Neuronal damage and blood-retinal barrier disruption in retinal ischemia/reperfusion injury: protective effects of Lycium barbarum polysaccharides

Abstract

Objective Neuronal cell death,glial cell activation,retinal swelling and oxidative injury are complications in retinal ischemia/reperfusion(I/R) injuries.Lycium barbarum polysaccharides(LBP),extracts from the wolfberries, are good for 'eye health' in Chinese medicine.The aim of our present study is to explore the use of LBP in retinal I/R injury.Methods Retinal I/R injury was induced by surgical occlusion of the internal carotid artery.Prior to induction of ischemia,mice were fed orally with either vehicle(PBS) or LBP(1 mg/kg) once a day for 1 week. Ischemia was maintained for 2 hours and reperfusion was then allowed for 22 hours.Paraffin-embedded retinal sections were prepared.Viable cells were counted while apoptosis was assessed using TUNEL assay.Expression levels of glial fibrillary acidic protein(GFAP),aquaporin-4(AQP4),poly(ADP-ribose)(PAR) and nitrotyrosine (NT) were investigated by immunohistochemistry.The integrity of blood-retinal barrier(BRB) was examined by IgG extravasation experiment.Results Decreased viable cell count and apoptosis were found in the ganglion cell layer (GCL) and the inner nuclear layer(INL) of the vehicle-treated I/R retina.Additionally,increased retinal thickness, GFAP activation,AQP4 up-regulation,IgG extravasation and PAR expression level were observed in the vehicletreated I/R retina.Most importantly,many of these changes were diminished or abolished in the LBP-treated I/R retina.Conclusion Pre-treatment with LBP for 1 week effectively protected the retina from neuronal death,apoptosis, glial cell activation,aquaporin water channel up-regulation,disruption of BRB and oxidative stress.The present study suggests that LBP may have a neuroprotective role in ocular diseases in which I/R is a feature.