Opiate withdrawal intensity correlates with the presence of DSLET high-affinity binding

Abstract The goal of this study was to compare the characteristics of μ- and δ-opioid receptors in the cortex of DBA/2 and C57BL/6 mice, which differ in sensitivity to the long- and short-term effects of morphine. The characteristics of μ-opiate receptors were not different in the cortex of both strains. Both high- and low-affinity binding sites of DSLET, a specific ligand of δ-opiate receptors, were present in the cortex of C57BL/6 mice, whereas the high-affinity binding sites were not found in the cortex of DBA/2ice. The absence of high-affinity DSLET binding sites, which are similar to the δ 2 type of opioid receptors, may explain the less intensive naloxone-precipitated withdrawal reaction of DBA/2 as compared with C57BL/6 mice.