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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

(a) The effects of treatment with Gynostemma pentaphyllum (GP) (0.3 g/kg of body weight) in GK rat (n = 5) on (a) blood glucose level in the oral glucose tolerance test, GP-treated (—) or placebo (—), (b) area under the glucose curves in the oral glucose tolerance test ∗∗P < 0.01, GP versus Placebo. (c) Plasma insulin levels in GP-treated group compared to placebo group at 0, 30, and 120 min in the oral glucose tolerance test. ∗∗P < 0.01 (GP-treated group versus placebo group at 0 min), ∗∗∗P < 0.001 (GP-treated group versus placebo group at 30 and 120 min resp.). (d) Insulin secretion ∗∗∗P < 0.001 (when compared with the placebo group at 16.7 mM glucose). All data are presented as means ± SEM and analyzed using unpaired t-test.
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fig1: (a) The effects of treatment with Gynostemma pentaphyllum (GP) (0.3 g/kg of body weight) in GK rat (n = 5) on (a) blood glucose level in the oral glucose tolerance test, GP-treated (—) or placebo (—), (b) area under the glucose curves in the oral glucose tolerance test ∗∗P < 0.01, GP versus Placebo. (c) Plasma insulin levels in GP-treated group compared to placebo group at 0, 30, and 120 min in the oral glucose tolerance test. ∗∗P < 0.01 (GP-treated group versus placebo group at 0 min), ∗∗∗P < 0.001 (GP-treated group versus placebo group at 30 and 120 min resp.). (d) Insulin secretion ∗∗∗P < 0.001 (when compared with the placebo group at 16.7 mM glucose). All data are presented as means ± SEM and analyzed using unpaired t-test.

Mentions: At baseline (day 0), glucose tolerance test was similar in both placebo and treatment groups with the area under the curves (AUCs) for glucose during 120 min (0–120 min) being 883.5 ± 63.4 versus 955.5 ± 74.1 mM, respectively. However, after two-week treatment with GP, glucose tolerance was significantly improved. The mean blood glucose levels at 120 min were found to decrease in the treated group as compared to the placebo group (11.0 ± 1.1 versus 13.9 ± 1.1 mM, resp.) (Figure 1(a)) with AUCs (0–120 min) being 639.6 ± 38.5 versus 842.4 ± 43.8 mM (P < 0.01) (Figure 1(b)). Plasma insulin levels after GP treatment were significantly increased both at 0 min (P < 0.01) and after glucose stimulation at 30 and 120 min (P < 0.001) when compared with the control group (Figure 1(c)). The body weights of GP- and placebo-treated GK rats showed comparable increase from day 0 to day 14 (data not shown).


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)

(a) The effects of treatment with Gynostemma pentaphyllum (GP) (0.3 g/kg of body weight) in GK rat (n = 5) on (a) blood glucose level in the oral glucose tolerance test, GP-treated (—) or placebo (—), (b) area under the glucose curves in the oral glucose tolerance test ∗∗P < 0.01, GP versus Placebo. (c) Plasma insulin levels in GP-treated group compared to placebo group at 0, 30, and 120 min in the oral glucose tolerance test. ∗∗P < 0.01 (GP-treated group versus placebo group at 0 min), ∗∗∗P < 0.001 (GP-treated group versus placebo group at 30 and 120 min resp.). (d) Insulin secretion ∗∗∗P < 0.001 (when compared with the placebo group at 16.7 mM glucose). All data are presented as means ± SEM and analyzed using unpaired t-test.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: (a) The effects of treatment with Gynostemma pentaphyllum (GP) (0.3 g/kg of body weight) in GK rat (n = 5) on (a) blood glucose level in the oral glucose tolerance test, GP-treated (—) or placebo (—), (b) area under the glucose curves in the oral glucose tolerance test ∗∗P < 0.01, GP versus Placebo. (c) Plasma insulin levels in GP-treated group compared to placebo group at 0, 30, and 120 min in the oral glucose tolerance test. ∗∗P < 0.01 (GP-treated group versus placebo group at 0 min), ∗∗∗P < 0.001 (GP-treated group versus placebo group at 30 and 120 min resp.). (d) Insulin secretion ∗∗∗P < 0.001 (when compared with the placebo group at 16.7 mM glucose). All data are presented as means ± SEM and analyzed using unpaired t-test.
Mentions: At baseline (day 0), glucose tolerance test was similar in both placebo and treatment groups with the area under the curves (AUCs) for glucose during 120 min (0–120 min) being 883.5 ± 63.4 versus 955.5 ± 74.1 mM, respectively. However, after two-week treatment with GP, glucose tolerance was significantly improved. The mean blood glucose levels at 120 min were found to decrease in the treated group as compared to the placebo group (11.0 ± 1.1 versus 13.9 ± 1.1 mM, resp.) (Figure 1(a)) with AUCs (0–120 min) being 639.6 ± 38.5 versus 842.4 ± 43.8 mM (P < 0.01) (Figure 1(b)). Plasma insulin levels after GP treatment were significantly increased both at 0 min (P < 0.01) and after glucose stimulation at 30 and 120 min (P < 0.001) when compared with the control group (Figure 1(c)). The body weights of GP- and placebo-treated GK rats showed comparable increase from day 0 to day 14 (data not shown).

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