Fig. 5: Chemogenetic manipulation of 5-HTMRN>DG circuit modulates ethanol intake following long-term exposure.
From: Neural serotonergic circuits for controlling long-term voluntary alcohol consumption in mice
A–C mCherry-control, hM3Dq-excitatory, and hM4Di-inhibitory DREADDs were injected in pet1-5-HT MRN neurons and bilateral cannulae were implanted in the hippocampus, above the dentate gyrus (A). Expression of DREADD constructs in TPH2-immunoreactive MRN neurons was verified by immunohistochemistry (B, field corresponding to the red dashed square in A) and the correct cannulae placement verified by histology (C). Chemogenetic manipulation of 5-HTMRN>DG neuron terminals by local infusion of CNO (100 μM) bidirectionally modulated the binge-consumption of ethanol (first 30 min of a 2 h drinking period) (D–E, repeated measure two-way ANOVA, n = 6, treatment x construct: F(4, 30) = 6.545, p = 0.0007). Bonferroni multiple comparison showed that the stimulation of these terminals increased the 30 min intake of ethanol (D–E, **p = 0.074), while their inhibition reduced the binge-intake of ethanol (D–E, *p = 0.013). Chemogenetic manipulation of 5-HTMRN>DG neuron terminals also modulated the 2 h consumption of ethanol (F–G, repeated measure two-way ANOVA, n = 6, treatment: F(1.883, 28.25) = 3.902, p = 0.0341), with Bonferroni multiple comparison showing that only the inhibition of these terminals reduced the overall 2 h intake of ethanol (F–G *p = 0.0239; **p = 0.0076), but no effect of chemogenetic activation (p > 0.99). Effect of intra-DG injection of CNO on locomotor activity (H) showing no effect over the 2-hour drinking period (I, One-way ANOVA on AUC [15–135 min], n = 4, F (2, 9) = 0.4343, p = 0.6606).
