Abstract
Purpose:
Glutathione S-transferase pi isoform (GSTP1) is an intracellular detoxification enzyme that catalyzes reduction of chemically reactive electrophiles and is a zeaxanthin-binding protein in the human macula. We have previously demonstrated that GSTP1 levels are decreased in human age-related macular degeneration (AMD) retina compared to normal controls. We showed that GSTP1 levels parallel survival of human retinal pigment epithelial (RPE) cells exposed to UV light, and GSTP1 over-expression protects them against UV light damage. We also showed that GSTP1 in murine retina increases with developmental maturity (from post-natal day 20 to 2 months of age) and is induced by light exposure. In the present work, we determined the GSTP1 expression in the retina in aging mice and in response to light challenge.
Methods:
Eyes from BALB/cBy mice at 2 months, 12 months, and 24 months of age were prepared for retinal protein extraction and cryo sectioning, and the GSTP1 levels in the retina were analyzed by Western blot and immunohistochemistry (IHC). Another group of BALB/cBy mice with the same age ranges was exposed to 1000 lux of white fluorescent light for 24 hours, and their retinas were analyzed for GSTP1 expression by Western blot and IHC in a similar manner.
Results:
GSTP1 levels in the murine retina decreased with increasing age at 2 months, 12 months, and 24 months of age. In response to brief light exposure, GSTP1 expression initially increased at age 2 months then decreased and plateaued at 12 months and 24 months of age compared to age-matched controls under normal condition.
Conclusions:
GSTP1 expression in murine retina decreases with aging. Brief exposure to light induces GSTP1 expression in the murine retina at younger developmental age but declines with aging. GSTP1 induction may be a protective response to light-induced oxidative damage in the murine retina, and this protective response may decline with aging.
Keywords: 634 oxidation/oxidative or free radical damage •
514 enzymes/enzyme inhibitors •
698 retinal development