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Lycium Barbarum Polysaccharides Reduce Neuronal Damage, Blood-Retinal Barrier Disruption and Oxidative Stress in Retinal Ischemia/reperfusion Injury

Goji berries (Lycium barbarum, wolfberry) grow on an evergreen shrub found in temperate and subtropical regions in China, Mongolia and in the Himalayas in Tibet. They are in the nightshade (Solonaceae) family. Goji berries are usually found dried. They are shriveled red berries that look like red raisins. Goji berries are rich in antioxidants, particularly carotenoids such as Beta-carotene and zeaxanthin. One of zeaxanthin's key roles is to protect the retina of the eye by absorbing blue light and acting as an antioxidant. Goji berries have been used for 6,000 years by herbalists in China, Tibet and India to: protect the liver, help eyesight, improve sexual function and fertility, strengthen the legs, boost immune function, improve circulation, and to promote longevity.

Li SY, Yang D, Yeung CM, Yu WY, Chang RC, So KF, Wong D, Lo AC. Lycium barbarum polysaccharides reduce neuronal damage, blood-retinal barrier disruption and oxidative stress in retinal ischemia/reperfusion injury. 1. PLoS One. 2011 Jan 26;6(1):e16380.

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" according to Chinese medicine. The aim of our present study is to explore the use of LBP in retinal I/R injury. Retinal I/R injury was induced by surgical occlusion of the internal carotid artery. Prior to induction of ischemia, mice were treated orally with either vehicle (PBS) or LBP (1 mg/kg) once a day for 1 week. Paraffin-embedded retinal sections were prepared. Viable cells were counted; 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 extravasations. Apoptosis and decreased viable cell count 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 extravasations and PAR expression levels were observed in the vehicle-treated I/R retina. Many of these changes were diminished or abolished in the LBP-treated I/R retina. 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 to play in ocular diseases for which I/R is a feature.