Stevia Nonsweetener Fraction Displays an Insulinotropic Effect Involving Neurotransmission in Pancreatic Islets

Abstract

Stevia rebaudiana (Bert.) Bertoni besides being a source of noncaloric sweeteners is also an important source of bioactive molecules. Many plant extracts, mostly obtained with ethyl acetate solvent, are rich in polyphenol compounds that present insulinotropic effects. To investigate whether the nonsweetener fraction, which is rich in phenolic compounds isolated from Stevia rebaudiana with the solvent ethyl acetate (EAF), has an insulinotropic effect, including interference at the terminals of the autonomic nervous system of the pancreatic islets of rats. Pancreatic islets were isolated from Wistar rats and incubated with EAF and inhibitory or stimulatory substances of insulin secretion, including cholinergic and adrenergic agonists and antagonists. EAF potentiates glucose-stimulated insulin secretion (GSIS) only in the presence of high glucose and calcium-dependent concentrations. EAF increased muscarinic insulinotropic effects in pancreatic islets, interfering with the muscarinic receptor subfamily M3. Adrenergic inhibitory effects on GSIS were attenuated in the presence of EAF, which interfered with the adrenergic α 2 receptor. Results suggest that EAF isolated from stevia leaves is a potential therapy for treating type 2 diabetes mellitus by stimulating insulin secretion only in high glucose concentrations, enhancing parasympathetic signal transduction and inhibiting sympathetic signal transduction in beta cells.

Whey protein sweetened with Stevia rebaudiana Bertoni (Bert.) increases mitochondrial biogenesis markers in the skeletal muscle of resistance-trained rats

“…The larger gastrocnemius and soleus muscle pads may explain, at least in part, the enhanced load-carrying capacity of these rats. It is possible that the insulinotropic effects of S. rebaudiana [32] enhanced the whey protein-induced protein synthesis in these skeletal muscles, as suggested by the higher levels of insulinemia found in those rats (Table 3). However, further studies are necessary to confirm this hypothesis.…”

Stevia rebaudiana Bertoni Leaves Extract as a Nutraceutical with Hypoglycemic Activity in Diabetic Rats

“…Stevioside, which is the major compound of S. rebaudiana Bertoni, has the effect of stimulating insulin secretion and increasing insulin sensitivity by acting directly on pancreatic beta cells. (28,29) Another study showed that S. rebaudiana Bertoni extract increased the expression of peroxisome proliferatoractivated receptor-γ (PPARγ) and insulin mRNA. (8) PPARγ plays an important role in maintaining glucose metabolism by stimulating glucokinase and GLUT2 in the pancreas and liver.…”

Stevia Improves the Antihyperglycemic Effect of Metformin in Streptozotocin-Induced Diabetic Rats: A Novel Strategy in Type 2 Diabetes Mellitus

“…Stevia aqueous extract significantly increased the fasting serum insulin leveland this finding is in the same side with jeppesen et al, (2002) 29 they stated that Steviosides could increase insulin secretion by direct action on beta cells. Recently, Piovan et al, (2018) found thatethyl acetate fraction of stevia increased insulin secretion in presence of high glucose concentration. This insulinotropic effect may be attributed to an enhancement of cholinergic and attenuation of adrenergic inhibitory effects on glucose stimulated insulin secretion with a result of an increase in insulin levels in the blood 30 .…”

“…Recently, Piovan et al, (2018) found thatethyl acetate fraction of stevia increased insulin secretion in presence of high glucose concentration. This insulinotropic effect may be attributed to an enhancement of cholinergic and attenuation of adrenergic inhibitory effects on glucose stimulated insulin secretion with a result of an increase in insulin levels in the blood 30 .…”