Polygonatum sibiricum polysaccharide potentially attenuates diabetic retinal injury in a diabetic rat model

AIMS/INTRODUCTION: To investigate the protective effect of Polygonatum sibiricum polysaccharide (PSP) on the retina in diabetic rats. MATERIALS AND METHODS: A total of 120 Sprague–Dawley rats were randomly divided into blank control, control model (meaning diabetes mellitus), and diabetes mellitus with PSP intervention of high, medium and low doses groups. The difference of retinal vascularization between groups was evaluated by fluorescein isothiocyanate‐dextran perfusion. Terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling staining was used to assess apoptosis in the retinal ganglion cells; reverse transcriptase polymerase chain reaction and western blotting were utilized to evaluate the expression of Bcl2‐associated X protein, B‐cell lymphoma‐2 factor, epidermal growth factor, p38 mitogen‐activated protein kinases, transforming growth factor‐β and vascular endothelial growth factor at the messenger ribonucleic acid and protein level. RESULTS: Fluorescein isothiocyanate‐dextran perfusion showed retinal vascular anomaly in diabetes mellitus rats, but vascular tortuosity and leakage were relatively alleviated after PSP intervention. Terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling staining showed numerous terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling‐positive retinal cells in the diabetes mellitus group, which then were reduced by PSP treatment. Reverse transcriptase polymerase chain reaction showed that PSP intervention decreased Bcl2‐associated X protein, epidermal growth factor, p38 mitogen‐activated protein kinases, vascular endothelial growth factor and transforming growth factor‐β messenger ribonucleic acid expression, but increased B‐cell lymphoma‐2 factor messenger ribonucleic acid expression. Western blot showed that PSP intervention upregulated the expression of B‐cell lymphoma‐2 factor, and downregulated the expression of Bcl2‐associated X protein, epidermal growth factor, p38 mitogen‐activated protein kinases, vascular endothelial growth factor and transforming growth factor‐β proteins. CONCLUSIONS: Polygonatum sibiricum polysaccharide shows a protective effect against diabetes‐induced retinal injury in a dose‐dependent manner. The mechanism of action deserves further study and exploration.