Neuroprotective effect of glycyrrhizin on diabetic retinopathy

To explore the potential anti-inflammatory effects and retinal neuroprotective effects of glycyrrhizin (GL) on diabetic retinopathy (DR),twenty-one male C57BL/6 mice were randomly divided into control group,model group and glycyrrhizin (GL) group. The diabetic mice model was established by intraperitoneal injection of STZ. The GL group was treated with GL (150 mg/kg/d) by gavage for 6 weeks after modeling. Retinal tissue sections were paraffin-embedded and morphological examinated with hematoxylin-eosin (HE). Immunohistochemistry was used to detect the expression of GLUT1,GFAP and GAP43. RT-PCR was adopted to detect retinal inflammation and expression of apoptotic mediators (TNF-α,IL6,iNOS,NF-κB and Tp53). The results showed that the diabetic mice developed retinal disorders and retinal degeneration. The expression of glial cell proliferation marker GFAP was up-regulated,while the expression of neuronal plasticity marker GAP43 was down-regulated;NF-κB,TNF-α,IL6,iNOS and Tp53 transcription in the retina of diabetic mice increased. In the GL group,the degree of down-regulation of GLUT1 expression in the retina of diabetic mice was reduced,retinal inflammation was eliminated and the structure was improved. The above results suggested that GL may be a potential neuroprotective agent for diabetic patients and has anti-inflammatory effects,but its efficacy and safety in DR patients requires further clinical studies.