Figure 1
DZP infused into the VTA reduces anxiety, and enhances social competition and mitochondrial respiration of the NAc. The effects of intra-VTA DZP or vehicle (saline, (SAL)) were studied on anxiety-like behavior on the EPM, social competition and the nucleus accumbens was examined for mitochondrial respiration and neurotransmitter release using microdialysis (a). Intra-VTA administration of DZP (N=23 SAL, 13 DZP) had an anxiolytic effect, increasing time spent on the open arms of the EPM (b), (t=2.88, df=34, P=0.007) and increased social competition for anxiety-matched animals (N=15 pairs) above chance level (c), (t=3.81, df=14, P=0.002). This treatment (N=4/group) also enhanced mitochondrial respiration in the NAc ((d) complex I [F(1,6)=8.88; P=0.025], complex I+II (F(1,6)=11.85; P=0.014), ETS (F(1,6)=12.14; P=0.013), ETS CII (F(1,6)=7.43; P=0.03)). Intra-VTA DZP did not affect mitochondrial respiration of the VTA as compared to vehicle (saline (SAL)) injected controls (e), (complex I (F(1,6)=1.23; P=0.31), complex I+II (F(1,6)=1.79; P=0.23), ETS (F(1,6)=0.925; P=0.37), ETS CII (F(1,6)=1.02; P=0.35), N=4/group)) or mtDNA copy number levels for ND1 (f), (t=0.211, df=20, P=0.85, N=10 SAL, N=12 DZP)) or ND4 (f), (t=0.015, df=20, P=0.99, N=10 SAL, N=12 DZP)). DZP or vehicle (saline, SAL) was i.p. injected after which the mPFC, NAc, BLA and VTA were taken out by microdissection. ATP levels were increased only in the NAc (g), mPFC (t=0.01, df=12, P=0.99); NAc (t=2.366, df=10, P=0.03, N=13 SAL, N=11 DZP); BLA (t=0.61, df=12, P=0.92)). Intra-VTA DZP increased the accumbal levels of accumbal dopamine, (h), treatment effect F(1,7)=8.55, P=0.022 with post test at 40 min t=4.29, P<0.001). The effects of intra-VTA DZP could be blocked by intra-NAc pre-infusion with rotenone (ROT) (i, interaction effect [F(1,43)=4.59, P=0.038] with post test DZP-VEH vs DZP-ROT (t=2.54, df=43, P=0.015)). Data are mean±s.e.m. (*P<0.05, **P<0.01, ***P<0.001, unpaired Student's t-test (bandf), one-sample t-test against chance level (c), or against vehicle-treated controls (g) or two-way ANOVA with repeated measures (h) and without (i)). Respiration data (d and e) are presented as estimated marginal means±s.e.m. of oxygen flux per mg tissue (*P<0.05, linear mixed model). See also Supplementary Figures 1–6. ANOVA, analysis of variance; BLA, basolateral amygdala; DZP, diazepam; EPM, elevated plus maze; mPFC, medial prefrontal cortex; NAc, nucleus accumbens; VAT, ventral tegmental area.
