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

Abstract

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.

Physiological functions of glucose transporter-2: From cell physiology to links with diabetes mellitus

“…A detailed interaction of the expression of glucose transport vector with circadian and clock genes in the pig small intestine by Kinoshita Yuki et al the study showed the levels of GLUT-2 mRNA exhibit significant diurnal variation that is always stronger in rats with a healthy metabolism. It also demonstrated significant diurnal changes in glucokinase mRNA, with higher levels of glucokinase mRNA in the pancreas of 6-week-old Landrace × Large White cross-breeds rats than in Wistar rats [ 28 ]. This effect causes glucose phosphorylation capacity to synchronize with food intake, enhancing glucose-stimulated insulin secretion and preventing postprandial hyperglycemia.…”