Two of the most essential areas involved in the brain reward pathway include the nucleus accumbens and the ventral tegmental area, which have both been identified as regions that are linked together between dopaminergic activity in response to painful stimuli. Dopamine regulation is enhanced by phosphorylation of the phosphoprotein DARPP-32, whose levels have been shown to increase after acute administration of morphine due to activation of D1 receptors in both the nucleus accumbens and striatum.  In this study, neuropathic pain was induced by a chronic constrictive nerve injury to both DARPP-32 WT and KO mice to assess the effects of morphine on pain threshold, by measuring mechanical sensitivity, and brain reward-like properties, by measuring conditioned place preference on mice.