The cacao procyanidin extract-caused anti-hyperglycemic effect was changed by the administration timings

Abstract

Mammals have the biological clocks with approximately 24 h-rhythm. Energy metabolism including glucose metabolism is regulated by the biological clocks. Glucose metabolism is affected by not only meal volume and its energy but also meal timing. We have reported that cacao liquor procyanidin-rich extract (CLPr) ameliorated the postprandial hyperglycemia through AMP-activated protein kinase pathway. However, the effect of administration timing of CLPr on the postprandial hyperglycemia and its signaling pathway are still unclear. In the present study, we compared the effect of CLPr-administration at the rest-phase (light-period) and active-phase (dark-period) on glucose metabolism. Single oral administration of CLPr to ICR mice at the rest-phase, but not at the active-phase, promoted phosphorylation of AMP-activated protein kinase and its upstream liver kinase B1 and translocation of glucose transporter 4 to the plasma membrane in the skeletal muscle, resulting in reduced postprandial hyperglycemia. These results indicated that the intake of CLPr at the rest-phase more effectively suppressed postprandial hyperglycemia.

Keywords: cacao liquor procyanidin rich extract; circadian rhythm; hyperglycemia; muscle; timing.

Fig. 1

The effect of CLPr administration at ZT 1 or ZT 13 on AMPK phosphorylation in the skeletal muscle of mice. ICR mice were orally administered CLPr at 50 and 150 mg/kg body weight or water (5.0 ml/kg body weight) at ZT1 or 13. The muscle was collected 1 h after the CLPr administration and phosphorylation of AMPK was measured by western blotting. Typical result is shown in the upper panel, while the density of phosphorylation protein after normalized by that of expression protein is shown in the bottom one. Data are represented as the means ± SE (n = 5). Different letters indicate significant differences (p<0.05 by Tukey-Kramer test).

Fig. 2

The effect of CLPr administration at ZT 1 or ZT 13 on the LKB1 and CaMKK2 phosphorylation in the skeletal muscle of mice. Animal treatment was the same as in Fig. 1. Phosphorylation of (A) LKB1 and (B) CaMKK2 was measured in the skeletal muscle by western blotting. Typical results are shown in the upper panel, while the density of phosphorylation protein after normalized by that of corresponding expression protein is shown in the bottom one. Data are represented as the means ± SE (n = 5). Different letters indicate significant differences (p<0.05 by Tukey-Kramer test).

Fig. 3

The effect of CLPr administration at ZT 1 or ZT 13 on the LKB1 nucleocytoplasmic transport in the skeletal muscle of mice. Animal treatment was the same as in Fig. 1. The nuclear and post-nuclear fractions, and tissue lysate were prepared from the skeletal muscle and subjected to western blotting analysis for detection of the protein level of the LKB1. Typical results are shown in the upper panel, while the density of LKB1 protein after normalized by that of Lamin B1 (for the nuclear fraction), GAPDH (for the post-nuclear fraction) and β-actin (for tissue lysate) is shown in the bottom one. The results are presented as the mean ± SE (n = 5). Different letters indicate significant differences (p<0.05 by Tukey-Kramer test).

Fig. 4

The effect of CLPr administration at ZT 1 or ZT 13 on GLUT4 translocation to the plasma membrane in the skeletal muscle of mice. Animal treatment was the same as in Fig. 1. (A) The plasma membrane fraction and (B) tissue lysate were prepared and subjected to western blotting for estimation of GLUT4 translocation. Typical results are shown in the upper panel, while the density of GLUT4 protein after normalized by that of IR (for the plasma membrane fraction), and β-actin (for tissue lysate) is shown in the bottom one. The results are presented as the mean ± SE (n = 5). Different letters indicate significant differences (p<0.05 by Tukey-Kramer test).

Fig. 5

Effects of administration timing of CLPr on the postprandial hyperglycemia. ICR mice were orally administered CLPr at 50 and 150 mg/kg body weight or water (5.0 ml/kg body weight) at ZT1 or 13. Then, OGTT was carried out 1 h after the CLPr administration. The plasma glucose level was measured at 0, 15, 30, 60 and 120 min after the glucose loading. The results are presented as the mean ± SE (n = 5). Asterisks indicate significant differences (p<0.05, vs water group by Dunnett’s multiple comparison test).