Rhododendron groenlandicum (Labrador tea), an antidiabetic plant from the traditional pharmacopoeia of the Canadian Eastern James Bay Cree, improves renal integrity in the diet-induced obese mouse model

Abstract

Content Our team has identified Labrador tea [Rhododendron groenlandicum L. (Ericaceae)] as a potential antidiabetic plant from the traditional pharmacopoeia of the Eastern James Bay Cree. In a previous in vivo study, the plant extract was tested in a high-fat diet (HFD)-induced obese model using C57BL/6 mice and it improved glycaemia, insulinaemia and glucose tolerance.

Objective In the present study, we assessed the plant’s potential renoprotective effects.

Materials and methods Rhododendron groenlandicum was administered at 250 mg/kg/d to mice fed HFD for 8 weeks to induce obesity and mild diabetes. Histological (periodic acid–Schiff (PAS), Masson and Oil Red O staining), immunohistochemical (IHC) and biochemical parameters were assessed to evaluate the renoprotective potential of R. groenlandicum treatment for an additional 8 weeks.

Results Microalbuminuria and renal fibrosis were developed in HFD-fed mice. Meanwhile, there was a tendency for R. groenlandicum to improve microalbuminuria, with the values of albumin-creatinine ratio (ACR) reducing from 0.69 to 0.53. Renal fibrosis value was originally 4.85 arbitrary units (AU) in HFD-fed mice, dropped to 3.27 AU after receiving R. groenlandicum treatment. Rhododendron groenlandicum reduced renal steatosis by nearly one-half, whereas the expression of Bcl-2-modifying factor (BMF) diminished from 13.96 AU to 9.43 AU.

Discussion and conclusions Taken altogether, the results suggest that R. groenlandicum treatment can improve renal function impaired by HFD.

Keywords:

• BMF
• fibrosis
• HFD
• microalbuminuria
• vacuoles

Acknowledgements

The authors thank the laboratories of Drs. John Chan (notably, Ms. Isabelle Chenier) and Shao Ling Zhang for precious help with the biochemical measures of microalbuminuria and for histological and immunohistochemistry treatment and interpretation. Very special thanks are due to Cree Elders of Eeyou Istchee who kindly agreed to be interviewed. They made this paper 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.

Disclosure statement

The authors report that they have no conflicts of interest.

Funding information

A Team Grant from the Canadian Institutes of Health Research (CIHR Team in Aboriginal Antidiabetic Medicines; CTP-79855) to Pierre S. Haddad funded these studies.