We assessed: (1) whether conditioned fear (PTSD model) modifies the rewarding effect of mephedrone, and (2) if repeated mephedrone injections have impact on trauma-related behaviors (fear sensitization, extinction, and recall of the fear reaction), or (3) whether NMDA receptor subunits (GluN1, GluN2B) and MMP-9 in such brain structures as the hippocampus (HIPP) and basolateral amygdala (BLA) are involved in these behavioral effects (Figure 1). Here, MMP9 is linked to post-traumatic stress disorder.