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Brain-gut health consequences of chronic exposure to sublethal microcystin levels in drinking water

Wilson Chung (Biological Sciences, Â鶹ÊÓƵ) and Xiaozhen Mou, (Biological Sciences, Â鶹ÊÓƵ)

Clean drinking water is imperative for maintaining high standards in public health. However, worldwide an increased incidence of persistent and detrimental environmental events such as cyanobacterial harmful algal blooms (CyanoHABs) have been detected in freshwaters. These adverse events disrupt the availability of clean and safe drinking water and consequently threaten human health. The primary hazard of these CyanoHABs is the production and release of cyanotoxins, mainly microcystins (MCs). Upon ingestion, MCs in high concentrations cause acute liver toxicity resulting in apoptotic or necrotic cell death. Importantly, the detrimental impact of MCs is not limited to the liver. For instance, studies showed that low-dose MC exposure not only disrupted the gut microbiota, but also led to symptoms of stress-related brain health disorders, such as anxiety and depressive behaviors. These findings indicate neurological toxicity of MCs. MC contamination is predicted to persist and expand in freshwaters based on current climate models; accidental and long-term exposure to low levels of MCs is almost inevitable, through ingestion of, aerosol inhalation of or dermal contact with MC contaminated drinking and recreational waters as well as consumption of foods that have been irrigated (such as vegetables) or lived in (such as fish and shellfish) MC contaminated waters. Therefore, there is a great need to obtain a comprehensive view of MC toxicity. This exploratory project will study how sublethal long-term MC exposure affects mouse brain control of stress physiology, gut microbiome and mental health.