Figure 5.

Experimental design to study the metabolic effects of IGF1R deficiency in middle-aged mice, IGF1R protein levels and changes in body weight in middle-aged IGF1R-deficient mice either on normal feeding or after a high-fat diet challenge. (A) TMX was administered daily for 5 consecutive days to Igf1r^fl/fl and UBC-CreERT2; Igf1r^fl/fl in two sessions, the first to four-weeks-old and the second to eight-months-old animals, to generate control Igf1r^fl/fl and IGF1R-deficient (CreERT2) mice. Body weight was measured weekly up to their sacrifice on month 12. Nine and a half month-old Igf1r^fl/fl and CreERT2 mice were subdivided into two different diet groups: one kept on normal standard diet (STD), and the other changed to a high-fat diet (HFD) feeding during the last 10 weeks before their sacrifice. (B) Representative Western blots for IGF1R protein levels and graphical representation of densitometric measurements of band intensities normalized to Ponceau staining in perigonadal fat and liver of one year-old middle-aged male and female IGF1R-deficient mice (CreERT2) with respect to controls (Igf1r^fl/fl ), either fed with standard (STD) or challenged with HFD for the last 10 weeks (n= 2-6 mice per group). (C) Final body weight of middle-aged Igf1r^fl/fl and CreERT2 mice on STD and HFD, compared to young Igf1r^fl/fl control (generated as mentioned in Figure 1A ). Body weight data are expressed as mean ± SEM of at least 4 animals per group (n= 4-11 mice per group). ^aap < 0.01 and ^aaap < 0.001 vs. Igf1r^fl/fl young mice; *p < 0.05, **p < 0.01 vs. Igf1r^fl/f middle-aged STD animals; ^#p < 0.05 vs. Igf1r^fl/fl middle-aged HDF mice, and ^$$ p < 0.01 vs. middle-aged STD CreERT2 mice.