (ii) wide dynamic range (WDR) neurones which responded to both noxious and nonnoxious chemical or mechanical stimuli applied to the nasal cavity.
刺激鼻黏膜可引发保护性反射，尤其是打喷嚏和呼吸暂停。对于鼻腔中引发这些反射的受体，人们了解甚少，这些反射被认为是由三叉神经而非嗅觉通路介导的。在猫中，三叉神经眼支的筛骨分支传递这种传入信息。本研究的目的是确定一组能够引发这些保护性反射的适当鼻受体刺激；通过记录从神经中分离出的单根纤维，来表征筛神经传入纤维所携带的信息类型；通过记录三叉神经节中筛神经传入纤维的细胞体，来确定这些传入纤维的传导速度；并研究这些传入纤维与之接触的脑干中的二级神经元。单纤维记录结果表明，除了具有触觉感受外，所研究的神经元中约有一半也对有害化学刺激有反应。发现这些传入纤维中的大多数传导速度处于A-δ范围内。接受筛神经输入的脊髓三叉神经核中的二级神经元可分为两类：(i)低阈值机械感受器(LTM)神经元，它们接受轻微触觉输入，对施加于鼻腔的有害化学或机械刺激无反应；(ii)广动力范围(WDR)神经元，它们对施加于鼻腔的有害和无害化学或机械刺激均有反应。
