Figure 1.

Activation of glutamatergic neurons in the dDG mediated context-induced reinstatement of heroin seeking. (a) Overview of the paradigm used in this experiment. (b) The ABA context-induced reinstatement model. Left, number of heroin infusions, active and inactive nose-pokes during the heroin SA training and extinction. Right, number of active and inactive nose-pokes in rats tested in the context A (renewal) or B (control). Two-way ANOVA, ^#P<0.05 vs active nose-poke of control; *P<0.05 vs inactive nose-poke of renewal, n=8 per group. (c) Fos induction in the dDG after exposure to context A or B for 90 min. Representative photomicrographs (× 20) of Fos (green) and NeuN (red) labeling in the dDG. Scale bar, 100 μm; n=4 per group. (d) Number of Fos-immunoreactive neurons per mm² in the dDG. *P<0.05 vs control group using unpaired t-test. (e) Representative photomicrographs (× 100) of Hoechst (blue)+Fos (green)+EAAC1 (red) or GAD67 (red) in the dDG of the renewal group. Scale bar, 20 μm; n=4 per group. (f) Percentage of Fos⁺ cells with EAAC1 and GAD67 in the dDG. *P<0.05 vs GAD67 using unpaired t-test. (g) Number of active and inactive nose-pokes during context-induced reinstatement after intra-dDG B+M pretreatment. Two-way ANOVA, ^#P<0.05 vs active nose-poke of control; *P<0.05 vs inactive nose-poke of each group, n=10 per group. Inset, cannula placement (× 1.25). (h) Number of active and inactive nose-pokes during context-induced reinstatement after intra-vDG B+M pretreatment. There was no difference in active and inactive nose-pokes between control and B+M group using two-way ANOVA; n=8–9 per group. (i) Bilateral inactivation of the dDG using B+M 5–10 min before test session did not affect saccharin-reinforced behavior. Left, saccharin-reinforced behavior training. Right, number of liquids, active and inactive nose-pokes during saccharin-reinforced behavior test after intra-dDG B+M treatment; n=10 per group. Data are depicted as mean±SEM.