| Objective:1. To establish animal model of diabetic retinopathy (DR) in Wistar rats, and to study the expression of apoptotic cells and fibrosing cytokine that connective tissue growth factor (CTGF) in retina of DR in rats with the extension of disease and their effects to the microcirculation.2. To discuss the effect of simvastatin to the expression of CTGF in the retina after intravitreal injection on rats with DR.3. To discuss the security of intravitreal injection with simvastatin, and to provide a theoretical basis for the treatment of DR.Methods:1. One hundred male Wistar rats weighted 200-220g with two months old were involved in this study. They were randomly divided into normal control group and diabetes mellitus group. Diabetes mellitus animal model were created by intraperitoneal injection with STZ (streptozotocin, STZ). According to the cours of diabetes, the rats were divided to sub-groups with diabetes mellitus of 2,4,6 months. Structure of retina was observed by HE staining. Vascular conditions were observed by periodic acid schiff (PAS) staining. Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL). Expression of CTGF was determined by immunohistochemistrical study.2. Thirty rats with diabetes mellitus of 4 months were involved in this study. Twenty rats were randomly selected from them. The right eye as intervention group which was intravitreal injected with simvastatin, and the left eye as blank control group which was intravitreal injected with dimethyl sulfoxide (DMSO). The rest of 10 diabetic rats weren't inject any drug in the eye, as diabetic positive control group. Structure of retina was observed by HE staining. Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL). Expression of CTGF was determined by immunohistochemistrical study. Electroretinogram (ERG) was checked. Results:1. Compared with normal control group, HE staining showed that retina of diabetes mellitus of 2 months group began to thin, disordered arrangement, part of the blood vessels began to dilate. Diabetes mellitus of 4 months group showed slight swelling of the retinal internal limiting membrane, and the surface was uneven and thickened. Ganglion cells arranged irregularly. Diabetes mellitus of 6 months group showed that the retina became thinner, more obviously deranged, and internal limiting membrane was swelling, and vasodilation was more apparent; PAS staining showed that retinal blood vessels were good shape in normal control group and diabetes mellitus of 2 months group. Retinal vascular was gradient stiff and narrow in diabetes mellitus of 4 months group. Backbone of retinal vascular was stiff, part of capillaries were narrow obviously in diabetes mellitus of 6 months group. The number of retinal pericytes began to decline in diabetes mellitus of 4 group. The number of pericytes was further reduced in diabetes mellitus of 6 group (t=3.367,6.667; P<0.05); The apoptosis index in the retina of diabetes mellitus of 2,4,6 months groups was increased gradually (t2-4=21.432, t2-6=50.843, t4-6=29.410; P<0.05), and the expression of CTGF was increased (t2-4=15.345, t2-6=26.316, t4-6=10.971; P<0.05).2. The expression of retinal CTGF in intervention group was significantly lower (t=12.112,1.257; P<0.05) than diabetic positive control group and blank control group 7 days after intravitreal injection with simvastatin. The retinal apoptosis index in intervention group was significantly lower (t=4.745,4.802; P<0.05) than diabetic positive control group and blank control group; Pathologic examination results were shown that retinal tissue was edema and cells were disordered arranged in diabetic positive control group and blank control group. Retinal tissue edema was reduced and cells were arranged gradually rules in intervention group. There was no systemic adverse reaction, no lens opacity, no endophthalmitis, no pigment membrane reaction and any other eye lesions, and there was no chang of ERG after intravitreal injection with simvastatin.Conclusion:1. Successfully established animal model of DR in rats. The appearances of cellular apoptosis and fibrosing factor CTGF in the retina of diabetes mellitus rats were increased gradually, and they were occurred earlier than the changes of microcirculation and the number of capillary pericytes.2. Simvastatin could inhibit the general expression of CTGF in the retina of DR in rats.3. Intravitreal injection with simvastatin to treat DR had some security, and provided theoretical basis for the treatment of DR. |
PDF Full Text Request