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Labrador tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model

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.

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Acknowledgments

Very special thanks are due to E. Coon Come, M. Gunner, C. Husky Swallow, J. Husky Swallow, R. Loon and G. Loon from the Cree Nation of Mistissini as well as 27 other elders and healers, who kindly agreed to be interviewed. They made this article possible by allowing us to use, for the purposes of this research, their knowledge relating to medicinal plants, transmitted to them by their elders. Their trust has also enabled a useful exchange between indigenous knowledge and Western science. This work was supported by a Team Grant from the Canadian Institutes of Health Research (CIHR Team in Aboriginal Antidiabetic Medicines) to P.S.H. and J.T.A. It was conducted with the consent and support of the Cree Nation of Mistissini, of the Whapmagoostui First Nation, of the Cree Nation of Nemaska, of the Waskaganish First Nation and of the Cree Board of Health and Social Services of James Bay (Quebec, Canada).

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Authors declare no conflict of interest.

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Correspondence to Pierre S. Haddad.

Additional information

Meriem Ouchfoun and Hoda M. Eid have contributed equally to this work.

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Ouchfoun, M., Eid, H.M., Musallam, L. et al. Labrador tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model. Eur J Nutr 55, 941–954 (2016). https://doi.org/10.1007/s00394-015-0908-z

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Keywords

  • Labrador tea
  • AMPK
  • GLUT4
  • SREBP-1
  • Natural health products
  • Diabetes