Figure 4.

Pancreas β cell function in aged fIrs2:cr² and fIrs2:cr²:Irs1^+/_ mice.(A) Random-fed blood glucose levels were determined at the indicated ages. Averages ± SE were determined from at least 5 male mice per genotype. (B) Random insulin levels were determined in male mice of the indicated genotypes and ages. Averages ± SE were determined from at least 5 mice per genotype. (C) Cre-mediated recombination/deletion of fIrs2 alleles was determined by real-time PCR analysis in single islets isolated from male fIrs2:cr² mice at the indicated ages; or determined in hypothalamus from 10-month-old fIrs2 or fIrs2:cr² mice. (D) Real-time PCR analysis of cr² expression in isolated fIrs2:cr² islets at the indicated ages; mRNA levels were normalized against cyclophilin expression, and the averages ± SE were determined for 2 male mice at each age. (E) Body weight of male littermates of the indicated genotypes that were fed regular chow and weighed weekly from postnatal day 21 until 16 weeks of age; each point represents the average ± SE of at least 6 mice. (F) Three representative pancreatic sections obtained from 6-month-old mice of the indicated genotypes immunostained with antibodies against insulin (green) or glucagon (red).