Fig. 5: Drd2 overexpression in PL-NAc core pathway promotes compulsivity.
a Scheme of combinatorial viral strategy for selective D2R-mVenus expression in PL-NAc core projecting neurons. b Representative immunofluorescence images showing Cre-induced D2R-mVenus protein at PL injection site (left) and Cre recombinase protein at NAc core injection site (right). c–f Overexpression of D2R in PL-NAc core neurons induces changes in excitatory transmission in the PL and NAc core. c Representative recordings showing evoked (150 pA) action potential in WT mice injected with AAV-control (left) and AAV-D2R (right) in PL layer 5 mVenus visualized neurons at baseline and after quinpirole (2 µM) application. d Quantification of the firing rate (Hz) (mean and individual values; Wilcoxon test, *P < 0.05, n = 9 cells from n = 3 animals injected with AAV-control and n = 9 cells from n = 3 animals overexpressing D2R). e Representative traces of miniature excitatory postsynaptic currents (mEPSCs) recorded at a holding potential of −75 mV in NAc from mice injected with AAV-control (left) or AAV-D2R (right) in baseline and after quinpirole application (above). Cumulative probability plot of the mEPSC amplitudes from both control (left) and D2R (right) expressing mice in baseline conditions and after quinpirole bath application (below). f Changes of mEPSCs frequency in percentage (mean and individual values; Wilcoxon test, **P < 0.01, n = 7 cells from n = 5 animals injected with AAV-control and n = 10 cells from n = 7 animals overexpressing D2R). g Timeline of the experimental sequence of the early period of food addiction mouse model. h Number of reinforcers during operant training sessions maintained by chocolate-flavored pellets. i–k Behavioral tests of the three addiction-like criteria in the early period showed increased compulsivity in mice overexpressing D2R (individual values with the median and the interquartile range, t-test, *P < 0.05). The 75th percentile of distribution of control mice is indicated by the dashed horizontal line. Addicted mice in gray filled circles for control and green for D2R mice. l Increased percentage of mice overexpressing D2R classified as food addicted animals (chi-square, **P < 0.01). m–o Pearson correlations between individual addiction-like criteria and m non-reinforced active responses in 10 min, n breaking point in 5 h, o number of shocks in 50 min (n = 12 for control mice and n = 13 for D2R mice; PL prelimbic, NAc nucleus accumbens, Amg amygdala, Hip hippocampus, VTA ventral tegmental area, ACC anterior cingulate cortex, IL infralimbic; see also Supplementary Figs. 8–10; statistical details are included in Supplementary Table 6).
