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. 2008 Mar 19;28(12):3170–3177. doi: 10.1523/JNEUROSCI.5129-07.2008

Figure 1.

Figure 1.

Increased extracellular glutamate in the NAcore during heroin seeking (3 h reinstatement test). A, Extracellular glutamate before and after a noncontingent heroin injection (0.25 mg/kg, s.c.; arrow). The TTX (1 μm) group consisted of animals trained to self-administer heroin that had TTX administered through the dialysis probe beginning 1 h after the start of sample collection (sample 4). Data were evaluated using a two-way ANOVA with repeated measures over time, and there was a significant main effect of group (F(3,518) = 8.351; p < 0.001), no effect of time, and a significant interaction (F(42,518) = 2.128; p < 0.0001). Data are shown as mean ± SEM percentage change from the average of all six baseline samples. B, The data from A were averaged over the baseline and during the first hour after administration of heroin. Data were evaluated using a two-way ANOVA with repeated measures over time, and there was a significant main effect of group (F(3,38) = 7.318; p < 0.001), no effect of time, and a significant interaction (F(3,38) = 7.362; p < 0.001). The dashed line refers to the average 100% baseline for all groups. C, Active lever pressing during heroin seeking induced by the heroin injection in animals shown in A. Rats receiving TTX via reverse dialysis did not increase active lever pressing after a heroin prime (active lever presses for extinction, 30.6 ± 6.9; reinstatement, 49.6 ± 14.4). D, Extracellular dopamine was elevated in both heroin self-administration and yoked-saline groups by a heroin injection. These data were obtained from a portion of the samples measured for glutamate in A. A significant main effect of time (F(14,224) = 4.148; p < 0.0001) was measured, with no significant effect of group and no interaction. E, The data from D were averaged over the baseline and during the first hour after administration of heroin. Data were evaluated using a two-way ANOVA with repeated measures over time, and there was a significant main effect of time (F(1,16) = 14.12; p < 0.01), no effect of group, and no interaction. The dashed line refers to the average 100% baseline for all groups. *p < 0.05, post hoc comparison between heroin self-administration animals and all other groups at individual times after heroin administration for dialysis (A), comparison between group and baseline (B, E), or comparison between heroin-induced reinstatement and extinction levels of lever pressing (C). SA, Self-administration.