Figure 6.
Effect of intrastriatal morphine (100 μM) on the extracellular concentration of dopamine (DA) in the striatum of rats withdrawn for 48 h from repeated saline (SAL) or morphine (10 to 25 mg kg−1, s.c. twice daily for 7 days) treatment. Morphine (MO) was administered intrastriatally via microdialysis probe instead of Ringer solution as shown by the shaded horizontal bar. All values are presented as percentages of the basal level±s.e.mean (n=5). Contrast analysis after analysis of variance for repeated measurements; 0–220 min: Repeated saline+morphine vs repeated morphine+morphine P<0.05.