Fig. 4.

Adrenal responsivity to ACTH challenge in 6-month-old wild-type and Apoe^−/−mice. Naive mice were housed in metabolic cages. After 1 week of habituation to the novel environment, urine was collected from 5:00 P.M. to 7:00 A.M. (PM bars) and from 7:00 A.M. to 5:00 P.M. (AM bars). After the 5:00 P.M. collection, mice were challenged with saline (0.1 ml/mouse, i.p.) on the second and fourth days and with 0.4 U of ACTHar (0.1 ml/mouse, i.p.) on the seventh day. **p < 0.01 versus A.M.;^●●p < 0.01 versus wild-type;n = 6 or 7 mice per group.