Antihyperglycemic and blood pressure-reducing effects of stevioside in the diabetic Goto-Kakizaki rat.
Stevioside, a glycoside present in the leaves of the plant, Stevia rebaudiana Bertoni (SrB), has acute insulinotropic effects in vitro. Its potential antihyperglycemic and blood pressure-lowering effects were examined in a long-term study in the type 2 diabetic Goto-Kakizaki (GK) rat. Rats were fed 0.025 g x kg(-1) x d(-1) of stevioside (purity > 99.6%) for 6 weeks. An intra-arterial catheter was inserted into the rats after 5 weeks, and conscious rats were subjected to arterial glucose tolerance test (2.0 g x kg(-1)) during week 6. Stevioside had an antihyperglycemic effect (incremental area under the glucose response curve [IAUC]): 985 +/- 20 (stevioside) versus 1,575 +/- 21 (control) mmol/L x 180 minutes, (P <.05), it enhanced the first-phase insulin response (IAUC: 343 +/- 33 [stevioside] v 136 +/- 24 [control] microU/mL insulin x 30 minutes, P <.05) and concomitantly suppressed the glucagon levels (total AUC: 2,026 +/- 234 [stevioside] v 3,535 +/- 282 [control] pg/mL x 180 minutes, P <.05). In addition, stevioside caused a pronounced suppression of both the systolic (135 +/- 2 v 153 +/- 5 mm Hg; P <.001) and the diastolic blood pressure (74 +/- 1 v 83 +/- 1 mm Hg; P <.001). Bolus injections of stevioside (0.025 g x kg(-1)) did not induce hypoglycemia. Stevioside augmented the insulin content in the beta-cell line, INS-1. Stevioside may increase the insulin secretion, in part, by induction of genes involved in glycolysis. It may also improve the nutrient-sensing mechanisms, increase cytosolic long-chain fatty acyl-coenzyme A (CoA), and downregulate phosphodiesterase 1 (PDE1) estimated by the microarray gene chip technology. In conclusion, stevioside enjoys a dual positive effect by acting as an antihyperglycemic and a blood pressure-lowering substance; effects that may have therapeutic potential in the treatment of type 2 diabetes and the metabolic syndrome.
Jeppesen
P B
PB
Department of Endocrinology and Metabolism, Molecular Diagnostic Laboratory, Aarhus Amtssygehus, Aarhus University Hospital, Aarhus, Denmark.
Gregersen
S
S
Rolfsen
S E D
SE
Jepsen
M
M
Colombo
M
M
Agger
A
A
Xiao
J
J
Kruhøffer
M
M
Orntoft
T
T
Hermansen
K
K
D000818:Animals; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000503:physiopathology; D004224:Diterpenes / Q000627:therapeutic use*; D045786:Diterpenes, Kaurane; D005215:Fasting; D020869:Gene Expression Profiling; D005934:Glucagon / Q000097:blood; D005951:Glucose Tolerance Test; D005960:Glucosides / Q000627:therapeutic use*; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D000959:Antihypertensive Agents; D001786:Blood Glucose; D004224:Diterpenes; D045786:Diterpenes, Kaurane; D005960:Glucosides; D007004:Hypoglycemic Agents; D007328:Insulin; C012043:stevioside; D005934:Glucagon