Figure 8. Silencing LC neurons and knocking down CB1Rs specifically in CeA blocked reduction of feeding induced by fear memory retrieval; knocking down CB1Rs also blocked loss of weight induced by Phenylephrine.
(A) Bilateral injection of AAV-hSyn-DIO-hM4D(Gi)-mCherry into the LC of TH-cre mice.
(B and C) Bath application of CNO (3 μM) inhibits LC neuron firing in ex vivo recordings.
(D) Systemic injection of CNO (1 mg/kg) blocked retrieval-induced suppression of feeding. Dashed lines: median of historical data in WT mice in Figure 1C.
(E) Bilateral injection of AAV-Cre-tdTomato into the CeA of CB1Rlox/lox mice.
(F and G) Cre injection significantly reduced CB1R mRNA expression in the CeA (F), but not BLA (G). FC per se did not affect CB1R expression in both CeA and BLA (WT).
(H and I) Knocking down CB1Rs in CeA significantly blocked tone-induced suppression of feeding (H) and retrieval-induced suppression of feeding (I). Dashed lines: medians of historical data in WT mice in Figures 1B and 1C.
(J) Single injection of 10 mg/kg, but not 1 or 0.1 mg/kg, of Phenylephrine-induced weight loss ten days afterward in WT mice.
(K) Knocking down CB1Rs in CeA significantly diminished Phenylephrine-induced weight loss.
Scale bars: 200 μm in (A) and (E). 30 s and 100 pA in (C). Statistics: *p ≤ 0.05, **p ≤ 0.005, ****p ≤ 0.0001, Wilcoxon test (B), Mann-Whitney U test (D, H, and I), Kruskal Wallis with Dunn’s correction (F and G). Also see Figure S8 and Table S1.