Fig 1.
Expression levels of GPR 142 mRNA in the various mouse tissues.
GPR142 expression levels determined by quantitative RT-PCR in (A) the various tissues and isolated pancreatic islets (B) of 8-week old wild type C57BL / 6 male mice. n = 6, A.U.: Arbitrary Units.
Fig 2.
Effects of feeding status and body weight on expression levels of GPR142 mRNA.
A-F. The effects of overnight fasting (A, and D) and 2-hours re-feeding (B, and E) on GPR142 expression levels in the stomach (A, and B) and pancreas (D, and E) of nine-week old C57BL / 6 male mice. n = 6, *: p<0.05. C, and F. The effects of tryptophan gavage on GPR142 expression levels in the stomach (C) and pancreas (F). n = 7, *: p<0.05. G, H. GPR142 expression levels in the stomach (G) and pancreas (H) of mice fed with standard diet (SD) and 60% high fat diet (HFD) for eighteen weeks. n = 6, **: p<0.01, *: p<0.05. I, J. GPR142 expression levels in the stomach (I) and pancreas (J) of ad libitum-fed 11-week-old ob/ob and their control (con) littermates. n = 9, **: p<0.01, *: p<0.05.
Fig 3.
Effects of tryptophan on glucose tolerance in DIO mice.
A-C. Body weights (A), basal blood glucose (B), and serum insulin (C) levels in the mice fed with standard diet (SD) and 60% high fat diet (HFD) for eighteen weeks. D, G. Blood glucose levels after oral glucose load (1.0 g/kg) with tryptophan (150mM, 0.5g/kg, Trp) or vehicle (Veh) in 18-week-old mice fed with standard diet (SD, D) or high fat diet (HFD, G). E, H. Area under the curve (AUC) of glucose levels in D and G. F, I, J-M. Serum insulin (F, I), plasma GIP (J), GLP-1(K), acylated ghrelin (L), and desacyl ghrelin (M) concentrations 15 minutes after glucose load in the mice fed with standard diet (SD) or high fat diet (HFD). n = 6–7 per group, **: p<0.01, *: p<0.05.
Fig 4.
Effects of tryptophan on glucose tolerance in ob/ob mice.
A-C. Body weights (A), basal blood glucose (B), and serum insulin (C) levels in 11-weeks old male ob/ob mice and their control littermates. D, G. Blood glucose levels after oral glucose load (1.0 g/kg) with tryptophan (150mM, 0.5g/kg, Trp) or vehicle (Veh) in ob/ob (E) or control mice (G). E, H. Area under the curve (AUC) of glucose levels in D and G. F, I, J-M. Serum insulin (F, I), plasma GIP (J), GLP-1(K), acylated ghrelin (L), and desacyl ghrelin (M) concentrations 15 minutes after glucose load in ob/ob and control (con) mice. n = 6–7 per group, **: p<0.01, *: p<0.05.
Fig 5.
Effects of tryptophan on glucose tolerance in GPR142KO mice.
A. Body weight changes of GPR142KO and their wild type littermate mice on standard (SD) and 60% high fat diet (HFD). B. Food intake of 12 weeks-old GPR142KO mice and their wild type littermates. C. Blood glucose levels after oral glucose load (1.0 g/kg) with tryptophan (150mM, 0.5g/kg, Trp) or vehicle (Veh) in GPR142KO (24–26 weeks old) fed with standard diet (C) or high fat diet (F). D, G. Area under the curve (AUC) of glucose levels in C and F. E, H. Serum insulin (E, H) concentrations 15 minutes after glucose load. n = 6–7 per group, *: p<0.05.
Fig 6.
Role of CaSR signaling on the effects of tryptophan in GPR142KO mice.
A, B. CaSR mRNA expression levels determined by quantitative RT-PCR in (A) the stomach and pancreas (B) of C57/BL6 mice fed with standard diet (SD) or high fat diet (HFD). n = 6, **: p<0.01.C. CaSR mRNA expression levels in pancreas of GPR142KO mice fed with standard diet (SD) or high fat diet (HFD). n = 6, *: p<0.05. D. Glucose levels after oral glucose load in GPR142KO (22–24 weeks old) mice fed with HFD with L-tryptophan (150 mM, 0.5g/kg, Trp) and NPS 2143(1μM) or NPS2143 alone. E. Area under the curve (AUC) of glucose levels in D. F. Serum insulin concentrations 15 minutes after glucose load. n = 8–9 per group, *: p<0.05.