An Experimental Study Of The Oxidative Stress Of Cavernosum In Diabetic Rats With Erectile Dysfunction

Objective:To observe the level of oxidative stress of cavernosum tissues in rats and the expression of eNOS in cavernosum endothelial cells of rats with erectile dysfunction, to explore the relation and the molecular mechanisms between Oxidative stress and erectile dysfunction.Methods:60male SD rats (10weeks old) were divided randomly into three groups which were nomal control group (group A.20), buffer control group (group B.20)and diabetes group (group C.20).By the method of tail vein injection of STZ,we chose group C to establish the rat model of diabetes.All rats were bred for eight weeks regularly.we chose the method of subcutaneous injection of APO to observer whether the penis erectile and record the erection frequency in30minutes.We surgically removed the cavernous body of penis after anesthetizing and weighing and then divided the penis into three portions:one of them was made into tissue bomogenate.the level of SOD.MDA and NO were assayed by Colorimetry; one of them was determined to observe the change of its ultramicrostructure by electron microscope; The morphology of cavernosum in the last one was observed with microscopy. And the expression of eNOS protein in endothelial cells were detected using streptavidin-biotin peroxidase (S-P) method. The data were analyzed with SPSS17.0. P<0.05as statistically significant difference.Results:(1Establishment of diabetic rat model and APO test results:19of20group C rats were successfully modeled and appear the diabetic complications such as polydipsia, polyphagia. polyuria and apparent weight loss.8weeks later,4of19rats died of infection and other diabetic complications. All of the A,B group rats had no ED:only one of the remained15of group C was not suffered from ED.Compared with group A and B. the eretile positive rate of group C was significantly different(p<0.05).(2)Oxidative Stress:In the erectile tissues of group C,MDA level were apparently higher (P<0.05) and SOD activities were apparently lower (P<0.05) than the groupA and B.(3) Histological ultramicrostructure changes:Cavernosum of groupA.B rats contain a large of sinusoids.and sinusoid trabeculum contains a lot of smooth muscle and collagen fibers. In the erectile tissues of group C.the number of smooth muscle fibers decreased;the density of collagen fiber increased;penis blood vessel wall thickened:Lumen became irregular.By the electron microscope,group A.B showed well-developed vascular endothelial cells.smooth sinusoid lumen.uniform distribution of endothelial cells.vascular wall continuous and comlete.Under the electron microscope,in the group C we observed that sinusoidal endothelial cells of cavernous were roughed and breakaged.small vascular endothelial cell proliferated.blood capillary became stenosis and were thrombogenesised.the mitochondria swelled and expanded and so on.(4) Expression of eNOS and content of NO:In the erectile tissues of group C.NO level were apparently lower (P<0.05) than the groupA and B. eNOS expressed in sinusoidal endothelial cells of all group.The expression of eNOS in group C significantly down-regulated compared with groupA.B. The expression of eNOS betwwen group C and groupA.B was statistically significant difference(P<0.05).Conclusions:(1)That the increase of MDA content, the decrease of SOD activity、the expression of eNOS and the NO content,the occurrence of oxidative stress could be induced by diabetes in the cavernosum of adult male rats.(2) It was indicated that the oxidative stress induced by diabetes in the cavernosum had close relationship with the impairment of structure and/or function of endothelial cells.(3) The important cause of the pathogenesis of diabetic ED could include the oxidative stress induced by diabetes in the cavernosum. the decrease of the expression of eNOS in endothelial cells and the endothelial NO content.