Circadian rhythms of the mRNA abundances of clock genes and glucose transporters in the jejunum of weanling-growing pigs.

BACKGROUND

Whether abundance of glucose transporter mRNAs in the small intestine of pigs shows circadian rhythms and its regulation by clock genes was still unknown.

OBJECTIVES

We examined whether the abundance of glucose transporters and clock genes mRNAs in the small intestine of pigs shows circadian rhythms.

METHODS

Twenty barrows (4 weeks old) were reared under 12 h bright and 12 h dark lighting conditions. During the 3-week feeding trial, pigs were allowed free access to feed. The abundances of the mRNA of glucose transporters (SGLT1 and GLUT2) and clock genes (Bmal1, Per1, Per2, and Cry2) in the intestine were measured at four time points (ZT2, ZT8, ZT14, and ZT20).

RESULTS

In the jejunum, the abundance of SGLT1 mRNA was higher at ZT20 and ZT2 and lower at ZT8 and ZT14 (p < 0.05). The abundances of GLUT2 mRNA in the jejunum at ZTs 20 and 2 were tended to be higher than those at ZTs 8 and 14 (p = 0.05). In the jejunum, the abundance of Bmal1 mRNA was higher at ZT8 and ZT14 than at ZT20 and ZT2 (p < 0.05). Further, the abundance of Per1 mRNA at ZT2 was higher than those at the other sampling times (p < 0.05). The abundance of Per1 mRNA at ZT8 was higher than that at ZT14 (p < 0.05), while that of Per2 mRNA was higher at ZT2 than those at ZTs 20 and 14 (p < 0.05).

CONCLUSION

We speculate that these circadian rhythms of abundances of glucose transporter mRNAs are regulated by the clock genes expressed in the jejunum.