Effect of CXCL12 and μ-opioids agonists on [35S]GTPγS binding in P15–P21 rat brain slices. Brains of 15- to 21-day-old pups were used in this study. Analysis was performed in different brain areas as indicated previously. Data are expressed as mean ± SEM of n=3 animals per group (basal vs CXCL12, 50 nM, p<0.001; basal vs morphine, 10 μM; basal vs DAMGO, 10 μM, p<0.001; CXCL12 vs morphine, 10 μM; CXCL12 vs DAMGO, 10 μM, p<0.001, for each area reported in graph. Newman–Keuls multiple comparison test after ANOVA)