The
protein sericin is the main constituent of
silk. We investigated the effects of
sericin on corneal wound healing in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model for human
type 2 diabetes. Corneal
wounds were prepared by removal of the corneal epithelium, and documented using a TRC-50X equipped with a digital camera.
Sericin solutions were instilled into the eyes of rats five times a day following
corneal abrasion. Plasma
glucose and
triglycerides were determined using an Accutrend GCT.
Cholesterol and
insulin were measured using a
Cholesterol E-Test Kit and ELISA
Insulin Kit, respectively. The plasma levels of
glucose,
triglycerides,
cholesterol and
insulin in 38-week-old OLETF rats were significantly higher than in Long-Evans Tokushima Otsuka (LETO) rats used as normal controls, and the rate of corneal wound healing in OLETF rats was slower than in LETO rats. The corneal
wounds of rats instilled with saline showed almost complete healing by 72 h after corneal epithelial abrasion. On the other hand, the corneal healing rate of OLETF rats instilled with 10%
sericin solution was significantly higher than that of LETO rats instilled with saline, and the
wounds showed almost complete healing at 48 h after abrasion. The corneal healing rate increased with increasing
sericin concentration. The present study demonstrates that the corneal wound healing rate in OLETF rat is slower than in LETO rats, and the instillation of
sericin solution has a potent effect in promoting wound healing and
wound-size reduction in LETO and OLETF rats.