Long-term changes in reward-seeking following morphine withdrawal are associated with altered N-methyl-d-aspartate receptor 1 splice variants in the amygdala

► Acute opiate withdrawal increases motivational behavior in non-aversive conditions. ► Extended opiate withdrawal inhibits motivational behavior in aversive conditions. ► The C1 and C2 cassettes of NMDAR1 in the amygdala are associated with inhibition.