Using commercially-available probiotics to mitigate methylmercury-induced neurotoxicity in rats

Methylmercury (MeHg) is a potent neurotoxin and can lead to neurodegeneration in animals and humans. Fecal microbiota transplantation has been found to regulate the neurotoxicity of MeHg in rats. This study investigated the therapeutic potential of orally-given commercially-available probiotics (primarily Bifidobacterium and Lactobacillus acidophilus ) against MeHg-poisoning in rats. It was found that probiotics intervention promoted the demethylation of MeHg in the liver and intestines, accompanied by upregulation of demethylating bacteria such as Desulfovibrionaceae and Geobacteraceae . It also reshaped the gut microbiota, significantly increasing beneficial short-chain fatty acids(SCFA)-producing bacteria like Ruminococcaceae and Lachnospiraceae. SCFA, amino acids and bile acids were found increased in feces. The expression of pro-inflammatory cytokines TNF-α and IL-6, and up-regulated IL-10 in the gut, serum and brain was found reduced, showing the decreased inflammation. Besides, the capability of spatial learning, memory, and motor coordination of MeHg-poisoned rats was improved as showed through Morris water maze test. Histologically, H&E staining revealed neatly arranged neurons with reduced nuclear condensation, while Nissl staining showed increased Nissl bodies and restored neuronal activity. In all, this study provides a simple and potentially translational strategy for MeHg-poisoning and sheds lights for the treatment of neurodegenerative diseases.