Pups-naïve adult mice display two opposite responses when they are exposed to pups for the first time. Females rapidly display maternal behavior (MB); however, males display infanticidal behavior (IB). In previous studies, we found a different pattern of expression of c-Fos in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAcc) when females and males displayed MB and IB respectively for the first time.We investigated if NMDA-induced lesions in the mPFC or the NAcc inhibited MB or IB in pups-naïve adult female and male mice. Furthermore, we investigated whether 6-OHDA-induced lesions in the NAcc inhibited these behaviors.We found that lesioning mPFC delayed the onset of MB but not the IB. However, while an intact NAcc is not necessary for the expression of MB and IB, dopaminergic inputs to the NAcc play a different role in MB and IB. Damaging dopaminergic terminals into the NAcc did not affect IB, but clearly delayed the expression of MB, a more flexible and rewarding behavior.Altogether, our results suggest that these two antagonistic behaviors could be controlled differently, by different or interconnected microcircuits. MB would be a complex behavior triggered by a rewarding stimulus (a pup), in which the neurons in the mPFC and motivation circuitry would be recruited to promote more flexible behavior like this. On the other hand, IB, triggered by an aversive stimulus (a newborn), would be a more stereotyped and hard wired behavior.Fundings: CSIC and PEDECIBA.