Abstract
Purpose: :
To compare levels of diabetic and non-diabetic corneal γ-glutamyltranspeptidase (GGT; an ectoenzyme key to glutathione recapture and protection against oxidative stress).
Methods: :
Corneas were obtained from human donor eyes (25 non-diabetic and 15 diabetic). Whole cornea, epithelial and endothelial GGT activities were determined using a standard colorimetric assay.
Results: :
Diabetic and non-diabetic donors were similar with respect to cause of death and corneal endothelial cell density, but non-diabetic donors were younger on average than the diabetic donors. Total (p=0.08) and endothelial GGT (p=0.7), but not epithelial (p=0.85) GGT activities were lower in diabetic than non-diabetic human corneas. Total (m=-0.11), endothelial (m=-0.27) and epithelial (m=-0.46) GGT activity of non-diabetic corneas decreased with donor age. Endothelial cell density and GGT activity was significantly higher (p’s< 0.01) in the younger (≤55 years-old) donors than the senior (>55 years-old) donors. Epithelial GGT activity was higher in diabetic than non-diabetic senior donor corneas (p=0.04).
Conclusions: :
GGT activity was reduced in non-diabetic human corneas. Human corneal GGT activity and endothelial cell density declined with age, but epithelial GGT activity was higher in senior diabetic than non-diabetic donor corneas suggesting GGT is increased in the diabetic corneal epithelial possibly in response to diabetic oxidative stress.
Keywords: cornea: clinical science • diabetes • pathology: human