Glucose-responsive neurons of the paraventricular thalamus control sucrose-seeking behavior

a, Acquisition curves showing mean nosepokes performed on inactive port under FR1 schedule with sucrose 10 % as a reward in control (grey circles, n = 22) versus NG2KO (white circles, n = 18) mice. Both genotypes exhibited similar performance (genotype effect, F(1,341) = 0.74, P>0.05; interaction, F(9,341) = 0.81, P>0,05; two-way ANOVA followed by Bonferroni’s test). b, Similar as a with saccharin 0.2 % as a reward (genotype effect, F(1,341) = 1.87, P>0.05; interaction, F(9,341) = 0.42, P>0,05; two-way ANOVA followed by Bonferroni’s test). Graphs show means ± s.e.m.. n.s.: non significant.

a, Visualization of Glut2 positive fibers (tdtomato, red fluorescence) in the NAc of a Slc2a2-cre;Rosa26tdtomato mouse. Scale bar represents 100 μm. b, Stereomicroscopic view of coronal NAc-containing brain slice showing CTxB injection sites (green fluorescence). Scale bar represents 500 μm. Nucleus accumbens core (AcbC), shell (AcbSh), lateral ventricule (LV) and anterior commissure (aca).

a, Mean firing frequency monitored under the indicated extracellular glucose concentrations from PVT Glut2-expressing neurons in the presence of a cocktail of synaptic blockers (n = 10 neurons in 7 mice). Hypoglycemia induced a significant increase of the firing rate (P<0.05, one-way ANOVA followed by a Bonferroni’s test). b, Mean firing frequency monitored under the indicated extracellular glucose concentrations from PVT Glut2-expressing neurons in the presence or the absence of fructose (Fru) (n = 10 neurons in 6 mice). The presence of extracellular fructose did not affect Glut2 neurons firing rate (P>0.05; one-way ANOVA followed by a Bonferroni’s test). c, Mean firing frequency monitored under the indicated extracellular glucose concentrations from PVT Glut2-negative neurons (n = 12 neurons in 8 mice). Note that Glut2-negative cells were unresponsive to hypoglycemia (P>0.05, one-way ANOVA followed by a Bonferroni’s test). Boxplots show median, lower and upper quartiles (box), and minimum and maximum (whiskers). * P<0.05; n.s.: non significant.

a, Acquisition curves showing mean nosepokes performed on inactive port during FR1 operant conditioning for sucrose coupled with in vivo light stimulation of PVT Glut2 neurons in control (grey circles, n = 13) or Slc2a2-cre mice (white circles, n = 15) who received prior PVT injection of AAV-DIO-ChR2. Blue rectangles indicate light pulses (473 nm, 10 ms light pulses at 20 Hz, 1 s on/1s off). Light-evoked neuronal activation transiently increased number of inactive nosepokes performed in Slc2a2-cre mice on day 3 (genotype effect, F(1,182) = 18.49, P<0.001; interaction, F (6,182) = 2.57, P<0,05; two-way ANOVA followed by Bonferroni’s test). b, Mean reward (sucrose 10 %) and c, breakpoint value monitored under progressive ratio tested one month later without light stimulation in the same mice used in fig. 3h–k. Note that light pulses no longer increased motivation for sucrose seeking (P>0.05, t-test). Graphs show means ± s.e.m; Boxplots show median, lower and upper quartiles (box), and minimum and maximum (whiskers). The levels of significance are: *** P<0.001; n.s.: non significant. Paraventricular thalamic nucleus (PVT) and nucleus accumbens (NAc).

a, Schematic of the experimental approach. ChR2 was virally delivered in PVT of Slc2a2-cre or control mice and fiber-optic cannulas were bilaterally implanted in the NAc, b,c, FR1 operant conditioning for sucrose 10% coupled with in vivo light stimulation of Glut2 terminals in NAc in control (grey circles, n = 8) or Slc2a2-cre mice (white circles, n = 10) which received prior PVT injection of AAV-DIO-ChR2. Blue rectangles indicate light pulses (473 nm, 10 ms light pulses at 20 Hz, 1 s on/1s off). Light-evoked neuronal activation increased operant responses to obtain sucrose (Reward: genotype effect, F(1,128) = 14.63, P<0.001; interaction, F(7,128) = 1.63, P = 0.1336; Active nosepokes: genotype effect, F(1,128) = 23.60, P<0.001; interaction, F (7,128) = 1.76, P = 0.0999; two-way ANOVA followed by Bonferroni’s test). d, Mean sucrose reward and e, breakpoint value monitored under progressive ratio schedule with in vivo light stimulation of Glut2 terminals in control (grey boxes) or Slc2a2-cre mice (white boxes)(P<0.01; unpaired t-test). f,g, Mean sucrose reward and breakpoint value monitored under progressive ratio 3 days later without light stimulation (same mice as those used in panels d and e). Note that in the absence of light stimulation no longer increased in motivation for sucrose is observed (P>0.05, unpaired t-test). h, Acquisition curves showing mean nosepokes performed on inactive port during FR1 operant conditioning for sucrose coupled with in vivo light stimulation of Glut2 PVT neurons in control (grey circles) or Slc2a2-cre mice (white circles) who received prior PVT injection of AAV-DIO-ChR2. Blue rectangles indicate light pulses (473 nm, 10 ms light pulses at 20 Hz, 1 s on/1s off). Graphs show means ± s.e.m; Boxplots show median, lower and upper quartiles (box), and minimum and maximum (whiskers). The levels of significance are: *** P<0.001; ** P<0.01; n.s.: non significant.

a, PCR analysis of genomic DNA revealed the presence of the Slc2a2^loxP allele (281 bp) and of the recombined Slc2a2^Δ allele (326 bp) in dissected PVT from the injected mice. b, Fluorescence micrograph showing GFP expression in the PVT of mice after stereotactic injection of AAV-Cre-GFP in the PVT. Scale bar represents 100 μm. c, Full-size picture of the original PCR amplification product separation gel. Paraventricular thalamic nucleus (PVT) and third ventricule (3V).