[Mechanisms of action of acetonic and hexanic extracts of leaves of Vernonia colorata (Willd.) Drake (Composeae) on blod glucose regulation].
BACKGROUND
This study aimed to investigate the mechanism of action of acetonic and hexanic extracts of the leaves of Vernonia colorata on blood glucose regulation.


METHODS
Experiments were performed in normoglycaemic, type 1 and 2 diabetic rats. The effects of acetonic and hexanic extracts on blood glucose were evaluated. The antagonism effect of hexanic extract on the decrease of blood glucose induced with glibenclamide and metformin was also tested.


RESULTS
The hexanic extract of the leaves of V. colorata (HELVC) dose dependently increased the blood glucose in normoglycaemic rats. At the dose of 30 and 100 mg/kg, the glycaemia varied from 0.84 +/- 0.02 to 1.11 +/- 0.10 g/l and 0.68 +/- 0.02 to 1.31 +/- 0.30 g/l (p<0.05, n = 5). Such glibenclamide, the acetonic extract of the leaves of V. colorata (AELVC) induced hypoglycaemia in normoglycaemic rats. The HELVC prevents significantly the AELVC and glibenclamide induced hypoglycaemia. The chronic administration of the AELVC and HELVC as well as glibenclamide in type 1 diabetic rats did not change significantly the level of blood glucose. In type 2 diabetic rats, the single dose administration of metformin (300 mg/kg, per os) decreased the glycaemia which is completely prevented by a HELVC pretreatment.


CONCLUSIONS
These results suggest that: i) The respective hypo- and hyperglycaemic effects of AELVC and HELVC require the presence of the pancreatic beta cells. ii) The AELVC would act by a sulfonylurea-like mechanism as glibenclamide to induce an hypoglycaemic effect.
Sy
G Y
GY
Laoratoire de Pharmacologie, Faculté de Médecine, Pharmacie et d'Odonto-Stomatologie, Université Cheikh Anta Diop, BP 5005, Dakar, Sénégal. guatayoro_sy@yahoo.fr
Nongonierma
R B
RB
Cisse
A
A
Dieye
A M
AM
Wele
A
A
Gadiaga
N F
NF
Faye
B
B
D000818:Animals; D001786:Blood Glucose / Q000187:drug effects*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy*; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves; D051381:Rats; D017208:Rats, Wistar; D035741:Vernonia
D001786:Blood Glucose; D010936:Plant Extracts