Bletilla striata polysaccharides protect against mercury-induced oxidative damage to Drosophila midguts via modulation of sestrin

Abstract: Oxidative stress was one of the major causes of heavy metal-induced toxicity in organisms including Drosophila melanogaster. Bletilla striata polysaccharide (BSP) with anti-oxidative property has been recently recognized as a novel player in the management of oxidative stress response in organisms. Here, we took Drosophila midgut as a model to evaluate the protective effects of BSP (50 µg/mL) on mercury chloride-induced gastrointestinal adversities. As a result, BSP was found to significantly improve the survival rates and climbing ability of flies exposed to mercury. Further study demonstrated that BSP significantly alleviated the mercury-induced injury to midgut epithelium, at least partly, through increasing antioxidant enzyme activity (glutathione-S-transferase and superoxide dismutase), decreasing reactive oxidative species production, inhibiting cell apoptosis, restoring intestinal epithelial barrier and regulating stem cell-mediated tissue regeneration. Additionally, oxidative stress responsive gene sestrin was involved in the protection of BSP against mercury-induced oxidative damage to midguts. This study suggested that BSP has great potential for future application in the treatment and prevention of heavy metal-induced gastrointestinal adversities in mammals.