Purpose: Previously, we have shown that ocular sympathectomy (SCGectomy) decreases cell proliferation in the rat corneal epithelium. The mechanism underlying this decrease is unknown; however, it is likely due to the loss of some trophic substance released by the sympathetic nerves. The purpose of the current study was to test the hypothesis that norepinephrine (NE) is this trophic substance. Methods. Adult rats were divided into 3 groups. Group 1 was composed of normal animals with intact ocular innervations. Group 2 and Group 3 animals received unilateral and bilateral SCGectomies, respectively, two weeks prior to sacrifice. Twenty-four hours before sacrifice, Alzet osmotic pumps filled with bromodeoxyuridine (BrdU) solution were implanted subcutaneously in each animal to label S-phase cells. Immediately after pump implantation, and every hour for an additional 4 hours, 50μl of NE (Group 1 - 3mM; Group 2 - 6μM; Group 3 - 0.6μM) were administered topically to the left eye, while vehicle only was applied to the contralateral (control) eye. All corneas were then paraffin-sectioned and processed for BrdU immunohistochemistry. Results. In Group 1 animals, unilateral topical application of NE increased cell proliferation 8% over control eyes (p<0.05). In Group 2 animals, ocular sympathectomy decreased epithelial cell proliferation by 40%; NE application completely reversed this decrease. In Group 3 animals, proliferation increased 28% (p<0.05) on the NE-treated side. Conclusions. Topical application of NE to normal and sympathetically denervated rat eyes increases DNA synthesis in the corneal epithelium.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience