Histological, morphometric, protein and gene expression analyses of rat retinas with ischaemia–reperfusion injury model treated with sildenafil citrate

Diogo S. Zanoni, Germana A. Da Silva, Raaya Ezra-Elia, Márcio Carvalho, Juliany G. Quitzan, Ron Ofri, José L. Laus, Renee Laufer-Amorim*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Summary: The aim of this study was to better understand the role of apoptosis in a retinal ischaemia–reperfusion injury model and to determine whether sildenafil citrate treatment can prevent retinal cell apoptosis. Thirty-six rats were divided into a control group (n = 6) and two experimentally induced ischaemia–reperfusion groups (7 and 21 days; n = 15 per group). The induced ischaemia–reperfusion groups were treated with sildenafil for 7 and 21 days (n = 10 per group), and 10 animals were treated with a placebo for the same period (n = 5 per group). Paracentesis of the anterior chamber was performed with a 30-G needle attached to a saline solution (0.9%) bag positioned at a height of 150 cm above the eye for 60 min. Intraocular pressure was measured by rebound tonometer (TonoVet®). The eyes were analysed by histology and morphometry, and by immunohistochemistry and qRT-PCR for expression of Caspase-7, Caspase-6, Caspase-9, Tnf-r2, Fas-l, Bcl-2 and Bax. Sildenafil-treated animals showed lower levels of histopathological changes (inflammatory, cellular and tissue) than their placebo-treated counterparts at both 7 and 21 days. The retinal ganglion cell layer (RGC) was preserved in the sildenafil groups (SG), with a cell count closer to control than in the placebo groups (PG). Caspase-7 expression was significantly higher in both treated groups at 7 days compared to controls. Gene expression levels in both treatment groups differed from the controls, but in SG Bax and Caspase-6 expression levels were similar to control animals. These results suggest that the main mechanism of retinal cell death in this model is apoptosis, as there is an increase in pro-apoptotic factors and decrease in the anti-apoptotic ones. Also, sildenafil seems to protect the retinal ganglion cell layer from apoptosis. Cell survival was evident in the histological and morphometric analyses, and sildenafil treatment had a protective effect in the apoptosis pathways, with gene expression levels in SG similar to the controls.

Original languageAmerican English
Pages (from-to)147-157
Number of pages11
JournalInternational Journal of Experimental Pathology
Issue number3
StatePublished - Jun 2017

Bibliographical note

Publisher Copyright:
© 2017 The Authors. International Journal of Experimental Pathology © 2017 International Journal of Experimental Pathology


  • apoptosis
  • ischaemia–reperfusion
  • retinal ganglion cells


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