Abstract
Purpose:
Oxidative stress and inflammation play key roles in the light damage (LD) model of retinal degeneration, as well as in age-related macular degeneration (AMD). We sought to determine if berberine (BBR), an antioxidant herb extract, protects the retina against LD.
Methods:
Two-month-old male Balb/c mice were treated with BBR or PBS via gavage for 7 days, and then were placed in constant cool white light-emitting diode (LED) light (10,000 lux) for 4 hours. Retinal function and degeneration were evaluated via electroretinography (ERG) and optical coherence tomography (OCT) at 7d after LD. The mRNAs of several oxidative stress genes (Heme oxygenase1, Ceruloplasmin, Catalase, Glutathione peroxidase-1) were quantified by quantitative PCR (qPCR) 24h after LD. mRNA level of Rhodopsin (Rho) and retinal pigment epithelium 65 (Rpe65) were measured in neurosensory retina (NSR) and RPE samples respectively 7d after LD.
Results:
LD resulted in substantial photoreceptor-specific cell death. Dosing with BBR protected photoreceptors. The ERG analysis demonstrated functional protection by BBR in both rod-b, -a, and cone-b waves. In OCT images, mice receiving PBS showed severe thinning and disorganization of the photoreceptor layer 7 days after LD , whereas mice receiving BBR had significantly less thinning and disorganization (P<0.05). Consistent with OCT results, the mRNA level of Rho and Rpe65 were significantly higher in the NSR and RPE respectively from the mice treated with BBR. The retinal mRNA levels of oxidative stress genes were significantly lower in BBR treated mice compared to controls 24h after LD, which indicates oxidative stress was reduced by BBR in light-damaged eyes.
Conclusions:
Systemic BRB is protective against light-induced retinal degeneration associated with diminished oxidative stress in the retina. These results suggest that BRB could prove protective against retinal diseases associated with oxidative stress.