Typhae pollen polysaccharides ameliorate diabetic retinal injury in a streptozotocin-induced diabetic rat model

Abstract Ethnopharmacological relevance According to ancient traditional Chinese medicine, Typhae Pollen (TP) is commonly used to treat fundus haemorrhage because it improves blood circulation. Aims of the study This study evaluated the role of the main TP component, polysaccharides (TPP), on diabetic retinopathy (DR) and its possible mechanisms of inhibiting inflammation and improving blood circulation. Materials and methods After successful establishment of a diabetic rat model, TPP was administered to diabetic rats for treatment, and the rats were sacrificed at 12 weeks. Retinal electrophysiology and ultrastructures were observed, and serum interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) levels were also measured. Changes in the retinal expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were examined by immunofluorescence. A mouse model of acute blood stasis was then established, and the effects of TPP on haemorheology were observed. The anti-inflammatory effect of TPP was analysed based on the changes in abdominal capillary permeability and the degree of auricle swelling in the mice. Results In streptozotocin (STZ)-induced DR rats, TPP (0.4 g/kg) treatment restored electrophysiology indexes and retinal ultrastructures, reduced serum IL-6 and TNF-α levels, decreased VEGF and bFGF expression in retinal tissues, and improved haemorheology indexes. Moreover, TPP reduced abdominal capillary permeability and relieved auricle swelling in a dose-dependent manner. Conclusions TPP treatment ameliorated DR by inhibiting inflammation and improving blood circulation.