Glucokinase activation leads to an unsustained hypoglycaemic effect with hepatic triglyceride accumulation in db/db mice.

ABSTRACT

AIM: To investigate how subchronic administration of a glucokinase activator (GKA) results in attenuation of the hypoglycaemic effect in the 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 those in 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 upregulation of the gene expression of carbohydrate response element-binding protein beta (Chrebp-b) and 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 ß cells nor in 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 ß-cell function and mass.