The effect of L-carnosine on the circadian resetting of clock genes in the heart of rats.

It is reported that the circadian timing system may be included in the mechanism by which L-carnosine (Car) affects multiple physiological alterations including blood glucose, cardiovascular functions etc. However, it is not clear whether Car would affect the circadian rhythm of clock genes in the heart and what is the possible mechanism underlying. To clarify these issues, we compared the effects of Car on the expression of circadian genes in the heart of normal and vagotomized rats under control and jet lag conditions. The normal and vagotomized (va) male Wistar rats were divided into three groups respectively. The control and va-Control groups (fed with regular chow) were sampled before the reversal of LD cycle and feeding schedule (day 0). The normal and va-Normal resetting groups (fed with regular chow) as well as the Car and va-Car resetting groups (fed with Car-containing diet) were sampled on day 3 and day 5 after the experimental jet lag. Car-feeding obviously enhanced the resetting rates of clock genes (Bmal1, Dec1, Cry1) in the heart of normal rats after the experimental jet lag. The unilateral surgical vagotomy didn't alter the diurnal expression patterns and resetting rates of the examined clock genes in normal diet feeding rats. In contrast, it abolished the Car-induced rapid resetting of the clock genes in the heart. Therefore, Car feeding plays a positive role in the circadian resynchronization of the heart clock, which is underlied by the autonomic nervous system.