Inhibition of miR-219 Alleviates Arsenic-Induced Learning and Memory Impairments and Synaptic Damage Through Up-regulating CaMKII in the Hippocampus.

Epidemiological investigations and experimental studies indicate that chronic arsenic exposure can reduce learning and memory function. However, the underlying mechanism of this effect remains largely unknown. Emerging evidence suggests that microRNA (miRNA) play an important role in toxicant exposure and a regulatory role in cognitive function. In this study, we observed that subchronic arsenic exposure induced impairment of learning and memory and significantly up-regulated miRNA-219 (miR-219) expression in the mouse hippocampus. Furthermore, the expression of CaMKII, an experimentally validated target of miR-219, was decreased in the mice exposed to arsenic. Suppression of miR-219 by adeno-associated viral (AAV)-delivered anti-miR-219 prevented the arsenic-induced impairment of learning and memory and relieved the pathological changes in the synaptic structure of the hippocampus. Furthermore, we observed that the NMDA receptor subunit 2 (NR2) and the memory-related proteins c-Fos and c-Jun were up-regulated by inhibition of miR-219 in the mouse hippocampus. Taken together, the results of this study indicate that inhibition of miR-219 regulates arsenic-induced damage in the structure of the hippocampus and impairment of learning and memory, possibly by targeting CaMKII. Suppression of miR-219 may be a potential strategy to ameliorate arsenic-induced neurotoxicity.