Buddleja Prescription Preventing And Treating Diabetic Retinopathy Tgf-¦Â/smad Signal Transduction Mechanisms

Objective:To investigate the effect and mechainsm of Mimeng Flower decoction on theretinal function and molecular change of diabetic rat,and further to study themechanism of signal transduction,in order to provide experimental basis forMimeng Flower decoction preventing and curing diabetic retinophty(DR).Methods:We reproduced diabetic animal model by injecting of Streptozotozcin(STZ),and used calcium dobesilate as positive control medicine.Mimeng Flowerdecoction has been divided into three different concentration including lowdosage,median dosage and high dosage.Begaining with the blood glucose rising,wetreated the Chiese medicine groups with Mimeng Flower decoction and treated thecontrol group with calcium dobesilate.After 4 months,we made the followingexperimental studies:1.To observe and test the general status of diabetic rats induced by STZ,suchas hairs,food and drink,urine and stool,weight,blood glucose and so on.2.To evaluate the damage of blood-retina barrier(BRB) by using Evans blue totracing the leakage of retinal capillary barrier.3.Through immunohistochemistry method to detect the protein expression of NF-κB,TGF-β₂ in retina of diabetic rats induced by STZ.4.Through RT-PCR method to detect the expression of TGF-β₂ mRNA,Smad2 mRNA inretina of diabetic rats induced by STZ.5.Through Western blot method to detect the expression of Smad2,P-Smad2 in retinaof diabetic rats induced by STZ.ResultsWe draw the following conclusion after 4 months:1.General status:diabetic rats induced by STZ had lasting and stable hyperglycaemia,and displayed the obvious signs of"polydipsia,polyphagia,hyperdiuresis and loss of weight".With the extension of treatment,mediandosage and low dosage of Mimeng Flower decoction could improve the typicaldiabetic symptoms compared with DM model group;the calcium dobesilate couldincrease the body weight of rats compared with homeochronous DM modelgroup(P＜0.05).2.Blood glucose:Compared with homeochronous normal group,the blood glucose ofthe rats increaded remarkably in DM model group (P＜0.01);Compared with thehomeochronous DM model group,each dosage of Mimeng Flower decoction reduced theblood glucose of the rats (p＜0.05 or P＜0.01).3.The results of the leakage of retinal capillary barrier show that the highdosage and median dosage of Mimeng Flower decoction reduced the leakage ofretinal capillary barrier of the rats,compared with the homeochronous DM modelgroup (p＜0.01).4.The results of immunohistochemistry test show that the expression of NF-κB in retina increased in DM model group markedly compared with normal group(P＜0.01);Mimeng Flower decoction groups and the calcium dobesilate group coulddecrease the expression of NF-κB in retina compared with DM model grouprespectively(P＜0.01).The expression of TGF-β₂ in retina decreased in DM modelgroup markedly compared with normal group (P＜0.01);Mimeng Flower decoctiongroups could increase the expression of TGF-β₂ compared with DM model group andthe calcium dobesilate group (P＜0.01).5.The results of RT-PCR test show that the expression of TGF-β₂ mRNA,Smad2 mRNAweakened in DM model group compared with normal group visibly;The expressionof TGF-β₂ mRNA,Smad2 mRNA in Mimeng Flower decoction groups and calciumdobesilate weakened in different extent compared with normal group,butall increased compared with DM model group.6.The results of Western blot test show that the expression level of Smad2,P-Smad2 weakened in DM model group compared with normal group visibly;Theexpression level of Smad2,P-Smad2 in Mimeng Flower decoction groups and calcium dobesilate increased compared with DM model group in different extent.conclusion1.STZ induced diabetic rat is a simple,high-ratio and reliable animol model.Mimeng Flower decoction could improve the typical diabetic symptoms comparedwith DM model group except the body weight,the calcium dobesilate could increasethe body weight of rats compared with homeochronous DM model group.2.Mimeng Flower decoction could reduce the leakage of retinal capillary barrierof the DM rats.3.The effect of improving the leakage of retinal capillary barrier of the DMrats may be contributed to the down regulation of NF-κB and the up regulationof TGF-β₂ in rat retina.4.The up regulation of the mRNA expression and protein level of TGF-β₂,Smad2,p-Smad2 may play a significant role in improving the retinal function by MimengFlower decoction.