Objective To investigate the protective effect of Niacin on blood-retina barrier (BRB) in diabetic rats and related mechanism. Methods The male Wistar rats (60) were divided into control (CON) group, diabetes (DM) group and Niacin-treated (NA) group, 20 rats in each group. Rats diabetes models were induced with streptozotocin injection. Niacin (40 mg/kg·d) was administrated orally everyday in Niacin-treated group until sacrificed after 3 months. Pathological outcomes, total cholesterol (TC) and high-density lipoprotein (HDL) were evaluated at month 3. Optical microscopy was used to observe the retinal structure. The integrity of BRB and the vascular permeability was quantified by analyzing albumin leakage using Evans blue (EB) method. The relative expressions of Claudin-5, Occludin, zonula occluden (ZO)-1 and GPR109A mRNA in rat retinas were detected by reverse transcription PCR (RT-PCR) and relative expression of GPR109A, tumor necrosis factor (TNF)-α and interleukin (IL)-6 by Western blot. Results Compared to CON group, the TC content was increased and HDL content was decreased in DM group (t=4.034, 5.831; P < 0.05). Compared to DM group, the TC content was decreased and HDL content was increased in NA group (t=6.868, 3.369; P < 0.05). The retinal structure of CON group was normal. Pathological changes were found in the DM group, such as tumescent nuclei and disorganized structures. The retinal structure of NA group was similar to the control group. Evans blue dye that the microvascular leakage in DM group was increased compared with CON group (t=24.712, P < 0.05), while in NA group was decreased compared with DM group (t=16.414, P < 0.05). The mRNA expression of Occludin, Claudin-5, ZO-1 in DM group were decreased compared with CON group (t=11.422, 12.638, 12.060; P < 0.05), while in NA group were increased compared with DM group (t=5.278, 3.952, 8.030; P < 0.05). The mRNA expression of GPR109A in NA group were increased compared with DM group (t=5.053, P < 0.05). The protein expression of GPR109A, IL-6, TNF-αin DM group were increased compared with CON group (t=4.915, 11.106, 6.582; P < 0.05). Compared to DM group, the protein expression of GPR109A was increased (t=5.806, P < 0.05), while the protein expression of IL-6 and TNF-α were decreased (t=10.131, 5.017; P < 0.05). Conclusion Niacin has the protective effect for BRB by up-regulating GPR109A expression which may suppress inflammation.
Objective To investingate the ultrastructural changes of retinal pigment epithelium(RPE) and its permeability in spontaneously hypertensive rats(SHR)and explore the relation between these changes and hypertensive retinopathy.MethodsThe ultrastructure of RPE cells in the SHR aged five,six,seven months wasobserved with transmission electronmicroscope and compared to its normotensive control strain(WKY) with the same age.Then,lanthanum tracer procedures were carried out to investigate pathological changes of the blood-retinal barrier.Results (1)In SHR the main pathological changes involved swelling of mitochondria,enlargement of endoplasmic reticula,decrease of RPE cell infolding,and sparseness of microvilli.These degenerations were more serious in older rats with higher blood pressure.(2)The breakdown of outer blood-retinal barrier with permeation of lanthanum tracers were evident in SHR aged six or seven month,however,in WKY and five-month SHR the traces were prevented from passing by tight junctions.ConclusionThe degeneration of RPE owing to ischemia and anoxia arises in early periosd of hypertensive retinopathy.The pathological changes of ultrastructure and permeability might interact with the damage of visual cells and play a main role in the hypertensive retinopathy.
Objective To observe the effect of different concentration netrin-1 on retinal vascular permeability in diabetes mellitus (DM) rats. Methods Eighty adult Sprague-Dawley rats were randomly divided into 8 groups, 10 rats in each group, including normal control group (group A), normal＋balanced salt solution (BSS) group (group B), normal＋netrin-1 (500 μg/ml) group (group C) and DM group (50 rats in 5 sub-groups). DM rats were induced by intraperitoneal injection of streptozocin. Three months after intraperitoneal injection, 10 DM rats in the control group were injected with BSS (group D). Forty DM rats were injected with 5 μl of different concentrate netrin-1, and were divided into DM+netrin-1 10 μg/ml group (group E), DM+netrin-1 50 μg/ml group (group F), DM＋netrin-1 100 μg/ml group (group G), DM＋netrin-1 500 μg/ml group (group H) according to the different concentration. Non-DM rats in group C were injected with netrin-1 500 μg/ml. The expression of occludin was determined by immunohistochemistry for protein, and by real-time fluorescence quantitative reverse transcription polymerase chain reaction for mRNA level. Retinal vascular permeability was measured by Evans blue infusion. Results The expression of occludin protein and mRNA in group D were less than group A (t=27.71, 8.59;P=0.00, 0.00). However, the retinal vascular permeability increased in group D (t=−42.72,P=0.00). The expression of occluding protein, occludin mRNA and retinal vascular permeability showed significant differences between group D, E, F, G and H (F=146.31, 16.54, 67.77;P=0.00, 0.00, 0.00). Compared the group B with group C, there was no significant differences between the expression of occludin protein, occludin mRNA and the retinal vascular permeability (t=−1.13, 0.93, 1.04;P=0.27, 0.36, 0.31). The concentrate of netrin-1 showed a significant positive correlation to the expression level of occludin and occludin mRNA (r=0.73, 0.81;P=0.00, 0.00), but negative correlation to the vascular permeability (r=−0.61,P=0.00). Conclusion Netrin-1 can reduce the DM rats' retinal vascular permeability, which depended on the concentration of netrin-1.
Objective To investigate the effects of Hep-A and Hep-B on vascular endothelial growth factor (VEGF)-induced breakdown of blood-retinal barrier. Methods The mice were subcutaneously injected vehicle, Hep-A or Hep-B 10 mg/kg twice a day for 5 days. Then, 1 μl of 10-6mol/L VEGF were intravitreous injected. After 6 hours, 13.7×104Bq/g3H-mannital were injected intraperitoneally. The mice were sacrificed and the retinas, lungs, kidneys were removed and examined for radioactivity. The result were analyzed using SPSS software to calculate and compare retina/lung and etina/kidney leakage ratio among groups of different treatment. Result The retina/lung and retina/kidney leakage ratio were 0.38±0.04 and 0.21±0.03 respectively in normal mice; increased significantly to 1.05±0.11 and 0.46±0.04 respectively in model mice, both Plt;0.01 compared to those in normal mice; decreased to 0.59±0.06 and 0.32±0.03 respectively in mice treated with Hep-A, both Plt;0.01 compared to those in model mice; decreased 0.54±0.04 and 0.35±0.03 in mice treated with Hep-B,both Plt;0.01 compared to those in model mice. Conclusion Hep-A and Hep-B can significantly reduce VEGF-induced breakdown of blood-retinal barrier in mice. Chin J Ocul Fundus Dis，2004，20：352-354)
Obiective lt;brgt;To investigate the change of the activity of proliferation in cultivated Muuml;ller cells treated by advanced glycation endoproducts (AGEs), and the effect of these changes on expression of occludin in bovine retinal vascular endothelial cells (BREC). lt;brgt;Methods lt;brgt;The cultivated Muuml;ller cells were devided into normal growth group and cultured with AGEs group. The cultured BREC were devided into 4 groups:group 1, without any medium; group 2, with normal growth Muuml;ller cell medium (MCM); group 3,MCM treated by AGEs; group 4, without cell as the control. Enzyme-linked immuno sorbent assay was used to detect the content of occludin in the medium in the 4 groups. lt;brgt;Results lt;brgt;The content of expression of occludin was the most in group 2, less in group 1, and the least in group 3. lt;brgt;Conclusion lt;brgt;AGEs may promote the abnormal proliferation of Muuml;ller cells and inhibit the expression of occludin in BREC. lt;brgt;(Chin J Ocul Fundus Dis, 2006, 22: 28-30)
Objective To investigate the relationship between expression of retinal intercellular adhesion molecule-1 (ICAM-1) and blood-retinal barrier (BRB) rupture and therapeutic effect of intravitreous injection with triamcinolone acetonide (TA) on blood-retinal barrier rupture in rats with diabetes mellitus (DM). Methods Diabetic model of Wistar rats was induced and were divided into normal control group, DM-4-month group and DM-6-month group. Each group was subdivided into immunohistochemcial staining and BRB measurement groups. BRB measurement group was further divided into non-TA treatment group, 1-week-TA treatment group, and 2-week-TA treatment group. The rats were intravitreously injected with 5 mu;l TA. The digested retinal preparation was stained by immunohistochemcial method to observe the expression of retinal ICAM-1 and morphological changes. The mean optic density (A) value of endothelial cells was measured by image-analyzing software to quantify the expression of ICAM-1. BRB changes were measured by content test of retinal Evans blue (EB). Results In the immunohistochemcial staining groups, there was no significant positive expression of ICAM-1 in retinal capillary in control group. Compared with the control, there was significant positive expression of ICAM-1 in DM-4-month group (P＜0.001) with some morphological changes such as irregular width of capillary caliber, and there was enhanced positive expression of ICAM-1 in DM-6-month group (P＜0.001) with aggravated morphological changes and even acellular capillary. In the BRB measurement groups, there was no significant difference of EB content(P＞0.05) among control groups. The EB content in two DM groups significantly increased compared with that in the controls (Plt;0.001), and higher in DM-6-month group than that in DM-4-month group (Plt;0.01). In TA treatment groups, the EB content in all the DM groups significantly decreased (Plt;0.001) but with no significant difference among the groups(P＞0.05). EB content in DM-4-month group after 2-week treatment almost reached to normal value (P＞0.05) while was higher in the rest of TA treatment groups than that in the control group (Plt;0.05). Rectilinear correlation between A value of endothelial cells and the retinal EB content(r=－0.959)was found. Conclusion There is a positive relation between the expression of ICAM-1 and BRB rupture in retina of DM rats, and intravitreous injection with TA can effectively alleviate BRB rupture. (Chin J Ocul Fundus Dis, 2006, 22: 24-27)
Objective To verify the effect of Evans blue dye on determining the retina blood vessel leakage． Methods Male Sprague-Dawley rats were used in this study． The VEGF induced retinal blood vessel leakage was checked with Evans blue dye． Then the bloodretina barrier breakdown of 1 week diabetic animals was quantified with Evans blue．The dye was extracted from retina by formamide and the extraction was checked with spect rophotometer． Evans blue leakage was normalized against wet or dry retina weight． Results The retinal Evans blue content of eyes treated with VEGF was remarkably higher than that of the controls (n=17 ,Plt;0．0001)． And the eyes of 1 week diabetic duration animals had more Evans blue dye than that of the normal controls (Plt;0．05)． Conclusion Evans blue dye is a sensitive tracer in quantitatively diagnosing the blood retina barrier breakdown． (Chin J Ocul Fundus Dis, 2001,17:221-223)
Objective To investigate the effect of batroxobin on the blood-retinal barrier (BRB) and vascular endothelial growth factors (VEGF) in diabetic rats. Methods Sixty Sprague-Dawley rats were used to establish diabetic models by intraperitoneal injecting with streptozotocin (60 mg/kg), and were divided into 3 groups: diabetic group (n=20), batroxobin (40 mg/kg) group (n=20) and batroxobin (20 mg/kg) group (n=20). Twenty-five else rats were in control group. All of the rats were executed 7 days later. The function of BRB was observed by Evans blue method. Results concentration of VEGF protein was detected by enzyme-linked immunoabsorbert assay (ELISA). The results of each group were compared. Results The content of BRB leaked into retina was obvious lower in the control group than which in the other 3 diabetic groups（Plt;0.01）. There was no significant difference of the content of Evans blue between the two groups with different dosage of batroxobin (P＞0.05). The content of Evans blue was lower in the 2 diabetic groups with different dosage of batroxobin than which in the control group (Plt;0.05). The content of VEGF in retina was obviously lower in control group and 2 diabetic groups with different dosage of batroxobin than which in the diabetic group (Plt;0.01), and obviously lower in batroxobin (40 mg/kg) diabetic group than which in the control group (P＝0.01). The content of VEGF in control group and batroxobin (20 mg/kg) diabetic group (P＝0.06) didnprime;t differ much, which occurred similarly in batroxobin diabetic groups with different dosage (P＝0.78). Conclusions Batroxobin may alleviate the damage of function of BRB in diabetic rats and reduce the expression of VEGF, which suggests that batroxobin can protect the function of BRB to a certain extent. (Chin J Ocul Fundus Dis, 2006, 22: 16-19)
Objective To investigate the protective effect of blocking the signal path of p38 mitogen activated protein kinase on blood retinal barrier (BRB) and retinal ganglion cells (RGC) in early diabetic rats.Methods A total of 60 Wistar rats were divided into the control and diabetes group, with 30 rats in each group. Diabetes was induced in rats in diabetes group by peritoneal injection of streptozotocin (STZ);the plasma glucose level of ＞16.7 mmol/L indicated that the diabetes model was set up successfully.The rats in the control group underwent peritoneal injection of equivalent sodium citrate solution. IgG leakage method was used to measure the damage of BRB function and vascular leakage. The expression and localization of caspase-3 and vascular endothelial growth factor (VEGF) in retina of diabetic rats were examined by immunohistochemistry analyses.Two weeks after the establishment of the diabtes model, the rats in diabtes group underwent intravitreal injection with SB203580, a p38 inhibitor;six weeks after the injection, the expression of caspase-3 and VEGF was detected, and the number of apoptosis RGC was counted via immunofluorescence technique.Results In the contral group, IgG staining located in the blood vessels with little leakage; while the IgG leakage was much more obvious in the diabetes group eight weeks after the establishment of the model. Six weeks after intravitreal injection with SB203580, the leakage decreased in diabtes rats. The results of semiquantitative analysis and fluorescence immunohistochemistry showed that compared with the results in diabetes rats 8 weeks after intravitreal injection (2.9 times much more than that in the control group), the fluorescence expression of VEGF decreased in diabetes rats six weeks after intravitreal injection (1.8 times much more than that in the control group).The apoptisis RGC number in rats 6 weeks after intravitreal injection of SB203580 was much less than that in rats without intravitreal injection (t＝5.731, Plt;0.01). Conclusions SB203580 can alleviate the disruption of BRB and apoptosis of RGC in early diabetes rats, which suggests that p38 MAPK pathways appear to be directly involved in the pathogenesis of early diabetic retinopathy.