ABSTRACT
Background Retina fixed flat-mount perfused by Evans blue (EB) is a common method for the evaluation of blood-retinal barrier (BRB).However,previous method is inconvenient for some laboratories because the retinal specimen can not be observed by gereral microscope rather than confocal laser scanning microscope after the fixation.Objective This study was to modify the preparing way of flat-mounted retina in order to obtain transparent specimen for the observation of rat retinal vessels and the evaluation of leakage under the ordinary fluorescence microscope.Methods Forty male SD rats were divided into the control group,diabetes mellitus (DM) 1-month group,DM 3-month group and DM 6-month group according to the random number table.Streptozotocinum (STZ) of 2％ dissolved in 0.05 mmol/L sodium citrate-hydrochloric acid buffer was intraperitoneally injected in SD rats to establish DM models,and the equal volume of solvent was injected in the same way in the control rats.One month,three months and six months after injection,EB of 30 g/L was injected via rat femoral vein in the dose of 45 mg/kg.Fifteen minutes after injection of EB,the rats were sacrificed and the retinas were isolated and cut radially to prepare the flat-mounted retinas in PBS immediately and then were dried till the specimens were transparent.The specimens were examined under the fluorescence microscope.The percentage of EB leakage was quantitatively calculated by IPP 6.0 software.All procedures were performed following approval of the institutional animal care and use committee of Tianjin Medical University.Results The retina morphology was normal in the control group,and EB filled the vessels,exhibiting the red fluorescence under the fluorescence microscope.Compared with the control group,retinal background fluorescence was enhanced slightly in the DM 1-month group,and focal leakage of the EB from capillaries and focal dilated vessels were found in the DM 3-month group,further,vascular caliber inequality,retinal hypoperfusion area and a larger number of hyperfluorescence areas were seen in the DM 6-month group.The percentage of leakage area was (0.05 ±0.02) ％,(0.27 ±0.06) ％,(1.17 ±0.18)％ and (4.77 ±0.66)％ in the control group,DM 1-month group,DM 3-month group and DM 6-month group,respectively,showing a significant difference among the four groups (F =795.800,P＜0.001),and the leakage area was obviously larger in the DM 3-month group and DM 6-month group than that in thecontrol group (q'=10.338,q'=43.475,both at P＜0.001).Conclusions Modified EB-perfused retinal wholemount method is easy and helpful for clear visualization of retinal vessel leakage induced by BRB breakdown in the diabetic rats under the common fluorescence microscope.
ABSTRACT
Background The retinal degeneration 11 (rd11) mouse is a newly discovered naturally occurring recessive animal model with lysophosphatidylcholine acyltransferase 1 (Lpcatl) mutation.Previous studies showed that the photoreceptor cells are characterized by typical rod-cone degeneration pattern in rd1 1 mice,while cone degeneration pattern in rd11 mice is unclcar.Objective Using immunofluorescence staining techniques with retinal wholemount,we aim to clarify the degeneration patterns of cone-function related M-opsin or S-opsin in different ages of rd1 1 mice.Methods A total of thirty rd1 1 and C57BL/6J mice at postnatal (P) day 14,28,42 (five in each age group) were sacrificed and retinal wholemounts were prepared.Immunohistochemistry was performed to identify the expression of M-opsin or S-opsin in retinal wholemounts,which were photographed with a fluorescent microscope.Cone opsins were compared between rd1 1 retinas and age-matched normal C57BL/6J retinas by manually counting the opsin positive cone cells in different quadrants of the retinas.Results The number of M-opsin or S-opsin positive fluorescent dots in each quadrant was similar at all ages of normal C57BL/6J retina.M-opsin positive fluorescent dots in dorsal/temporal,ventral/temporal,dorsal/nasal and ventral/nasal quadrants of rdl 1 retina at P28 were (414±32),(300± 8),(324 ± 22) and (250± 20)/0.037 mm2,which were lower than the age-matched normal C57BL/6J mice (t =4.114,15.225,7.505,17.990,all at P＜0.05).At the same time the S-opsin positive fluorescent dots in P28 rd11 were (8 ±4),(175 ± 16),(74 ± 13) and (315 ±20)/0.037 mm2,with significant decrease in comparison with those in the age-matched normal C57BL/6J mice (t =8.555,17.076,21.637,13.498,all at P＜0.05).With the development of retinal degeneration in rd11 mice,the M-opsin degeneration spread from central to ventral,nasal and then to temporal and dorsal peripheral retina;and the S-opsin loss started from dorsal/temporal to ventral/nasal retina.Conclusions Most of the M-opsin and S-opsins,especially the S-opsins in rd11 mice,degenerate in 6 weeks.Retinal wholemount and cone opsin immunofluorescent staining provide a useful tool to show the cone degeneration pattern and to evaluate the therapeutic efficiency in ongoing gene therapy study.
ABSTRACT
PURPOSE: There were many studies on the distributions of the retinal ganglion cells(RGC) in the experimental model of the retinal ischemia. RGC was known to be more sensitive to the ischemic injury than the other types of the retinal cells. So, we would identify the changes of the retinal ganglion cell morphologies and distribution after the iatrogenic retinal ischemia induced by intraocular pressure(IOP) elevation. METHODS: Eight pigmented and six white rabbits were used and retinal ischemia was induced by increasing IOP higher than 120 mmHg for 60 minutes. Electroretinogram were recorded at 6 days or 13 days, and histologic findings were observed at 7 or 14 days. RESULTS: After 7 days, RGC densities decreased, cytoplasmic staining disappeared, and the intranuclear hyperpigmentation was noted. RGC densities decreased significantly at 14 days. In the vertical retinal section, some flattening of retinal ganglion cell layer and inner plexiform layer was observed. Changes in the cellular morphologies were prominent. CONCLUSIONS: It may be more appropriate to examine both the retinal whole-mount and the vertical tissue section for the estimatation of the changes of retinal ganglion cell layer in the pressure-induced retinal ischemia.