Nutr Res Pract.  2016 Oct;10(5):507-515. 10.4162/nrp.2016.10.5.507.

Gynura procumbens extract improves insulin sensitivity and suppresses hepatic gluconeogenesis in C57BL/KsJ-db/db mice

• Choi SI
• Lee HA
• Han JS

• KMID: 2434085
• DOI: http://doi.org/10.4162/nrp.2016.10.5.507

Abstract

BACKGROUND/OBJECTIVES
This study was designed to investigate whether Gynura procumbens extract (GPE) can improve insulin sensitivity and suppress hepatic glucose production in an animal model of type 2 diabetes.
MATERIALS/METHODS
C57BL/Ksj-db/db mice were divided into 3 groups, a regular diet (control), GPE, and rosiglitazone groups (0.005 g/100 g diet) and fed for 6 weeks.
RESULTS
Mice supplemented with GPE showed significantly lower blood levels of glucose and glycosylated hemoglobin than diabetic control mice. Glucose and insulin tolerance test also showed the positive effect of GPE on increasing insulin sensitivity. The homeostatic index of insulin resistance was significantly lower in mice supplemented with GPE than in the diabetic control mice. In the skeletal muscle, the expression of phosphorylated AMP-activated protein kinase, pAkt substrate of 160 kDa, and PM-glucose transporter type 4 increased in mice supplemented with GPE when compared to that of the diabetic control mice. GPE also decreased the expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase in the liver.
CONCLUSIONS
These findings demonstrate that GPE might improve insulin sensitivity and inhibit gluconeogenesis in the liver.

Keyword

Gluconeogenesis; db/db mice; Gynura procumbens; hyperglycemia; insulin resistance

MeSH Terms

AMP-Activated Protein Kinases
Animals
Diet
Gluconeogenesis*
Glucose
Glucose-6-Phosphatase
Hemoglobin A, Glycosylated
Hyperglycemia
Insulin Resistance*
Insulin*
Liver
Mice*
Models, Animal
Muscle, Skeletal
Phosphoenolpyruvate
AMP-Activated Protein Kinases
Glucose
Glucose-6-Phosphatase
Insulin
Phosphoenolpyruvate

Figure

• 

  Fig. 1 Weekly changes in blood glucose levels in C57BL/KsJ-db/db mice supplemented G. procumbens extract (GPE). db/db (diabetes mellitus control): C57BL/KsJ-db/db mice fed AIN-93G diet; db/db-RG: C57BL/KsJ-db/db mice fed AIN-93G diet supplemented with rosiglitazone (0.005 g/100 g diet); db/db-GPE: C57BL/KsJ-db/db mice fed AIN-93G diet supplemented with GPE (0.5 g/100 g diet). Values are presented as means ± SD, n = 7 per group, a-c Mean values designed by different letters are significantly different between groups (P < 0.05).

• 

  Fig. 2 Effect of G. procumbens extract (GPE) supplementation on intraperitoneal glucose tolerance tests (A) and insulin tolerance tests (B) in C57BL/KsJ-db/db mice. Blood glucose concentrations were measured at the indicated times and presented as percentages of glucose measured at the time of injection (t = 0) of glucose (0.5 g/kg of BW) or insulin (2 units/kg of BW). db/db (diabetes mellitus control): C57BL/KsJ-db/db mice fed AIN-93G diet; db/db-RG: C57BL/KsJ-db/db mice fed AIN-93G diet supplemented with rosiglitazone (0.005 g/100 g diet); db/db-GPE: C57BL/KsJ-db/db mice fed AIN-93G diet supplemented with GPE (0.5 g/100 g diet). Values are presented as means ± SD, n = 7 per group. a-c Mean values designated by different letters are significantly different between groups (P < 0.05).

• 

  Fig. 3 Effect of G. procumbens extract (GPE) supplementation on PM-GLUT4, pAMPK, and pAS160 expression in the skeletal muscle. Western blotting and signal intensities were determined by densitometric analysis using Multi Gauge V3.1 software. Representative blots of PM-GLUT4, pAMPK, and pAS160 protein expression are shown with protein expression levels quantified relative to the expression level observed in samples from db/db-control mice. Each value is expressed as mean ± SD of experiments performed in triplicate. a-c Values denoted by different letters are significantly different (P < 0.05), as analyzed by Duncan's multiple range test. PM-GLUT4: plasma membrane-glucose transporter type 4, pAMPK: phosphorylated AMP-activated protein kinase, pAS160: phosphorylated Akt substrate of 160 kDa.

• 

  Fig. 4 Effect of G. procumbens extract (GPE) supplementation on G6Pase and PEPCK expression and hepatic glycogen in the liver of C57BL/KsJ-db/db mice. Representative blots of G6Pase and PEPCK protein expression are shown with protein expression levels quantified relative to the expression level observed in samples from db/db-control mice. Each value is expressed as mean ± SD of experiments performed in triplicate. a-c Values denoted by different letters are significantly different (P < 0.05), as analyzed by Duncan's multiple range test. PEPCK: Phosphoenolpyruvate carboxykinase, G6Pase: Glucose-6-phosphatase.

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