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In-Beom Kim, Gyu Hyun Kim, Sun-Sook Paik, Yongsoo Park, Hyung Il Kim; Glycyrrhizic acid attenuates retinal degeneration induced by blue light-emitting diode exposure in mice. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5910.
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The root and rhizomes of licorice (Glycyrrhiza) have been used as an herbal medicine, because they have various therapeutic effects, such as anti-inflammatory and antioxidative activities. Glycyrrhizic acid (GA) is a major component in the root and rhizomes of licorice. In this study, we examined the effect of GA in an animal model for retinal degeneration (RD), which is the leading cause of blindness and characterized by the irreversible and progressive degeneration of photoreceptor cells in the retina.
RD was induced in BALB/c mice by exposure to a blue light-emitting diode (LED) (460 nm) for 2 hours. To examine retinal functions, electroretinography (ERG) was performed. To assess histopathological changes, hematoxylin and eosin (H&E) staining were conducted. Apoptotic cell death was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. In addition, changes in proinflammatory cytokines were detected by real time RT-PCR and retinal stress and inflammation were evaluated by immunohistochemistry with anti-ionized calcium binding adaptor molecule 1 (Iba-1) and anti-glial fibrillary acidic protein (GFAP).
Scotopic ERG showed that both a- and b-waves were significantly reduced in RD mice, while amplitudes of both waves were significantly increased in GA-treated RD mice, compared to those in non-treated RD animals. H&E and TUNEL assay showed that the outer nuclear layer where photoreceptors reside appeared to be more preserved and less apoptotic cells were observed in GA-treated RD retinas than in non-treated RD retinas. GA reduced expression of proinflammatory cytokines, such as TNF-α, IL-6, IL-1β, CCL2 and 6, iNOS, and Cox-2. In addition, GA reduced expression of Iba-1 and GFAP, indicating decreased glial response, retinal stress and inflammation.
These results demonstrate that GA reduces retinal inflammation and prevents photoreceptor cell death from experimentally induced RD, suggesting that GA may have a potential for the treatment of RD as a medication.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Evaluation of protective effect of GA against photoreceptor cell death at 3 day after blue LED exposure by TUNEL staining
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