Figure 1.
Immunofluorescence and quantitation of SIM1 neurons in PVN and SON of iDTR and Sim1Cre mice.
(A) PVN of iDTR mice shows robust expression of SIM1, (B) SIM1 staining was dramatically decreased in PVN of Sim1creiDTR mice. Robust expression of SIM1 was observed in SON of both iDTR (C) and Sim1creiDTR mice (D). (E) Quantitation of SIM1 positive neurons in PVN and SON reveals similar numbers of SIM1 positive neurons in SON of both iDTR and Sim1Cre mice but a significant decrease in SIM1 neurons of PVN of Sim1Cre mice relative to iDTR mice (n=3 for each group, * p<0.05). Scale bar: 40 µm for A, B; and 20 µm for C, D.
Figure 2.
Body weight (A)(D), food intake (B)(E) and feeding efficiency of male and female Sim1creiDTR and iDTR mice.
Body weight and food intake were measured weekly on a chow diet (n= 10 for male groups, n=9 for female groups, *p<0.05) (C) (F) feeding efficiency of male and female mice calculated as the ratio between weekly body weight change (g) and food intake (g) (n=8 for each group, * p<0.05).
Figure 3.
Food intake after 12 hour fast, food intake after AgRP injection and metabolic rate after MC4R agonist injection.
(A) (B) 4 hour and 24 hour intake of normal chow after fasting in Sim1creiDTR and iDTR mice after overnight 12 hour food deprivation (n≥4 for each group). (C)(D) 4 hour and 24 hour intake of normal chow in Sim1creiDTR and iDTR mice after injection of AgRP at 20 pmol into the PVN (n≥4 for each group). (E)(F) Oxygen consumption and metabolic rate of Sim1creiDTR and iDTR mice at 0min, 15 min, 30min, 60 min, and 120 min after injection of MC4R selective agonist into the PVN (n=3 for each group). Energy expenditure was measured in CLAMS cages during light cycle. *p< 0.05, **p<0.01, ***p<0.001.
Figure 4.
Response of Sim1creiDTR and iDTR mice to high fat diet.
(A) Food intake and (B) energy intake of Sim1creiDTR and iDTR mice. Mice were fed with chow for a week, switched to HF for a week, then back to chow(n=6 for each group). (C) Average daily body weight change of Sim1creiDTR and iDTR mice when fed with a chow diet or HF diet (n=6 for each group). (D)(E)Daily food intake (E) and energy intake (F) of Sim1creiDTR and iDTR mice fed with mixed diet of chow and HF (n=7 to 9 for each group). * p<0.05.
Figure 5.
Real-time quantitative PCR comparing Sim1 mRNA, MC4R mRNA, and Galanin mRNA in PVN and Amygdala of Sim1creiDTR and iDTR mice, and comparing OXTmRNA in PVN of Sim1creiDTR and iDTR mice.
Relative mRNA abundance of SIM1 (A), MC4R (B), OXT (C), and GAL (F) expression in the PVN and SIM1 (D), MC4R (E), and GAL (G) amygdala. (n=4 to 9 for each group, * p< 0.05, ** p<0.01, ***p<0.001) .
Figure 6.
Schema depicting Sim1 as global regulator of intake.
In this model loss of Sim1 neurons in the PVN leads to increased Sim1 mRNA transcription in the amygdala and increased sensitivity of the amygdala to the satiety inducing effects of fat.