Abstract
Purpose: :
To assess the effects of N-acetylcysteine (NAC) in 2 models of RP, rd1+/+ mice with rapid retinal degeneration and rd10+/+ mice with relatively slow degeneration.
Methods: :
Rd1+/+ or rd10+/+ mice were treated with 1 or 7 mg/ml of NAC in their drinking water and the effect on oxidative damage was assessed by ELISA for carbonyl adducts on proteins, the effect on cone function was assessed by photopic electroretinograms (ERGs), the effect on cone survival was assessed by measuring cone cell density in peanut-agglutinin-stained retinal whole mounts, and the effect on rod survival was assessed by scotopic electroretinograms (ERGs) and measurement of outer nuclear layer (ONL) thickness.
Results: :
Compared to untreated rd10+/+ mice, those treated with 1 mg/ml NAC showed slightly slowed rod degeneration, because scotopic ERG b-waves were greater and ONL was thicker in 2 of 6 measurement locations at P35, but there were no differences in either parameter at P50. Retinal carbonyl levels were not reduced at P35, but were significantly reduced at P50 indicating that NAC reduced oxidative damage in the retina of rd10+/+ mice after rods degenerated. At P50, NAC-treated rd10+/+ mice showed significant elevation of photopic b-wave amplitudes and dose-dependently increased cone cell density; mean cone cell density (cones/0.0529 mm2) was 77±7, 181±10, and 291±21 for 0, 1, and 7 mg/ml NAC, respectively. Treatment with 1 mg/ml NAC also resulted in significant elevation of photopic b-wave amplitude and cone cell density at P30 in rd1+/+ mice.
Conclusions: :
The orally active antioxidant, NAC, preserves cone function and reduces cone death in a dose-dependent manner in models of RP.
Keywords: retinitis • antioxidants • retinal degenerations: hereditary