1. Glucokinase activation leads to an unsustained hypoglycaemic effect with hepatic triglyceride accumulation in <scp> db/db </scp> mice
- Author
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Kelaier Yang, Hiraku Kameda, Kazuhisa Tsuchida, Ikumi Shigesawa, Shinichiro Kawata, Hideaki Miyoshi, Kyu Yong Cho, Yuki Yamauchi, Tatsuya Atsumi, Hiroshi Nomoto, Yasuo Terauchi, Kazuno Omori, Akinobu Nakamura, and Kiyohiko Takahashi
- Subjects
medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Mice ,chemistry.chemical_compound ,Endocrinology ,Internal medicine ,Glucokinase ,Internal Medicine ,medicine ,Animals ,Humans ,Hypoglycemic Agents ,Carbohydrate-responsive element-binding protein ,Triglycerides ,Triglyceride ,biology ,business.industry ,Pancreatic islets ,Gluconeogenesis ,Fatty acid synthase ,medicine.anatomical_structure ,Liver ,chemistry ,Lipogenesis ,biology.protein ,Phosphoenolpyruvate carboxykinase ,business - Abstract
Aims Glucokinase activators (GKAs) show a hypoglycaemic effect through augmentation of insulin secretion in pancreatic beta-cells and glucose utilization in the liver. The results from some clinical studies of GKAs suggested they show an unsustained hypoglycaemic effect. We investigated how sub-chronic administration of a GKA results in attenuation in the hypoglycaemic effect in a diabetic condition. Materials and methods Six-week-old db/db mice were fed standard chow containing a GKA or the sodium-glucose cotransporter 2 inhibitor, ipragliflozin for 1, 6, 14, or 28 days. We performed histological evaluation and gene expression analysis of the pancreatic islets and liver after each treatment and compared the results to untreated mice. Results The unsustained hypoglycaemic effect of GKAs was reproduced in db/db mice in conjunction with significant hepatic fat accumulation. The initial reactions to treatment with the GKA in the liver were the upregulation of the gene expression of carbohydrate response element-binding protein beta (Chrebp-b) and the downregulation of phosphoenolpyruvate carboxykinase (Pepck) on day 1. Subsequently, the initial changes in Chrebp-b and Pepck disappeared and increases in the expression of genes involved in lipogenesis, including acetyl-CoA carboxylase and fatty acid synthase, were observed. There were no significant changes in the pancreatic beta-cells nor hepatic insulin signalling. Conclusions The GKA showed an unsustained hypoglycaemic effect and promoted hepatic fat accumulation in db/db mice. Dynamic changes in the expression of hepatic genes involved in lipogenesis and gluconeogenesis could affect the unsustained hypoglycaemic effect of the GKA despite no changes in pancreatic beta-cell function and mass. This article is protected by copyright. All rights reserved.
- Published
- 2021
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