ObjectiveTo analyze the effects of Dan Huang Ming Mu Recipe (DHMMR) (a pharmaceutical preparation from herbs and having the function of replenishing vital essence, removing heat, promoting blood circulation and excreting pathogenic water) on diabetic retinopathy (DR) after retinal laser photocoagulation through regulating the expression of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF).
MethodsForty male Brown Norway (BN) rats were randomly divided into blank group (group A, 10 BN rats) and model group (30 BN rats). DR models were induced by 40 mg/kg streptozotocin (STZ) and the body weight and blood glucose of rats were monitored. After 12-week injection, fluorescein fundus angiography (FFA) and histopathological examination were detected to confirm the successful establishment of DR models. Subsequently, the right eyes of model group rats were conducted retinal laser photocoagulation with the left eyes having no retinal laser photocoagulation and rats of the model group were randomly divided into group B (the model control group), group C (the positive control group), and group D (the DHMMR group), with 10 rats in each group. Rats of the group A and the group B were given vehicle, and the group C were given calcium dobesilate suspension by gavage, and the group D were given DHMMR by gavage. After 4-week gavage, FFA was carried out to observe the fundus microvascular change. Then, the rats were sacrificed to do histopathological examinations and the serum levels of P-selectin, cAMP, cGMP, and the relative expression of the protein of VEGF and PEDF in retina were detected.
ResultsAfter 12-week STZ injection, the blood glucose of the model group were pronouncedly higher than the blank group (P < 0.01). Fundus micro-hemangioma changes were observed in the rats of the model group through FFA, and the rats of the blank group did not see any changes. The pictures of HE staining showed that the retinal structure of the model group was more disordered than the blank group. After 4-week gavage, treatments with DHMMR showed dramatic reduction of serum levels of P-selectin, cAMP and cGMP compared with the group B (P < 0.01). FFA and histopathological examinations of DHMMR-treated rats revealed significantly suppression of retinal edema, fundus microvascular destruction and retinal destruction distinguishing from the group B. And the relative expression of VEGF protein of the group D and the group A was markedly lower than that of the group B (P < 0.01). The relative expression of PEDF protein of the group D and the group A was dramatically higher than that of the group B to the contrary (P < 0.01).
ConclusionsDHMMR demonstrates pronounced suppressive effects on the progression of DR after retinal laser photocoagulation, through down-regulating VEGF and up-regulating PEDF.
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