Effect of Lycium Barbarum (Wolfberry) Polysaccharides on Preserving Retinal Function after Partial Optic Nerve Transection

Abstract

Lycium Barbarum Polysaccharides (LBP) are the active components of Wolfberry (a traditional Chinese medicine) which has long been used for improving visual function. This study aims to investigate localized changes of retinal function in a partial optic nerve transection (PONT) model, and effects of LBP on visual function. The multifocal electroretinograms (mfERG) were obtained from 30 eyes of 30 Sprague-Dawley rats. The rats were divided into 6 groups (five treatment groups and one control group). Starting from the first day of the experiment, the rats in the (PONT+LBP) group and the (LBP) group were dosed with LBP; rats in the (PONT+PBS (phosphate buffered saline)) group and the (PBS) group were dosed with PBS via nasogastric tube every day until euthanized. The dorsal part of the optic nerve was transected in the (PONT), (PONT+LBP) and (PONT+PBS) groups at the end of week 1 (day 7 after LBP or PBS feeding began). The mfERG was measured at three time points: week 2, week 3 and week 5. Significant reduction of P1 and PhNR amplitudes of the mfERG were observed in all retinal regions a week after PONT. Feeding with LBP prior to PONT preserved retinal function. All mfERG responses returned to the normal range in the superior retina, which corresponds to the transected dorsal region of the optic nerve, while most of the inferior retinal responses were significantly increased at week 4 after PONT. The ventral part of the retina had secondary degeneration which was not only limited to the ganglion cell layer, but is a widespread effect affecting the outer retina. LBP altered the functional reduction caused by PONT by regulating the signal from the outer retina.

Lycium Barbarum and Human Health

“…In addition to the primary and secondary degeneration of RGCs, the mfERG study showed that outer retinas (photoreceptors and bipolar cells) could also be affected subsequently after PONT, and L. barbarum could reverse the functional deterioration caused by primary and secondary degeneration of the outer and inner retina (Chu et al 2013). This protective effect might be related with the antioxidant effect of LBP and the inhibition of the JNK pathway ).…”

“…Although it seems that some RGCs will take a longer time period to die than others after CONT, the occurrence of secondary degeneration after CONT is uncertain because all the axons are transected, and the degeneration of axons can lead to the degeneration of RGC bodies. This model has been used extensively for studying the mechanisms of secondary degeneration and the possible neuroprotective agents from its establishment (Yoles and Schwartz 1998;Levkovitch-Verbin et al 2003;Fitzgerald et al 2009aFitzgerald et al , b, 2010aLevkovitch-Verbin et al 2010;Selt et al 2010;Levkovitch-Verbin et al 2011;Payne et al 2011Payne et al , 2012Wells et al 2012;Chu et al 2013;Cummins et al 2013;Fitzgerald et al 2013;Li et al 2013;Payne et al 2013;Savigni et al 2013;Szymanski et al 2013). However, the number of axons influenced was unknown and the intact and damaged axons were mingled together.…”

“…We investigated the activity of other retinal layers after PONT by electroretinogram (ERG), which is a functional recording of the retinal electrical signals in response to a flash of light received at the retina. The overall reduction of the P1 component indicates that the secondary degeneration could adversely influence the retinal layers beyond RGC level (Chu et al 2013). The mfERG measurement provides topographical responses of the retina (Sutter and Tran 1992), which can illustrate the retinal changes caused by glaucomatous damage Brown 1999, 2000;Chu et al 2006Chu et al , 2007.…”

Antioxidants Distribution in Pulp and Seeds of Black and Red Goji Berries as Affected by Boiling Processing

“…Goji is a good source of fiber, protein, carotenoids [3], and polysaccharides [4]. Recent research indicates that goji had a lot of biological activities, including antidiabetes [5], antiproliferative activity [4], preserving retinal function [6], and antioxidant activity [7,8]. A lot of research has focused on carotenoids [3] and polysaccharides [4,6].…”

“…Recent research indicates that goji had a lot of biological activities, including antidiabetes [5], antiproliferative activity [4], preserving retinal function [6], and antioxidant activity [7,8]. A lot of research has focused on carotenoids [3] and polysaccharides [4,6]. However, phytochemicals [9,10], such as phenolic compounds [11], including phenolic acids and flavonoids in goji and their antioxidant activity have been less evaluated.…”