Increase of Insulin Secretion by Ginsenoside Rh2 to Lower Plasma Glucose in Wistar Rats

Abstract

1. The aim of the present study was to clarify the role of ginsenoside Rh2 as the active compound in Panax ginseng root for lowering plasma glucose in animals. 2. Plasma glucose was assessed using the glucose oxidase method. Changes in the levels of insulin and C-peptide in plasma were measured by ELISA using commercially available kits. 3. After intravenous injection into fasting Wistar rats for 60 min, ginsenoside Rh2 (0.1-1.0 mg/kg) decreased plasma glucose in a dose-dependent manner. In parallel with the decrease in plasma glucose, increases in plasma insulin levels, as well as plasma C-peptide, were observed in rats receiving the same treatment. These effects of Rh2 were reversed by atropine (0.1-1.0 mg/kg), but not affected by the ganglionic nicotinic antagonists pentolinium or hexamethonium (both at 7.5 mg/kg). 4. Disruption of synaptically available acetylcholine (ACh) using an inhibitor of choline uptake (hemicholinium-3; 1-10 microg/kg) or an inhibitor of vesicular ACh transport (vesamicol; 1.5-3.5 mg/kg) abolished the actions of Rh2. In addition, physostigmine (0.1-0.5 mg/kg), at a concentration sufficient to inhibit acetylcholinesterase, enhanced the actions of the ginsenoside Rh2. Thus, mediation of the effects of Rh2 to enhance insulin secretion by ACh released from nerve terminals can be considered. 5. Blockade of the increase in plasma insulin and the plasma glucose-lowering action of Rh2 by 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP; 5-10 microg/kg) indicates the participation of muscarinic M(3) receptors. Increases in plasma C-peptide level induced by Rh2 were also sensitive to 4-DAMP. 6. The results of the present study suggest that ginsenoside Rh2 has the ability to increase insulin secretion as a result of the release of ACh from nerve terminals that then stimulates muscarinic M(3) receptors in pancreatic cells. This finding shows the mechanism for the plasma glucose-lowering action of ginsenoside Rh2, that is one of the major principles contained in P. ginseng root. Thus, ginsenoside Rh2 may be applied as an adjuvant for the management of diabetes.

Botanical characteristics, pharmacological effects and medicinal components of KoreanPanax ginsengC A Meyer

“…Korean ginseng includes insulin secretion stimulating activity and insulin-like activity substances [42][43][44][45] .…”

Simultaneous Enrichment of Deglycosylated Ginsenosides and Monacolin K in Red Ginseng by Fermentation withMonascus pilosus

“…It includes many functional chemical compounds. Among these, ginsenosides are major compounds contributing to various beneficial pharmacological effects, 2,3) including anti-cancer effects, 3,4) blood glucose and insulin regulation activities, [5][6][7][8] inhibition of Helicobacter pylori growth, 9) anti-inflammatory effects, 10) inhibition of catecholamine secretion, 11) and induction of apoptotic cell death. 12) While new ginsenosides are being reported, more than 80 have already been isolated from Panax species.…”

Merit of Ginseng in the Improvement of Insulin Resistance

“…As mentioned above, ginsenoside Rh2 from ginseng is mentioned to raise insulin secretion in Wistar rat [16]. Thus, ginsenoside Rh2 is valued as the bioactive principle in the glucose homeostasis.…”

“…Additionally, ginsenosides Rh2 can also exhibit antiallergic activity originating from cell membrane-stabilizing activity and anti-inflammatory activity by the inhibition of nitric oxide and prostaglandin E 2 production [15]. In recent, ginsenoside Rh2 from ginseng is mentioned to raise insulin secretion in Wistar rat [16]. It seems that ginsenoside Rh2 is valued as the bioactive principle in the glucose homeostasis.…”