Abstract
Abstract: :
Purpose: Antioxidant enzymes are very important protective systems against oxidative stress, especially on body surface including ocular one. We have investigated the developmental changes of the expressions of antioxidant enzymes in the rat fetal, neonatal, and adult cornea using an immunohistochemical technique. Methods: This study was carried out on Spraque-Dawley rat cornea from 15 fetuses (15, 17, and 20 days of gestation), 15 neonates (0, 7, 14, 17, and 21 days of age) and 6 adults (over 28 days of age). The specimens of the cornea were embedded in paraffin, and cut into 6-µm-thick sections. The sections were stained with hematoxylin and eosin, and used for the immunohistochemical staining. The following primary antibodies were used: rabbit polyclonal antibodies against rat Cu,Zn-superoxide dismutase (SOD1), Mn-SOD (SOD2) , glutathione peroxidase (GPx) and thioredoxin peroxidase (TPx). Results: Intense immunoreactivities of SOD1, SOD2, and GPx were detected in the epithelia and endothelia of the adult rat cornea, and mild immunoreactivity of TPx was also observed. The expressions of SOD1, SOD2, and GPx in the corneal epithelia were observed at 15 days’ gestation, and after that, these expressions were gradually increased. However, the intensity of each enzyme expression was decreased temporarily at neonate day 0 (immediately after birth) and day 17 (immediately after enlightment). After birth, the cornea showed histologically the multiplication of the epithelia, and the staining intensities of all antioxidant enzymes in corneal epithelia were increased in association with epithelial multiplication. Conclusions: The expressions of antioxidant enzymes in corneal epithelia were detected from neonatal period. These expressions were thought to be prepared as the protective device against the oxidative stress after birth. The temporal decrease of the expression intensity of all antioxidant enzymes after birth and enlightment was considered to be the result of consumption by the external stimuli such as an ultraviolet ray. A possibility that oxidation stress and redox system are related to the multiplication of the corneal epithelia was suggested.
Keywords: cornea: basic science • antioxidants • immunohistochemistry