Effect of Retinol Palmitate on Corneal and Conjunctival Mucin Gene Expression in a Rat Dry Eye Model After Injury.

Abstract

We examined the wound-healing effect of retinol palmitate (VApal) on mucin gene and protein expressions in a rat dry eye model based on lacrimal gland (LG) resection after injury. The rat dry eye model was prepared by surgical resection of the main LG in male Long-Evans rats. After alkaline injury of the central part of the lower palpebral conjunctiva bilaterally, VApal eye drops at 1,500 IU/mL in one eye and a vehicle in the fellow eye were both administered 6 times a day for 7 days. The expression of mucin gene and protein was analyzed by real-time polymerase chain reaction or enzyme-linked immunosorbent assay in the cornea and conjunctiva of MUC1, MUC4, MUC16, and MUC5AC after 1, 3, (5), and 7 days of treatment with VApal. Significant decreases in fluorescein-stained areas and rose bengal scores were observed in VApal-treated dry eyes compared with vehicle-treated dry eyes at both 3 (P < 0.05) and 7 days (P < 0.01). Significant increases in corneal rMuc4 and conjunctival rMuc5AC after 1 day (P < 0.01) and conjunctival rMuc16 gene expression after 3 days were observed with VApal treatment (P < 0.05). Furthermore, conjunctival MUC16 expression significantly increased after 3 days of VApal treatment (P < 0.05). VApal promoted corneal rMuc4, conjunctival rMuc5AC, and conjunctival rMuc16 gene expression in a rat dry eye model after injury. VApal also promoted conjunctival MUC16 expression. These results indicate that VApal has efficacy in improving keratoconjunctival epithelial damage associated with decreased tear production.