3.2 Chronic caffeine treatment induced circasemidian
(~12h), circadian, and longer activity rhythms in
CryDKO.
We administered 0.05% caffeine to
CryDKO (n=16; Table 1) under LD.
After 7 days, the mice were moved
to DD. In DD, CryDKO exhibited behavioral rhythms that changed over time
(Table 1). Of the 16 CryDKO, 15 exhibited circasemidian (8.75-17.16 h
period) activity rhythms. 7 animals demonstrated circadian (20.75-26.66
h period) activity rhythms. For example, CryDKO#13 displayed an altered
activity period from 13.75 h (7d) to 23.83 h (3d) and 15.16 h (6d)
(Figure 2a). CryDKO#09 displayed an altered activity period from
17.08 h (7d) to 14.33 h (4d) and
12.00 h (5d) (Figure 2b). CryDKO#14 displayed an altered activity
period from 15.16 h (6d) to 20.75 h (6d) and 13.08 h (3d) (Figure 2c). 7
animals demonstrated much longer activity periods (28.16-39.41 h). For
example, CryDKO#07 displayed an altered activity period from 29.25 h
(5d) to 13.33 h (2d) and 30.00 h (10d) (Figure 3a). CryDKO#10 displayed
an altered activity period from 28.33 h (5d) to 17.16 h (3d) and 30.91 h
(5d) (Figure 3b). One animal did not demonstrate circasemidian or
circadian rhythms for 37 days. The average amount of spontaneous
caffeine intake was 2.8±0.19
mg/day/animal. After caffeine withdrawal, all the CryDKO became
arrhythmic.