FIGURE 2.

Morphine withdrawal induced a transient increase in corticosterone levels in WT but not in MORKO mice. Plasma samples were collected from WT and MORKO mice (n ≥ 3/group) at different time points just following MW, and corticosterone levels were measured using the ¹²⁵I double antibody radioimmunoassay method. Mean concentrations are expressed as ng/ml ± S.D. (error bars) and represent three independent experiments. *, p < 0.05.