Pimozide injections into the Nucleus accumbens disrupt maternal behaviour in lactating rats

In rodents ongoing maternal behaviour requires activation of dopamine receptors. Therefore, it is possible that some motor components of maternal behaviour might be mediated by concurrent dopaminergic stimulation. It has been previously demonstrated that peripheral injections of some antipsychotic drugs such as pimozide have disruptive effects on maternal behaviour. The present experiments were designed to verify the effects of pharmacological blockade of limbic dopamine receptors on ongoing maternal behaviour in lactating rats. The hypothesis that central injections of the drug pimozide would have an effect on maternal behaviour was tested. We investigated the effects of central bilateral intra-accumbens microinjections of the dopamine D2 receptor antagonist pimozide (1.5 and 3.0 microg) on maternal behaviour. Animals treated with 3.0 microg of pimozide showed significantly longer latencies for all parameters of maternal behaviour compared to controls. These results suggest that dopamine receptors in the nucleus accumbens play a role in ongoing maternal behaviour.