Functional Properties of Sensory Nerve Terminals of the Mouse Cornea.
Por:
González-González O, Bech F, Gallar J, Merayo-Lloves J and Belmonte C
Publicada:
1 ene 2017
Resumen:
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 ~ 50 µm), 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 mOsm·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°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°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.
Filiaciones:
González-González O:
Instituto Universitario Fernández-Vega, Universidad de Oviedo & Fundación de Investigación Oftalmológica, Oviedo, Spain
Bech F:
Instituto Universitario Fernández-Vega, Universidad de Oviedo & Fundación de Investigación Oftalmológica, Oviedo, Spain
:
Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Cientificas, San Juan de Alicante, Spain
Merayo-Lloves J:
Instituto Universitario Fernández-Vega, Universidad de Oviedo & Fundación de Investigación Oftalmológica, Oviedo, Spain
Belmonte C:
Instituto Universitario Fernández-Vega, Universidad de Oviedo & Fundación de Investigación Oftalmológica, Oviedo, Spain 2Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Cientificas, San Juan de Alicante, Spain
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