Ethanol drinking-in-the-dark facilitates behavioral sensitization to ethanol in C57BL/6J, BALB/cByJ, but not in mu-opioid receptor deficient CXBK mice

► Elevated ethanol drinking facilitates ethanol-induced psychomotor sensitization. ► Mu-opiod receptor deficiency prevents drinking-mediated sensitization to ethanol. ► Drinking-in-the-Dark tests can be used to study ethanol-induced neuroplasticity.