1. Glutamatergic neurons in the vlPAG drive fear responses, as assessed using open field and light/dark behavioral tests (mCherry = controls, hM3 = excitatory DREADD, hM4 = inhibitory DREADD).
Glutamatergic neurons in the vlPAG drive fear responses, as assessed using open field and light/dark behavioral tests (mCherry = controls, hM3 = excitatory DREADD, hM4 = inhibitory DREADD). A, Open field test. DREADD activation (hM3, n = 8) of vlPAG glutamate neurons in vglut-2-cre mice produced decrease in distance traveled, velocity of travel, and time spent in the center of an open field along with increase in the time spent frozen when compared with control mice, while inhibition (hM4, n = 8) had no effect on these endpoints (ANOVA with Dunnett’s multiple comparison test, *p < 0.05, **p < 0.001). In contrast, DREADD activation (hM3, n = 8) or inhibition (hM4, n = 8) of dopaminergic vlPAG/dorsal raphe neurons in DAT-cre mice had no effect on distance traveled, travel velocity, center time, or freezing time (one-way ANOVA). B, In the light/dark test, DREADD activation (hM3, n = 8) of vlPAG/dorsal raphe glutamatergic neurons lead to decreased distance traveled, travel velocity, and time spent in the light side of the chamber as well as increased time spent in the dark, enclosed side of the chamber (Kruskal–Wallis with Dunn’s multiple comparison test, *p < 0.05, **p < 0.001). CNO inhibition of glutamatergic vlPAG/dorsal raphe neurons (hM4, n = 8) had no effect on these end points. In contrast, DREADD activation or inhibition of dopaminergic vlPAG/dorsal raphe neurons (hM3, n = 8) also had no effect on distance traveled, travel velocity, or time spent on the light side of the enclosure nor on time spent in the dark, enclosed side (Kruskal–Wallis).
Norman E. Taylor et al. eNeuro 2019;6:ENEURO
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