CENEXA   05419
CENTRO DE ENDOCRINOLOGIA EXPERIMENTAL Y APLICADA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Mechanism of the preventive effect of sitagliptin upon changes in liver glucokinase activity induced by short-term fructose administration
Autor/es:
MASSA ML; FRANCINI F; CASTRO MC; GAGLIARDINO JJ
Lugar:
Lisboa
Reunión:
Congreso; 47th European Association for the Study of Diabtes Annual Meeting; 2011
Institución organizadora:
EASD
Resumen:
Background. The effects of exendin-4 (GLP-1 analogue) and DPP-IV inhibitors upon insulin secretion, β-cell replication, islet neogenesis, β-cell apoptosis, glucagon and somatostain secretion, appetite and delay of gastric emptying have been widely reported; however, little is known about their effect upon liver glucokinase (GK) activity and the physiologic modulators of such activity. Aim. To evaluate the effect of exendin-4 and des-F-sitagliptin upon fructose (F)-induced changes in liver GK activity and the regulatory mechanism of GK activity (genic and protein expression, cellular compartmentation and positive interaction with PFK2). Methods. Adult male Wistar rats were fed a standard commercial diet (C) and the same diet plus 10% F (w/v) in the drinking water (F). C and F were treated daily either with sitagliptin (CS and FS) or exendin-4 (CE and FE). After 3 weeks of treatment, we measured serum glucose (enzymatic method), insulin (RIA), triglyceride (enzymatic method) and fructosamine (colorimetric method) levels. In liver, we measured GK activity in both cytosolic (CF) and nuclear (DNF) fraction (enzyme-coupled photometric assay). The nuclear-to-cytosolic GK ratio was calculated dividing the activity measured in DNF by that of CF. Total liver RNA was isolated, performing RT-PCR and gene expression analysis by real-time PCR. GK and PFK2 immune detection were done in CF and DNF (Western blot). Results: C CE CS F FE FS Glucose 4.5 ± 0.12 4.2 ± 0.1 4.5 ± 0.2 4.9 ± 0.2 4.2 ± 0.2 4.7 ± 0.3 Triglyceride 0.47 ± 0.01 0.48 ± 0.06 0.63 ± 0.09 1.14±0.12?? 0.72 ± 0.09* 0.67 ± 0.05** Insulin 0.30 ± 0.02 0.25 ± 0.03 0.27 ± 0.03 1.09 ± 0.28? 0.30 ± 0.05* 0.31 ± 0.05* Fructosamine 175 ± 9 151 ± 6 191 ± 10 219 ± 8? 155 ± 8** 173 ± 7* Values are means ± SEM (n =20). Triglyceride: ?? F vs. C, P < 0.0001; * FE vs. F, P < 0.003; ** FS vs. F, P < 0.001. Insulin: ? F vs. C, P < 0.02; * FE or FS vs. F, P