Fig. 5
From: Nucleus accumbens medium spiny neurons subtypes signal both reward and aversion
Aversion induced by prolonged MSN stimulation is mediated by opioids. a A Cre-dependent ChR2 was injected in the NAc of D1-cre mice and a guide cannula was placed in the VTA to allow injection of drugs and optical stimulation of D1-MSN terminals. b D1-cre mice were injected with nor-BNI (KOR antagonist, 1 μg/0.5 μl) in the VTA 20 min before the CPP conditioning session with brief or prolonged optical stimulation. In the VTA, KOR is mainly expressed in dopaminergic neurons. c, d Nor-BNI administration had no effect on D1-MSN brief stimulation-induced CPP (nD1-eYFPveh = 5, nD1-eYFPnor-BNI = 5, nD1-ChR2veh = 6, nD1-ChR2veh = 6). e, f Nor-BNI occluded D1-MSN prolonged optical stimulation-induced aversion (nD1-eYFPveh = 5, nD1-eYFPnor-BNI = 5, nD1-ChR2veh = 6, nD1-ChR2nor-BNI = 6). D1-ChR2 nor-BNI mice did not show preference for any chamber. g A Cre-dependent ChR2 was injected in the NAc of D2-cre mice and a guide cannula was placed in the VP to allow injection of drugs and optical stimulation of D2-MSN terminals. h D2-cre mice were injected with Nal (DOR- antagonist 0.1 μg/0.5 μl) in the VP 20 min before the CPP conditioning session with brief or prolonged optical stimulation. In the VP, DOR is expressed in D2-MSN terminals arising from the NAc. i, j Nal administration had no effect on D2-MSN brief stimulation-induced CPP (nD2-eYFPveh = 5, nD2-eYFPNal = 5, nD2-ChR2veh = 6, nD1-ChR2Nal = 6). k, l Nal occluded the effect of D2-MSN prolonged optical stimulation, blocking the aversive effect (nD2-eYFPveh = 5, nD2-eYFPNal = 5, nD2-ChR2veh = 6, nD2-ChR2Nal = 6). ***p < 0.001. Data are represented as mean ± SEM
