Fig. 2. Chemogenetic activation of ZI DA neurons promoted motivational vigor in food seeking to regulate food consumption.
(A) AAV was injected to bilateral ZI of TH-Cre mice to express excitatory hM3D(Gq) in ZI DA neurons. (B) A representative trace from slice recording shows that CNO (3 μM) excited an hM3D(Gq)-positive ZI DA neuron. (C) Regular food consumption during light cycle in both male (n = 12) and female (n = 8) TH-Cre mice with hM3D(Gq) expression in ZI DA neurons following IP injection of saline or CNO (2.0 mg/kg). (D) Breakpoints reached by both fed (n = 9) and partially fasted mice (70% of their daily food intake, n = 9) during PR sessions following IP injections of saline or CNO (2.0 mg/kg). (E to G) Real-time feeding bout sizes of a female ZITH-hM3D(Gq) mouse following IP injection of saline and CNO (2.0 mg/kg). FED devices at free-feeding modes were used for collecting real-time food intake in home cages. (H to J) Bar graphs showing meal numbers, intermeal intervals, and meal sizes of 6 hours. n = 9 female mice each group. Three-way ANOVA with post hoc Bonferroni test for (C), two-way repeated-measures (RM) ANOVA with post hoc Bonferroni test [(D) and (H) to (J)].