AIM: To investigate the role of histidine-rich glycoprotein(HRG)in the neovascularization of diabetic retinopathy in rats.METHODS: Streptozocin(STZ)-induced diabetic Sprague-Dawley(SD)rats were utilized as an experimental model, the protein expression of HRG and vascular endothelial growth factor(VEGF)in the retinas of normal(Wild type, WT)and diabetic(diabetic mellitus, DM)groups was detected using Western blot(WB). The protein expression of HRG in high-glucose-induced human retinal microvascular endothelial cells(hRMECs)was verified by WB after transfection with HRG small interfering RNA(siRNA)low-expression sequences. The optimal si-HRG#298 sequence was selected for further experiments. In the animal experiment, HRG gene silencing was achieved using an adeno-associated virus(AAV)vector, with AAV2-sh-NC and AAV2-sh-HRG#298 serving as the HRG gene silencing group and the HRG empty vector control group, respectively. The protein expression of HRG and VEGF in each group was then detected by WB following the verification of HRG protein expression. Retinal structural changes were observed by HE staining, and neovascularization changes were observed by PAS staining.RESULTS: HE staining found that the retinal structure in the DM group was disordered, the number of cells in the ganglion cell layer decreased, the number of cells in the inner and outer nuclear layers decreased, and the total retinal thickness also decreased(P<0.05); cellular capillaries were significantly increased in DM rats observed by PAS staining(P<0.05); the protein expression of HRG and angiogenesis factor VEGF was up-regulated in the retina of DM group(P<0.05); the protein expression of HRG was significantly downregulated in high glucose-induced hRMECs(P<0.05); the inhibition of neovascularization in diabetic retinas and the downregulation of VEGF protein expression were achieved through HRG gene silencing(P<0.05).CONCLUSION: HRG promotes neovascularization in the retinas of diabetic rats, and HRG gene silencing can inhibit neovascularization.