Figure 7: Reduced alanine content and enhanced fatty acid utilization in the liver of GRmKO mice.

(a) Intrahepatic contents of alanine, glucose, glycogen, triglyceride and branched-chain amino acid (BCAA) in fed or 24 h-fasted 20-week-old male GRf/f (blue) and GRmKO (red) mice. Error bars represent mean±s.e.m. (n=6). *P<0.05 determined by two-tailed Student’s t-test for unpaired data. (b) Kinetics of alanine conversion to pyruvate by liver extracts from ad libitum-fed 20-week-old male GRf/f (blue) and GRmKO (red) mice. Error bars represent mean±s.e.m. (n=5). (c) Intraperitoneal pyruvate tolerance test (IPPTT) in 15-week-old male GRf/f (blue) and GRmKO (red) mice. After 4-h fasting, mice were intraperitoneally injected (i.p.) with 23 mmol kg⁻¹ body weight of sodium chloride (dotted lines, iso) or sodium pyruvate (solid lines, pyr) and blood glucose levels were monitored. Time course of blood glucose clearance (left panel) and area under the curve (AUC, right panel) are shown. Error bars represent mean±s.e.m. (n=12). *P<0.05 determined by two-tailed Student’s t-test for unpaired data. (d) Oral alanine tolerance test (OATT) in 15-week-old male GRf/f (blue) and GRmKO (red) mice. After 4-h fasting, mice were orally administrated (p.o.) with vehicle (dotted lines, veh) or 23 mmol kg⁻¹ body weight of alanine (solid lines, ala) and blood glucose levels were monitored. Time course of blood glucose clearance (left panel) and area under the curve (AUC, right panel) are shown. Error bars represent mean±s.e.m. (n=12). *P<0.05 determined by two-tailed Student’s t-test for unpaired data. (e) Expression levels of the indicated mRNA in the liver from 20-week-old male GRf/f and GRmKO mice after fasting for the indicated time periods. Data are normalized to 36B4 mRNA levels and are shown as fold induction to expression levels in fed (0 h) GRf/f mice. Error bars represent mean±s.e.m. (n=8). *P<0.05 determined by two-tailed Student’s t-test for unpaired data.