Effect of substance P, insulin-like growth factor-1 and vasoactive intestinal polypeptide on corneal re-epithelialization in galactosemic rats

Purpose. The purpose of the study was to examine the effect of topical appl ication of substance P (SP), insulin-like growth factor-1 (IGF-1) and vasoa ctive intestinal polypeptide (VIP) on corneal re-epithelialization in galac tosemic rats. Methods. Experimental galactosemia was induced by feeding a diet containing 30% galactose for 4-6 months. The corneal epithelium was debrided bi-later ally by scraping with a blunted scalpel blade. One eye (control) received o nly a saline solution whilst the other eye received a solution of SP and/or IGF-1 or VIP. A single drop of control or test solution was administered 4 times daily until wound closure. Corneas were stained with fluorescein and videotaped under ultraviolet illumination at regular time intervals after debridement. After digitizing the video image, the wound area was calculate d using an image analysis program (NIH Image). Results. Corneal re-epithelialization was significantly delayed in galactos emic compared to normal animals. Rates of healing were 1.3 +/- 0.07 mm(2)/h our and 1.02 +/- 0.02 mm(2)/hour for normal and galactosemic animals, respe ctively. Topical application of SP in concentrations ranging from 25 pg/ml up to 250 mu g/ml had no significant effect on the rate of corneal re-epith elialization. Similarly, IGF-1 (1 mu g/ml) or VIP (1 mu g/ml) when applied alone did not affect re-epithelialization. Furthermore, resurfacing of the debrided area was not affected by co-application of SP (250 mu g/ml) and IG F-1 or VIP. Conclusions. Independent or combined topical application of SP, VIP or IGF- 1 at the concentrations tested, does not modulate corneal epithelial wound healing in rats with galactosemia induced by 30% galactose.