Functional Properties of Sensory Nerve Terminals of the Mouse Cornea
Functional Properties of Sensory Nerve Terminals of the Mouse Cornea
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DOI：
10.1167/iovs.16-20033
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发表时间：
2017-01-01
影响因子：
4.4
通讯作者：
Belmonte, Carlos
中科院分区：
文献类型：
--
作者：
Gonzalez-Gonzalez, Omar;Bech, Federico;Belmonte, Carlos
目的.目的：研究支配成年小鼠角膜的感觉神经末梢对不同形式的外界刺激的放电特性。在C57 BL/6 J小鼠离体眼记录单个角膜感觉神经末梢的细胞外电活动。将眼睛置于记录室中，并连续灌注温盐水溶液。通过施加在角膜表面上的玻璃移液管（尖端类似于50 lm）记录神经末梢冲动（NTI）活性。神经末梢脉冲放电被存储在计算机中用于离线分析。在小鼠角膜中鉴定了三种功能不同的神经末梢群体。纯mechanonoceptor终端（9.5%）的相位，只对机械刺激。热和高渗溶液（850 mOs.kg（-1））、机械力和/或TRPV 1和TRPA 1激动剂（分别为辣椒素和异硫氰酸烯丙酯[AITC]）可紧张性激活多模态伤害感受器末梢（41.1%）。冷敏感终端（49.4%）响应冷却。大约三分之二的细胞在34摄氏度时持续放电，并对温度的小幅降低做出强烈反应，被归类为高背景活动，低阈值（HB-LT）冷温度感受器终端。其余三分之一在34 ℃时表现出非常低的持续活动，并对强烈的冷却反应微弱，被命名为低背景活动，高阈值（LB-HT）冷温度感受器终末。小鼠角膜受三叉神经节（TG）神经元的神经支配，这些神经元对与其他哺乳动物物种的角膜受体相同的刺激方式作出反应。机械和多模态结束的基础检测机械和化学伤害性刺激，而HB-LT和LB-HT冷热感受器似乎是负责基础和刺激诱发的流泪和眨眼，分别。
PURPOSE. To define the firing properties of sensory nerve terminals innervating the adult mouse cornea in response to external stimuli of differing modality.METHODS. Extracellular electrical activity of single corneal sensory nerve terminals was recorded in excised eyes of C57BL/6J mice. Eyes were placed in a recording chamber and were continuously superfused with warm saline solution. Nerve terminal impulse (NTI) activity was recorded by means of a glass pipette (tip similar to 50 lm), applied on the corneal surface. Nerve terminal impulse discharges were stored in a computer for offline analysis.RESULTS. Three functionally distinct populations of nerve terminals were identified in the mouse cornea. Pure mechanonociceptor terminals (9.5%) responded phasically and only to mechanical stimuli. Polymodal nociceptor terminals (41.1%) were tonically activated by heat and hyperosmolal solutions (850 mOs.kg(-1)), mechanical force, and/or TRPV1 and TRPA1 agonists (capsaicin and allyl isothiocyanate [AITC], respectively). Cold-sensitive terminals (49.4%) responded to cooling. Approximately two-thirds of them fired continuously at 34 degrees C and responded vigorously to small temperature reductions, being classified as high-background activity, low-threshold (HB-LT) cold thermoreceptor terminals. The remaining one-third exhibited very low ongoing activity at 34 degrees C and responded weakly to intense cooling, being named low-background activity, high-threshold (LB-HT) cold thermoreceptor terminals.CONCLUSIONS. The mouse cornea is innervated by trigeminal ganglion (TG) neurons that respond to the same stimulus modalities as corneal receptors of other mammalian species. Mechano- and polymodal endings underlie detection of mechanical and chemical noxious stimuli while HB-LT and LB-HT cold thermoreceptors appear to be responsible for basal and irritation-evoked tearing and blinking, respectively.