Limits...
Evaluation of Antidiabetic Effects of the Traditional Medicinal Plant Gynostemma pentaphyllum and the Possible Mechanisms of Insulin Release.

Lokman EF, Gu HF, Wan Mohamud WN, Östenson CG - Evid Based Complement Alternat Med (2015)

Bottom Line: Opening of ATP-sensitive potassium (K-ATP) channels by diazoxide and inhibition of calcium channels by nifedipine significantly decreased insulin response to GP.Conclusion.The antidiabetic effect of GP is associated with the stimulation of insulin release from the islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden ; Diabetes and Endocrine Unit, Cardiovascular, Diabetes and Nutrition Research Centre (CDNRC), Institute for Medical Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia.

ABSTRACT
Aims. To evaluate the antidiabetic effects of Gynostemma pentaphyllum (GP) in Goto-Kakizaki (GK) rat, an animal model of type 2 diabetes, and to investigate the mechanisms of insulin release. Methods. Oral glucose tolerance test was performed and plasma insulin levels were measured. Results. An oral treatment with GP (0.3 g/kg of body weight daily) for two weeks in GK rats improved glucose tolerance versus placebo group (P < 0.01). Plasma insulin levels were significantly increased in the GP-treated group. The insulin release from GP-treated GK rats was 1.9-fold higher as compared to the control group (P < 0.001). GP stimulated insulin release in isolated GK rat islets at high glucose. Opening of ATP-sensitive potassium (K-ATP) channels by diazoxide and inhibition of calcium channels by nifedipine significantly decreased insulin response to GP. Furthermore, the protein kinase A (PKA) inhibitor H89 decreased the insulin response to GP (P < 0.05). In addition, GP-induced insulin secretion was decreased after preincubation of GK islets with pertussis toxin to inhibit exocytotic Ge proteins (P < 0.05). Conclusion. The antidiabetic effect of GP is associated with the stimulation of insulin release from the islets. GP-induced insulin release is partly mediated via K-ATP and L-type Ca(2+) channels, the PKA system and also dependent on pertussis toxin sensitive Ge-protein.

No MeSH data available.


Related in: MedlinePlus

Effect of different concentrations of Gynostemma pentaphyllum (GP) (1,5, 10,15 mg/mL) on the insulin secretion in GK rat islets (n = 5). ∗∗P < 0.01, ∗∗∗P < 0.001 (when compared with the control group at 16.7 mM glucose only). Results of insulin release (μU/islet/hour) are the means ± SEM of five independent experiments with three replicates for each experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4493304&req=5

fig2: Effect of different concentrations of Gynostemma pentaphyllum (GP) (1,5, 10,15 mg/mL) on the insulin secretion in GK rat islets (n = 5). ∗∗P < 0.01, ∗∗∗P < 0.001 (when compared with the control group at 16.7 mM glucose only). Results of insulin release (μU/islet/hour) are the means ± SEM of five independent experiments with three replicates for each experiment.

Mentions: In separate in vitro experiments, isolated GK rat islets were incubated with different concentrations of GP to identify the insulin-stimulatory effect. At 3.3 mM glucose, GP at any concentration did not stimulate insulin release when compared to the control incubations (Figure 2). At 16.7 mM glucose, the addition of GP at 5, 10 and 15 mg/mL increased insulin release by 1.6, 2.2 (P < 0.01) and 3.6-fold (P < 0.001), respectively, when compared to the control group.


Evaluation of Antidiabetic Effects of the Traditional Medicinal Plant Gynostemma pentaphyllum and the Possible Mechanisms of Insulin Release.

Lokman EF, Gu HF, Wan Mohamud WN, Östenson CG - Evid Based Complement Alternat Med (2015)

Effect of different concentrations of Gynostemma pentaphyllum (GP) (1,5, 10,15 mg/mL) on the insulin secretion in GK rat islets (n = 5). ∗∗P < 0.01, ∗∗∗P < 0.001 (when compared with the control group at 16.7 mM glucose only). Results of insulin release (μU/islet/hour) are the means ± SEM of five independent experiments with three replicates for each experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4493304&req=5

fig2: Effect of different concentrations of Gynostemma pentaphyllum (GP) (1,5, 10,15 mg/mL) on the insulin secretion in GK rat islets (n = 5). ∗∗P < 0.01, ∗∗∗P < 0.001 (when compared with the control group at 16.7 mM glucose only). Results of insulin release (μU/islet/hour) are the means ± SEM of five independent experiments with three replicates for each experiment.
Mentions: In separate in vitro experiments, isolated GK rat islets were incubated with different concentrations of GP to identify the insulin-stimulatory effect. At 3.3 mM glucose, GP at any concentration did not stimulate insulin release when compared to the control incubations (Figure 2). At 16.7 mM glucose, the addition of GP at 5, 10 and 15 mg/mL increased insulin release by 1.6, 2.2 (P < 0.01) and 3.6-fold (P < 0.001), respectively, when compared to the control group.

Bottom Line: Opening of ATP-sensitive potassium (K-ATP) channels by diazoxide and inhibition of calcium channels by nifedipine significantly decreased insulin response to GP.Conclusion.The antidiabetic effect of GP is associated with the stimulation of insulin release from the islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden ; Diabetes and Endocrine Unit, Cardiovascular, Diabetes and Nutrition Research Centre (CDNRC), Institute for Medical Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia.

ABSTRACT
Aims. To evaluate the antidiabetic effects of Gynostemma pentaphyllum (GP) in Goto-Kakizaki (GK) rat, an animal model of type 2 diabetes, and to investigate the mechanisms of insulin release. Methods. Oral glucose tolerance test was performed and plasma insulin levels were measured. Results. An oral treatment with GP (0.3 g/kg of body weight daily) for two weeks in GK rats improved glucose tolerance versus placebo group (P < 0.01). Plasma insulin levels were significantly increased in the GP-treated group. The insulin release from GP-treated GK rats was 1.9-fold higher as compared to the control group (P < 0.001). GP stimulated insulin release in isolated GK rat islets at high glucose. Opening of ATP-sensitive potassium (K-ATP) channels by diazoxide and inhibition of calcium channels by nifedipine significantly decreased insulin response to GP. Furthermore, the protein kinase A (PKA) inhibitor H89 decreased the insulin response to GP (P < 0.05). In addition, GP-induced insulin secretion was decreased after preincubation of GK islets with pertussis toxin to inhibit exocytotic Ge proteins (P < 0.05). Conclusion. The antidiabetic effect of GP is associated with the stimulation of insulin release from the islets. GP-induced insulin release is partly mediated via K-ATP and L-type Ca(2+) channels, the PKA system and also dependent on pertussis toxin sensitive Ge-protein.

No MeSH data available.


Related in: MedlinePlus