Immunohistochemical localization of heme oxygenase isozymes in the aged rat retina / 대한해부학회지

ABSTRACT

Heme oxygenase (HO)-1 and -2 isozymes are important markers for the oxidative stress. We localized HO-1 and HO-2 immunoreactivities and assessed the effect of aging on distribution of HO in the young and aged rat retina by immunohistochemical method. HO-1 and HO-2 showed partly different patterns of localization, indicating possibilities of different regulation of these two isozymes in the retina. HO-2 immunoreactivity was localized to some retinal neurons in ganglion cell layer and inner nuclear layer involving both of plexiform layers and pigment epithelium. The distribution of HO-2 positive cells did not show any difference between aged and young rat. In the case of HO-1, the immunoreactivity is found in retinal layers except outer nuclear layer and layer of rods and cones of young rat retina. The distribution of HO-1 immunoreactivity in old rat retina does not show remarkable difference compared with that in young rat retina, except in inner nuclear layer, outer plexiform layer and pigment epithelium. HO-1 positive components increased in inner nuclear layer, and decreased in outer plexiform layer and pigment epithelium with aging. This may suggest that the possibility of decrease in HO-1 mediated protective function against oxidative stress in outer retinal region of old rat. Another isozyme, HO-2, may not be influenced by normal aging process in rat retina. However, the localization of HO-1 and HO-2 in retina suggests that these two isozymes contribute to visual impairment in normal aging process.