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. Author manuscript; available in PMC: 2008 Dec 28.
Published in final edited form as: Behav Brain Res. 2007 Jul 21;185(2):88–98. doi: 10.1016/j.bbr.2007.07.024

Figure 6.

Figure 6

Levels of Fos expression in enkephalin-positive and enkephalin-negative neurons in the nucleus accumbens and caudate-putamen after repeated amphetamine administration in the locomotor activity chamber. For nucleus accumbens (A,B), asterisk indicates significantly more amphetamine-induced Fos-IR in enkephalin-positive neurons after repeated administration of amphetamine versus saline. Pound sign indicates that amphetamine challenge injections produced a significant decrease of Fos-IR in enkephalin-positive neurons after repeated saline administration. Cross sign indicates that amphetamine challenge injections significantly increased Fos-IR in enkephalin-negative neurons. For caudate-putamen (C,D), asterisks indicate significantly more Fos-IR after repeated administration of amphetamine versus saline. Cross signs indicate that amphetamine challenge injections significantly increased overall Fos-IR. Values represent mean±SEM (n=8 per group for amphetamine challenge injections; n=4 per group for saline challenge injections).