Abstract
Purpose :
We evaluated the expression profile of neuropathic pain-related genes of trigeminal ganglion (TG), which give afferent nerves to ocular surface, in the experimental animal models with inflammatory dry eye.
Methods :
Inflammatory dry eye was induced by treating 0.1% benzalkonium chloride (BAC) solution 2 time a day for 1 week on unilateral eyes of Spraue-Dawley rats. Some rats were administrated with artificial tear 4 times a day after 1 week BAC treatment. We extracted corneas and the ipsilateral TGs from controls, 1 week BAC treated group, and post-treatment 2 month group (n = 9 in all groups). All groups were assessed for corneal staining using surgical microscope before euthanasia. Whole mount corneas were stained with beta3 tubulin to measure the density of subbasal corneal nerves (µm/mm2). RT-PCR microarray (RT2 Profiler PCR Arrays, Qiagen) fromTG tissue homogenate was performed for screening the pain related 96 genes and PCR and immunohistochemistry were done for genes having over 2 fold-increase in post-treatment 2 month group versus controls and 1 week BAC treated group.
Results :
One week 0.1% BAC treatment resulted in decrease in tear secretion and goblet cells density of treated eyes of rats. In 2 month recovery group, tear secretion and goblet cell density recovered to normal controls. The density of subbasal nerves (µm/mm2) was significantly lower in 1 week BAC group and post-treatment 2 month group than in controls. The density of subbasal nerves in 2 month recovery group increased compared to that in 1 week BAC group, although that in the former was lower than in controls. The expression of P2rx3, P2rx4, and P2rx7 were significantly upregulated in 2 month recovery group, while those expression in 1 week BAC group was not changed compared to controls. The others revealed lack of significant fold change or agreement between microarray and qPCR.
Conclusions :
The experimental inflammatory dry eye rats showed recovery in corneal erosions, tear secretion, goblet cell density, and corneal nerve density over 2 months. Nevertheless, P2rx3, P2rx4, and P2rx7 among pain related genes in TG were upregulated over the period. These result suggested that purinergic receptors of corneal sensory neurons may have relevance to the discrepancy between signs and symptoms in dry eye syndrome.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.