FIGURE 2

Dose–response clonidine alleviation of naloxone-induced conditioned place aversion in sham-operated (a) and in 5,7-DHT-lesioned (b) morphine-dependent rats (subcutaneous implantation of 2 morphine pellets). Place aversion conditioning was induced by naloxone (15 g/kg s.c.). The following doses of clonidine were tested: 0, 6, 12, 25, 50, 100, 200 and 400 g/kg. Clonidine was injected 60 min before naloxone. Each bar represents the difference of the time spent by rats in a given compartment during the test session minus the preconditioning score. Black bars, naloxone-paired compartment (D–D0); striped bars, saline-paired compartment (S–S0); white bars, neutral compartment (N–N0). Wilcoxon paired test, D/D0, S/S0, N/N0: *p< 0.05, **p< 0.01.