Meriem Ouchfoun1,2,3, Hoda M Eid1,2,3,4, Lina Musallam1,2,3, Antoine Brault1,2,3, Shilin Li1,2,3, Diane Vallerand1,2,3, John T Arnason5,2,3, Pierre S Haddad6,7,8. 1. Natural Health Products and Metabolic Diseases Laboratory, Department of Pharmacology, Université de Montréal, P.O. Box 6128, Station Centre-Ville, Montréal, QC, H3C 3J7, Canada. 2. Canadian Institutes of Health Research Team in Aboriginal Antidiabetic Medicines, Montréal, QC, Canada. 3. Montreal Diabetes Research Center, Montréal, QC, Canada. 4. Department of Pharmacognosy, University of Beni-seuf, Beni-Seuf, Egypt. 5. Centre for Research in Biotechnology and Biopharmaceuticals, Department of Biology, University of Ottawa, Ottawa, ON, Canada. 6. Natural Health Products and Metabolic Diseases Laboratory, Department of Pharmacology, Université de Montréal, P.O. Box 6128, Station Centre-Ville, Montréal, QC, H3C 3J7, Canada. pierre.haddad@umontreal.ca. 7. Canadian Institutes of Health Research Team in Aboriginal Antidiabetic Medicines, Montréal, QC, Canada. pierre.haddad@umontreal.ca. 8. Montreal Diabetes Research Center, Montréal, QC, Canada. pierre.haddad@umontreal.ca.
Abstract
PURPOSE: Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. METHODS: C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant's molecular mechanisms. RESULTS: Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). CONCLUSIONS: Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
PURPOSE: Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. METHODS: C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant's molecular mechanisms. RESULTS:Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). CONCLUSIONS:Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
Entities:
Keywords:
AMPK; Diabetes; GLUT4; Labrador tea; Natural health products; SREBP-1
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