The kallikrein–kinin system has been implicated in body weight and glucose homeostasis. Their major effectors act by binding to the kinin B2 and B1 receptors. It was assessed the role of the kinin B1 receptor in weight and glucose homeostasis in B1 receptor knockout mice (B1RKO) subjected to a cafeteria diet (CAF). Wild-type (WT) and B1RKO male mice (C57BL/6 background; 8 weeks old) were fed a standard diet (SD) or CAF for 14 weeks, ad libitum, and four groups were formed: WT-SD; B1RKO-SD; WT-CAF; B1RKO-CAF. Body weight and food intake were assessed weekly. It was performed glucose tolerance (GTT) and insulin tolerance tests (ITT), and HOMA-IR, HOMA-β and HOMA-β* 1/HOMA-IR were calculated. Islets from WT and B1RKO were isolated in order to measure the insulin secretion. Western blot was used to assess the hepatic AKT phosphorylation and qPCR to assess gene expression. CAF induced a higher body mass gain in B1RKO compared to WT mice. CAF diet increased epididymal fat depot mass, hepatic fat infiltration and hepatic AKT phosphorylation in both genotypes. However, B1RKO mice presented lower glycemic response during GTT when fed with CAF, and a lower glucose decrease in the ITT. This higher resistance was overcomed with higher insulin secretion when stimulated by high glucose, resulting in higher glucose uptake in the GTT when submitted to CAF, despite lower insulin sensitivity. Islets from B1RKO delivered 4 times more insulin in 3-month-old mice than islets from WT. The higher insulin disposition index and high insulin delivery of B1RKO can explain the decreased glucose excursion during GTT. In conclusion, CAF increased the β-cell function in B1RKO mice, compensated by the diet-induced insulin resistance and resulting in a healthier glycemic response despite the higher weight gain.
Background: The kinin B1 receptor (B1R), an inducible effector of Kallikrein-Kinin System during inflammation, has been blamed also to influence glucose metabolism and leptin sensitivity. Aim: To investigate the effects of cafeteria diet (CAF) on hepatic glucose metabolism in B1R knockout mice (B1RKO). Methods: Two months old male C57Bl/6 wild type and B1RKO mice were fed with standard chow (SC) or CAF ad libitumfor 14 weeks (WT-SC n=7; B1RKO-SC n=8; WT-CAF n=7; B1RKO-CAF n =10). We performed glucose tolerance test (GTT) and insulin tolerance test (ITT) at the last week before organs collection. HOMA IR index was calculated. Quantitative PCR was used to determine hepatic expression of glucose-6-phospatase (G6Pase), glucokinase (GK), phosphoenolpyruvate carboxykinase (PEPCK), fructose 1,6-bisphosphatase (FBPase1) and hepatocyte nuclear factor 4 alpha (HNF4A). We also performed western blot to analyze AKT phosphorylation in liver. Two-way ANOVA was used to analyze differences between groups. Values were expressed as mean ± SEM and p ≤0.05 was considered statistically significant. Results: Although the increment of glucose area under the curve during GTT was lower in B1RKO-CAF than WT-CAF (WT-SC 46.246 ± 4.302 vs. B1RKO-SC 35.699 ± 3.383; p=0.03; and B1RKO-CAF 28.521 ± 5.338 vs. WT-CAF 56.564 ± 3.477; AUC p=0.0001), B1RKO mice presented a similar decay in glucose levels during ITT as well as HOMA-IR values . While there was a decrease in liver mRNA expression of G6Pase and PEPCK, GK expression increased in mice fed with CAF diet, without differences between genotypes. FBPase1 and HNF4A mRNA expression were not different between groups. Liver AKT phosphorylation increased with CAF in both C57Bl/6 wild type and B1RKO mice. Conclusion: The increased glucose uptake of B1RKO mice during GTT might not be related to insulin signaling in the liver, since no changes were observed in insulin resistance or in the hepatic expression of gluconeogenesis regulatory enzymes. Disclosure P. Espíndola Correia: None. C.B. Gomes: None. P.N. Merello: None. G.R. Natividade: None. C.C. Barros: None. F. Gerchman: None. Funding Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (16-0397)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.