Cytoprotective effects of Lycium barbarum against reducing stress on endoplasmic reticulum

Abstract

Chinese medicinal herbs have been consumed for thousands of years for the purpose of healthy aging. Lycium barbarum is valued in Chinese culture for its benefits to anti-aging, vision, kidney and liver. Recent studies showed that extracts from L. barbarum possess biological activities including anti-aging, anti-tumor, immune-stimulatory and cytoprotection. Most of these studies emphasized that the protective function of L. barbarum is due to its anti-oxidative effects. We have previously demonstrated that extract from L. barbarum can protect neurons against β-amyloid (Aβ) peptide-induced apoptosis. Since Aβ toxicity may be mediated via oxidative stress, it is still unclear whether the extract from L. barbarum is a simple anti-oxidant exhibiting cytoprotective effects. We hypothesized that extract from L. barbarum is not simply an anti-oxidant in order to function as a neuroprotective agent. The aim of this study is to investigate whether the extract from L. barbarum (LBG) protect neurons via mechanisms independent of anti-oxidative effects. Using a reducing agent, dithiothreitol (DTT), we found that LBG exhibits cytoprotective effects against reducing stress by lowering the DTT-induced LDH release and caspase-3 activity. DTT can trigger endoplasmic reticulum (ER) stress leading to PKR-like ER kinase (PERK) activation. We also showed that LBG attenuates DTT-induced PERK phosphorylation. The extract from L. barbarum is not simply an anti-oxidant; it can also exhibit cytoprotective effects against reducing stress by DTT.