Pain Mechanisms and Sensory NeuroscienceResearch PaperBehavioral and neurophysiological correlates of nociception in an animal model of photokeratitis
Section snippets
Experimental procedures
The animal protocols were approved by the Institutional Animal Care and Use Committee of the University of Minnesota and conformed to the established guidelines set by The National Institutes of Health guide for the care of laboratory animals (PHS Law 99–158, revised 2002).
General effects of UVR
There were no visible signs of ocular inflammation immediately and for several hours after UVR regardless of intensity. By 1 day after moderate or high intensity UVR (200 or 300 mJ/cm2) the irradiated eye displayed a dilated pupil and signs of inflammation such as hyperemia of the sclera and corneal opacities that gradually diminished over 7 days. After low intensity UVR (100 mJ/cm2), the pupil was dilated slightly for 1–2 days, with some hyperemia of the sclera and corneal opacity that
Discussion
These data indicated that acute exposure of the eye to UVR produced, after a 1 day latent period, a transient increase in ocular-specific nociceptive behavior evoked by hypertonic saline applied to the ocular surface. The time course for UVR-induced changes in behavior matched well the increase in responsiveness of neurons in superficial laminae at the Vc/C1 region to hypertonic saline. By contrast, although ocular neurons at the Vi/Vc transition region, located 4–5 mm rostral to the Vc/C1
Acknowledgments
The authors thank Randall Thompson for excellent technical assistance. This work was supported in part by a grant from the NIH (NS26137).
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