Fig. 2.

Nkx2.1iCre/+;Ngn3^flox/flox mice become viscerally obese and are hyperphagic. (A) Examples of control (left) and conditional mutant (right) 8-week-old female littermates. (B,C) Mutant Nkx2.1iCre/+;Ngn3^flox/flox mice become significantly heavier than control and Nkx2.1iCre/+;Ngn3^flox/+ littermates from postnatal week 5 (around 1 week after weaning), and continue to gain mass well into mature adult stages. The rate of weight gain is more rapid in females than males (C). (D) Ad libitum-fed Nkx2.1iCre/+;Ngn3^flox/flox mice gain more weight per week between 4 and 6 weeks of age than do Nkx2.1iCre/+;Ngn3^flox/flox mutants pair-fed to control littermates. (E) Body weight, fat mass, lean mass and free body fluids (FBF) presented as percentage body weight (%) and as total mass (g) in 14-week-old control and mutant male and female mice. Body weight and proportion of body mass made up of fat tissue is significantly increased in mutant animals, whereas the percentage lean mass is reduced. The percentage free body fluid is significantly reduced in female mutant mice compared with controls, but not in males. (F) Both male and female Nkx2.1iCre/+;Ngn3^flox/flox mice show a significant increase in daily and cumulative weekly food intake. Student’s t-test: *P<0.05, **P<0.01, ***P<0.005; NS, not significant.