Fig. 1.

Metabolic and circadian phenotype of neuromedin U receptor 2 knockout (KO; NMUr2^−/−) mice. NMUr2^−/− mice exhibited normal body weight (A; body weight at 10 wk of age) and daily food intake (B) compared with congenic wild-type (WT) mice (n = 12 mice/genotype), although the KO mice did consume a greater amount of food during the light phase of the day (B; *P < 0.05, 2-way ANOVA with Bonferroni's post hoc test). Daily profiles of metabolic rate were determined for both genotypes, and no pronounced differences were observed in V̇o₂ (C), V̇co₂ (D), or respiratory quotient (RQ; E). Running wheel activity of WT (F) and NMUr2^−/− (G) mice was monitored under both light-dark and constant dark conditions (n = 10 mice/genotype). The period of wheel running activity based on activity onset was significantly shorter in KO mice (F; **P < 0.01, Student's t-test.). No differences were observed in animals' phase-shift response to a 1-h light pulse delivered at circadian time 14 (CT14; F, G). F and G: shading in indicates dark period; red lines illustrate activity onsets from which circadian periods were calculated, with the break showing the day the light pulse was administered.