Short-Term Memory Deficit Associates with miR-153-3p Upregulation in the Hippocampus of Middle-Aged Mice.

The early stages of ageing are a critical time window in which the ability to detect and identify precocious molecular and cognitive markers can make the difference in determining a healthy vs unhealthy course of ageing. Using the 6-different object task (6-DOT), a highly demanding hippocampal-dependent recognition memory task, we classified a population of middle-aged (12-month-old) CD1 male mice in Impaired and Unimpaired based on their short-term memory. This approach led us to identify a different microRNAs expression profile in the hippocampus of Impaired mice compared to Unimpaired ones. Among the dysregulated microRNAs, miR-153-3p was upregulated in the hippocampus of Impaired mice and appeared of high interest for its putative target genes and their possible implication in memory-related synaptic plasticity. We showed that intra-hippocampal injection of the miR-153-3p mimic in adult (3-month-old) mice is sufficient to induce a short-term memory deficit similar to that observed in middle-aged Impaired mice. Overall, these findings unravel a novel role for hippocampal miR-153-3p in modulating short-term memory that could be exploited to prevent early cognitive deficits in ageing.