Circadian clock genes and implications for intestinal nutrient uptake.

There has recently been increasing interest in the phenomenon of circadian rhythmicity. We have used circadian rhythms as a means to understanding the regulation of glucose absorption in the intestine. We and others have previously demonstrated rhythmicity in intestinal glucose uptake, mediated by rhythmicity in the expression of the sodium glucose cotransporter 1. Rhythmicity of clock gene expression was subsequently confirmed in the intestine, a phenomenon also demonstrated in other viscera. Clock genes have since been shown via a combination of in vitro and in vivo techniques to play a role in the transcriptional regulation of key absorptive proteins.