Basic–alimentary tractInsight Into the Circadian Clock Within Rat Colonic Epithelial Cells
Section snippets
Experimental Animals
Two-month-old male Wistar rats (Bio Test, Konarovice, Czech Republic) were maintained for at least 4 weeks in a temperature of 23°C ± 2°C under light–dark cycle with 12 hours of light and 12 hours of darkness per day. Light was provided by overhead 40-W fluorescent tubes, and illumination was between 50 and 300 lux, depending on cage position in the animal room. Animals had free access to food and water. On the day of the experiment, animals were divided into 2 groups. The control group was fed
Profiles in clock gene expression
In the rat colon (Figure 1, colon), the one-way ANOVA revealed a significant effect of time on expression of Per1, Per2, Cry1 (P < .05), Rev-erbα, and Bmal1 (P < .01) but not on expression of Clock. Per1 mRNA level at CT12 was significantly higher than those at CT8, CT20, and CT24 (P < .05); the levels thus rose between CT8 and CT12 and declined between CT12 and CT20. Per2 mRNA level at CT12 and CT16 was higher than that at CT8 (P < .05); the levels rose between CT8 and CT12 and then declined
Discussion
In this study, we show daily rhythms of expression of canonical clock genes Per1, Per2, Rev-erbα, Cry1, Bmal1, but not of Clock within the rat colonic epithelial cells. Moreover, PER1 and BMAL1 proteins are expressed within these cells. These findings provide evidence of the presence of a functional circadian clock in the intestinal compartment. This colonic clock is in phase with the clock in the liver and phase-delayed relative to the master clock in the SCN. In the colon, the clock is
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Supported by the Academy of Sciences of the Czech Republic grant No. A500110605.
All authors declare that they have no conflict of interest to disclose.