ABSTRACT
AIM:To investigate the changes of visual development produced by monocular atropinization in rats. METHODS: Twenty normal SD rats were randomly divided into two groups: control group ( n = 10 ) and atropinization ( experimental) group ( n=10 ) . All the left eyes were selected as the experimental eyes, and the right eyes served as the normal eyes. The left eyes in atropinization group was produced by 1% atropine, 3 times a day and the right eyes in control group was treated with normal saline, 3 times a day. The flash visual evoked potentials ( F-VEP ) and retinoscopy refraction of the rats'both eyes were detected at five time points:0, 7, 14, 21, and 28d after atropinization, respectively. After 28d, six rats were randomly selected from both groups and each group had three rats. The expression of the c- fos mRNA was observed in both visual cortexes. Another six rats were chosen for the same test after 2d dark environment with 2h light later. The expression of c-fos mRNA was detected again. RESULTS: After 14d anisometropia was observed in experimental group, the difference was 3. 9D ( P 0.0 5 ) , F-VEP P1 wave of the rats left in experimental group was reached to 88. 9±1. 889ms at 21d, there was statistical difference compared with the right eye ( PCONCLUSION: In the critical period of visual development, monocular chronic atropine in rats can form anisometropia, may delay the transmission of the optic nerve, hinder the normal development of the visual cortex. Monocular atropinization in rats can be used as the model of anisometropia.
ABSTRACT
Background Oxidative stress plays an important role in the pathogenesis of diabetic complications.Peroxiredoxin 6(Prx6) is a doubly-functional protein.and its ability to eliminate phospholipid hydroperoxides is essential. Objective The aim of this study was to investigate the dynamic expression of Prx6 in the retina of streptozotocin(STZ)-induced diabetes and explore its correlation with the progression of diabetic retinopathy. Methods Diabetes was induced by an intraperitoneal injection of streptozotocin(STZ)in 48 clean Wistar rats.The rats were sacrificed at 1,2,and 4 months after the injection of STZ,and expressions of Prx6 protein and Prx6 mRNA in the retina was determined by immunohistochemistry and reverse transcription polymerase chain reaction.Another 12 matched normal Wistar rats were used as the control group. Results The resuh of immunohistochemistry showed that Prx6 protein was expressed in the cytoplasm of the outer nuclear layer(ONL)and inner nuclear layer(INL)in normal rats,and low expression of Prx6 protein was observed in the ganglion cell layer (GCL).In the first month,Prx6 protein was strongly expressed in the INL and the ONL of diabetic rats.However.two and three months after STZ administration,the expression of Prx6 protein was absent in the retina,showing a considerable difference among different course groups(F=22 967.63,P＜0.05).Furthermore,the expression trend of Prx6 mRNA in the retina was similar to that of the Prx6 protein with a significant difference among different course groups(F=942.84,P＜0.05). Conclusion It is conceivable that normal maintenance of Prx6 expression may be important to the prevention of diabetic retinopathy.We hypothesize that oxidative impairments in the retina that develop over time may partly contribute towards the development of retinal dysfunction,which eventually leads to retinal degeneration during the progressive phase of STZ-induced diabetes in adult rats.
ABSTRACT
<p><b>BACKGROUND</b>Retinal pigment epithelial (RPE) cells play an important role in the occurrence of choroidal neovascularization (CNV). Vascular endothelial growth factor (VEGF) as a positive regulatory growth factor is produced by the RPE in an autocrine or paracrine manner, promoting CNV development. Duplexes of 21 nt RNAs, known as short interfering RNAs (siRNAs), efficiently inhibit gene expression by RNA interference when introduced into mammalian cells. We searched for an efficient siRNA to interfere with VEGF expression in RPE cells and shed light on the treatment of CNV.</p><p><b>METHODS</b>Human primary RPE (hRPE) cells were cultured and identified. Three pairs of siRNAs were designed according to the sequence of VEGF 1-5 extrons and synthesized by T7 RNA polymerase transcription in vitro. To evaluate the inhibitory activity of T7-siRNAs, hRPE cells were transfected via siPORT Amine. The interfering effect of T7-siRNAs in hRPE cells was examined by semiquantitative reverse transcription-polymerase chain reaction and immunofluorescence.</p><p><b>RESULTS</b>Three pairs of T7-siRNAs synthesized by in vitro transcription with T7 RNA polymerase suppressed VEGF gene expression with efficiency from 65% to 90%. T7-siRNA (B), targeted region at 207 nt to 228 nt and double stranded for 21 nt with 2 nt UU 3' overhangs, was the most effective sequence tested for inhibition of VEGF expression in hRPE cells. Compared with nontransfected cells, the mean fluorescence in hRPE cells transfected with T7-sRNAs was significantly less (P < 0.01). siRNA with a single-base mismatch and ssRNA(+) did not show suppressing effect. Furthermore, it was found that siRNAs had a dose dependent inhibitory effect (5 to 10 pmol).</p><p><b>CONCLUSION</b>T7-siRNA can effectively and specifically suppress VEGF expression in hRPE cells and may be a new way to treat CNV.</p>