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. Author manuscript; available in PMC: 2008 Nov 28.
Published in final edited form as: Neuroendocrinology. 2008 Jun 19;88(4):246–255. doi: 10.1159/000140676

Figure 1.

Figure 1

Concentration of corticosterone in serum over a 24 hour period in wild-type (WT) and Vip−/− (VIP KO) mice. Serum was sampled every 3 hours (n=3 per time point) under light-dark conditions (LD) and every 4 hours under constant darkness (DD). Circulating corticosterone concentration (ng/ml) was determined by ELISA.

A. Serum corticosterone concentration under 12:12 LD conditions plotted against zeitgeber time (ZT). The WT peak in corticosterone at ZT8 was 30-fold higher than the trough at ZT2 and cycling conditions for WT concentrations were determined to be significant (P<0.001) by ANOVA. In contrast, VIP KO mice displayed no such rhythmicity in basal concentration of corticosterone.

B. Corticosterone measurements plotted against circadian time (CT) in DD. Again, WT concentrations were determined to be significantly different by ANOVA (P<0.05) with a fourfold difference between peak and trough values at CT10 and CT2 respectively.