| Diabetic retinopathy is one of the most important disease,caused to blindness in our country in recent years.With the level of life improving and lifestyle changing,the incidence of DR increased year by year.The pathological mechanism of DR is complicated.Recent studies suggested that DR is a mild chronic inflammatory disease.Pericytes decreasing and retinal basement membrane thickening can be founded in early stage.The key of the treatment of DR is improving retinal microangiopathy in early phases.Sericin is a natural protein of silkworm,consisting of 18 kinds of amino acids.About 25% of the silkworm is discarded in reeling and refining,causing a great waste.The studies suggested that sericin can reduce the activation of many inflammatory factors,resist inflammations,and have less side effects.However,the role of sericin in DR is rarely studied.The diabetic models were established by intraperitoneal injection of streptozotocin for 3consecutive days and feeding up with high calorie and high sugar foods.Compared with the expressions of retinal ICAM-1,VCAM-1 and Cx43 in each group,to investigate the effects of sericin in diabetic retinopathy and find a new approach for the treatment and premunition of DR.Objective:To observe the effects of sericin on intercellular adhesion molecule-1,vascular cell adhesion molecule-1 and Cx43 expressions in retina and explore the protection of sericin to retinal microangiopathy in diabetic rats.Methods:1 Forty-eight specific pathogen free male SD rats were divided into normal control group,diabetes model group,sericin-treated group and calcium dobesilate positive control group by computer random numbermethod,the number of rats in each group is 12.The diabetic model was established by intraperitoneal injection of streptozotocin for 3 consecutive days and feeding up with high calorie and high sugar foods.Normal saline solution,2.4 g/(kg·d)sericin soulution and 0.2 g/(kg·d)calcium dobesilate were used by gavage administration in the rats of the diabetes model group for35 days,sericin-treated group and calcium dobesilate positive control group,respectively.2 Fasting blood glucose meter was used to test the blood glucose of rats in each group.3 The retinal morphology was examined by hematoxylin-eosin staining.4 The expressions of ICAM-1,VCAM-1 and Cx43 proteins in retinas were detected by Western blot assay.5 The expressions of ICAM-1,VCAM-1 and Cx43 mRNA in retinas were detected by reverse transcription PCR.Results:1 Before the diabetic models established,the FBG of rats in each group has no significant difference,after the model completely established,except the normal control group,the FBG of rats in other groups significantly increased,compared with the normal control group(P<0.05).After treated with sericin soulution and calcium dobesilate repectively,the FBG of rats in sericin-treated group and calcium dobesilate positive control group were obviously reduced,compared with diabetes model group(P<0.05).2 The retinal structure was normal in the normal control group.The swell and rupture of inter limiting membrane(ILM),scatter vascular endothelial cell nuclei breakthrough ILM and decrease of retinal ganglion cells(RGCs)were displayed in the diabetic model group;while in the sericin-treated group and calcium dobesilate positive control group,the mild thickening of ILM and disorder of retinal cells were obtained.3 The relative expression levels of ICAM-1 and VCAM-1 proteins were obviously raised and those of Cx43 were reduced in the diabetic model group compared with the normal control group(all at P<0.05).Compared with thediabetic model group,the expressions of ICAM-1 and VCAM-1 proteins in the sericin-treated group and calcium dobesilate positive control group were significantly reduced and those of Cx43 protein were evidently elevated(all at P<0.05).4 The relative expression levels of ICAM-1 and VCAM-1 mRNA were significantly raised and those of Cx43 mRNA were reduced in the diabetic model group,when compared with the normal control group(all at P<0.05).Compared with the diabetic model group,the expressions of ICAM-1 and VCAM-1 mRNA in the sericin-treated group and calcium dobesilate positive control group were significantly reduced and those of Cx43 mRNA were evidently elevated.Conclusion:Sericin can relieve retinal microangiopathy and protect retina against the pathogenesis and development of DR by down-regulating the expressions of ICAM-1,VCAM-1 and up-regulating the expression of Cx43 in retinas of diabetic rats. |
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