Number of Fos-positive nuclei/mm2 in the nucleus accumbens shell (A), nucleus accumbens core (B) and dorsal caudate/putamen (C) regions of rats following challenge injections under isoflurane (ISO groups, shaded) or no anesthesia (NoA groups, white). Rats received repeated daily treatments across 7 days of either cocaine (C; 2 mg/kg, i.v.) or saline (S), followed by a challenge injection of C or S, with group names representing these sequential treatments. Values are presented as mean ± SEM. * p < 0.05, different from CC-ISO (Newman-Keuls). + p < 0.05, different from SS-NoA. # p < 0.05, different from SS-ISO. @ p < 0.05, different from CC-NoA. Group sizes are SC-NoA: n=6, CC-NoA: n=9, CC-ISO: n=5, SS-NoA: n=5, SS-ISO: n=6.