Purchase this article with an account.
I. Kovacs, S. Quirce, C. Luna, M. C. Acosta, C. Belmonte, J. Gallar; Increased Responsiveness of Corneal Cold Receptors in an Experimental Model of Dry Eye. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3403.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate the effect of decreased tear secretion on nerve impulse activity of corneal cold thermoreceptors in an animal model of dry eye.
Main lacrimal gland was surgically removed in 9 guinea pigs. 18 animals served as a control group. One week afterwards, the cornea was excised, placed in a recording chamber and superfused continuously with physiological solution. Single nerve terminal impulses of cold thermoreceptors were recorded using a glass pipette applied onto the cornea and conventional recording equipment. Spontaneous activity (SA) at 34-36°C was first recorded, followed by cooling pulses to 22-25°C, changing the temperature of the perfusing solution at variable rates. Mean frequency of spontaneous activity (SA), peak frequency value (PF) during the cooling pulses and temperature at the peak firing response (PT) were analyzed. Multiple regression analysis was applied to evaluate the effect of basal temperature, basal frequency and cooling velocity on cooling responses.
Tear secretion decreased compared to baseline after surgery (2.3±1.1 mm vs. 17.6±4.3 mm, p<0.05). 97 cold nerve terminals were analysed in the dry eye and 74 in the control group. SA at 32-36ºC was increased in dry eye corneas (10.2±0.6 Hz) compared to controls (7.9±0.4 Hz, p=0.003). Significant correlation was found between basal frequency and PF in both groups (dry eye: r=0.61, control: r=0.72, p<0.05), and between cooling velocity and PF in both groups (dry eye: r=0.69, control: r=0.51, p<0.05). Multiple regression analysis showed significant effect of surgery on PF (p=0.006) and PT (p<0.001). PF in response to cooling was significantly higher (16.1±0.9 Hz) in corneas of dry eyes than in control corneas (11.9±0.7 Hz, p=0.006). The temperature decrease required to reach the maximum response was 6.2±0.3 °C in the dry eye group and 6.8±0.5 °C in the control group (p<0.001).
Decreased tear secretion induced by removal of the main lacrimal gland altered the response characteristics and sensitivity of corneal cold nerve terminals. Increased nerve impulse activity in this population of sensory afferents may contribute to dryness sensations in dry eye pathologies.
This PDF is available to Subscribers Only