Expression of Nerve Growth Factor during Corneal Epithelial Wound Healing in Rats

ABSTRACT

PURPOSE: To evaluate the expression of nerve growth factor (NGF) in the rat cornea and lacrimal gland before and after corneal epithelial wounding. METHODS: Twenty-nine Sprague-Dawley male rats were used in the present study. Corneal trephination was performed using a 4.0-mm diameter trephine before scratch and at 24, 48, 72 hours after debridement. The lacrimal gland was excised before scratch and at 24 hours after epithelial debridement. NGF levels of the excised cornea and lacrimal gland were measured in rat corneas by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry staining was performed on rat corneas and lacrimal glands. RESULTS: The NGF/total protein ratio (NGF/tP) increased after wounding in the cornea and lacrimal gland. NGF levels in the cornea significantly increased in the wounded group until the 2nd day after wounding (p < 0.05). After NGF concentration peaked on the 1st day, there was a progressive decline after wounding. Additionally, the NGF concentration in the lacrimal gland of the wounded group was significantly higher than that of the control group at 24 hours after epithelial debridement (p = 0.001). Immunohistochemistry staining showed that NGF staining was stronger in rat corneas and lacrimal glands after epithelial debridement than before. CONCLUSIONS: Expression of NGF increased in rat corneas and lacrimal glands after corneal epithelial wounding, which suggests that NGF may play an important role in corneal wound healing.