Abstract
MicroRNAs are short non-coding molecules that play a major role in regulating gene expression. Peripheral levels of miR-1202 have been shown to predict and mediate antidepressant response. However, it is not clear to what extent these peripheral measures reflect central neural changes in vivo. We approached this problem with the combined use of peripheral miR-1202 measures and neuroimaging. At baseline and after 8 weeks of desvenlafaxine (50-100 mg die), 20 patients were scanned with 3T magnetic resonance imaging, first at rest then during the Go/NoGo task, a classical test of response inhibition. Blood samples were collected at both time points. During resting state, lower baseline miR-1202 levels were predictive of increased connectivity from T0 to T8 between the posterior cingulate and the prefrontal, parietal, and occipital cortices. Changes in miR-1202 levels following desvenlafaxine treatment were negatively correlated with changes in activity in right precuneus within the default-mode network, and in connectivity between the posterior cingulate and the temporal and prefrontal cortices, and the precuneus. During the Go/NoGo task, baseline miR-1202 levels and changes in these levels were correlated with activity changes in different regions, including bilateral prefrontal, insular, cingulate, and temporal cortices, and left putamen and claustrum. Finally, secondary analyses in a subset of patients showed a trend for a significant correlation between miR-1202 levels and glutamate levels measured by spectroscopy. Changes in peripheral miR-1202 levels were therefore associated with changes in brain activity and connectivity in a network of brain regions associated with depression and antidepressant response. These effects may be mediated by the glutamatergic system.