Induction of insulin secretion by an aqueous extract of Tabernanhte iboga Baill. (Apocynaceae) in rat pancreatic islets of Langerhans

• Published in: Journal of ethnopharmacology 2011-02, Vol.133 (3), p.1015-1020
• Main Authors: Souza, Alain, Mbatchi, Bertrand, Herchuelz, Andre
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Diabetes; Female; General pharmacology; Insulin - metabolism; Insulin Secretion; Islets of Langerhans - drug effects; Islets of Langerhans - metabolism; Langerhans islets; Medical sciences; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Extracts - pharmacology; Rats; Rats, Wistar; Tabernaemontana - chemistry; Tabernanthe iboga
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2010.11.028

The aqueous extract of Tabernanthe iboga (TBEt) stimulated insulin secretion in dose- and glucose (G)-dependent manners by inducing the closure of K+-ATP channels and the intensification of Ca2+ influx through voltage-dependent calcium channels. The effect of an aqueous extract of Tabernanthe iboga (TBEt) was studied in the rat islets insulin secretion based on its use in traditional medicine for the treatment of diabetes. Rats islets were isolated by collagenase digestion. In insulin release experiments, the insulin content was determined by Enzyme-Link Immunosorbent Assay (ELISA). For experiments on 45Ca2+ Uptake, the radioactive content was determined using a liquid scintillation analyzer. The extract (10−3μg/ml–100μg/ml) did not exert a significant increase of insulin secretion (p>0.05) in the presence of 2.8mM of glucose (a none stimulatory concentration). Whereas, in the presence of 11.1mM of glucose (stimulatory concentration), TBEt augmented glucose-stimulated insulin secretion in a dose-dependent manner. Interestingly, the secretory effect of the extract was glucose-dependent (5.6–16.7mM). Furthermore, the insulinotropic effect of TBEt (1μg/ml) was significantly potentiated (p