Effects of Fasting on Circadian-Clock Gene Expressions in Rat Colons

Abstract

The most common rhythm of organisms on earth is the circadian rhythm. In mammals, the main molecular circadian-clock systems are originally found to play important roles in regulating circadian rhythms. Recent studies showed that circadian patterns of circadian-clock genes exist in the gastrointestinal tract and implied that these genes might play an important role in the homeostasis of gastrointestinal functions. The main objective in this study is to build up the patterns of circadian-clock gene expressions in the colons of rats and to study whether fasting affect these circadian-clock gene expressions. Using the real-time quantitative PCR as the tool to detect gene expressions, we found that the circadian-clock genes, Period1 (Per1), Per2, Per3, brain and muscle Arnt like protein 1 (Bmal1), Crytochrome1 (Cry1) and Cry2 showed the diurnal patterns in male rat colons, but the circadian locomotor output cycle kaput (Clock) had no rhythmicity. Fasting elevated the levels of Per1, Per2, Per3, Bmal1, Cry1 and Cry2 mRNA expressions at all time points, but did not interrupt the rhythmic patterns. Although the Clock mRNA expression did not show the rhythmic pattern, fasting still elevated its expression levels. These data implied that the circadian-clock genes in the gastrointestinal tract might play a homeostasis role.