METHODS: Fifty SPF rats were randomly divided into five groups: control group with normal feeding, DR group was given the same amount of normal saline by gavage, experimental group A with Pollen Typhae extract 50mg/(kg·d), experimental group B with Pollen Typhae extract 100mg/(kg·d)and experimental group C with Pollen Typhae extract 200mg/(kg·d). Determination of fasting blood glucose in rats of each group. HE staining was used to observe the pathological changes of retina of rats in each group. The expression of IL-6 and TNF-α in the serum of rats were measured by ELISA. The VEGF, VEGFR2 and Ang-1 protein expression in retina tissue were observed by Western blot. The VEGF, VEGFR2 and Ang-1 mRNA expression in retinal tissue were observed by qRT-PCR.

RESULTS: Compared with the control group, the fasting blood glucose, the expression of IL-6 and TNF-α in serum and VEGF, VEGFR2 and Ang-1 protein and mRNA expression in retina tissue in DR group and each experimental group were significantly higher(P<0.05). Compared with DR group, fasting blood glucose decreased in all experimental groups, and the fasting blood glucose of experimental groups B and C was significantly decreased than that of DR group(P<0.05). In addition, the contents of IL-6 and TNF-α in serum, the protein and mRNA expression levels of VEGF, VEGFR2 and Ang-1 in retina tissue in experimental group B and group C were significantly lower than those in group DR(P<0.05). The results of HE showed that the structure of retinal photoreceptor cell layer in DR group was obviously destroyed, the cell edema and gap widened, and the retinal histopathology of rat retina in group B and group C were improved in varying degrees.

CONCLUSION: Pollen Typhae extract can down-regulate the level of inflammation and the expression of VEGF, VEGFR2 and Ang-1 in DR rats, so as to improve the retinopathy.