Article Figures & Data
Figures
- Figure 1.
Glp-1r mRNA expressed within the GC. A, Localization of the GC (shaded gray) in a coronal section of the mouse brain. B, Representative image of Glp1r mRNA and DAPI in GC layer II/III. C, View of yellow-indicated region in B with (top) and without (bottom) DAPI to aid in visualization of Glp1r expression. D, View of Glp1r mRNA in the GC and in the NAc from the same coronal section. E, Quantification of Glp1r mRNA for each region; n = 5 mice, 2–12 sections per mouse.
- Figure 2.
GLP-1Rs are neuronally expressed within the GC. A, Representative image of the GC from a Glp1r-Cre;Ai9 mouse immunolabeled for the neuronal marker NeuN and a merged image showing tdTomato+ somatic colocalization with NeuN (white arrowheads). B, Quantification of tdTomato+ neurons and NeuN+/tdTomato+ neurons in the GC; ****p < 0.0001 layer II/III versus V/VI. C, Pie charts depicting percentage of NeuN-expressing and NeuN+/tdTomato+-coexpressing cells within layers II/III and V/VI. Data in B are mean + SEM. Data in B and C are from n = 6 mice, 5–10 sections per mouse. D, Representative images of tdTomato+-expressing cells throughout the anterior–posterior axis of the insula cortex. Coordinates are relative to bregma. Scale bar, 100 µm. E, tdTomato+ cell count throughout the anterior–posterior axis of insula cortex layer II/III from the same mouse as in D.
- Figure 3.
GC GLP1-R+ neurons are depolarized by Ex-4 and exhibit distinct electrophysiological properties versus neighboring GLP-1RØ neurons. A, Whole-cell voltage-clamp recordings were made from GC layer II/III GLP-1R+ and GLP-1RØ neurons from Glp1r-Cre;Ai9 mice (n = 9 mice, 6 male, 3 female; 1–4 neurons/mouse). B, Example recording from GLP-1RØ neuron showing no Ex-4-mediated current (top trace) and an example recording from GLP-1R+ neuron showing slow inward current induced by bath application of Ex-4 (100 nm; bottom trace). C, Ex-4-mediated inward currents were larger in GLP-1R+ neurons compared with GLP-1RØ neurons; ***p = 0.0008, two-tailed Mann–Whitney test. D, Number of action potentials elicited with increasing current steps was different in GLP-1R+ and GLP-1RØ neurons (two-way ANOVA, F(1,13) = 5.95, p = 0.0298). E–G, GLP-1R+ and GLP-1RØ neurons had different intrinsic properties, including capacitance (E), membrane resistance (F), and resting membrane potential (G). Data are mean ± SEM, n = 7–10/group; *p < 0.05 by unpaired t test.
- Figure 4.
Chemogenetic activation of GC GLP-1R+ neurons reduces dark-cycle chow intake. A, Example image of DREADD expression (YFP+) in the GC from one mouse. Scale bar, 50 µm. B, Shaded regions illustrating representative spread of AAV-DIO-hM3D(Gq)-mCitrine expression within the GC. Anterior–posterior (AP) coordinates are relative to bregma. Arrow indicates example mouse shown in A. C, Schematic of experimental timeline. D, Effect of DREADD ligand J60 (0.1 mg/kg, i.p.) on dark-cycle chow intake in Glp1r-Cre mice bilaterally expressing GC AAV-DIO-hM3D(Gq)-mCitrine, and in Glp1r-Cre mice that do not express DREADD receptors. Mean + SEM of chow consumed (corrected to kcal consumed divided by body weight); n = 7/group, 3 females, 4 males (blue circles, males; pink circles, female; *p < 0.05 vs vehicle).
- Figure 5.
Pharmacological activation of GC GLP-1Rs reduced dark-cycle chow intake. A, Schematic of experimental timeline. B, Effect of intra-GC Ex-4 on chow intake at 1 and 2 h into the dark cycle. B, Mean + SEM of chow consumed (corrected to kcal consumed divided by body weight); n = 10/group, 5/sex; blue circles, males; pink circles, female; *p < 0.05 versus vehicle. C, Representative cannula placements. Anterior–posterior (AP) coordinates are relative to bregma.
- Figure 6.
Impact of intra-GC Ex-4 in context of a chronic high-fat diet. A, Weekly elevations in body weight of mice on the LF or HF diet during the development of weight gain over 6 weeks. B, Weekly elevations in body weight from A, divided by sex. C, Comparing the average change in body weight on the sixth week of HF maintenance in males and females; ***p < 0.001 males versus females. D, Intake (kcal/body weight) of HF by the HF-maintained group, 2 h into the dark cycle following intra-GC Ex-4 (left) or the same when LF group was monitored for LF intake (right). E, Schematic of experimental timeline, cohort of animals on HF acutely switched to LF (top), or cohort of animals on LF acutely switched to HF (bottom). F, Left, LF food intake (kcal/body weight) of the HF-maintained group, 2 h into the dark cycle following intra-CG Ex-4 infusion; *p < 0.05, ***p < 0.001 versus 0 µg Ex-4. Right, HF food intake (kcal/body weight) of the LF-maintained group, 2 h into the dark cycle following intra-GC Ex-4; *p < 0.05 0.3 versus 0 µg Ex-4. G, Visceral fat (g) calculated over body weight (g) at the end of the experiment (see above, Materials and Methods); ***p < 0.005 HF males versus HF females. H, Representative cannula infusion tip placements of mice included in D, F, and G; n = 13–22 mice/diet condition.
