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World J Diabetes. Dec 15, 2013; 4(6): 282-289
Published online Dec 15, 2013. doi: 10.4239/wjd.v4.i6.282
Therapeutic effects of sericin on diabetic keratopathy in Otsuka Long-Evans Tokushima Fatty rats
Noriaki Nagai, Yoshimasa Ito
Noriaki Nagai, Yoshimasa Ito, Faculty of Pharmacy, Kinki University, Osaka 577-8502, Japan
Author contributions: Nagai N performed the research and analyzed the data; Nagai N and Ito Y wrote the paper.
Correspondence to: Yoshimasa Ito, PhD, Faculty of Pharmacy, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan. itoyoshi@phar.kindai.ac.jp
Telephone: +81-6-43073638 Fax: +81-6-43073638
Received: September 14, 2013
Revised: October 19, 2013
Accepted: November 15, 2013
Published online: December 15, 2013
Abstract

An Otsuka Long-Evans Tokushima Fatty (OLETF) rat provides a useful model for studies to develop corneal wound healing drugs for use in diabetic keratopathy resulting from type 2 diabetes mellitus. We investigated the effects of sericin on corneal wound healing in OLETF rats. Corneal wounds were prepared by removal of the corneal epithelium and documented using a TRC-50X. Sericin was instilled into the eyes of rats five times a day following corneal abrasion. The plasma levels of glucose, triglycerides, cholesterol and insulin in 38 wk old OLETF rats were significantly higher than in normal control rats (LETO rats), and the rate of corneal wound healing in OLETF rats was slower than in normal rat, probably due to the suppression of cell migration and proliferation caused by high plasma glucose levels. The corneal wounds of OLETF rats instilled with saline showed almost complete healing 72 h after corneal epithelial abrasion. On the other hand, the instillation of sericin has a potent effect in promoting wound healing and wound size reduction in OLETF rats and the wounds showed almost complete healing at 48 h after abrasion. The sericin may be an effective and safe drug to promote corneal wound healing in diabetic keratopathy.

Keywords: Sericin, Diabetic keratopathy, Cornea, Type 2 diabetes mellitus, Otsuka Long-Evans Tokushima Fatty rat

Core tip: Otsuka Long-Evans Tokushima Fatty (OLETF) rats provide a useful model for studies to develop corneal wound healing drugs for use in diabetic keratopathy resulting from type 2 diabetes mellitus. The present study demonstrates that the rate of corneal wound healing in OLETF rats is slower than in normal rat, probably due to the suppression of cell migration and proliferation caused by high plasma glucose levels. The instillation of sericin has a potent effect in promoting wound healing and wound size reduction in OLETF rats. The sericin may be an effective and safe drug to promote corneal wound healing in diabetic keratopathy.