Another interesting study performed by Eipper-Mains et al. (2011) links cocaine exposure to Ago2 induction (Eipper-Mains et al., 2011). Characterization of the subcellular fractions of the striatum shows that Ago2 is localized in synapses and is cocaine-responsive. Specifically, chronic cocaine exposure resulted in increased Ago2 mRNA and protein in the striatum, and concomitantly altered miRNA expression levels. This increase in Ago2 protein was associated with postsynaptic densities (PSDs) in striatum but not in medial prefrontal cortex (mPFC). Intriguingly, a large number of cocaine-responsive miRNAs identified so far (miR-8 family, miR-145, miR-451) can putatively target genes implicated in addiction, including TrkB receptor, which transduces the actions of BDNF in brain and play a crucial role in activity-dependent synaptic plasticity.
