Figure 7.

Change in the increased dialysate dopamine level induced by morphine in preproorexin knock-out mice. A, Localization of microdialysis probe sites in the mouse NAcc. Stippled lines represent regions in which microdialysis probes were inserted in the mouse brain. B, Effects of treatment with morphine (MRP) on the dialysate dopamine level in the NAcc in wild-type (WT) and prepro-orexin knock-out (OXKO) mice. Morphine (10 mg/kg, s.c.) or saline (SAL) was injected at time 0. The data are expressed as percentages of the corresponding baseline levels with SEM of four to seven mice. F_{(1, 11)} = 5.25, p < 0.05 wild-type mice treated with morphine versus prepro-orexin knock-out mice treated with morphine.