Activation of Brown Adipose Tissue Metabolism Using Mirabegron

Overview

Could sympathomimetics and sympatholytics drugs safe for the management of Type 2 Diabetes (T2D)? Based on recent evidence, we propose that pharmacological stimulation of Beta-3 adrenergic receptor (ADBR3) at higher doses of Mirabegron may be required to elicit changes in glycemia, but should be combined with Beta-1 adrenergic receptor (ADRB1) antagonists to suppress the unwanted effects on the cardiovascular system. Together, several results establish a previously unappreciated cross-talk between Gs-coupled ADRB1 and ADRB3 in adipose tissue for the control of glucose homeostasis. Moreover, these data suggest that antagonizing ADRB1 may be a good way to significantly lower the dose of ADRB3 agonist required for glucose control. Therefore, we believe that there are therapeutic opportunities in targeting adrenergic receptors for the treatment of T2D at least in young/middle aged people.

In brief, participants will take part in 2 metabolic studies (A and B) performed in random order and at an interval of 7 to 14 days. Each metabolic study will last 8.5 hours with a baseline period of 2.5 hours. Participants will ingest either 200 mg of the ADRB3 agonist mirabegron (Myrbetriq, Astellas Pharma Canada) alone (study A) or in combination with 10 mg of bisoprolol, an ADRB1-antagonist (study B), at time 0. The radioactive PET tracers (PET: positron emission tomography) used in this study are the \[11C\]-acetate and \[18F\]-FDG to estimate BAT oxidative metabolism and glucose metabolism, respectively. The perfusion of \[6,6 D2\]-glucose, \[1,1,2,3,3-2H\]-glycerol and \[U-13C\]-palmitate stable isotopes will also be performed in this study from time -150 min. to +300 min to examine the systemic appearance rate of glucose, glycerol and fatty acids, respectively. These studies will be almost identical (same perfusion of stable and radioactive tracers, same number of PET acquisitions) except for the drug which will be administered orally at time 0.