Lycium barbarum polysaccharides attenuates N-methy-N-nitrosourea-induced photoreceptor cell apoptosis in rats through regulation of poly (ADP-ribose) polymerase and caspase expression

Ethnopharmacological relevanceLycium barbarum L., popularly known as “Goji berry”, a classic of Traditional Chinese Medicine has long been used to treat ocular diseases and cardiovascular diseases. Recently, the photoreceptor cell protection of Lycium barbarum polysaccharides (LBP), a water extract from Lycium barbarum L. has received more attention. The present study was designed to investigate the effect of LBP on N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis, and the involvement of the poly (ADP-ribose) polymerase (PARP) and caspase.Materials and methodsPhotoreceptor cell injury was induced in male Sprague-Dawley rats by an intraperitoneal injection of MNU 60 mg/kg. Seven days prior to MNU injection, LBP were intragastrical administered daily, rats were sacrificed at 24 h and 7 days after MNU injection. Retinal morphologies, photoreceptor cells apoptosis, and protein expression were evaluated at 24 h and 7 days after MNU injection.ResultsMorphologically, the outer nuclear layer was well preserved in the LBP-treated rat retinas throughout the experimental period. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) assays showed that LBP could significantly suppress the loss of photoreceptor cells, as determined by the photoreceptor cell ratio at the central retina 24 h and 7 days after MNU administration. Western-blot analysis demonstrated the expression levels of procaspase-9, -7, -3 and cleaved caspase-9, -7, -3 were upregulated, and PARP were downregulated both 24 h and 7 days after MNU injection. LBP treatment significantly decreased protein levels of procaspase and cleaved caspase, increased the level of PARP and cleaved PARP on 24 h and 7 days.ConclusionsLBP inhibits MNU-induced rat photoreceptor cell apoptosis and protects retinal structure via the regulation of the expressions of PARP and caspase.

Graphical abstractLycium barbarum L., a Traditional Chinese Medicine. Lycium barbarum polysaccharides(LBP), a working extract from Lycium barbarum L. was proved possessing inhibiting photoreceptor cell apoptosis and protecting retinal structure, the possible mechanism via regulating the expressions of PARP and caspase.Figure optionsDownload full-size imageDownload high-quality image (199 K)Download as PowerPoint slide