Figure 4.

Effect of pretreatment with repeated cocaine (20 mg·kg⁻¹, i.p. twice daily separated by 8 h for 3 days) finishing 1 or 4 days before 3,4-methylenedioxymethamphetamine (MDMA) (20 mg·kg⁻¹, i.p., two injections separated 3 h) on horizontal locomotor activity measured during the 30 min immediately after the second MDMA injection. Data shown as mean ± SEM, n= 5 − 11. There were no differences between the data obtained from saline controls pretreated 1 or 4 days earlier with cocaine and therefore data were grouped. Different from saline: *P < 0.001; different from MDMA: ^ΔP < 0.001; different from cocaine + MDMA 1 day later: ^δP < 0.001; different from cocaine + saline: ^fP < 0.001. One-way anova followed by Newman–Keuls test.