Glucagon signalling in the dorsal vagal complex is sufficient and necessary for high-protein feeding to regulate glucose homeostasis in vivo.
High-protein feeding acutely lowers postprandial glucose concentration compared to low-protein feeding, despite a dichotomous rise of circulating glucagon levels. The physiological role of this glucagon rise has been largely overlooked. We here first report that glucagon signalling in the dorsal vagal complex (DVC) of the brain is sufficient to lower glucose production by activating a Gcgr-PKA-ERK-KATP channel signalling cascade in the DVC of rats in vivo. We further demonstrate that direct blockade of DVC Gcgr signalling negates the acute ability of high- vs. low-protein feeding to reduce plasma glucose concentration, indicating that the elevated circulating glucagon during high-protein feeding acts in the brain to lower plasma glucose levels. These data revise the physiological role of glucagon and argue that brain glucagon signalling contributes to glucose homeostasis during dietary protein intake.
Toronto General Research Institute & Department of Medicine UHN, Toronto, Canada Department of Physiology, University of Toronto, Toronto Canada.
Mary P
MP
LaPierre
Toronto General Research Institute & Department of Medicine UHN, Toronto, Canada Department of Physiology, University of Toronto, Toronto Canada.
Mona A
MA
Abraham
Toronto General Research Institute & Department of Medicine UHN, Toronto, Canada.
Jessica T Y
JT
Yue
Toronto General Research Institute & Department of Medicine UHN, Toronto, Canada.
Beatrice M
BM
Filippi
Toronto General Research Institute & Department of Medicine UHN, Toronto, Canada Department of Physiology, University of Toronto, Toronto Canada Department of Medicine, University of Toronto, Toronto Canada Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada tony.lam@uhnres.utoronto.ca.
Tony K T
TK
Lam
D000818:Animals; D001786:Blood Glucose; D001921:Brain / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D005934:Glucagon / Q000097:blood / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D008297:Male; D051381:Rats; D015398:Signal Transduction; D014630:Vagus Nerve / Q000502:physiology*
D001786:Blood Glucose; D004044:Dietary Proteins; D005934:Glucagon; D005947:Glucose
brain; glucagon; glucose homeostasis; protein‐feeding