Fig. 5.

Per2 is required and specific for alterations in glucose homeostasis induced by glucocorticoids in vivo. (A) Blood glucose levels were monitored in mice following an injection with 2 mg/kg glucose. Glucocorticoid-induced glucose intolerance depends on Per2. Per2^Brdm1 mice (n = 10) are protected from glucocorticoid-induced glucose intolerance (red) compared with WT mice (n = 6) (blue) (mean ± SEM; P = 0.0574 at 15 min, P = 0.002 at 30 min). Per2^Brdm1 (n = 7) and WT mice (n = 8) injected with PBS (gray and black) had similar glucose tolerance. (B) The decline in blood glucose from basal levels of mice was monitored following injections with 0.75 units/kg insulin. Per2^Brdm1 mice (red) were more sensitive to insulin than WT mice (blue) (mean ± SEM; P = 0.0104 at 15 min, P = 0.0048 at 30 min, P = 0.021 at 60 min). (C) DEXA scans of mice injected with glucocorticoids were compared with those of PBS-injected animals. Per2^Brdm1 mice treated with glucocorticoids had a similar decrease in lean mass (P = 0.0014) as WT animals. Probability values were calculated using unpaired Student's t tests.