FIGURE 8.

Effect of IGF-1 on sprout formation. A, effects of insulin, IGF-1 and IGF-2, and of IGFbp4 on the percent of explants displaying capillary sprouts after 14 days in culture. Statistical significance of the difference from no treatment was calculated by one-way analysis of variance corrected for multiple comparisons (Holm-Sidak). **, p < 0.005; ****, p < 0.0001. B, Western blotting for IGF-1 receptor (top panel) and insulin receptor (bottom panel) β subunits in tissue from 8-week ND- and HFD-fed mice. a indicates lane with extract from isolated adipocytes. C, whole mount staining of adipose tissue after 24 h of incubation in the absence (top panels) or presence (bottom panels) of 150 nm insulin. Arrows highlight regions of coincidence between phosphorylated receptors and IB4 staining. Arrowhead points to cell outside the vascular wall. D, model for interaction between high fat diet, insulin, and IGFbp4 to enhance adipose tissue growth.