This Week in The Journal

Ventral tegmental area (VTA) dopamine neurons regulate reward-related behavior and are hijacked by drugs of abuse, like opiates, to facilitate addiction.However, how opiates interact with distinct VTA dopamine neuron subpopulations is unclear.In this issue, Quiles et al. used mice to explore how the opiate morphine targets VTA dopamine neuron subpopulations.The researchers looked at gene expression changes in VTA dopamine neurons following long-term morphine exposure and discovered increased expression of the neuropeptide neuromedin S (NMS).Using a genetic mouse model enabling the targeting of NMS-expressing neurons, Quiles and colleagues found that artificially stimulating or inhibiting these neurons bidirectionally influenced locomotor activity associated with morphine use.Inhibiting NMS neurons also reduced morphine reward as measured by a conditioned place preference paradigm.The researchers used more experimental controls to highlight the morphine and NMS specificity of their findings.This identification of a new neuron subpopulation that morphine interacts with to affect behavior may inform treatment development for opiate addiction.