Abstract
Abstract: :
Purpose: To examine gene expression in the rat lacrimal gland (LG) by microarray gene analysis following parasympathetic denervation. Methods: Sprague-Dawley rats underwent unilateral pre-ganglionic parasympathetic denervation by severing the greater superficial petrosal nerve, input to the pterygopalatine ganglion. Ocular surface changes were monitored using the Schirmer's Tear Test and Rose Bengal staining after 7 days. The LG from the contralateral control (n=2) and denervated side (n=2) were removed. The LG from the sham control was also removed (n=1). Total RNA was extracted and analyzed for gene expression using the rat genome U34A array. Arrays were globally scaled and average density and absolute call (present, marginal, absent) were determined using Affymetrix Microarray Suite software. Fold changes in gene expression were analyzed using both the Affymetrix Datamining Tools 2.0 and GeneSpring software. Genes (present, marginal, and unknown) with an average density of at least 500 in one of the three conditions (sham, contralateral, and denervated) were filtered and clustered using the K-means and Self Organizing Map algorithm. Results: The Schirmer's tear value for the control and the denervated side were 9.0 + 1.6 mm and 3.7 + 0.4 mm (Mean + SEM; n=3), respectively. Rose Bengal score was 1.00 + 0.00 for the control and 5.33 + 1.20 (n=3) for the denervated side, on a scale of 0 to 9. Moreover, severe corneal ulcers developed in the center of the cornea in the denervated side, but not in the contralateral or the sham. Analysis of gene expression after denervation showed a general profile of downregulation in the rat LG. Of the 3853 genes obtained after filtering, 649 genes were at least 1.5 fold downregulated and 225 genes were at least 1.5 fold upregulated expression after denervation. Genes that showed similar patterns of expression among the three conditions were obtained after cluster analysis, of which 116 genes showed decreased expression and 73 genes showed increased expression in the denervated LG. Conclusion: Parasympathetic denervation of the rat resulted in severe pathological changes to the ocular surface similar to severe dry eye symptoms in humans. Microarray analysis suggests denervation leads to an overall greater gene downregulation in the denervated LG, resulting in an alteration in lacrimal function.
Keywords: 452 lacrimal gland • 417 gene/expression • 441 innervation: neural regulation