IL6 and depressive symptom measurement: In the present study, we demonstrate increased Il6 levels and in parallel decreased levels of let-7 miRNA family in the PFC of a well-established model of depression, the FSL rat.36, 37 Since the let-7 family is known to target Il6, the results suggest that the let-7 family dysregulation contributes to the overexpression of Il6 in the PFC of FSL.