Figure 5: Effects of lentivirus-mediated knockdown of D2R in the NAc.
From: Role of dopamine D2 receptors in plasticity of stress-induced addictive behaviours
(a) Schematic of the lentiviral vector encoding D2R short hairpin RNA (top) and the injection sites (green circles) in the NAc core shown in a coronal diagram of the brain (bottom left). A fluorescence image of enhanced green fluorescent protein (EGFP) expression in the NAc core of a mouse injected with Lenti-shD2R is also shown (bottom right); scale bar, 500 μm. (b) Real-time PCR analysis of D2R mRNA in the NAc core, striatum and ventral tegmental area (VTA). (c) Representative immunoblot analysis of D2R (top) and densitometric quantification of the relative amount of D2R (bottom) in the NAc core of mice injected with Lenti-shDR2 or Lenti-control. (d) Effect of Lenti-shD2R injection into the NAc core on initiation of sensitization to cocaine (n=17–22 mice per group). Total locomotor counts were determined during 30 min after injection of saline or cocaine as in Fig. 2a. The first injection of cocaine was administered 1 week after virus injection. (e, f) Effect of Lenti-shD2R injection into the NAc core on expression of sensitization to cocaine. Locomotor activity of mice (n=10-11 per group) injected with Lenti-control (e) or Lenti-shD2R (f) was measured during the initiation and expression of behavioural sensitization to cocaine as in Fig. 4c. Expression of sensitization on day 18: (f) stress effect F1,36=9.31, P=0.0043 and stress × cocaine interaction F1,36=11.25, P=0.0019. P<0.01 for each saline- versus cocaine-pretreated group, with the exception of the stressed group injected with Lenti-shD2R (e, f). (g, h) Effect of chronic stress on LTD induction in the NAc of cocaine-exposed mice injected with Lenti-shD2R or Lenti-control into the NAc core (n=7–12 slices per group). Single-pulse low-frequency stimulation-induced LTD formation in the indicated groups (g) and the mean percentage LTD at 50–60 min (h) were determined as in Fig. 4c (virus effect × stress interaction F1,31=3.95, P=0.0559). Two-tailed Student’s t-test for d, ***P<0.001. Two-way analysis of variance post hoc test for expression of sensitization in e and f; †††P<0.001 versus mice injected with Lenti-control; &&&P<0.001 versus non-stressed (NSt) mice. All data are means±s.e.m.
