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Jiawei Wang, sida chen, Wenbin Huang, Xiulan Zhang, Jost B Jonas; Intravitreal injection triamcinolone acetonide delays RGCs apoptosis through inhibiting inflammatory responses of retinal microglia in an optic nerve crush rat model. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5743.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the effects of intravenous injection triamcinolone acetonide (TA) on the activation of retinal microglia and ganglion cells (RGCs) survival in optic nerve crush (ONC) model.<br />
Dynamic modification of retinal microglia was observed at different time points using experimental optic nerve crush model. Then, the right eyes were injected intravitreally with 1ul TA (80 mg/ml TA, TA group) or 1ul PBS (PBS group). Rats were subsequently sacrificed at 14D and 28D post-injury. Number of survival RGCs and morphologic change of retina were determined by H&E staining. Detection and quantification of the apoptosis of RGCs were performed by an apoptosis detection kit (Roche Diagnostics GmbH, Mannheim, Germany). Activation of retina microglia was explored by immunofluorescent labeling of iba-1. Western Blot analysis was used to assess the levels of inflammatory factors in retina.
At baseline, the mean number of microglia, determined by iba-1, in the retina was 0.8±0.9 cells/HPF. Activation of retinal microglia could be obviously induced by ONC and peaked at 14D (9.3±2.2 cells/HPF). After intravitreal injection of TA, activation of retinal microglia was significantly inhibited when sacrificed at 14D and 28D post-injury(4.2±1.6 cells/HPF versus 9.0±2.1 cells/HPF, 2.3±1.1 cells/HPF versus 4.4±1.5 cells/HPF, all P<0.0001, respectively). Besides, inflammatory responses of retinal microglia, including TNF-α, iNOS and ICAM-1, were also decreased. H &E staining showed a significantly better preserved RGCs in TA group than PBS treated group(23.1±3.0 cells/HPF in the sham group, 13.2±2.9 cells/HPF and 11.3±2.3 cells/HPF in TA group, 11.5±2.1 cells/HPF and 8.7±2.2 cells/HPF in PBS group, at 14D and 28D, respectively). TUNEL assays showed that the average apoptotic rates were 24.8% and 21.3% after 14D and 28D in PBS group and fewer apoptotic cells in the retinal sections were found in the TA group(21.0% and 18.3%, respectively, all p<0.05).<br />
Intravitreal injection of TA appeared to have protective effect on RGCs and delayed the apoptosis of RGCs through inhibiting inflammatory responses of retinal microglia in ONC rats.<br />
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