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Juana Gallar, Kamila Mizerska, Carolina Luna García, Susana Quirce, M Carmen Acosta; Characterization of corneal sensory nerve activity in young and adult guinea pigs. Invest. Ophthalmol. Vis. Sci. 2018;59(9):154.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the activity of corneal sensory nerve fibers in young and adult guinea pigs (1-18 months old).
The spontaneous and stimulus evoked nerve activity of corneal sensory nerve fibers in response to mechanical (von Frey filaments), thermal (cooling the bath solution from 34oC to 20oC) and chemical stimulation (CO2 gas pulses of 30s) were recorded extracellularly from nerve terminals or axons (ciliary nerve filaments) from ex-vivo eyes of guinea pigs of different ages (young: 1-4 months old; young-adult: 8-9 months; adult: 15-18 months). For mechano- and polymodal nociceptors, mechanical threshold (MT) and percentage of incidence of spontaneous activity (SA) were determined. For polymodal nociceptors impulse response to CO2 was also measured. For cold thermoreceptors, ongoing activity (OA) at basal temperature (34oC), cold threshold (CTH) and peak response (PR) to cold stimulus were studied.
No significant changes were found in corneal nerve activity from corneas of young and young-adult guinea pigs. Activity recorded from adult corneas was different compared with young corneas. Mechanonociceptors had lower MT values. Polymodal nociceptors had slightly higher MT, impulse response to CO2 and incidence of SA. Cold thermoreceptors showed significant differences in their ongoing activity and response to cold stimulation (see Table).
The characteristics of the spontaneous and stimulus-evoked activity of corneal sensory nerves are similar in young (1-4 months old) and young-adult animals (8-9 months old). Activity of mechano- and polymodal nociceptors was modified in adult animals (15-18 months old), while activity of cold thermoreceptors appears to be significantly lower compared with young animals.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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