Fig. 7: Mice overexpressing barr1 in beta-cells (RIPII-barr1 mice) exhibit improved glucose homeostasis on an obesogenic diet.
From: β-Arrestin-1 is required for adaptive β-cell mass expansion during obesity
For all experiments, adult male RIPII-barr1 mice and WT littermates maintained on a high-fat diet (HFD) for at least 8 weeks were used. a Body weight gain of RIPII-barr1 mice and WT littermates maintained on a HFD. b, c Blood glucose (b) and plasma insulin (c) levels of freely fed or fasted (14–16 h overnight) mice. Measurements were performed with male littermates that had consumed the HFD for at least 8 weeks. d I.p. glucose tolerance test (IGTT). After an overnight fast, mice were injected with glucose (1 g/kg i.p.). e Oral glucose tolerance test (OGTT). After an overnight fast, mice received glucose via oral gavage (1 g/kg i.p.). f Insulin tolerance test (ITT). Mice were fasted for 4 h and then injected with insulin (1 U/kg i.p.). g Glucose-stimulated increases in plasma insulin levels. Mice that had been fasted overnight were injected with glucose (1 g/kg i.p.), followed by the monitoring of plasma insulin levels. h Bethanechol-stimulated insulin secretion. Freely fed mice were injected with bethanechol (2 mg/kg s.c.). i Exendin-4-stimulated insulin secretion. Mice that had been fasted for 4 h were injected with exendin-4 (12 nmoles/kg i.p.) in combination with glucose (1 g/kg i.p.). j Insulin content of pancreatic islets (n = 6–11 batches of ten islets from at least three different mice per genotype were analyzed). k, l Morphometric analysis of beta-cell mass (k) and islet size (l) in HFD control and RIPII-barr1 mice (three slices from three or four mice/genotype were analyzed). Data were given as means ± s.e.m. (number of mice used: a, 8 per group; b, 10 for fasted and 8 for fed mice, respectively; c, 8 per group; d, 6 control and 8 for RIPII-barr1 mice, respectively; e, 8 control and 10 for RIPII-barr1 mice, respectively; f, 16 control and 20 RIPII-barr1 mice, respectively; g, h, 7 control and 8 RIPII-barr1 mice, respectively; i, 5 control and 9 RIPII-barr1 mice, respectively; j, 6 control and 11 RIPII-barr1 mice, respectively; k, l, 9 control and 12 RIPII-barr1 mice, respectively (mouse age: 15–22 weeks). P values are indicated in the different panels (unpaired two-tailed t-test). Source data are provided as a Source data file.
